Isothermally phase-separable elastin-like polypeptides, compositions, and methods of use thereof

Abstract

The present disclosure provides isothermally phase-separable elastin-like polypeptides (ELPs), the ELPs comprising: i) a first ELP domain having a first lower critical solution temperature (LCST); and ii) a second ELP domain having a second LCST that is different from the first LCST, wherein the first and second ELP domains are separated by an enzymatic cleavage site. Also included in the present disclosure are conjugates of the subject ELPs, nucleic acids encoding the subject ELPs, cells comprising nucleic acids encoding the subject ELPs, methods of use for the subject ELPs, and related kits.

Description

[0001]Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 ISOTHERMALLYPHASE-SEPARABLEELASTIN-LIKEPOLYPEPTIDES,COMPOSITIONS, AND METHODS OF USE THEREOF CROSS-REFERENCE TORELATEDAPPLICATIONSPursuant to 35 U.S.C. § 119 (e), this application claims priority to the filing date of United States Provisional Patent Application Serial No.63 / 542,394 filed October 4, 2023, the disclosure of which application is incorporated herein by reference in its entirety. REFERENCE TO ANELECTRONICSEQUENCELISTINGThe contents of the electronic sequence listing (STAN-2151WO_SEQLIST; Size: 112,328 bytes; and Date of Creation: October 3, 2024) is herein incorporated by reference in its entirety. INTRODUCTIONElastin-like polypeptides (ELPs) underlie advances in drug delivery, tissue engineering, and biomolecular actuators. ELPs have garnered attention for their thermoresponsive properties, such that they undergo phase separation into insoluble coacervates when raised above a transition temperature. Regulation of ELPs has also been demonstrated using pH and light, which influence ELP phase behavior by modulating hydrophilicity. pH-responsive ELPs contain acidic or basic guest residues with pH-dependent protonation states. When residues are charged, ELP solubility is enhanced. When residues are neutral, phase separation is favored. ELP hydrophilicity can also be tuned by integrating guest residues with nonstandard amino acids that undergo photochemical transformations. For example, photoisomerizable residues undergo reversible changes in polarity upon irradiation with different wavelengths of light. These changes in polarity impact ELP hydrophilicity and emergent ELP phase behavior. Temperature, however, is relatively constant in many biological contexts. Likewise, biological systems do not typically use pH or light to modulate their physical environments, limiting the effectiveness and applicability of existing ELPs. Thus, a need exists for new, isothermally phase-separable ELPs that can be modulated by more biologically relevant cues. Such an isothermally phase-separable ELP would prove useful across a wide-variety of applications where selective activation by a biologically relevant cue is desired. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 SUMMARYThe present disclosure provides isothermally phase-separable elastin-like polypeptides (ELPs), the ELPs comprising: i) a first ELP domain having a first lower critical solution temperature (LCST); and ii) a second ELP domain having a second LCST that is different from the first LCST, wherein the first and second ELP domains are separated by an enzymatic cleavage site. Also included in the present disclosure are conjugates of the subject ELPs, nucleic acids encoding the subject ELPs, cells comprising nucleic acids encoding the subject ELPs, methods of use for the subject ELPs, and related kits. In certain embodiments, an ELP may comprise a first LCST that is greater than the second LCST. In some embodiments, the first and second ELP domain of a subject may comprise one or more pentapeptide repeats. In some cases, each pentapeptide repeat of the first and second ELP domain may comprise an amino acid sequence VPGXG (SEQ ID NO:1), wherein X is any amino acid other than proline. In some cases, each pentapeptide repeat of the first and second ELP domain may comprise an amino acid sequence VPGXG (SEQ ID NO:2), wherein X is selected from valine, alanine, glycine, lysine, histidine, serine, and glutamate. In certain embodiments, the first ELP domain of a subject ELP comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO: 5), VPGAG (SEQ ID NO:6), VPGGG (SEQ ID NO: 7), VPGKG (SEQ ID NO: 8), VPGSG (SEQ ID NO: 9), and VPGEG (SEQ ID NO: 10), and the second ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat of the second ELP domain comprising an amino acid sequence selected from: VPGVG (SEQ ID NO: 5) and VPGHG (SEQ ID NO: 11). In some embodiments of a subject ELP, the first and second ELP domain each comprises from 1 to 250 pentapeptide repeats. In some cases, the first ELP domain comprises from 50 to 150 pentapeptide repeats, and the second ELP domain comprises 30 to 90 pentapeptide repeats. In some cases, the first ELP domain comprises from 75 to 125 pentapeptide repeats, and the second ELP domain comprises 45 to 75 pentapeptide repeats. In certain embodiments, a subject ELP comprises a first and second ELP domain, wherein the first ELP domain comprises an amino acid sequence having at least 80% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:12, and the second ELP domain comprises an amino acid sequence having at least 80% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:13. In a particular embodiment, a subject ELP comprises a first and second ELP domain, wherein the first ELP domain comprises the amino acid sequence set forth in SEQ ID NO:12, and the second Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 ELP domain comprises the amino acid sequence set forth in SEQ ID NO:13. In certain embodiments of a subject ELP, the first and second ELP domains are separated by two or more enzymatic cleavage sites. In some embodiments, the enzymatic cleavage site of a subject ELP is a protease cleavage site. In some cases, the protease cleavage site is a cleavage site for a eukaryotic protease, a prokaryotic protease, or a viral protease. In certain embodiments, the protease cleavage site may be, for example, a TEV protease cleavage site, an enterokinase cleavage site, a cleavage site for a protease of the clotting cascade (e.g., a thrombin cleavage site, a factor IXa cleavage site), a matrix metalloproteinase (MMP) cleavage site (e.g., a MMP-9, MMP-11, or MMP-26 cleavage site), a furin cleavage site, a caspase cleavage site (e.g., a Caspase 1 cleavage site) and the like. In certain embodiments, a subject ELP further comprises i) a first linker between the first ELP domain and the enzymatic cleavage site; and / or ii) a second linker between the second ELP domain and the enzymatic cleavage site. In some embodiments, the first and second linkers may each comprise the amino acid sequence set forth in SEQ ID NO: 14, wherein n is an integer equal to or greater than 1. In some embodiments, the first and second linkers may each comprise the amino acid sequence set forth in SEQ ID NO: 15, wherein n is an integer equal to or greater than 1. In certain embodiments, a subject ELP comprises, in order from N-terminus to C-terminus: a) a subject first ELP domain, b) a subject first linker, c) an enzymatic cleavage site, d) a subject second linker, and e) a subject second ELP domain. In certain embodiments, a subject ELP comprises, in order from N-terminus to C-terminus: a) a subject second ELP domain, b) a subject second linker, c) an enzymatic cleavage site, d) a subject first linker, and e) a subject first ELP domain. In addition, the present disclosure provides isothermally phase-separable ELPs, wherein the ELP further comprises a payload polypeptide. In some embodiments, the payload polypeptide comprises a single-chain antibody, a cytokine, a peptide hormone, or a therapeutic peptide. In some embodiments, the payload polypeptide is fused to the second ELP domain via a linker. In certain embodiments, the payload polypeptide is fused N-terminally to the second ELP domain. In certain embodiments, the payload polypeptide is fused C-terminally to the second ELP domain. In some embodiments, a subject ELP further comprises an N-terminal leader domain. In some cases, the N-terminal leader domain encodes a signal peptide. In some cases, a subject ELP is non-immunogenic. The present disclosure also provides isothermally phase-separable ELPs, wherein the ELP is conjugated to a payload molecule. In certain embodiments, the payload molecule may be, for example, a nucleic acid, a polypeptide, a carbohydrate, or a small molecule. In some cases, the payload molecule is conjugated to the second ELP domain. The present Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 disclosure additionally provides ELP compositions, an ELP composition comprising a subject ELP as described herein, and a pharmaceutically acceptable excipient. Further, the present disclosure provides nucleic acids encoding a subject ELP. Expression vectors comprising said nucleic acids are also provided. In some cases, the expression vector may further comprise a nucleic acid encoding a transgene. The present disclosure also provides cells comprising said expression vectors. In some embodiments, a subject cell is a eukaryotic cell. In some cases, the eukaryotic cell is a mammalian cell. In some cases, the mammalian cell is a human cell. In certain embodiments, a subject cell is in vitro. In certain embodiments, a subject cell is in vivo. The present disclosure provides methods for assembling a cell-protective biopolymer on the surface of a target cell, the methods comprising: contacting the surface of a target cell with a subject ELP, as described herein, to assemble a cell-protective biopolymer, wherein the surface of the target cell comprises an enzyme that can cleave the enzymatic cleavage site of the ELP. In addition, the present disclosure provides methods for assembling a cell-protective biopolymer on the surface of a target cell, the methods comprising: expressing a subject ELP, as described herein, in the target cell to assemble a cell-protective biopolymer on the surface of said cell, wherein the target cell comprises an enzyme that can cleave the enzymatic cleavage site of the ELP. In some embodiments of the methods, the target cell comprises a subject expression vector as described herein. In some embodiments of the methods, the enzyme is present on the surface of the target cell. In some embodiments of the methods, the enzyme is present inside of the target cell. In some cases, the target cell is a eukaryotic cell. In some cases, the eukaryotic cell is a mammalian cell. In some cases, the mammalian cell is a human cell. In certain embodiments of the methods, the target cell is in vivo. In certain embodiments of the methods, the target cell expresses a transgene. In addition, the present disclosure provides methods for reducing blood loss at a hemorrhage site in a subject, the method comprising: administering to a hemorrhage site in a subject an effective amount of a subject ELP composition, as described herein, to reduce blood loss at the hemorrhage site, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the hemorrhage site. In some embodiments of the methods, the enzymatic cleavage site of the subject ELP is a protease cleavage site. In some cases, the protease cleavage site is a cleavage site for a protease of the clotting cascade (e.g., a thrombin cleavage site, a factor IXa cleavage site). In certain embodiments of the methods, the hemorrhage Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 site is an external hemorrhage site. In such cases, the administering may comprise applying the ELP composition to the external hemorrhage site. In certain embodiments of the methods, the hemorrhage site is an internal hemorrhage site. In such cases, the administering may comprise intravenously administering the ELP composition to the subject. The present disclosure also provides methods for delivering a therapeutic agent to a target site in a subject, the method comprising: administering a subject ELP composition, as described herein, to a subject, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the target site. In certain embodiments of the methods, the administering comprises intravenously administering the ELP composition to the subject. In certain embodiments, the administering comprises intramuscular injection, intradermal injection, or subcutaneous injection of the ELP composition in a subject. In some embodiments of the methods, the target site is a tumor. In some embodiments of the methods, the enzymatic cleavage site of the ELP is a protease cleavage site. In some cases, protease cleavage site is a matrix metalloproteinase cleavage site (e.g., a MMP-9, MMP-11, or MMP-26 cleavage site). The present disclosure further provides methods for producing a tissue scaffold at a site of injury in a subject, the method comprising: administering a subject ELP composition, as described herein, to a subject, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the site of injury. In some embodiments of the methods, the administering comprises applying the ELP composition to the site of injury. In some embodiments of the methods, the administering comprises intramuscular injection, intradermal injection, or subcutaneous injection of the ELP composition in a subject. The present disclosure also provides kits comprising a) a subject ELP, as described herein, and b) a pharmaceutical excipient. In some embodiments, the ELP is lyophilized. In certain embodiments, the kit further comprises a substrate material. In some cases, the substrate material comprises a gauze. In certain embodiments, the kit further comprises a syringe. The present disclosure additionally provides a kit comprising a) a subject expression vector, as described herein, b) an endonuclease, and c) a ligase. BRIEFDESCRIPTION OF THEFIGURESFIGs.1A-1C: Molecular design of protease-cleavable elastin-like polypeptides. (A) Phase behavior that is sensitive to temperature and sequence. (B) A protease derived from Tobacco Etch Virus (TEV) will generate insoluble ELP components that assemble into protective Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 coatings (SEQ ID NO: 111). (C) Protease display at cell surfaces will allow genetically modified cells to guide the assembly of protective coatings. FIGs.2A-2C: (A) Protease-responsive ELP generates a self-assembling fragment upon protease exposure. (B) Polyacrylamide gel of TEV protease-responsive ELP without and with TEV protease. (C) Turbidity of ELP solutions without and with TEV protease over time. FIGs.3A-3C: (A) Polyacrylamide gel of TEV protease-responsive ELP without and with TEV protease under different incubation times. (B) Expected molecular weights (MW) of the TEV protease-responsive ELP, ELP fragments, and the TEV protease. (C) Turbidity of ELP solutions without and with TEV protease over time, including additional controls. FIG.4: MALDI-TOF mass spectrometry analysis of TEV protease-responsive ELP. FIGs. 5A-5B: Isothermal phase separation of ELPs proceeds through proteolytic cleavage. (A) Protease-cleavable ELPs are diblock ELPs with hydrophilic and hydrophobic blocks separated by a protease cleavage site. These ELPs are soluble before protease cleavage and produce an insoluble ELP post-cleavage. (B) Primary sequences for protease-cleavable ELP variants. Four variants are designed for cleavage by either tobacco etch virus protease, thrombin, factor Xa, or enterokinase (cleavage sequences are from top to bottom SEQ ID NOs: 27-30, respectively). FIGs.6A-6B: Incubation of TEVP-cleavable ELP with TEVP produces a hydrophobic ELP cleavage product that undergoes phase separation under isothermal conditions. (A) Time-resolved turbidimetry at 37 °C shows dynamic phase separation of TEVP-cleavable ELP co- incubated with TEVP (purple). Cleavable-ELP (blue) and TEVP-only (red) controls show no changes in turbidity. Replicates are included in the supplementary information (FIG.9). (B) 12% SDS-PAGE validates sample compositions at the end of the 3-hour turbidimetry experiment. Lane 1: cleavable ELP only; Lane 2: cleavable ELP and TEVP; Lane 3: TEVP only; Lane 4: pellet (P) of centrifuged reaction mixture; Lane 5: supernatant (S) of centrifuged reaction mixture; Lane 6: recombinant ELP[V]60. Samples were detected using Stain-Free imaging. FIG.7: At all concentrations, transition temperatures of TEVP-cleavable ELP (blue) are higher than cleavage products (purple) and recombinant ELP[V]60 (black). The concentration of cleavage products is reported as the initial concentration of TEVP-cleavable ELP before incubation with TEVP. Unless shown, horizontal and vertical error bars are smaller than data points. In region I (light red), cleavage reactions result in protease-driven phase separation. In Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 region II (light blue), cleavage reactions do not result in ELP phase separation. Time-resolved, isothermal cleavage experiments at 37 °C and 32 °C demonstrated these distinct phase behaviors (open and closed triangles, respectively). Transition temperatures were determined from temperature-dependent turbidity data; raw data (FIG.15) and equations to determine transition temperature are included in the supplementary information. FIG.8: Four cleavable ELP variants undergo isothermal phase separation in response to their respective proteases: TEVP, thrombin, factor Xa, or enterokinase. Final OD350values are reported from time-resolved turbidimetry of 30 µM cleavable ELP solutions at 37 °C for 6 hours. Time traces of OD350and replicates are included in FIG.19. FIG.9: Cloning of cleavable ELP variants proceeded with two rounds of Golden Gate assembly and two rounds of directional ligation. Custom gene fragments (Twist Bioscience) flanked by BsmBI recognition sites were purchased to assemble genes for the hydrophilic and hydrophobic ELP blocks. Golden Gate assembly overhangs (5’՜3’) are indicated above the BsmBI recognition sites. First, two Golden Gate assembly reactions with BsmBI-v2 proceeded in parallel to assemble genes for the hydrophilic and hydrophobic ELP blocks in the pGGAselect vector (step 1). Genes encoding the ELP blocks were directionally ligated using SacI-HF and HindIII-HF to encode for the full-length diblock ELP (step 2). This diblock ELP gene was moved into a modified pET-22b(+) expression vector (SI Section 4) using XhoI and NdeI (step 3). ssDNA oligos encoding protease recognition sequences (SI Section 5) were annealed and inserted into the diblock ELP gene using a second round of Golden Gate Assembly with BsaI-HF v2 (step 4). Golden Gate assembly overhangs (5’՜3’) are indicated above the BsaI recognition sequences. FIG.10: The hydrophilic ELP cleavage product between the 37 kDa and 50 kDa standards (lanes 2 and 5, lower gel; same image as FIG.1B) cannot be visualized with Coomassie Brilliant Blue dye (lanes 2 and 5, upper gel). Upper and lower gels show 12% SDS-PAGE analysis of sample compositions at the end of a 3-hour turbidimetry experiment with TEVP-cleavable ELP and TEVP. Protein bands were visualized using Coomassie Brilliant Blue staining (upper gel) or Stain-Free imaging (lower gel). Lane 1: TEVP-cleavable ELP only; Lane 2: TEVP-cleavable ELP and TEVP; Lane 3: TEVP only; Lane 4: pellet (P) of centrifuged reaction mixture; Lane 5: supernatant (S) of centrifuged reaction mixture; Lane 6: recombinant ELP[V]60. FIG.11: Replicates of time-resolved turbidimetry at 37 °C. Purple: TEVP-cleavable ELP and TEVP; Blue: TEVP-cleavable ELP; Red: TEVP. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 FIGs.12A-12E: MALDI-TOF MS of ELPs. (A) MALDI-TOF MS of TEVP-cleavable ELP (expected 64.0 kDa). Raw data (gray curve) was smoothed (blue curve) with a moving average over 21 data points. (B) MALDI-TOF MS of Thr-cleavable ELP (expected 63.7 kDa). Raw data (gray curve) was smoothed (blue curve) with a moving average over 21 data points. (C) MALDI- TOF MS of FXa-cleavable ELP (expected 63.6 kDa). Raw data (gray curve) was smoothed (blue curve) with a moving average over 21 data points. (D) MALDI-TOF MS of EK-cleavable ELP (expected 63.7 kDa). Raw data (gray curve) was smoothed (blue curve) with a moving average over 21 data points. (E) MALDI-TOF MS of ELP[V]60(expected 26.4 kDa). Raw data (gray curve) was smoothed (blue curve) with a moving average over 5 data points. FIGs.13A-13C: Transition temperature determination from turbidity of A) TEVP-cleavable ELP, B) cleavage products, and c) ELP[V]60. Temperature-dependent OD350at each concentration were min-max normalized. Normalized OD350(OD350,norm) were differentiated with respect to temperature (dOD350,norm / dT). The transition temperature is defined as the temperature at which dOD350,norm / dT is maximized. Replicates are offset vertically within each plot. FIGs.14A-14B: Incubation of TEVP-cleavable ELP with TEVP did not result in ELP phase separation at 32 °C. A) Purple: TEVP-cleavable ELP and TEVP; Blue: TEVP-cleavable ELP; Red: TEVP. Each plot is a replicate of the time-resolved turbidimetry experiment at 32 °C. The bottom right plot does not contain the TEVP-only control. B) SDS-PAGE analysis at the end of the 4-hour time-resolved turbidimetry experiment at 32 °C (bottom right from panel a). Lane 1: TEVP-cleavable ELP only, lane 2: TEVP-cleavable ELP and TEVP. The TEVP-cleavable ELP band near 75 kDa is not present after incubating TEVP-cleavable ELP with TEVP for 4 hours at 32 °C, which suggests complete cleavage of the initial TEVP-cleavable ELP. The gel was visualized with Coomassie Brilliant Blue staining. FIG.15: TEVP did not influence the transition temperature of 30 µM ELP[V]60. TEVP was added to a 30 µM ELP[V]60 solution at a volume ratio of 1:25, respectively, to match the ratio used in time-resolved turbidimetry. Turbidimetry was subsequently performed on 30 µM ELP[V]60 solutions with (green) and without (red) TEVP. Transition temperatures (temperature at which dOD350,norm / dT was maximized) remained unchanged upon addition of TEVP. Replicates are offset vertically. FIGs. 16A-16B: The presence of 30 µM hydrophilic ELP[V1A8G7]6 cleavage product in solution does not influence the transition temperature of 30 µM hydrophobic ELP[V]60 cleavage product. A) Turbidimetry data for 30 µM TEVP-cleavable ELP cleavage products (blue) and 30 Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 µM hydrophobic cleavage product (purple). Transition temperatures (temperatures at which dOD350,norm / dT was maximized) were nearly identical with (blue) and without (purple) 30 µM hydrophilic ELP cleavage product. Replicates are offset vertically. 30 µM TEVP-cleavable ELP cleavage products were obtained by incubating 100 µM TEVP-cleavable ELP with TEVP (10 units / µL) at a 60:1 volume ratio at 34 °C for 3 hours. This sample was subsequently diluted to 30 µM with PBS. The hydrophobic cleavage product was isolated from a sample of 100 µM cleavage products via centrifugation at 17000 ×g at 37 °C for 15 mins. The insoluble pellet was resuspended in PBS and diluted to a concentration of 30 µM, which was confirmed by UV absorbance at 280 nm. B) Representative SDS-PAGE analysis to characterize the composition of samples used in turbidimetry measurements. Lane 1: TEVP-cleavable ELP only, lane 2: TEVP- cleavable ELP cleavage products, lane 3: hydrophobic TEVP-cleavable ELP cleavage product. Samples were detected using Stain-Free imaging. FIG.17: Time-resolved turbidimetry of unique cleavable ELP–protease pairings. Each row corresponds to a different cleavable ELP variant (TEVP-, Thr-, FXa-, EK-cleavable ELP from top to bottom). Each column is an experimental replicate. All plots show time-resolved turbidity for the specified cleavable ELP incubated with all four proteases, with line color denoting the protease (legend). The protease-only control is different for each row and is the intended compatible protease for the ELP. FIG.18: SDS-PAGE analysis of unique cleavable ELP–protease pairings at the endpoint of time-resolved turbidimetry. Each column is a replicate with samples taken from an independent time-resolved turbidimetry experiment. Each row corresponds to a different cleavable-ELP variant (TEVP-, Thr-, FXa-, EK-cleavable ELP from top to bottom). For all gels: Lane 1: Cleavable ELP; Lane 2: TEVP and cleavable ELP; Lane 3: Thr and cleavable ELP; Lane 4: FXa and cleavable ELP; Lane 5: EK and cleavable ELP, Lane 6: Protease (varies by row, corresponds to the intended compatible protease for the cleavable ELP). Due to low protease concentration, bands for thrombin, factor Xa, and enterokinase are not visible. FIGs.19A-19F: Cleavage kinetics of cleavable ELP influences time-resolved profile of OD350. A) Time-resolved turbidimetry of TEVP-cleavable ELP over 6 hours at 37 °C with varying amounts of TEVP.150 µL of 30 µM TEVP-cleavable ELP was incubated with 6 µL of TEVP (60 units) or 6 µL of TEVP diluted in PBS (6 and 0.6 units). Incubating TEVP-cleavable ELP with 60 units of TEVP resulted in a local maximum in the OD350 profile. The local maximum became less pronounced when TEVP-cleavable ELP was incubated with 6 units of TEVP. Incubating TEVP- Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 cleavable ELP with 0.6 units of TEVP did not result in a substantial increase in solution turbidity. B) SDS-PAGE analysis reveals sample compositions at the end of the 6-hour time-resolved turbidimetry experiment. All lanes include TEVP-cleavable ELP; lane 1: no TEVP (control), lane 2: 60 units TEVP, lane 3: 6 units TEVP, lane 4: 0.6 units TEVP. At the end of 6-hour experiments, the TEVP-cleavable ELP band near 75 kDa becomes more pronounced when fewer TEVP units are used. This result indicates slower ELP cleavage kinetics with fewer TEVP units. The gel was visualized using Stain-Free imaging. C) Time-resolved turbidimetry of FXa-cleavable ELP over 6 hours at 37 °C with varying masses of FXa.150 µL of 30 µM FXa-cleavable ELP was incubated with 10 µL of FXa (10 µg), 10 µL of diluted FXa (3 μg in reaction buffer), or 10 µL of reaction buffer (0 µg). Incubating FXa-cleavable ELP with 10 µg of FXa resulted in a local maximum in the OD350profile, similar to those observed for TEVP-cleavable ELP. Incubating FXa-cleavable ELP with 3 µg of FXa produced a slight increase in turbidity after approximately 5 hours. No increase in turbidity was observed with the FXa-cleavable ELP-only control. D) SDS-PAGE analysis indicates sample compositions at the end of the 6-hour time-resolved turbidimetry experiment. All lanes include FXa-cleavable ELP; lane 1: no FXa (control), lane 2: 3 µg FXa, lane 3: 10 µg FXa. At the end of 6-hour experiments, the FXa-cleavable ELP band near 75 kDa becomes more pronounced when a smaller mass of FXa is used. This result indicates slower ELP cleavage kinetics with less FXa. The gel was visualized with Coomassie Brilliant Blue staining. E) Time-resolved turbidimetry of FXa-cleavable ELP incubated with 3 µg of FXa in 160 µL (blue) and 153 µL (light blue) reaction volumes. Turbidity profiles were similar despite the slight dilution of FXa and FXa-cleavable ELP in the 160 µL reaction volume condition. The turbidity profile with 3 µg of FXa in panel C) (160 µL reaction volume) is anomalous and is expected to more closely match the FXa and FXa-cleavable ELP profiles reported in FIG. 19 (153 µL reaction volume). F) SDS-PAGE analysis of samples reported in panel e) reveals near complete conversion of FXa-cleavable ELP (lane 1) with 3 µg of FXa in a reaction volume of 160 µL (lane 2) and 153 µL (lane 3). In contrast, the replicate of the 160 µL reaction volume in panel C) demonstrates a lower conversion (panel D, lane 2). Faster cleavage kinetics in panel E) therefore produces an earlier increase in turbidity than the reaction in panel C). The gel was visualized with Coomassie Brilliant Blue staining. DEFINITIONS The terms “phase transition” and “phase separation”, as used herein, refer to physical processes whereby a material, substance, composition, or the like undergoes a change from one physical state to another (e.g., from a liquid to a solid, from a state of solubility to a state of Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 insolubility) and / or is separated or de-mixed from another material, substance, or composition by undergoing a change from one physical state to another (e.g., in the case of a liquid-liquid phase separation). The terms “isothermal”, “isothermic”, and “isothermally”, as used herein, refer to processes that occur at, involve, or possess a constant, or substantially constant temperature. The term “lower critical solution temperature (LCST)”, as used herein, refers to the temperature at, or above, which a material, substance, composition, or the like undergoes a change from one physical state to another (e.g., from a liquid to a solid, from a state of solubility to a state of insolubility), all other factors (e.g., concentration, pH, pressure, etc.) being constant. The terms “polypeptide,” “peptide,” and “protein”, used interchangeably herein, refer to a polymeric form of amino acids of any length, which can include genetically coded and non- genetically coded amino acids, chemically or biochemically modified or derivatized amino acids, and polypeptides having modified peptide backbones. The term “amino acid” includes, but is not limited to, naturally-occurring α-amino acids and their stereoisomers. “Stereoisomers” of amino acids refer to mirror image isomers of the amino acids, such as L-amino acids or D-amino acids. For example, a stereoisomer of a naturally- occurring amino acid refers to the mirror image isomer of the naturally-occurring amino acid (i.e., the D-amino acid). Naturally-occurring α-amino acids are those encoded by the genetic code as well as those amino acids that are later modified (e.g., hydroxyproline, γ-carboxyglutamate, and O- phosphoserine). Naturally-occurring α-amino acids include, without limitation, alanine (Ala), cysteine (Cys), aspartic acid (Asp), glutamic acid (Glu), phenylalanine (Phe), glycine (Gly), histidine (His), isoleucine (Ile), arginine (Arg), lysine (Lys), leucine (Leu), methionine (Met), asparagine (Asn), proline (Pro), glutamine (Gln), serine (Ser), threonine (Thr), valine (Val), tryptophan (Trp), tyrosine (Tyr), and combinations thereof. Stereoisomers of a naturally-occurring α-amino acids include, without limitation, D-alanine (D-Ala), D-cysteine (D-Cys), D-aspartic acid (D-Asp), D-glutamic acid (D-Glu), D-phenylalanine (D-Phe), D-histidine (D-His), D-isoleucine (D- Ile), D-arginine (D-Arg), D-lysine (D-Lys), D-leucine (D-Leu), D-methionine (D-Met), D-asparagine (D-Asn), D-proline (D-Pro), D-glutamine (D-Gln), D-serine (D-Ser), D-threonine (D-Thr), D-valine (D-Val), D-tryptophan (D-Trp), D-tyrosine (D-Tyr), and combinations thereof. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 Amino acids may be referred to herein by either their commonly known three letter symbols or by the one-letter symbols recommended by the IUPAC-IUB Commission on Biochemical Nomenclature. For example, an L-amino acid may be represented herein by its commonly known three letter symbol (e.g., Arg for L-arginine) or by an upper-case one-letter amino acid symbol (e.g., R for L-arginine). A D-amino acid may be represented herein by its commonly known three letter symbol (e.g., D-Arg for D-arginine) or by a lower-case one-letter amino acid symbol (e.g., r for D-arginine). The terms “polynucleotide” and “nucleic acid,” used interchangeably herein, refer to a polymeric form of nucleotides of any length, either ribonucleotides or deoxyribonucleotides. Thus, terms “polynucleotide” and “nucleic acid” encompass single-stranded DNA; double-stranded DNA; multi-stranded DNA; single-stranded RNA; double-stranded RNA; multi-stranded RNA; genomic DNA; cDNA; DNA-RNA hybrids; and a polymer comprising purine and pyrimidine bases or other natural, chemically or biochemically modified, non-natural, or derivatized nucleotide bases. By “small molecule” is meant a compound having a molecular weight of 1000 atomic mass units (amu) or less. In some embodiments, the small molecule is 900 amu or less, 750 amu or less, 500 amu or less, 400 amu or less, 300 amu or less, or 200 amu or less. In some instances, the small molecule is not made of repeating molecular units such as are present in a polymer. A “restriction site” refers to a nucleotide sequence recognized and cleaved by a given restriction endonuclease. In certain embodiments, the restriction site present in the circular nucleic acid template is for a restriction endonuclease that generates cohesive (or “sticky”) ends, including but not limited to, AscI, Aval, BamHI, BclI, BglII, BstEI, Bst, BI, BstYI, EcoRI, MluI, NarI, NheI, NotI, PstI, PvuI, SacI, SalI, SpeI, StyI, XbaI, XhoI and XmaI. According to some embodiments, the restriction site present in the circular nucleic acid template is for a restriction endonuclease that generates blunt ends, including but not limited to, EcoRV, FspI, NaeI, NruI, PvuII, SmaI, SnaBI, and StuI. The term “antibody” may include an antibody or immunoglobulin of any isotype (e.g., IgG (e.g., IgG1, IgG2, IgG3, or IgG4), IgE, IgD, IgA, IgM, etc.), whole antibodies (e.g., antibodies composed of a tetramer which in turn is composed of two dimers of a heavy and light chain polypeptide); single chain antibodies (e.g., scFv); fragments of antibodies (e.g., fragments of whole or single chain antibodies) which retain specific binding to the cell surface molecule of the target cell, including, but not limited to single chain Fv (scFv), Fab, (Fab’)2, (scFv’)2, and diabodies; Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 chimeric antibodies; monoclonal antibodies, human antibodies, humanized antibodies (e.g., humanized whole antibodies, humanized half antibodies, or humanized antibody fragments, e.g., humanized scFv); and fusion proteins comprising an antigen-binding portion of an antibody and a non-antibody protein. According to some embodiments, the antibody is selected from an IgG, Fv, single chain antibody, scFv, Fab, F(ab')2, or Fab'. In certain embodiments, the antibody is a nanobody (an antibody fragment consisting of a single monomeric variable antibody domain – also known as a single-domain antibody (sdAb)), a monobody (a synthetic binding protein constructed using a fibronectin type III domain (FN3) as a molecular scaffold), or a Bi-specific T- cell engager (BiTE). DETAILED DESCRIPTION As summarized above, the present disclosure provides isothermally phase-separable elastin-like polypeptides (ELPs), the ELPs comprising: i) a first ELP domain having a first lower critical solution temperature (LCST); and ii) a second ELP domain having a second LCST that is different from the first LCST, wherein the first and second ELP domains are separated by an enzymatic cleavage site. Also included in the present disclosure are conjugates of the subject ELPs, nucleic acids encoding the subject ELPs, cells comprising nucleic acids encoding the subject ELPs, methods of use for the subject ELPs, and related kits. Before the present invention is described in greater detail, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 Certain ranges are presented herein with numerical values being preceded by the term "about." The term "about" is used herein to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. In determining whether a number is near to or approximately a specifically recited number, the near or approximating unrecited number may be a number which, in the context in which it is presented, provides the substantial equivalent of the specifically recited number. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described. All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed. It is noted that, as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order which is logically possible. While the apparatus and method has or will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 U.S.C. §112, are not to be construed as necessarily limited in any way by the construction of "means" or "steps" limitations, but are to be accorded the full scope of Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 U.S.C. §112 are to be accorded full statutory equivalents under 35 U.S.C. §112. Elastin-like Polypeptides Elastin-like polypeptide domains The present disclosure provides isothermally phase-separable elastin-like polypeptides (ELPs) that can be phase-separated from surrounding solute in an inducible manner under isothermal conditions. Elastin-like polypeptides (ELPs) are a class of synthetic polypeptides derived, in part, from the human tropoelastin protein. ELPs comprise ELP domains that are generally composed of repeated units of a pentapeptide sequence. The pentapeptide repeat of an ELP domain is of the sequence VPGXG, where X is any amino acid other than proline. ELPs undergo a phase separation when raised above a transition temperature (i.e., when raised above the lower critical solution temperature of the ELP) to form insoluble coacervates. In other words, when raised above a transition temperature, ELPs in solution can transition from a soluble liquid phase to an insoluble disperse phase composed of ELP particles. In contrast to traditional ELPs, the ELPs of the present disclosure can undergo a phase transition in isothermal conditions, that is without a change in temperature. The ELPs of the present disclosure comprise: i) a first ELP domain having a first lower critical solution temperature (LCST); and ii) a second ELP domain having a second LCST that is different from the first LCST, wherein the first and second ELP domains are separated by an enzymatic cleavage site. Upon contact of the ELP with an enzyme specific to the enzymatic cleavage site, the ELP is cleaved and thus enables one of the first or second ELP domains to undergo an isothermal phase-separation. In some embodiments of a subject ELP, the first LCST (i.e., the LCST of the first ELP domain) is greater than the second LCST (i.e., the LCST of the second ELP domain). In such cases, upon contact of the ELP with an enzyme specific to the enzymatic cleavage site, the ELP is cleaved and can thus enable the second ELP domain to undergo an isothermal phase- separation. In some embodiments, the first LCST is greater than the second LCST, such that the whole ELP, comprising the first and second ELP domains has a phase transition temperature that is from 2 °C to 10 °C higher than the second LCST of the second ELP domain alone, e.g., the whole ELP has a phase transition temperature that is from 2 °C to 9 °C, from 2 °C to 8 °C, from 2 °C to 8 °C, from 3 °C to 7 °C, from 3 °C to 6 °C, from 4 °C to 5 °C higher than the second LCST Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 of the second ELP domain alone. The phase transition temperature of the whole ELP can be modulated by the choice of the first and second LCSTs of the first and second ELPs, respectively. In certain embodiments, the first LCST of the first ELP domain is 39 °C or higher, e.g., in some cases the first LCST is 40 °C or higher, 41 °C or higher, 42 °C or higher, 43 °C or higher, 44 °C or higher, 45 °C or higher, 46 °C or higher, 47 °C or higher, 48 °C or higher, 49 °C or higher, 50 °C or higher, 60 °C or higher, or 70 °C or higher. In certain embodiments, the second LCST of the second ELP domain ranges from 30 °C to 38°C, e.g., the LCST of the second ELP domain ranges from 31°C to 37 °C, from 32 °C to 36 °C, or from 33 °C to 35 °C. In a particular embodiment, the whole ELP has a phase transition temperature that is from 4 °C to 5 °C higher than the second LCST of the second ELP domain, wherein the first ELP domain has a first LCST that is 45 °C or higher, and the second ELP domain has a second LCST from 33 °C to 35 °C. The phase transition temperature and / or LCST of a polypeptide in solution can be determined through a variety of means known in the art. By way of example, the LCST of a polypeptide can be determined through turbidemitry approaches. Briefly, turbidemitry is the measurement of turbidity (e.g., opaqueness, cloudiness) of a sample. Turbidity in a liquid can be caused by the presence of suspended particles in the liquid. The turbidity of a sample can be quantified by measuring the degree of attenuation of a beam of light, of known intensity, that is beamed through the sample. As an example, a substance in a liquid solute which undergoes a phase transition from a liquid to a solid, thus forming suspended solid particles in a liquid solute will increase the turbidity of the liquid solute. In some embodiments, the first and / or second ELP domain comprises one or more pentapeptide repeats. A pentapeptide repeat is a contiguous, five residue long, amino acid sequence of the form VPGXG, where X is any amino acid other than proline. The one or more pentapeptide repeats of an ELP domain may all be identical in sequence to one another or they may differ in sequence. The lower critical solution temperature (LCST) of an ELP domain (i.e., the transition temperature at, or above, which the ELP domain undergoes a phase transition) can be influenced by both the choice of residue for X in each pentapeptide repeat and the total number of pentapeptide repeats in the ELP. Generally, increasing the hydrophilicity of the X residues and / or decreasing the number of pentapeptide repeats will increase the LCST of the ELP domain. Conversely, increasing the hydrophobicity of the X residues and / or increasing the number of pentapeptide repeats will decrease the LCST of the ELP domain. Accordingly, the sequence and length of an ELP domain can be varied to achieve a desired LCST for the ELP domain. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 In certain embodiments, a pentapeptide repeat comprises the amino acid sequence VPGXG (SEQ ID NO:1), wherein X is any amino acid other than proline. In some cases, each pentapeptide repeat of the first and / or second ELP domain comprises the amino acid sequence VPGXG (SEQ ID NO:2), wherein X is selected from valine, alanine, glycine, lysine, histidine, serine, and glutamate. Elastin-like polypeptides comprising pentapeptide repeats as described herein exhibit little to no immunological response. Thus, in some embodiments, a subject ELP is non-immunogenic. The LCST of an ELP domain can be increased (e.g., the ELP can be made more hydrophilic), as an example, by the inclusion of pentapeptide repeats having the amino acid sequence VPGXG (SEQ ID NO:3), wherein X is selected from alanine, glycine, lysine, serine, and glutamate. The LCST of an ELP domain can be decreased (e.g., the ELP can be made more hydrophobic), as an example, by the inclusion of pentapeptide repeats having the amino acid sequence VPGXG (SEQ ID NO:4), wherein X is selected from valine or histidine. In some embodiments, the first ELP domain of a subject ELP comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5), VPGAG (SEQ ID NO:6), VPGGG (SEQ ID NO:7), VPGKG (SEQ ID NO:8), VPGSG (SEQ ID NO:9), and VPGEG (SEQ ID NO:10). In some embodiments, the second ELP domain of a subject ELP comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5) and VPGHG (SEQ ID NO:11). In certain embodiments of the subject ELP: i) the first ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5), VPGAG (SEQ ID NO:6), VPGGG (SEQ ID NO:7), VPGKG (SEQ ID NO:8), VPGSG (SEQ ID NO:9), and VPGEG (SEQ ID NO:10); and ii) the second ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5) and VPGHG (SEQ ID NO:11). In some embodiments, the first ELP domain of a subject ELP comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGAG (SEQ ID NO:6), VPGSG (SEQ ID NO:9), and VPGEG (SEQ ID NO:10). In some embodiments, the second ELP domain of a subject ELP comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5) and VPGHG (SEQ ID NO:11). In certain embodiments of the subject ELP: i) the Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 first ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGAG (SEQ ID NO:6), VPGSG (SEQ ID NO:9), and VPGEG (SEQ ID NO:10); and ii) the second ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5) and VPGHG (SEQ ID NO:11). In some embodiments, the first ELP domain of a subject ELP comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5), VPGAG (SEQ ID NO:6), VPGGG (SEQ ID NO:7). In some embodiments, the second ELP domain of a subject ELP comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5) and VPGHG (SEQ ID NO:11). In certain embodiments of the subject ELP: i) the first ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5), VPGAG (SEQ ID NO:6), VPGGG (SEQ ID NO:7); and ii) the second ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5) and VPGHG (SEQ ID NO:11). In some cases, the first and / or second ELP domains of a subject ELP each comprises from 1 to 250 pentapeptide repeats. For example, in some cases, the first and / or second ELP domains of a subject ELP each comprises from 5 to 140 pentapeptide repeats, from 10 to 130 pentapeptide repeats, from 20 to 120 pentapeptide repeats, from 30 to 110 pentapeptide repeats, from 40 to 100 pentapeptide repeats, from 50 to 90 pentapeptide repeats, from 60 to 80 pentapeptide repeats, or from 65 to 75 pentapeptide repeats. As another example, the first and / or second ELP domains of a subject ELP can each comprise from 40 to 160 pentapeptide repeats, e.g., from 50 to 150 pentapeptide repeats, from 75 to 125 pentapeptide repeats, and from 85 to 95 pentapeptide repeats. As yet another example, the first and / or second ELP domains of a subject ELP can each comprise from 20 to 100 pentapeptide repeats, e.g., from 30 to 90 pentapeptide repeats, from 40 to 80 pentapeptide repeats, from 50 to 70 pentapeptide repeats, and from 55 to 65 pentapeptide repeats. In some embodiments of a subject ELP: i) the first ELP domain comprises from 50 to 150 pentapeptide repeats; and ii) the second ELP domain comprises 30 to 90 pentapeptide repeats. In some embodiments of a subject ELP: i) the first ELP domain comprises from 75 to 125 pentapeptide repeats; and ii) the second ELP domain comprises 45 to 75 pentapeptide repeats. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 In some embodiments of a subject ELP: i) the first ELP domain comprises from 85 to 95 pentapeptide repeats; and ii) the second ELP domain comprises 55 to 65 pentapeptide repeats. In a particular embodiment of a subject ELP, the first ELP domain comprises an amino acid sequence having 80% or more, 90% or more, 95% or more, 98% or more, 99% or more, or 100% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:12, below: VPGVGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGGGVPGGGVPGGGVPGGGVPGGG VPGGGVPGGGVPGVGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGGGVPGGGVPGGG VPGGGVPGGGVPGGGVPGGGVPGVGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGGG VPGGGVPGGGVPGGGVPGGGVPGGGVPGGGVPGVGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAGVPGAG VPGAGVPGGGVPGGGVPGGGVPGGGVPGGGVPGGGVPGGGVPGVGVPGAGVPGAGVPGAGVPGAGVPGAG VPGAGVPGAGVPGAGVPGGGVPGGGVPGGGVPGGGVPGGGVPGGGVPGGGVPGVGVPGAGVPGAGVPGAG VPGAGVPGAGVPGAGVPGAGVPGAGVPGGGVPGGGVPGGGVPGGGVPGGGVPGGGVPGGG (SEQ ID NO:12). In a particular embodiment of a subject ELP, the second ELP domain comprises an amino acid sequence having 80% or more, 90% or more, 95% or more, 98% or more, 99% or more, or 100% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:13, below: VPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVG VPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVG VPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVG VPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVGVPGVG VPGVGVPGVGVPGVGVPGVG (SEQ ID NO:13). In another particular embodiment of a subject ELP: i) the first ELP domain comprises an amino acid sequence having 80% or more, 90% or more, 95% or more, 98% or more, 99% or more, or 100%amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:12; and ii) the second ELP domain comprises an amino acid sequence having 80% or more amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:13. Enzymatic Cleavage Sites. As noted above, a subject ELP of the present disclosure comprises a first and second ELP domain, wherein the first and second ELP domain are separated by an enzymatic cleavage site. An enzymatic cleavage site refers to an amino acid sequence in a polypeptide that renders the polypeptide susceptible to enzymatic cleavage (e.g., through hydrolysis of a peptide bond). The Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 susceptibility to enzymatic cleavage can be generated due to the amino acid sequence of the enzymatic cleavage site preferentially interacting with the enzyme at or near the active site of the enzyme. The enzymatic cleavage of the polypeptide can occur within the amino acid sequence of the enzymatic cleavage site or adjacent to the enzymatic cleavage site. In some embodiments of a subject ELP, the first and second ELP domains are separated by two or more enzymatic cleavages, e.g., in some cases, the first and second ELP domains are separated by two enzymatic cleavage sites, are separated by 3 enzymatic cleavage sites, are separated by four enzymatic cleavage sites, or are separated by 5 or more enzymatic cleavage sites. In certain embodiments, the two or more enzymatic cleavage sites are different enzymatic cleavage sites. In such cases, phase-separation of the subject ELP may be induced by a plurality of different enzyme stimuli. Any suitable enzyme cleavage site may be chosen, e.g., any suitable enzyme for the desired application. In some embodiments, the enzymatic cleavage is a protease cleavage site. In some embodiments, the protease cleavage site is a cleavage site for a eukaryotic protease, a prokaryotic protease, or a viral protease. In some cases, the suitable eukaryotic protease cleavage site is a mammalian protease cleavage site. In some cases, a suitable mammalian protease cleavage site is a human protease cleavage site. Suitable human protease cleavage sites include, without limitation, an enterokinase cleavage site, a clotting cascade protease cleavage site, a furin cleavage site, a matrix metalloproteinase (MMP) cleavage site, a caspase cleavage site, a paracaspase cleavage site, a granzyme B cleavage site, and a proline-endopeptidase cleavage site. In some embodiments, a suitable enterokinase cleavage site comprises the amino acid sequence: X1X2X3K, wherein X1 is selected from D or E, X2 is selected from D or E, and X3 is selected from D or E. In some embodiments, a suitable furin cleavage site comprises the amino acid sequence RXXR, wherein X is any amino acid. In some embodiments, a suitable granzyme B cleavage site comprises the amino acid sequence IEXDG (SEQ ID NO: 20), wherein X is any amino acid. In some embodiments, a suitable proline-endopeptidase cleavage site comprises the amino acid sequence X1PX2, wherein X1 is selected from H, K, or R; and X2 is any amino acid except P. In some embodiments, a suitable clotting cascade protease cleavage site includes, without limitation, a thrombin cleavage site, a factor Xa cleavage site, a factor VIIa cleavage site, a factor IXa cleavage site, a factor XIa cleavage site, a factor XIIa cleavage site, a kallikrein Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 cleavage site, or a plasmin cleavage site. In some embodiments, a suitable thrombin cleavage site comprises the amino acid sequence X1X2PRX3X4, wherein X1is selected from A, F, G, I, L, T, V or M, X2 is selected from A, F, G, I, L, T, V, W or A, X3is any amino acid except D or E, and X4 is any amino acid except D or E. In some embodiments, a suitable FXa cleavage site comprises the amino acid sequence X1X2GR, wherein X1is selected from A, F, G, I, L, T, V or M, and X2is any amino acid except D or E. The protein substrate specificities of clotting factor proteases are known in the art and described, for example, in Uliana, Federico, et al. "Mapping specificity, cleavage entropy, allosteric changes and substrates of blood proteases in a high-throughput screen." Nature communications 12.1 (2021): 1693, the disclosure of which is incorporated by reference herein in its entirety. In some embodiments, a MMP cleavage site includes, without limitation, a MMP-1 cleavage site, a MMP-13 cleavage site, a MMP-11 cleavage site, a MMP-12 cleavage site, a MMP-7 cleavage site, a MMP-26 cleavage site, a MMP-2 cleavage site, a MMP-9 cleavage site, a MMP-14 cleavage site, a MMP-16 cleavage site, a MMP-17 cleavage site, a MMP-24 cleavage site, and a MMP-25 cleavage site. In some embodiments, a suitable MMP cleavage site comprises the amino acid sequence X1AX2X3X4X5, wherein X1is selected from P, A, or V, X2is selected from N, A, or G, X3is selected from L, I, C, M, V, or G, X4is selected from V, I, K, or H, and X5is selected from A,G, or V. The protein substrate specificities of MMPs are known in the art and described, for example, in Eckhard, Ulrich, et al. "Active site specificity profiling of the matrix metalloproteinase family: Proteomic identification of 4300 cleavage sites by nine MMPs explored with structural and synthetic peptide cleavage analyses." Matrix biology 49 (2016): 37- 60, the disclosure of which is incorporated by reference herein in its entirety. In some embodiments, a caspase cleavage site includes, without limitation, a Caspase 1 cleavage site, a Caspase 1 cleavage site, a Caspase 2 cleavage site, a Caspase 3 cleavage site, a Caspase 4 cleavage site, a Caspase 5 cleavage site, a Caspase 6 cleavage site, a Caspase 7 cleavage site, a Caspase 8 cleavage site, a Caspase 9 cleavage site, and a Caspase 10 cleavage site. In some embodiments, a suitable Caspase 1 cleavage site comprises the amino acid sequence X1X2X3DX4, wherein X1 is selected from F, W, Y, or L, X2 is any amino acid, X3 is selected from H, A, or T, and X4 is any amino acid except for P, E, D, Q, K, or R. In some embodiments, a suitable Caspase 2 cleavage site comprises the amino acid sequence DVADX (SEQ ID NO:21), wherein X is any amino acid other than P, E, D, Q, K or R. In some embodiments, a suitable Caspase 3 cleavage site comprises the amino acid sequence DMQDX (SEQ ID NO:22), wherein X is any amino acid other than P, E, D, Q, K or R. In some embodiments, a suitable Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 Caspase 4 cleavage site comprises the amino acid sequence LEVDX (SEQ ID NO:23), wherein X is any amino acid other than P, E, D, Q, K or R. In some embodiments, a suitable Caspase 5 cleavage site comprises the amino acid sequence XEHD, wherein X is L or W. In some embodiments, a suitable Caspase 6 cleavage site comprises the amino acid sequence VEX1DX2, wherein X1is I or L, and X2any amino acid other than P, E, D, Q, K or R. In some embodiments, a suitable Caspase 7 cleavage site comprises the amino acid sequence DEVDX (SEQ ID NO:24), wherein X is any amino acid other than P, E, D, Q, K or R. In some embodiments, a suitable Caspase 8 cleavage site comprises the amino acid sequence X1ETDX2, wherein X1is I or L, and X2is any amino acid other than P, E, D, Q, K or R. In some embodiments, a suitable Caspase 9 cleavage site comprises the amino acid sequence LEHD (SEQ ID NO:25). In some embodiments, a suitable Caspase 10 cleavage site comprises the amino acid sequence IEAD (SEQ ID NO:26). In some cases, the suitable eukaryotic protease cleavage site is a plant protease cleavage site. Suitable plant protease cleavage sites include, without limitation, a plant metacaspase cleavage site, a phytaspase cleavage site, a plant subtilase cleavage site, and a plant papain-like protease. Plant proteases and their cleavage substrates are known in the art and described, for example, in Minina, Elena A., et al. "Plant metacaspase activation and activity." Caspases, paracaspases, and metacaspases: Methods and protocols (2014): 237-253, Tsiatsiani, Liana, et al. "Metacaspases." Cell Death & Differentiation 18.8 (2011): 1279-1288, . Chichkova, Nina V., et al. "Plant phytaspases and animal caspases: structurally unrelated death proteases with a common role and specificity." Physiologia Plantarum 145.1 (2012): 77-84, Vartapetian, A. B., et al. "A plant alternative to animal caspases: subtilisin-like proteases." Cell Death & Differentiation 18.8 (2011): 1289-1297, and Liu, Huijuan, et al. "Role of papain-like cysteine proteases in plant development." Frontiers in Plant Science 9 (2018): 1717, the disclosures of which are each incorporated by reference herein in their entirety. In some embodiments, the protease cleavage site is a bacterial protease cleavage site. Suitable bacterial protease cleavage sites include, without limitation, a ftsH protease and the like, a rseP protease and the like, a IClip protease and the like, a GxGD-aspartyl protease, and a lepB protease and the like. Bacterial proteases and their cleavage substrates are known in the art and described, for example, in De Castro, Rosana E., and Ansgar Poetsch. "Proteases of the prokaryotic cell envelope." Frontiers in Microbiology 13 (2022): 988067 and Culp, Elizabeth, and Gerard D. Wright. "Bacterial proteases, untapped antimicrobial drug targets." The Journal of antibiotics 70.4 (2017): 366-377, the disclosures of which are each incorporated by reference herein in their entirety. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 In some embodiments, the protease cleavage site is a viral protease cleavage site. Suitable viral protease cleavage sites include, without limitation, a TEV protease (TEVP) cleavage site, a HIV-1 protease cleavage site, a HCV NS3 / 4A protease cleavage site, a HTLV-1 protease cleavage site, a flavivirus protease cleavage site, an enterovirus protease cleavage site, and a coronavirus protease cleavage site. Viral proteases and their cleavage substrates are known in the art and described, for example, in Zephyr, Jacqueto, Nese Kurt Yilmaz, and Celia A. Schiffer. "Viral proteases: Structure, mechanism and inhibition." The enzymes. Vol.50. Academic Press, 2021.301-333 and Rodamilans, Bernardo, et al. "Plant viral proteases: beyond the role of peptide cutters." Frontiers in Plant Science 9 (2018): 666, the disclosures of which are each incorporated by reference herein in their entirety. In certain embodiments, a suitable protease cleavage site for use in a subject ELP includes, without limitation, any one of the protease cleavage sites set forth in Table 1. [will add any more specific sites that we can find before filing] Table 1: Exemplary Protease Cleavage Sites Protease Cleavage Site Sequence SEQ ID NO: TEVPENLYFQS27 Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 MMP-2 TSFTSQVLAHPG 43 MMP-2 TTPFSPLVATSE 44 Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 MMP-14 MIDAATLKSRKM 74 MMP-14 SSKPNMIDAATL 75 Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 Furin protease RKKR 114 Linkers Flexible linkers are amino acid sequences of varying length that can join two polypeptide domains and provide a degree of free movement for each of the joined domains relative to one another. In addition to providing flexibility, the solubility of the flexible linker can reduce unfavorable interactions between the linker and the connected protein domains. Flexible linkers are often rich in small or polar amino acids such as Gly and Ser to provide good flexibility and solubility. In some embodiments, a subject ELP further comprises: i) a first linker between the first ELP domain and the enzymatic cleavage site; and / or ii) a second linker between the second ELP domain and the enzymatic cleavage site. In some cases, a subject ELP comprises: i) a first linker between the first ELP domain and the enzymatic cleavage site; and ii) a second linker between the second ELP domain and the enzymatic cleavage site. In some embodiments, the first and / or second linker may be a flexible linker. In certain embodiments, a Gly-Ser (GS) linker is employed, non-limiting examples of which are those comprising one or more GGGGS (SEQ ID NO: 18) units, i.e., (GGGGS)n(SEQ ID NO: 19) where n is an integer of 1 or greater, e.g., 1 to 10. As another example, a suitable linker may comprise one or more GGGS (SEQ ID NO: 16) units, i.e., (GGGS)n(SEQ ID NO: 14), where n is an integer of 1 or greater, e.g., 1 to 10. In yet another example, a suitable linker may comprise one or more SGGG (SEQ ID NO: 17) units, i.e., (SGGG)n(SEQ ID NO: 15), where n is an integer of 1 or greater, e.g., 1 to 10. In some embodiments, a flexible linker comprising Gly and Ser, and one or more threonine (Thr) residues is employed. According to some embodiments, a flexible linker comprising Gly or Ser residues, and one or more Thr residues is employed. In a particular embodiment, a subject ELP comprises: i) a first linker between the first ELP domain and the enzymatic cleavage site, wherein the first linker comprises the amino acid sequence (GGGS)n (SEQ ID NO: 14); and ii) a second linker between the second ELP domain and the enzymatic cleavage site, wherein the second linker comprises the amino acid sequence (SGGG)n (SEQ ID NO: 15), and wherein n is an integer of 1 or greater, e.g., 1 to 10. In another particular embodiment, a subject ELP comprises: i) a first linker between the first ELP domain and the enzymatic cleavage site, wherein the first linker comprises the amino acid sequence (SGGG)n (SEQ ID NO: 15); and ii) a second linker between the second ELP domain and the enzymatic Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 cleavage site, wherein the second linker comprises the amino acid sequence (GGGS)n(SEQ ID NO: 14), and wherein n is an integer of 1 or greater, e.g., 1 to 10. In some embodiments, a subject ELP of the present disclosure comprises, in order from N-terminus to C-terminus: a) the first ELP domain; b) a first linker; c) the enzymatic cleavage site; d) a second linker; and e) the second ELP domain. In another embodiment, comprises, in order from N-terminus to C-terminus: a) the second ELP domain; b) a first linker; c) the enzymatic cleavage site; d) a second linker; and e) the first ELP domain. In some embodiments, a subject ELP of the present disclosure comprises, in order from N-terminus to C-terminus: a) the first ELP domain; b) a first linker; c) two or more enzymatic cleavage sites; d) a second linker; and e) the second ELP domain. In another embodiment, comprises, in order from N-terminus to C-terminus: a) the second ELP domain; b) a first linker; c) two or more enzymatic cleavage sites; d) a second linker; and e) the first ELP domain. Payload Polypeptides In some embodiments, a subject ELP further comprises a payload polypeptide. A “payload polypeptide”, as used herein, is an amino acid sequence or polypeptide domain that can exert a desired pharmacological, biological, or physical effect. The payload polypeptide can be fused to a subject ELP so that the ELP may function as an isothermally phas-separable delivery vehicle for the payload polypeptide. Suitable payload polypeptides include, without limitation, single-chain antibodies, cytokines, growth factors, peptide hormones, or therapeutic peptides. In some embodiments of a subject ELP, the payload polypeptide is fused to the second ELP domain via a linker (e.g., a flexible linker as disclosed herein). In some embodiments of a subject ELP, the payload polypeptide is fused N-terminally to the second ELP domain. In some embodiments of a subject ELP, the payload polypeptide is fused C-terminally to the second ELP domain. In cases where the payload polypeptide is fused to the second ELP domain, the LCST of the second ELP domain may be less than the LCST of the first ELP domain, such that, upon cleavage of the subject ELP, the second ELP domain that is fused to the payload polypeptide undergoes a phase transition. Suitable single-chain antibodies for use as a payload polypeptide in a subject ELP include, without limitation, a single-chain antibody comprising variable regions derived from Adecatumumab, Ascrinvacumab, Cixutumumab, Conatumumab, Daratumumab, Drozitumab, Duligotumab, Durvalumab, Dusigitumab, Enfortumab, Enoticumab, Figitumumab, Ganitumab, Glembatumumab, Intetumumab, Ipilimumab, Iratumumab, Icrucumab, Lexatumumab, Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 Lucatumumab, Mapatumumab, Narnatumab, Necitumumab, Nesvacumab, Ofatumumab, Olaratumab, Panitumumab, Patritumab, Pritumumab, Radretumab, Ramucirumab, Rilotumumab, Robatumumab, Seribantumab, Tarextumab, Teprotumumab, Tovetumab, Vantictumab, Vesencumab, Votumumab, Zalutumumab, Flanvotumab, Altumomab, Anatumomab, Arcitumomab, Bectumomab, Blinatumomab, Detumomab, Ibritumomab, Minretumomab, Mitumomab, Moxetumomab, Naptumomab, Nofetumomab, Pemtumomab, Pintumomab, Racotumomab, Satumomab, Solitomab, Taplitumomab, Tenatumomab, Tositumomab, Tremelimumab, Abagovomab, Igovomab, Oregovomab, Capromab, Edrecolomab, Nacolomab, Amatuximab, Bavituximab, Brentuximab, Cetuximab, Derlotuximab, Dinutuximab, Ensituximab, Futuximab, Girentuximab, Indatuximab, Isatuximab, Margetuximab, Rituximab, Siltuximab, Ublituximab, Ecromeximab, Abituzumab, Alemtuzumab, Bevacizumab, Bivatuzumab, Brontictuzumab, Cantuzumab, Cantuzumab, Citatuzumab, Clivatuzumab, Dacetuzumab, Demcizumab, Dalotuzumab, Denintuzumab, Elotuzumab, Emactuzumab, Emibetuzumab, Enoblituzumab, Etaracizumab, Farletuzumab, Ficlatuzumab, Gemtuzumab, Imgatuzumab, Inotuzumab, Labetuzumab, Lifastuzumab, Lintuzumab, Lorvotuzumab, Lumretuzumab, Matuzumab, Milatuzumab, Nimotuzumab, Obinutuzumab, Ocaratuzumab, Otlertuzumab, Onartuzumab, Oportuzumab, Parsatuzumab, Pertuzumab, Pinatuzumab, Polatuzumab, Sibrotuzumab, Simtuzumab, Tacatuzumab, Tigatuzumab, Trastuzumab, Tucotuzumab, Vandortuzumab, Vanucizumab, Veltuzumab, Vorsetuzumab, Sofituzumab, Catumaxomab, Ertumaxomab, Depatuxizumab, Ontuxizumab, Blontuvetmab, Tamtuvetmab, or a tumor antigen- binding variant thereof. Suitable cytokines for use as a payload polypeptide in a subject ELP include, without limitation, Interleukin-1, Interleukin-2, Interleukin-3, Interleukin-4, Interleukin-5, Interleukin-6, Interleukin-7, Interleukin-9, Interleukin-11, Interleukin-12, Interleukin-13, Interleukin-15 , Interleukin-18, Interleukin-21 , Interleukin-23, Interleukin-27, TGF-β, IFN-λ, TNF-α, PD-L1, 4- 1BBL, OX40L, ICOSLG, and variants thereof. Suitable peptide hormones and / or growth factors for use as a payload polypeptide in a subject ELP include, without limitation, Human growth hormone (HGH), angiotensin, insulin, glucagon, glucagon-like peptide-1, vasopressin, vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and variants thereof. Therapeutic peptides suitable for use as a payload polypeptide are known in the art and described, for example, in Wang, Lei, et al. "Therapeutic peptides: current applications and future Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 directions." Signal transduction and targeted therapy 7.1 (2022): 48, the disclosure of which is incorporated by reference herein in its entirety. Conjugates In some embodiments, a subject ELP of the present disclosure is conjugated to a payload molecule. By “conjugated” it is meant that the payload molecule is covalently linked to the ELP via any suitable chemistry. The payload molecule can be any molecule that can exert a desired pharmacological, biological, or physical effect. The payload molecule can be conjugated to the ELP so that the ELP may function as an isothermally phas-separable delivery vehicle for the conjugated payload molecule. In some cases, the payload molecule may be a nucleic acid, a polypeptide, a carbohydrate, or a small molecule. In some embodiments, the payload molecule may be conjugated to a lysine residue present in the subject ELP. The linker moiety and / or payload molecule may be covalently attached via the primary amine of the lysine residue. In such cases, a linker moiety and / or the payload molecule may be reacted with the lysine via amide coupling using an activated carboxylic ester in the linker moiety. For example, the primary amine of the lysine can be reacted with N- hydroxysuccinimide (NHS) esters introduced into the linker moiety, forming a stable amide bond. Exemplary linker types that may be conjugated to a lysine residue include, without limitation, N- succinimidyl-4-(2-pyridyldithio)butanoate (SPDB) linkers, sulfo-SPDB linkers, maleimidomethyl cyclohexane-1-carboxylate (MCC), 4-(4-acetylphenoxy)butanoic acid (AcBut) linkers, and derivatives thereof. In some embodiments, the payload molecule may be conjugated to a cysteine residue present in the subject ELP. The linker moiety and / or payload molecule may be covalently attached via the thiol group of the cysteine residue. In such cases, free thiol groups of any cysteines in the subject ELP may serve as reactive attachment sites to conjugate the linker moiety and / or payload molecule via a variety of chemical reactions. In some cases, the subject ELP may be introduced to reducing conditions to ensure any disulfide bonds are reduced. For example, the linker moiety may be reacted with the free thiol group by Michael addition, a-halo carbonyl alkylation, or disulfide formation. Exemplary linker types that may be conjugated to a cysteine residue include, without limitation, maleimidocaproyl (MC) linkers, maleimidomethyl cyclohexane-1-carboxylate (MCC) linkers, and derivatives thereof. Available conjugation chemistries for attaching linker moieties to lysine and cysteine residues of a polypeptide (e.g., as in antibody-drug conjugates) are known in the art and reviewed, Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 for example, in Lu et al. 2016 (Lu, Jun, et al. "Linkers having a crucial role in antibody–drug conjugates." International journal of molecular sciences 17.4 (2016): 561), McDonagh et al.2006 (McDonagh, Charlotte F., et al. "Engineered antibody–drug conjugates with defined sites and stoichiometries of drug attachment." Protein Engineering, Design and Selection 19.7 (2006): 299- 307), and Sun et al. 2005 (Sun, Michael MC, et al. "Reduction− alkylation strategies for the modification of specific monoclonal antibody disulfides." Bioconjugate chemistry 16.5 (2005): 1282-1290). In addition, methods for conjugating linkers to cysteine residues of a polypeptide are described, for example, in WO 2014 / 197612. Exemplary linker moieties for conjugating a payload molecule to a subject ELP include, without limitation, maleimidocaproyl (MC) linkers, maleimidomethyl cyclohexane-1-carboxylate (MCC) linkers, N-succinimidyl-4-(maleimidomethyl) cyclohexane-1-carboxylate (SMCC) linkers, and derivatives thereof. In some embodiments, the linker moiety may be a cleavable linker moiety. In some cases, the cleavable linker may be a reducible or glutathione sensitive linker or comprises a reducible or glutathione sensitive moiety. For example, the release of a payload molecule from a reducible linker can be facilitated by a reducing environment and / or high glutathione concentration. Notably, glutathione is released during cell replication and thus proliferating cancer cells exhibit high concentrations of glutathione, offering an additional dimension of target-selectivity for delivery of the payload molecule. A suitable glutathione sensitive moiety for incorporation into a reducible linker is a disulfide moiety. In some embodiments, the linker moiety may be a pH sensitive (i.e., acid labile) linker moieties. Notably, tumor microenvironments are often acidic, and pH sensitive linker moieties can offer an additional dimension of target-selectivity for delivery of the payload molecule to a tumors. Suitable pH sensitive moieties for incorporation into an acid-labile linker include hydrazone moieties, which are hydrolyzed under acidic conditions. Additional acid-labile moieties that may be incorporated into a pH sensitive include carbonate and cis-aconityl moieties. Exemplary cleavable linker types that incorporate pH sensitive moieties include, without limitation, AcBut-like linkers incorporating a hydrazone moiety, MC-like linkers incorporating a hydrazone moiety, and MCC-like linkers incorporating a hydrazone moiety. In some embodiments, the payload molecule is conjugated to the second ELP domain. In such cases, the LCST of the second ELP domain may be less than the LCST of the first ELP Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 domain, such that, upon cleavage of the subject ELP, the second ELP domain that is conjugated to the payload molecule undergoes a phase transition. In some embodiments, the payload molecule may be a nucleic acid, e.g., an RNA or DNA oligonucleotide. A feature of nucleic acid payloads is the capability to offer highly selective modulation of, in theory, any gene of interest by designing to the nucleic acid payload to bind to a target nucleic acid through relatively simple Watson-Crick base pairing mechanisms. Nucleic acid payloads can be used to, for example, modulate the expression of a target gene through a variety of mechanisms that involve base-pairing to the target, e.g., base-pairing to a complementary sequence of a transcript of the target gene. In some embodiments, the nucleic acid payload molecule may be an anti-sense oligonucleotide (ASO). ASOs are designed to be complementary (i.e., anti-sense) to a target nucleic acid RNA transcript (e.g., an mRNA). In some cases, an ASO can modulate expression of a desired gene (e.g., a disease associated gene) by triggering degradation of the target gene transcript. For example, an DNA, or DNA-like, ASO can be designed to be complementary to a target RNA transcript and hybridize to form a DNA / RNA complex with the transcript. The ASO / transcript complex is then susceptible to the activity of RNAse H, which selectively degrades the RNA strands of DNA / RNA complexes, thereby degrading the hybridized target transcript. In some cases, the ASO can be designed to alter the expression of a specific isoform of a gene through modulation of RNA splicing. For example, an ASO can be designed to bind the intron-exon junction of the pre-mRNA of a target gene and sterically interfere with the spliceosome machinery and thereby alter splicing events. In some embodiments, the nucleic acid payload molecule may be a short-interfering RNA (siRNA). An siRNA is a double-stranded RNA molecule, a strand of which can hybridize to a complementary target RNA, that can induce degradation of the target RNA through recruitment of and incorporation into an RNA-induced silencing complex (RISC) in a target cell. In some embodiments, the payload molecule may be a polypeptide (i.e., a polypeptide that is covalently linked to the subject ELP, other than through a peptide bond as part of the ELP polypeptide chain. Suitable polypeptides for use as a payload molecule for a subject ELP include, without limitation, single-chain antibodies, cytokines, growth factors, peptide hormones, or therapeutic peptides as described herein. In some embodiments, the nucleic acid payload molecule of a subject ELP of the present disclosure comprises one or more modifications (e.g., a nucleobase modification, a sugar modification, a backbone modification) to improve, for example, affinity or the stability of the Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 nucleic acid payload in circulating plasma. Suitable nucleic acid modifications include, by way of example, locked nucleic acid (LNA) modified nucleotides, peptide nucleic acid (PNA) modified nucleotides, 2’-O-Methyl modified nucleotides, 2’ fluoro modified nucleotides, and phosphorothioate linkages, among others. Nucleic acid modifications useful for nucleic acids (e.g., RNA or DNA oligonucleotides) with therapeutic applications are known in the art and described, for example, in WO 2007 / 047913, Ochoa et al.2020 (Ochoa, Steven, and Valeria T. Milam. "Modified nucleic acids: Expanding the capabilities of functional oligonucleotides." Molecules 25.20 (2020): 4659), Kulkarni et al. 2021 (Kulkarni, Jayesh A., et al. "The current landscape of nucleic acid therapeutics." Nature nanotechnology 16.6 (2021): 630-643) and Moumné et al. 2022 (Moumné, Lara, Anne-Céline Marie, and Nicolas Crouvezier. "Oligonucleotide therapeutics: from discovery and development to patentability." Pharmaceutics 14.2 (2022): 260), of which the entirety of each is incorporated herein by reference. In some embodiments, the payload molecule may be a carbohydrate. Suitable carbohydrates for use a payload molecule include hyaluronic acids, glycosaminoglycans, chitosans, and the like. In some embodiments, the payload molecule may be a small molecule. Candidate small molecules comprise functional groups for structural interaction with proteins, particularly hydrogen bonding, and may include an amine, carbonyl, hydroxyl or carboxyl group, and in some instances two or more of the functional chemical groups. The candidate agents may include cyclical carbon or heterocyclic structures and / or aromatic or polyaromatic structures substituted with one or more of the above functional groups. In certain embodiments, the small molecule may be a modulator of a G-protein Couple Receptor (GPCR). GPCRs encompass the largest protein family encoded in the human genome and are involved in diverse physiological processes and have been implicated in many diseases ranging from type 2 diabetes to schizophrenia. GPCRs transduce extracellular signals in the form of varying ligands which induce a conformational change in the GPCR upon binding, subsequently leading to activation of G proteins and other downstream intracellular molecular pathways. GPCRs can be grouped into four classes based on their amino acid sequences: class A (rhodopsin-type), class B (secretin / adhesion-type), class C (glutamate-type), and class F (frizzled- type) GPCR subfamilies. The class A type GPCRs can be further subdivided into aminergic, peptide, lipid, protein, nucleotide, and steroid receptor GPCRs. Hundreds of known and clinically approved GPCR modulators are known in the art and reviewed extensively in several Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 publications, including Hauser et al. 2017 (Hauser, Alexander S., et al. "Trends in GPCR drug discovery: new agents, targets and indications." Nature reviews Drug discovery 16.12 (2017): 829-842) and Yang et al.2021 (Yang, Dehua, et al. "G protein-coupled receptors: structure-and function-based drug discovery." Signal transduction and targeted therapy 6.1 (2021): 7), of which the entirety of each is incorporated herein by reference. In some embodiments, the small molecule may be a microtubule inhibitor. Microtubule inhibitors are commonly used, e.g., to treat tumors. Microtubule assembly plays a critical role in cell division and cellular transport, among other key cellular functions, and inhibition of microtubule assembly leads to arrest of cell division and / or cell death. In some cases, the microtubule inhibitor may be an auristatin or analogues and derivatives thereof. Auristatins are synthetic analogues of the natural molecule Dolostatin 10, isolated from Dolabella Auricularia. Suitable auristatins and auristatin derivatives for use as a payload include, without limitation, monomethyl auristatin E (MMAE; CAS Registry No. 474645-27-7), monomethyl auristatin F (MMAF; CAS Registry No. 745017-94-1), and monomethyl auristatin D (MMAD; CAS Registry No.203849-91-6). In some cases, the microtubule inhibitor may be a maytansinoid or derivatives thereof. Maytansinoids are derived from the natural molecule maytansine, isolated from Maytenus ovatus. Suitable maytansinoids and maytansinoid derivatives for use as a payload include, without limitation, maytansine (CAS Registry No. 35846-53-8) and mertansine (DM1; CAS Registry No.139504-50-0). Other suitable microtubule inhibitors include, by way of example and without limitation, colchicine (CAS Registry No. 64868), halichondrin B (CAS Registry No. 103614-76-2), rhizoxin (CAS Registry No.90996-54-6), paclitaxel (CAS Registry No.33069-62- 4), and vinca alkaloids such as vindesine (CAS Registry No. 53643-48-4). Microtubule inhibitors / disrupting agents are known in the art and described, for example, in Wang et al.2023 (Wang, Xingyu, et al. "MicrotubuleǦtargeting agents for cancer treatment: Seven binding sites and three strategies." MedComm–Oncology 2.3 (2023): e46), the entirety of which is incorporated herein by reference. In some embodiments, the small molecule may be a DNA-damaging agent. DNA- damaging agents are commonly used, e.g., to treat tumors. DNA-damaging agents act through a variety of mechanisms and include, for example, alkylating agents, DNA intercalators, and topoisomerase inhibitors. In some cases, the DNA-damaging agent may be a calicheamicin or derivatives thereof. Calicheamicins are anticancer antiobiotics isolated from the actinomycete Micromonospora Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 echinospora spp. Calichensis. Calicheamicins bind the minor groove of DNA in a site-specific manner and reductive cleavage by thiols present in a cell generates reactive diradical species that lead to strand scission of the DNA and, subsequently, cell death. Suitable calicheamicins and calicheamicin derivatives for use as a payload include, without limitation, calicheamicin γ1 (CAS Registry No. 108212-75-5) and N-acetyl-gamma calicheamicin 1,2-dimethyl hydrazine. Calicheamicin and derivatives thereof are known in the art and described, for example, in Maiese at al. 1989 (Maiese, William M., et al. "Calicheamicins, a novel family of antitumor antibiotics: taxonomy, fermentation and biological properties." The Journal of antibiotics 42.4 (1989): 558- 563), the entirety of which is incorporated herein by reference. In some cases, the DNA-damaging agent may be a pyrrolobenzodiazepine (PBD) or derivatives thereof. PBDs can alkylate and cross-link opposite DNA strands, preventing strand separation during genomic replication and inducing cell death. Suitable PBDs for use as a payload include, without limitation, tesirine (SG3249; CAS Registry No.1595275-62-9) and SJG-136 (CAS Registry No.232931-57-6). PBDs and derivatives thereof are known in the art and are described, for example, in: Mantaj et al. 2017 (Mantaj, Julia, et al. "From anthramycin to pyrrolobenzodiazepine (PBD)Ǧcontaining antibody–drug conjugates (ADCs)." Angewandte Chemie International Edition 56.2 (2017): 462-488), the entirety of which is incorporated herein by reference. In some cases, the DNA-damaging agent may be a topoisomerase inhibitor, e.g., a topoisomerase I or topoisomerase II inhibitor. Topoisomerases are necessary for regulating DNA topology and torsional stresses during DNA replication, repair and transcription. In certain embodiments, the topoisomerase inhibitor may be a topoisomerase I inhibitor, e.g., a camptothecin or a derivative thereof. Camptothecin and its derivates inhibit topoisomerase I, inhibiting replication and causing cleavage of the DNA. Suitable camptothecins and camptothecin derivatives for use as a payload include, without limitation, camptothecin (CAS Registry No.7689- 03-4), topotecan (CAS Registry No. 123948-87-8), irinotecan (CAS Registry No. 97682-44-5), belotecan (CAS Registry No. 256411-32-2), exatecan (CAS Registry No. 171335-80-1), deruxtecan (CAS Registry No. 1599440-13-7), and SN-38 (CAS Registry No. 86639-52-3). In certain embodiments, the topoisomerase inhibitor may be a topoisomerase II inhibitor, e.g., an anthracycline, anthracenedione, acridine, epipodophyllotoxin, or derivatives thereof. Anthracyclines intercalate DNA and poison DNA-topoisomerase II complexes, inhibiting DNA replication and causing cell death. Additionally, anthracyclines generate free-radicals in an iron- dependent manner, further enhancing their cytotoxic effects. Suitable anthracycline and Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 anthracycline derivatives for use as a payload include, without limitation, doxorubicin (CAS Registry No. 23214-92-8), epirubicin (CAS Registry No. 56420-45-2), valrubicin (CAS Registry No. 56124-62-0), daunorubicin (CAS Registry No. 20830-81-3), idarubicin (CAS Registry No. 58957-92-9), and PNU-159682 (Cas Registry No.202350-68-3). Anthracenediones, acridines, epipodophyllotoxins, and derivatives thereof intercalate DNA and poison DNA-topoisomerase II complexes, inhibiting DNA replication and causing cell death. Suitable anthracenediones and anthracenedione derivatives for use as a payload include, without limitation, mitoxantrone (CAS Registry No. 65271-80-9) and pixantrone (CAS Registry No. 144510-96-3). Suitable epipodophyllotoxins and epipodophyllotoxin derivatives include, without limitation, etoposide (CAS Registry No.33419-42-0) and teniposide (CAS Registry No.29767-20-2). Various classes of topoisomerase inhibitors are known in the art and described, for example, in Yakkala et al.2023 (Yakkala PA, Penumallu NR, Shafi S, Kamal A. “Prospects of Topoisomerase Inhibitors as Promising Anti-Cancer Agents”. Pharmaceuticals (Basel).2023 Oct 13;16(10):1456), the entirety of which is incorporated herein by reference. In some cases, the DNA-damaging agent may be an alkylating agent. Alkylating agents interact with DNA and form covalent adducts to cross-link DNA or cross-link DNA with protein, leading to DNA cleavage, inhibition of replication, and cell death. Suitable alkylating agents for use as a payload include, without limitation, adozelesin (CAS Registry No. 110314-48-2) carboplatin (CAS Registry No.41575-94-4), chlorambucil (CAS Registry No.305-03-3), cisplatin (CAS Registry No.15663-27-1), cyclophosphamide (CAS Registry No.50-18-0), lomustine (CAS Registry No.13010-47-4), melphalan (CAS Registry No.148-82-3), mitomycin C (CAS Registry No.50-07-7) and temozolomide (CAS Registry No.85622-93-1). N-terminal Leader Domains In some embodiments, a subject ELP of the present disclosure comprises an N-terminal leader domain. The N-terminal leader domain is located at the N-terminus of the ELP and can generally range from, without limitation, 5 to 50 amino acids in length. The N-terminal leader domain may serve a variety of desired functions. As an example, an N-terminal leader domain may comprise tryptophan residues that facilitate visualization of the subject ELP using stain-free PAGE gels. As another example, an N-terminal leader domain may encode an epitope to facilitate immuno-detection of the ELP or to facilitate affinity purification of the ELP. In certain embodiments, the N-terminal leader domain encodes a signal peptide. A signal peptide may enable secretion of the subject ELP when the ELP is expressed in a cell (e.g., when Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 expressed in a eukaryotic cell). By way of example, suitable signal peptide amino acid sequences for use in a subject N-terminal leader domain include, without limitation, MKWVTFISLLFSSAYS (SEQ ID NO: 105), METDTLLLWVLLLWVPGSTG (SEQ ID NO: 106), and MKCLLYLAFLFIGVNC (SEQ ID NO: 107. Signal peptide sequences, in addition to methods for identifying them, are known in the art and described, for example, in Teufel, Felix, et al. "SignalP 6.0 predicts all five types of signal peptides using protein language models." Nature biotechnology 40.7 (2022): 1023- 1025, the disclosure of which is incorporated by reference herein in its entirety. Nucleic Acids The present disclosure also provides nucleic acids encoding a subject ELP as described herein. The subject nucleic acids may be DNA or RNA (e.g., double-stranded DNA or single- stranded RNA) comprising an open reading frame that encodes a subject ELP. The nucleic acids of the present disclosure are of any sufficient length to comprise an open reading frame that encodes a subject ELP. Because of the knowledge of the codons corresponding to the various amino acids, availability of an amino acid sequence of a polypeptide of interest provides a description of all the polynucleotides capable of encoding the polypeptide of interest. The degeneracy of the genetic code, where the same amino acids are encoded by alternative or synonymous codons allows an extremely large number of nucleic acids to be made, all of which encode an ELP as disclosed herein. Thus, having identified a particular amino acid sequence, those skilled in the art could make any number of different nucleic acids by simply modifying the sequence of one or more codons in a way which does not change the amino acid sequence of the polypeptide of interest. In this regard, the present disclosure specifically contemplates each and every possible variation of polynucleotides that could be made by selecting combinations based upon the possible codon choices, and all such variations are to be considered specifically disclosed for any ELP disclosed herein. The nucleotide sequences of the nucleic acids of the present disclosure may be codon- optimized. “Codon-optimized” refers to changes in the codons of the polynucleotide encoding a protein to those preferentially used in a particular organism such that the encoded protein is efficiently expressed in the organism of interest. Although the genetic code is degenerate in that most amino acids are represented by several codons, called “synonyms” or “synonymous” codons, it is well known that codon usage by particular organisms is nonrandom and biased towards particular codon triplets. This codon usage bias may be higher in reference to a given Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 gene, genes of common function or ancestral origin, highly expressed proteins versus low copy number proteins, and the aggregate protein coding regions of an organism's genome. In some embodiments, a nucleic acid of the present disclosure encoding a subject ELP may be codon- optimized for optimal production from the host organism selected for expression, e.g., human cells. The present disclosure additionally provides expression vectors comprising a nucleic acid encoding a subject ELP as described herein. In some embodiments, a subject expression vector may further comprise a nucleic acid sequence encoding a transgene. By “transgene” it is meant any gene that is heterologous or exogenous to the host cell harboring the expression vector. Any suitable transgene may be chosen by the person of skill in the art, depending on the desired goal or application. The term “expression vector”, as used herein, includes a recombinant DNA molecule containing a desired coding sequence and appropriate nucleic acid sequences necessary for the expression of the subject ELP in a particular host organism. Expression vectors can provide for extrachromosomal maintenance in a host cell or can provide for integration into the host cell genome. The expression vector provides transcriptional and translational regulatory sequences, and may provide for inducible or constitutive expression, where the coding region (e.g., encoding the subject ELP or encoding a transgene) is operably linked under the transcriptional control of the transcriptional initiation region, and a transcriptional and translational termination region. In general, the transcriptional and translational regulatory sequences may include, but are not limited to, promoter sequences, ribosomal binding sites, transcriptional start and stop sequences, translational start and stop sequences, and enhancer or activator sequences.. Suitable promoters for use in an expression vector described herein include any eukaryotic promoter (i.e., a promoter functional in a eukaryotic cell, e.g., a mammalian cell or a human cell). The promoter can be a constitutively active promoter (i.e., a promoter always in an active or “ON” state), and inducible promoter (i.e., a promoter whose activity is controlled by an external stimulus, e.g., a specific temperature, small molecule, or protein). Suitable eukaryotic promoters are well known in the art and include, without limitation, cytomegalovirus (CMV) immediate early promoters, herpes simplex virus (HSV) thymidine kinase promoters, SV40 early and late promoters, Rous-Sarcoma virus (RSV) promoters, β-actin promoters, tubulin promoters, and EF1α promoters. In some cases, the eukaryotic promoter may be a cell or tissue-specific promoter. Cell and tissue-specific Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 promoters are well known in the art and described, e.g., in “Tissue-specific Promoters” (www[.]invivogen[.]com / tissue-specific-promoters). In some embodiments, the nucleic acid encoding the ELP or the transgene may further comprise a ribosome binding site for initiation of translation (e.g., an internal ribosome entry site; IRES) and / or a transcription terminator. Expression constructs generally have convenient restriction sites located near the promoter sequence to provide for the insertion of nucleic acid sequences encoding proteins of interest. A selectable marker operative in the expression host may be present to facilitate selection of cells containing the vector. In addition, the expression construct may include additional elements. For example, the expression vector may have one or two replication systems, thus allowing it to be maintained in organisms, for example in mammalian cells for expression and in a prokaryotic host for cloning and amplification. In addition the expression construct may contain a selectable marker gene to allow the selection of transformed host cells. Selectable genes are well known in the art and will vary with the host cell used. In some cases, the expression vector may be an episome (i.e., a plasmid). The episome may include one or more elements in addition to the promoter region and the region that encodes the ELP (or transgene). As an example, the episome may include an origin of replication, one or more regions that encode a protein that confers antibiotic resistance to the host cell (e.g., ampicillin resistance (AmpR), hygromycin resistance, and / or the like), one or more poly(A) signals, a pause site, an SV40 late poly(A) signal, an SV40 enhancer, an SV40 early promoter, etc., and any desired combination of such elements. In some cases, the expression vector may be a viral vector. Viral vectors are known in the art and described, for example, in Warnock, James N., Claire Daigre, and Mohamed Al-Rubeai. "Introduction to viral vectors." Viral vectors for gene therapy: methods and protocols (2011): 1-25, the entirety of which is incorporated herein by reference. Suitable viral vectors for use in the present methods and compositions include, without limitation, adenovirus vectors (see, e.g., WO 94 / 12649, WO 93 / 03769; WO 93 / 19191; WO 94 / 28938; WO 95 / 11984 and WO 95 / 00655), adeno-associated virus (AAV) vectors (see, e.g., Ali et al., Hum Gene Ther 9:81 86, 1998, Flannery et al., PNAS 94:69166921, 1997), lentiviral and retroviral vectors (e.g., lentivirus, Rous- Sarcoma virus, Murine Leukemia virus, and human immunodeficiency virus related vectors). In some cases, the expression vector may be a non-viral vector. Non-viral vectors are known in the art and described, for example, in Yin, Hao, et al. "Non-viral vectors for gene-based therapy." Nature Reviews Genetics 15.8 (2014): 541-555, the entirety of which is incorporated Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 herein by reference. Suitable non-viral vectors for use in the present methods and compositions include, without limitation, lipid-based vectors (such as a liposome or lipid nanoparticle, see, e.g., Liposomes: Methods and Protocols, Volume 1: Pharmaceutical Nanocarriers: Methods and Protocols. (ed. Weissig). Humana Press, 2009, ISBN 160327359X. and Liposome Technology, volumes I, II & III, (ed. Gregoriadis). Informa Healthcare, 2006.), polymeric vectors (e.g., polymeric poly(L-lysine), poly(lactic acid), and poly(D,L-lactide-co-glycolide) vectors, see, e.g., Functional Polymer Colloids and Microparticles volume 4 (Microspheres, microcapsules & liposomes). (eds. Arshady & Guyot). Citus Books, 2002 and Polymers in Drug Delivery. (eds. Uchegbu & Schatzlein). CRC Press, 2006.) Host Cells The present disclosure provides cell comprising an expression vector as described herein. The cell comprising a subject expression vector is also referred to as a “host cell” herein. In some cases, the host cell is a eukaryotic cell. Suitable eukaryotic host cells include, without limitation, a plant (e.g., cells from plant crops, fruits, vegetables, grains, soy bean, corn, maize, wheat, seeds, tomatoes, rice, cassava, sugarcane, pumpkin, hay, potatoes, cotton, cannabis, tobacco, flowering plants, conifers, gymnosperms, angiosperms, ferns, clubmosses, hornworts, liverworts, mosses, dicotyledons, monocotyledons, etc.), an algal cell, (e.g., Botryococcus braunii, Chlamydomonas reinhardtii, Nannochloropsis gaditana, Chlorella pyrenoidosa, Sargassum patens, C. agardh, and the like), seaweeds (e.g. kelp) a fungal cell (e.g., a yeast cell, a cell from a mushroom), an animal cell, a cell from an invertebrate animal (e.g., fruit fly, cnidarian, echinoderm, nematode, etc.), a cell from a vertebrate animal (e.g., fish, amphibian, reptile, bird, mammal), a cell from a mammal (e.g., an ungulate (e.g., a pig, a cow, a goat, a sheep); a rodent (e.g., a rat, a mouse); a non-human primate; a human; a feline (e.g., a cat); a canine (e.g., a dog); etc.), and the like. In some cases, the cell is a cell that does not originate from a natural organism (e.g., the cell can be a synthetically made cell; also referred to as an artificial cell). A host cell may also be an in vitro cell (e.g., a cell culture line). A host cell may be an ex vivo cell, (e.g., derived and cultures from an individual). A host cell may also be an in vivo cell (e.g., a cell in an individual). A cell can be an isolated cell. A cell can be a cell inside of an organism. A cell can be an organism. A cell can be a cell in a cell culture (e.g., in vitro cell culture). A cell can be one of a collection of cells. A cell can be a eukaryotic cell or derived from a eukaryotic cell. A cell can be a plant cell or derived from a plant cell. A cell can be an animal cell or derived from an Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 animal cell. A cell can be an invertebrate cell or derived from an invertebrate cell. A cell can be a vertebrate cell or derived from a vertebrate cell. A cell can be a mammalian cell or derived from a mammalian cell. A cell can be a rodent cell or derived from a rodent cell. A cell can be a human cell or derived from a human cell. ELP Compositions The present disclosure provides ELP compositions comprising: a) a subject ELP (or ELP conjugate) as described herein; and b) a pharmaceutically acceptable excipient. In some cases, the pharmaceutically acceptable excipient may comprise a pharmaceutically acceptable salt. Suitable salts for use in a present composition include, without limitation, sodium chloride, sodium citrate, sodium benzoate, sodium phosphates (e.g., phosphate buffered saline), potassium phosphate, potassium citrate, calcium carbonate, and calcium phosphate, or combinations thereof. In some cases, the pharmaceutically acceptable excipient may comprise a pharmaceutically acceptable sugar or polyol. Suitable sugars or polyols for use in a present composition include, without limitation, sucrose, trehalose, mannose, mannitol, raffinose, lactitol, sorbitol and lactobionic acid, glucose, maltulose, iso-maltulose, lactulose, maltose, lactose, iso-maltose, maltitol, palatinit, stachyose, melezitose, dextran, or combinations thereof. In some cases, the pharmaceutically acceptable excipient may comprise an amino acid(s). Suitable amino acids for use in a present composition include, without limitation, glycine, arginine, lysine, and glutamine. In some cases, the pharmaceutically acceptable excipient may comprise water in combination with any other of the compounds described above. Methods Cell-Protective Biopolymers The present disclosure provides methods for assembling a cell-protective biopolymer on the surface of a target cell. In certain embodiments, the method for assembling the cell-protective biopolymer comprises contacting the surface of a target cell with a subject ELP, as disclosed herein, to assemble a cell-protective biopolymer, wherein the surface of the target cell comprises an enzyme that can cleave the enzymatic cleavage site of the ELP. In such embodiments, the ELP may be part of an ELP composition as described herein. In some embodiments, the enzyme may (e.g., a protease, a membrane-bound protease) be present on the surface of the cell. In such a case, the LCST of the second ELP domain may be less than the LCST of the first ELP domain, such that, Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 upon contact of the ELP with the enzyme on the surface of the target cell, the ELP is cleaved and thus enables the second ELP domain to undergo a phase transition and form a cell-protective biopolymer on the surface of the target cell. In some embodiments of the methods, the ELP may further comprise a payload polypeptide as disclosed herein (e.g., a payload polypeptide fused to the second ELP domain via linker). In some embodiments of the methods, the ELP may be conjugated to a payload molecule as disclosed herein (e.g., a payload molecule conjugated to the second ELP domain). In certain embodiments, the method for assembling the cell-protective biopolymer comprises expressing a subject ELP, as disclosed herein, in the target cell to assemble a cell- protective biopolymer on the surface of said cell, wherein the ELP is secreted by the target cell, and wherein the target cell comprises an enzyme that can cleave the enzymatic cleavage site of the ELP. In such embodiments, the target cell may comprise an expression vector encoding the subject ELP, as disclosed herein. In some cases, the enzyme (e.g., a protease, a membrane- bound protease) is present on the surface of the target cell. In such a case, the LCST of the second ELP domain may be less than the LCST of the first ELP domain, such that, upon secretion of the ELP, the ELP contacts the enzyme on the surface of the target cell. Following contact with the enzyme, the ELP is cleaved and thus enables the second ELP domain to undergo a phase transition and form a cell-protective biopolymer on the surface of the target cell. In some cases, the enzyme is present inside the target cell. For example, the enzyme (e.g., a protease) may be present in the endosomal network (e.g., the endoplasmic reticulum, the golgi, etc.). In such a case, the LCST of the second ELP domain may be less than the LCST of the first ELP domain, such that, during secretion of the ELP, the ELP contacts the enzyme inside of the target cell. Following contact with the enzyme inside the cell (e.g., inside the endosomal network) the ELP is cleaved and the second ELP domain is liberated. In such embodiments, the LCST of the second ELP domain may vary depending on pH, such that the second ELP domain is soluble inside the acidic endosomal system but undergoes a phase transition upon secretion from the target cell, thus forming a cell-protective biopolymer on the surface of the target cell. In some embodiments of the methods, the ELP may further comprise a payload polypeptide as disclosed herein (e.g., a payload polypeptide fused to the second ELP domain via linker). In some cases, the ELP may further comprise an N-terminal leader domain, wherein the N-terminal leader domain encodes a signal peptide as disclosed herein. In certain embodiments, the target cell comprises an expression vector encoding the subject ELP, as disclosed herein. In some particular Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 embodiments, said expression vector further comprises a nucleic acid sequence encoding a transgene, as described herein. The target cell may be a eukaryotic cell. Suitable eukaryotic cells include, without limitation, a plant (e.g., cells from plant crops, fruits, vegetables, grains, soy bean, corn, maize, wheat, seeds, tomatoes, rice, cassava, sugarcane, pumpkin, hay, potatoes, cotton, cannabis, tobacco, flowering plants, conifers, gymnosperms, angiosperms, ferns, clubmosses, hornworts, liverworts, mosses, dicotyledons, monocotyledons, etc.), an algal cell, (e.g., Botryococcus braunii, Chlamydomonas reinhardtii, Nannochloropsis gaditana, Chlorella pyrenoidosa, Sargassum patens, C. agardh, and the like), seaweeds (e.g. kelp) a fungal cell (e.g., a yeast cell, a cell from a mushroom), an animal cell, a cell from an invertebrate animal (e.g., fruit fly, cnidarian, echinoderm, nematode, etc.), a cell from a vertebrate animal (e.g., fish, amphibian, reptile, bird, mammal), a cell from a mammal (e.g., an ungulate (e.g., a pig, a cow, a goat, a sheep); a rodent (e.g., a rat, a mouse); a non-human primate; a human; a feline (e.g., a cat); a canine (e.g., a dog); etc.), and the like. In some cases, the cell is a cell that does not originate from a natural organism (e.g., the cell can be a synthetically made cell; also referred to as an artificial cell). The target cell may also be an in vitro cell (e.g., a cell culture line). A target cell may be an ex vivo cell, (e.g., derived and cultures from an individual). A target cell may also be an in vivo cell (e.g., a cell in an individual). A cell can be an isolated cell. A cell can be a cell inside of an organism. A cell can be an organism. A cell can be a cell in a cell culture (e.g., in vitro cell culture). A cell can be one of a collection of cells. A cell can be a eukaryotic cell or derived from a eukaryotic cell. A cell can be a plant cell or derived from a plant cell. A cell can be an animal cell or derived from an animal cell. A cell can be an invertebrate cell or derived from an invertebrate cell. A cell can be a vertebrate cell or derived from a vertebrate cell. A cell can be a mammalian cell or derived from a mammalian cell. A cell can be a rodent cell or derived from a rodent cell. A cell can be a human cell or derived from a human cell. In some embodiments of the methods, the ELP may be non-immunogenic. In such cases, the cell-protective biopolymer formed by the subject ELP will likewise be non-immunogenic. Such cell-protective biopolymers find use in shielding the target cell (e.g., a genetically modified target cell expressing a therapeutic transgene) from being targeted from the immune system of the host organism or subject harboring the target cell. Reducing Blood Loss at a Hemorrhage Site Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 The present disclosure provides methods for reducing blood loss at a hemorrhage site in a subject, the method comprising administering to a hemorrhage site in a subject an effective amount of a subject ELP composition, as disclosed herein, to reduce blood loss at the hemorrhage site, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the hemorrhage site. In some embodiments, the LCST of the second ELP domain may be less than the LCST of the first ELP domain, such that, upon contact of the ELP with the enzyme present in or around the hemorrhage site, the ELP is cleaved thus enabling the second ELP domain to undergo a phase transition and form a physical barrier at the hemorrhage site to reduce bleeding loss. In some embodiments, the enzymatic cleavage of the subject ELP is a protease cleavage site. In some cases, the protease cleavage site is a cleavage site for a protease of the clotting cascade. Suitable clotting cascade protease cleavage sites include, without limitation, a thrombin cleavage site, a factor Xa cleavage site, a factor VIIa cleavage site, a factor IXa cleavage site, a factor XIa cleavage site, a factor XIIa cleavage site, a kallikrein cleavage site, or a plasmin cleavage site, each as described herein. In such cases, the enzyme that can cleave said cleavage site and is present in or around the hemorrhage site may be a thrombin, a factor Xa, a factor VIIa, a factor IXa, a factor XIa, a factor XIIa, a kallikrein, or a plasmin. In some embodiments, the hemorrhage site is an external hemorrhage site. In some embodiments, the hemorrhage site is an internal hemorrhage site. The hemorrhage site, whether external or internal, may be at the site of a wound. The wound may be a surgical wound or a trauma wound (e.g., a surgical or traumatic soft tissue wound). In some cases, the present methods may find use in reducing blood loss at a hemorrhage site in a subject under coagulopathic conditions. By “coagulopathic conditions” it is meant a condition where clot formation in a subject is impaired (i.e., coagulopathy). Coagulopathy may include one or more of a subset of conditions, such as dilution, hypothermia and acidosis. The wounds may vary in severity, ranging from superficial skin wounds to wounds involving the laceration or rupture of a major artery or vein (e.g., the femoral artery). In some embodiments of the present methods, the administering comprises applying a subject ELP composition to the external hemorrhage site. In such embodiments, the subject ELP composition may be applied via a substrate that is directly applied to the external hemorrhage wound. The substrate may be a sterile sponge, gauze, bandage, compression bandage, pillow (e.g., to facilitate application to a head wound), sleeve (e.g., for covering a wound on a limb), and Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 the like. For example, the ELP composition may permeate at least a portion of an absorbent substrate (e.g., a portion of a sponge, gauze, or bandage). In some cases, the ELP composition may be directly to the external hemorrhage site via a swab, spray, or aerosol. The substrate material may be composed of a natural fiber or polymer (e.g., cotton, silk, wool). The substrate material may be composed of a synthetic fiber or polymer (e.g., rayon or polyester). In some embodiments of the present methods, the administering comprises intravenously administering the ELP composition to the subject. In some cases, the methods comprise intravenously administering the ELP composition to a subject having an internal hemorrhage site. Said methods may include locating an appropriate intravenous site on the subject and injecting a subject ELP composition into the subject at the intravenous site. Upon injection of the ELP composition into the subject, the ELP composition may circulate through the circulatory system of the subject until cleaved by the corresponding enzyme present in or around the hemorrhage site. Therapeutic Agent Delivery The present disclosure provides methods for delivering a therapeutic agent to a target site in a subject, said methods comprising administering a subject ELP composition, as disclosed herein, to a subject, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the target site. In some embodiments, the LCST of the second ELP domain may be less than the LCST of the first ELP domain, such that, upon contact of the ELP with the enzyme present in or around the target site, the ELP is cleaved thus enabling the second ELP domain to undergo a phase transition and assemble in or around the target site (e.g., in some cases the second ELP domain may coat the target site). In such cases, the ELP may serve as a targeted and / or controlled release vehicle for a payload polypeptide or conjugates payload molecule as described herein. In some embodiments, the enzymatic cleavage site of the ELP may be a protease cleavage site. In such cases, the corresponding enzyme present in or around the target site is the corresponding protease. In some embodiments of the present methods, the administering comprises intravenously administering the ELP composition to the subject. Said methods may include locating an appropriate intravenous site on the subject and injecting a subject ELP composition into the subject at the intravenous site. Upon injection of the ELP composition into the subject, the ELP composition may circulate through the circulatory system of the subject until cleaved by the corresponding enzyme present in or around the target site. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 In some embodiments of the present methods, the administering may comprise intramuscular injection, intradermal injection, or subcutaneous injection of the ELP composition in a subject. Upon injection of the ELP composition into the subject, the ELP composition may diffuse into the circulatory system of the subject and circulate throughout the body until cleaved by the corresponding enzyme present in or around the target site. In some cases, the injection site may be at or near the target site. In such cases, the ELP composition may diffuse into the surrounding tissue, which may encompass the target site, until cleaved by the corresponding enzyme present in or around the target site. In some particular embodiments, the target site may be a tumor. “Tumor”, as used herein, refers to all neoplastic cell growth and proliferation, whether malignant or benign, and all pre- cancerous and cancerous cells and tissues. The tumor may be a solid tumor, a semi-solid tumor, a primary tumor, a metastatic tumor, and the like. In such embodiments, the enzymatic cleavage site of the ELP may be a protease cleavage site. In such cases, the corresponding enzyme present in or around the target site is the corresponding protease. In some embodiments of the present methods, the protease cleavage site is a matrix metalloproteinase cleavage site. The controlled remodeling of the extracellular matrix (ECM) is necessary for the growth, invasion of surrounding tissue, and metastasis of cancerous tumors. Matrix metalloproteinases can degrade ECM material and are known to play a role in tumor growth. It is also known that many tumors over-express MMPs. Suitable MMP cleavage sites for use in an ELP of the present methods include, without limitation, a MMP-1 cleavage site, a MMP-13 cleavage site, a MMP-11 cleavage site, a MMP-12 cleavage site, a MMP-7 cleavage site, a MMP-26 cleavage site, a MMP-2 cleavage site, a MMP-9 cleavage site, a MMP-14 cleavage site, a MMP-16 cleavage site, a MMP- 17 cleavage site, a MMP-24 cleavage site, and a MMP-25 cleavage site, as described herein. In some embodiments of the methods, the subject ELP may comprise a payload polypeptide (e.g., a payload polypeptide fused to the second ELP domain via a linker). In some embodiments, the payload polypeptide may comprise a single-chain antibody comprising variable domains derived from Adecatumumab, Ascrinvacumab, Cixutumumab, Conatumumab, Daratumumab, Drozitumab, Duligotumab, Durvalumab, Dusigitumab, Enfortumab, Enoticumab, Figitumumab, Ganitumab, Glembatumumab, Intetumumab, Ipilimumab, Iratumumab, Icrucumab, Lexatumumab, Lucatumumab, Mapatumumab, Narnatumab, Necitumumab, Nesvacumab, Ofatumumab, Olaratumab, Panitumumab, Patritumab, Pritumumab, Radretumab, Ramucirumab, Rilotumumab, Robatumumab, Seribantumab, Tarextumab, Teprotumumab, Tovetumab, Vantictumab, Vesencumab, Votumumab, Zalutumumab, Flanvotumab, Altumomab, Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 Anatumomab, Arcitumomab, Bectumomab, Blinatumomab, Detumomab, Ibritumomab, Minretumomab, Mitumomab, Moxetumomab, Naptumomab, Nofetumomab, Pemtumomab, Pintumomab, Racotumomab, Satumomab, Solitomab, Taplitumomab, Tenatumomab, Tositumomab, Tremelimumab, Abagovomab, Igovomab, Oregovomab, Capromab, Edrecolomab, Nacolomab, Amatuximab, Bavituximab, Brentuximab, Cetuximab, Derlotuximab, Dinutuximab, Ensituximab, Futuximab, Girentuximab, Indatuximab, Isatuximab, Margetuximab, Rituximab, Siltuximab, Ublituximab, Ecromeximab, Abituzumab, Alemtuzumab, Bevacizumab, Bivatuzumab, Brontictuzumab, Cantuzumab, Cantuzumab, Citatuzumab, Clivatuzumab, Dacetuzumab, Demcizumab, Dalotuzumab, Denintuzumab, Elotuzumab, Emactuzumab, Emibetuzumab, Enoblituzumab, Etaracizumab, Farletuzumab, Ficlatuzumab, Gemtuzumab, Imgatuzumab, Inotuzumab, Labetuzumab, Lifastuzumab, Lintuzumab, Lorvotuzumab, Lumretuzumab, Matuzumab, Milatuzumab, Nimotuzumab, Obinutuzumab, Ocaratuzumab, Otlertuzumab, Onartuzumab, Oportuzumab, Parsatuzumab, Pertuzumab, Pinatuzumab, Polatuzumab, Sibrotuzumab, Simtuzumab, Tacatuzumab, Tigatuzumab, Trastuzumab, Tucotuzumab, Vandortuzumab, Vanucizumab, Veltuzumab, Vorsetuzumab, Sofituzumab, Catumaxomab, Ertumaxomab, Depatuxizumab, Ontuxizumab, Blontuvetmab, Tamtuvetmab, or a tumor antigen- binding variant thereof. In some embodiments, the payload polypeptide may comprise a cytokine, such as Interleukin-1, Interleukin-2, Interleukin-3, Interleukin-4, Interleukin-5, Interleukin-6, Interleukin-7, Interleukin-9, Interleukin-11, Interleukin-12, Interleukin-13, Interleukin-15 , Interleukin-18, Interleukin-21 , Interleukin-23, Interleukin-27, TGF-β, IFN-λ, TNF-α, PD-L1, 4- 1BBL, OX40L, ICOSLG, or variants thereof. In some embodiments of the methods, the subject ELP may be conjugated to a payload molecule (e.g., a payload molecule conjugated to the second ELP domain). In some cases, the payload molecule may be a microtubule inhibitor as disclosed herein, such as an auristatin, a maytansinoid, or a derivatives thereof. In some embodiments, the payload molecule may be a DNA-damaging agent. In some cases, the DNA-damaging agent may be a calicheamicin, a pyrrolobenzodiazepine, a topoisomerase inhibitor, or an alkylating agent as disclosed herein. Tissue Scaffolds The present disclosure provides methods for producing a tissue scaffold at site of injury in a subject, the methods comprising administering a subject ELP composition to a subject, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the site of injury. In some embodiments, the LCST of the second ELP domain may be less than the LCST Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 of the first ELP domain, such that, upon contact of the ELP with the enzyme present in or around the site of injury, the ELP is cleaved thus enabling the second ELP domain to undergo a phase transition and assemble a tissue scaffold that facilitates regrowth of tissue at the site of injury. In some embodiments of the present methods, the administering comprises applying a subject ELP composition to the site of injury. In such embodiments, the subject ELP composition may be applied directly to the site of injury via a syringe, swab, spray, or aerosol. In some embodiments of the present methods, the administering comprises intramuscular injection, intradermal injection, or subcutaneous injection of the ELP composition in a subject. Upon injection of the ELP composition into the subject, the ELP composition may diffuse into the circulatory system of the subject and circulate throughout the body until cleaved by the corresponding enzyme present in or around the site of injury. In some cases, the injection site may be at or near the site of injury. In such cases, the ELP composition may diffuse into the surrounding tissue, which may encompass the site of injury, until cleaved by the corresponding enzyme present in or around the site of injury. Kits The present disclosure provides kits, said kits comprising: a) a subject ELP as disclosed herein; and b) a pharmaceutical excipient. In some cases, the subject ELP may comprise a payload polypeptide (e.g., a payload polypeptide fused to the second ELP domain via linker). In some cases, the subject ELP may be conjugated to a payload molecule (e.g., a payload molecule conjugated to the second ELP domain). In some embodiments, the subject ELP may be in liquid form. In some embodiments, the subject ELP may be lyophilized. In such cases, the lyophilized ELP may be resuspended in the pharmaceutically acceptable excipient (e.g., when the pharmaceutically acceptable excipient is in liquid form). In some cases, the pharmaceutically acceptable excipient may comprise a pharmaceutically acceptable salt. Suitable salts for use in a present composition include, without limitation, sodium chloride, sodium citrate, sodium benzoate, sodium phosphates (e.g., phosphate buffered saline), potassium phosphate, potassium citrate, calcium carbonate, and calcium phosphate, or combinations thereof. In some cases, the pharmaceutically acceptable excipient may comprise a pharmaceutically acceptable sugar or polyol. Suitable sugars or polyols for use Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 in a present composition include, without limitation, sucrose, trehalose, mannose, mannitol, raffinose, lactitol, sorbitol and lactobionic acid, glucose, maltulose, iso-maltulose, lactulose, maltose, lactose, iso-maltose, maltitol, palatinit, stachyose, melezitose, dextran, or combinations thereof. In some cases, the pharmaceutically acceptable excipient may comprise an amino acid(s). Suitable amino acids for use in a present composition include, without limitation, glycine, arginine, lysine, and glutamine. In some cases, the pharmaceutically acceptable excipient may comprise water in combination with any other of the compounds described above. A subject kit may further comprise one or more containers for storing the ELP and / or the pharmaceutically acceptable excipient. In some cases, the size of the container may depend on the volume of the ELP (in lyophilized or liquid form) to be held in the container. In certain embodiments, the container may be configured to hold an amount of a subject ELP and / or pharmaceutically acceptable excipient, ranging from 0.1 mg to 1000 mg, such as from 0.1 mg to 900 mg, such as from 0.1 mg to 800 mg, such as from 0.1 mg to 700 mg, such as from 0.1 mg to 600 mg, such as from 0.1 mg to 500 mg, such as from 0.1 mg to 400 mg, or 0.1 mg to 300 mg, or 0.1 mg to 200 mg, or 0.1 mg to 100 mg, 0.1 mg to 90 mg, or 0.1 mg to 80 mg, or 0.1 mg to 70 mg, or 0.1 mg to 60 mg, or 0.1 mg to 50 mg, or 0.1 mg to 40 mg, or 0.1 mg to 30 mg, or 0.1 mg to 25 mg, or 0.1 mg to 20 mg, or 0.1 mg to 15 mg, or 0.1 mg to 10 mg, or 0.1 mg to 5 mg, or 0.1 mg to 1 mg, or 0.1 mg to 0.5 mg. In some cases, the container is configured to hold an amount of ELP (in lyophilized or liquid form) and / or pharmaceutically acceptable excipient, ranging from 0.1 g to 10 g, or 0.1 g to 5 g, or 0.1 g to 1 g, or 0.1 g to 0.5 g. In some instances, the container may be configured to hold a volume (e.g., a volume of a liquid) ranging from 0.1 ml to 1000 ml, such as from 0.1 ml to 900 ml, or 0.1 ml to 800 ml, or 0.1 ml to 700 ml, or 0.1 ml to 600 ml, or 0.1 ml to 500 ml, or 0.1 ml to 400 ml, or 0.1 ml to 300 ml, or 0.1 ml to 200 ml, or 0.1 ml to 100 ml, or 0.1 ml to 50 ml, or 0.1 ml to 25 ml, or 0.1 ml to 10 ml, or 0.1 ml to 5 ml, or 0.1 ml to 1 ml, or 0.1 ml to 0.5 ml. In some cases, the container is configured to hold a volume ranging from 0.1 ml to 200 ml. Suitable containers for the compositions include, for example, bottles, vials, syringes, and test tubes. Containers can be formed from a variety of suitable materials, including glass or plastic. For example, the container may be composed of glass, such as, but not limited to, silicate glass, borosilicate glass, sodium borosilicate glass (e.g., PYREXTM), fused quartz glass, fused silica glass, and the like. Other examples of suitable materials for the containers include plastics, such as, but not limited to, polypropylene, polymethylpentene, polytetrafluoroethylene (PTFE), perfluoroethers (PFE), fluorinated ethylene propylene (FEP), perfluoroalkoxy alkanes (PFA), polyethylene terephthalate (PET), polyethylene (PE), polyetheretherketone (PEEK), and the like. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 In some embodiments, the container may be sealed. That is, the container may include a seal that substantially prevents the contents of the container from exiting the container. The seal of the container may also substantially prevent other substances from entering the container. For example, the seal may be a water-tight seal that substantially prevents liquids from entering or exiting the container, or may be an air-tight seal that substantially prevents gases from entering or exiting the container. In some instances, the seal is a removable or breakable seal, such that the contents of the container may be exposed to the surrounding environment when so desired, e.g., if it is desired to remove a portion of the contents of the container. In some instances, the seal is made of a resilient material to provide a barrier (e.g., a water-tight and / or air-tight seal) for retaining a sample in the container. Particular types of seals include, but are not limited to, films, such as polymer films, caps, etc., depending on the type of container. Suitable materials for the seal include, for example, rubber or polymer seals, such as, but not limited to, silicone rubber, natural rubber, styrene butadiene rubber, ethylene-propylene copolymers, polychloroprene, polyacrylate, polybutadiene, polyurethane, styrene butadiene, and the like, and combinations thereof. A container may have a sterile access port (for example, the container may be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle). In some embodiments, the kit may further comprise a syringe, needle, or cannula. In some embodiments, the kit may further comprise a substrate material. In some cases, the substrate material may be a sterile sponge, gauze, bandage, compression bandage, pillow, sleeve, and the like. The substrate may be any permeable or semi-permeable substrate that would enable absorption of the subject ELP into at least a portion of the substrate when the ELP is applied to the substrate. The substrate material may be composed of a natural fiber or polymer (e.g., cotton, silk, wool). The substrate material may be composed of a synthetic fiber or polymer (e.g., rayon or polyester). The present disclosure additionally provides kits comprising: a) a subject expression vector comprising a nucleic acid encoding a subject ELP as disclosed herein; b) an endonuclease; and c) a ligase. As noted above, a subject expression vector may comprise convenient restriction sites (i.e., restriction endonuclease sites) located near a promoter sequence to provide for the insertion of nucleic acid sequences encoding proteins of interest. In certain embodiments, the restriction site present in the expression vector is for a restriction endonuclease that generates cohesive (or “sticky”) ends, including but not limited to, AscI, Aval, BamHI, BclI, BglII, BstEI, Bst, BI, BstYI, Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 EcoRI, MluI, NarI, NheI, NotI, PstI, PvuI, SacI, SalI, SpeI, StyI, XbaI, XhoI and XmaI. According to some embodiments, the restriction site present in expression vector is for a restriction endonuclease that generates blunt ends, including but not limited to, EcoRV, FspI, NaeI, NruI, PvuII, SmaI, SnaBI, and StuI. In some embodiments, the endonuclease may be restriction endonuclease that generates cohesive (or “sticky”) ends, including but not limited to, AscI, Aval, BamHI, BclI, BglII, BstEI, Bst, BI, BstYI, EcoRI, MluI, NarI, NheI, NotI, PstI, PvuI, SacI, SalI, SpeI, StyI, XbaI, XhoI and XmaI. In some embodiments, the endonuclease is a restriction endonuclease that generates blunt ends, including but not limited to, EcoRV, FspI, NaeI, NruI, PvuII, SmaI, SnaBI, and StuI. In some embodiments, the ligase may be, without limitation, a T4 DNA ligase, a T7 DNA ligase, a T3 DNA ligase or a Taq DNA ligase. The endonuclease and / or ligase may be contained inside any suitable container as discussed above. Each of the kits described above may further include instructions for practicing one or more of the subject methods described herein. For example, a subject kit may include instructions for applying a subject ELP composition to a substrate (e.g., a gauze) for application to a hemorrhage site in a subject. As another example, a subject kit may include instructions for cloning a transgene into the expression vector comprising a nucleic acid encoding a subject ELP. One form in which these instructions may be present is as printed information on a suitable medium or substrate, e.g., a piece or pieces of paper on which the information is printed, in the packaging of the kit, in a package insert, and the like. Yet another form of these instructions is a computer readable medium, e.g., diskette, compact disk (CD), DVD, flash drive, and the like, on which the information has been recorded. Yet another form of these instructions that may be present is a website address which may be used via the internet to access the information at a removed site. For purposes of completeness, non-limiting aspects and embodiments of the present disclosure are further disclosed in the following numbered clauses. 1. An isothermally phase-separable elastin-like polypeptide (ELP), the ELP comprising: i) a first ELP domain having a first lower critical solution temperature (LCST); and ii) a second ELP domain having a second LCST that is different from the first LCST, wherein the first and second ELP domains are separated by an enzymatic cleavage site. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 2. The ELP of Clause 1, wherein the first LCST is greater than the second LCST. 3. The ELP of Clauses 1 or 2, wherein the first and second ELP domain each comprises one or more pentapeptide repeats. 4. The ELP of Clause 3, wherein each pentapeptide repeat comprises an amino acid sequence VPGXG (SEQ ID NO:1), wherein X is any amino acid other than proline. 5. The ELP of Clause 4, wherein each pentapeptide repeat comprises an amino acid sequence VPGXG (SEQ ID NO:2), wherein X is selected from valine, alanine, glycine, lysine, histidine, serine, and glutamate. 6. The ELP of Clause 5, wherein: i) The first ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5), VPGAG (SEQ ID NO:6), VPGGG (SEQ ID NO:7), VPGKG (SEQ ID NO:8), VPGSG (SEQ ID NO:9), and VPGEG (SEQ ID NO:10); and ii) The second ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5) and VPGHG (SEQ ID NO:11). 7. The ELP of any one of clauses 3-6, wherein the first and second ELP domain each comprises from 1 to 250 pentapeptide repeats. 8. The ELP of Clause 7, wherein: i) the first ELP domain comprises from 50 to 150 pentapeptide repeats; and ii) the second ELP domain comprises 30 to 90 pentapeptide repeats. 9. The ELP of Clause 8, wherein: i) the first ELP domain comprises from 75 to 125 pentapeptide repeats; and ii) the second ELP domain comprises 45 to 75 pentapeptide repeats. 10. The ELP of any one of clauses 4-9, wherein: i) the first ELP domain comprises an amino acid sequence having at least 80% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:12; and Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 ii) the second ELP domain comprises an amino acid sequence having at least 80% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:13. 11. The ELP of any one of clauses 4-10, wherein: i) the first ELP domain comprises the amino acid sequence set forth in SEQ ID NO:12; and ii) the second ELP domain comprises the amino acid sequence set forth in SEQ ID NO:13. 12. The ELP of any one of clauses 1-11, wherein the first and second ELP domains are separated by two or more enzymatic cleavage sites. 13. The ELP of any one of clauses 1-12, wherein the enzymatic cleavage site is a protease cleavage site. 14. The ELP of Clause 13, wherein the protease cleavage site is a cleavage site for a eukaryotic protease, a prokaryotic protease, or a viral protease. 15. The ELP of Clause 14, wherein the protease cleavage site is selected from: a TEV protease cleavage site, an enterokinase cleavage site a thrombin cleavage site, a factor Xa cleavage site, a factor VIIa cleavage site, a factor IXa cleavage site, a factor XIa cleavage site, a factor XIIa cleavage site, a kallikrein cleavage site, a plasmin cleavage site, a furin cleavage site, a matrix metalloproteinase cleavage site, a caspase cleavage site, a paracaspase cleavage site, a granzyme B cleavage site, and a proline-endopeptidase cleavage site. 16. The ELP of any one of clauses 1-15, wherein the ELP further comprises: i) a first linker between the first ELP domain and the enzymatic cleavage site; and / or ii) a second linker between the second ELP domain and the enzymatic cleavage site. 17. The ELP of Clause 16, wherein the first and second linkers each comprise an amino acid sequence comprising: a) the amino acid sequence set forth in SEQ ID NO: 14; or b) the amino acid sequence set forth in SEQ ID NO: 15, wherein n is an integer equal to or greater than 1. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 18. The ELP of Clause 16 or 17, wherein the ELP comprises, in order from N-terminus to C-terminus: a1) the first ELP domain; b1) the first linker; c1) the enzymatic cleavage site; d1) the second linker; and e1) the second ELP domain, or a2) the second ELP domain; b2) the second linker; c2) the enzymatic cleavage site; d2) the first linker; and e2) the first ELP domain. 19. The ELP of any one of clauses 1-18, wherein the ELP further comprises a payload polypeptide. 20. The ELP of Clause 19, wherein the payload polypeptide comprises a single-chain antibody, a cytokine, a growth factor, a peptide hormone, or a therapeutic peptide. 21. The ELP of Clause 19 or 20, wherein the payload polypeptide is fused to the second ELP domain via a linker. 22. The ELP of Clause 21, wherein the payload polypeptide: a) is fused N-terminally to the second ELP domain; or b) is fused C-terminally to the second ELP domain. 23. The ELP of any one of clauses 1-22, wherein the ELP further comprises an N- terminal leader domain. 24. The ELP of Clause 23, wherein the N-terminal leader domain encodes a signal peptide. 25. The ELP of any one of Clauses 1-24, wherein the ELP is non-immunogenic. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 26. The ELP of any one of clauses 1-25, wherein the ELP is conjugated to a payload molecule. 27. The ELP of Clause 26, wherein the payload molecule is a nucleic acid, a polypeptide, a carbohydrate, or a small molecule. 28. The ELP of Clause 26 or 27, wherein the payload molecule is conjugated to the second ELP domain. 29. A nucleic acid encoding the ELP of any one of clauses 1-25. 30. An expression vector comprising the nucleic acid of Clause 29. 31. The expression vector of Clause 30, wherein the expression vector further comprises a nucleic acid sequence encoding a transgene. 32. A cell comprising the expression vector of Clause 31. 33. The cell of Clause 32, wherein the cell is a eukaryotic cell. 34. The cell of Clause 33, wherein the eukaryotic cell is a mammalian cell. 35. The cell of Clause 34, wherein the mammalian cell is a human cell. 36. The cell of any one of clauses 32-35, wherein the cell is in vivo. 37. An ELP composition comprising: a) an ELP of any one of clauses 1-28; and b) a pharmaceutically acceptable excipient. 38. A method for assembling a cell-protective biopolymer on the surface of a target cell, the method comprising: contacting the surface of a target cell with an ELP of any one of clauses 1-25 to assemble a cell-protective biopolymer, wherein the surface of the target cell comprises an enzyme that can cleave the enzymatic cleavage site of the ELP. 39. A method for assembling a cell-protective biopolymer on the surface of a target cell, the method comprising: Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 expressing an ELP of any one of clauses 1-25 in the target cell to assemble a cell- protective biopolymer on the surface of said cell, wherein the ELP is secreted by the target cell, and wherein the target cell comprises an enzyme that can cleave the enzymatic cleavage site of the ELP. 40. The method of Clause 39, wherein the target cell comprises the expression vector of Clause 30 or 31. 41 The method of Clause 39 or 40, wherein the enzyme is present on the surface of the target cell. 42. The method of Clause 39 or 40, wherein the enzyme is present inside of the target cell. 43. The method of any one of clauses 38-42, wherein the target cell is a eukaryotic cell. 44. The method of Clause 43, wherein the eukaryotic cell is a mammalian cell. 45. The method of Clause 44, wherein the mammalian cell is a human cell. 46. The method of any one of clauses 43-45, wherein the target cell is in vivo. 47. The method of any one of clauses 38-46, wherein the target cell expresses a transgene. 48. A method for reducing blood loss at a hemorrhage site in a subject, the method comprising: administering to a hemorrhage site in a subject an effective amount of an ELP composition according to clause 37 to reduce blood loss at the hemorrhage site, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the hemorrhage site. 49. The method of Clause 48, wherein the enzymatic cleavage site of the ELP is a protease cleavage site. 50. The method of Clause 49, wherein the protease cleavage site is a thrombin cleavage site or a factor Xa cleavage site. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 51. The method of any one of clauses 48-50, wherein the hemorrhage site is an external hemorrhage site. 52. The method of Clause 51, wherein the administering comprises applying the ELP composition to the external hemorrhage site. 53. The method of any one of clauses 48-50, wherein the hemorrhage site is an internal hemorrhage site. 54. The method of Clause 53, wherein the administering comprises intravenously administering the ELP composition to the subject. 55. A method for delivering a therapeutic agent to a target site in a subject, the method comprising: administering an ELP composition according to Clause 37 to a subject, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the target site. 56. The method of Clause 55, wherein the administering comprises intravenously administering the ELP composition to the subject. 57. The method of Clause 55 wherein the administering comprises intramuscular injection, intradermal injection, or subcutaneous injection of the ELP composition in a subject. 58. The method of any one of clauses 55-57, wherein the target site is a tumor. 59. The method of Clause 58, wherein the enzymatic cleavage site of the ELP is a protease cleavage site. 60. The method of Clause 59, wherein protease cleavage site is a matrix metalloproteinase cleavage site. 61. A method for producing a tissue scaffold at a site of injury in a subject, the method comprising: administering an ELP composition according to Clause 37 to a subject, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the site of injury. Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 62. The method of Clause 61, wherein the administering comprises applying the ELP composition to the site of injury. 63. The method of Clause 61, wherein the administering comprises intramuscular injection, intradermal injection, or subcutaneous injection of the ELP composition in a subject. 64. A kit comprising: a) an ELP according to any one of clauses 1-28; and b) a pharmaceutical excipient. 65. The kit of Clause 64, wherein the ELP is lyophilized. 66. The kit of Clauses 64 or 65, wherein the kit further comprises a substrate material. 67. The kit of Clause 66, wherein the substrate material comprises a gauze. 68. The kit of any one of Clauses 64-67, wherein the kit further comprises a syringe. 69. A kit comprising: a) an expression vector according to Clause 30; b) an endonuclease; and c) a ligase. The following examples are provided by way of illustrations and not by way of limitation. EXAMPLES Example 1 Discovery of non-immunogenic biopolymers to protect genetically altered cells Goals & Objectives: This research seeks to discover biopolymers that protect genetically modified cells from immune responses. Gene replacement therapy is a promising approach to treat numerous inherited and acquired diseases; however, immune responses to genetically modified cells and transgene products pose significant hurdles to the clinical development and broader use Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 of gene therapy. It is aimed to produce cell-protective biopolymers inspired by natural physical barriers that evade immune responses through the following objectives: (1) investigate biochemical mechanisms to assemble biopolymers into physical barriers, (2) screen immune tolerance of biopolymers inspired by extracellular matrix proteins, and (3) engineer non-immunogenic biopolymers that assemble into protective coatings for cells. Molecular design rules to predict the self-assembly and immune tolerance of cell- protective biopolymers will be learned, and versatile biopolymers that form protective coatings around genetically modified cells will be produced. Overall, it is sought to expand access to gene therapy technologies by prolonging the survival and function of genetically modified cells. Significance: Numerous disorders can be treated using gene replacement therapy, or the reintroduction of missing genes into patients’ affected cells. However, proteins expressed from such genes are recognized as “non-self,” and cells expressing these proteins are inevitably attacked by the immune system. This immune response reduces therapeutic efficiency and can result in serious adverse effects. Immunogenicity is conventionally mitigated using immunosuppressants; however, these treatments increase susceptibility to infections and cancers, among other potential side effects. Innovation: Protective biopolymers will combine polypeptides that mimic the extracellular matrix (ECM) with protease-guided mechanisms that activate material assembly in the local cellular environment. Although proteases typically degrade the ECM, proteases can also induce material assembly by exposing functional peptide domains. For example, thrombin cleaves fibrinogen to guide the formation of fibrin clots during blood coagulation. We will leverage this counterintuitive design principle of “building by cutting” to produce immune evasive protein-based biopolymers that assemble into coatings for genetically modified cells. Technical Approach: Biopolymer assembly will be driven using elastin-like polypeptides (ELPs), which mimic the ECM and elicit minimal immune responses. ELPs have drawn interest as thermally sensitive biopolymers due to their “inverse” phase behavior. Specifically, ELPs are soluble in water at low temperatures and become insoluble upon heating above a lower critical solution temperature (LCST, FIG.1A). The LCST can be tuned from 10 to 90 °C by modifying the repetitive polypeptide sequence (Val-Pro-Gly-Xaa-Gly)n (SEQ ID NO:1), in which Xaa can be any Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 amino acid except proline and the sequence is repeated n times. The LCST is typically lowered by increasing hydrophobicity, molecular weight, and / or protein concentration. A class of protease-cleavable ELPs that are water soluble at physiological temperature (37 °C) in their full-length form and are cleaved into water soluble and insoluble components upon exposure to a specific protease are proposed (FIG.1B). Insoluble components will assemble into coatings that protect cells. Moreover, coatings can assemble at the surfaces of genetically altered mammalian cells that display the specific protease. Specifically, mixed charged / hydrophobic ELPs are soluble up to 45 °C under most physiological solution conditions, whereas hydrophobic-only ELPs are soluble up to 35 °C. A mixed charge / hydrophobic ELP will be soluble upon delivery to cells at physiological conditions (37 °C). Then, proteases expressed at the cell surface will trigger cleavage and subsequent insoluble ELP assembly into a protective coating (FIG. 1C). The molecular design for cleavage-induced assembly defies conventional wisdom in polypeptide design, in which low molecular- weight ELPs are typically more water soluble than high molecular- weight ELPs. Example 2 Encoding Cellular Self-Protective Biomaterials into Therapeutic Gene Delivery Systems Numerous genetic disorders can be treated using gene replacement therapy – the reintroduction of missing genes into patients’ affected cells. However, proteins expressed from such genes will be recognized as “non-self,” and cells expressing these proteins will be inevitably attacked by the immune system. This immune response leads to reduced therapeutic efficiency or, worse, serious adverse effects. Immunogenicity is conventionally mitigated using immunosuppressants; however, these treatments tend to either cause side effects or remain inadequate. To add a hitherto unexplored physical aspect to gene therapies, we propose that biomaterials can provide physical barriers to protect genetically modified cells from immune responses. Self-protective biomaterials will integrate recombinant proteins that mimic the extracellular matrix (ECM) with protease-dependent mechanisms to activate material assembly in the local cellular environment. Although proteases typically degrade the ECM, the modular, orthogonal nature of proteolytic cleavage will be leveraged to guide ECM generation. This counterintuitive design principle of “building by cutting” will enable engineering of ECM-mimetic biomaterial Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 systems for local delivery to genetically altered cells (Aim 1) and for secretion by genetically altered cells (Aim 2). In Aim 1, ECM-mimetic materials will be produced using recombinant protein engineering, and the delivery of purified materials will facilitate rapid in vitro screening and iteration between molecular designs. This work complements the design and optimization of genes that encode secretable ECM-mimetic materials in Aim 2, which will be co-delivered during gene replacement therapy and are more suitable for ultimate deployment to patients. We propose that programming genetically altered cells to produce their own protective physical barriers will enable their long-term survival and function after gene therapy. Aim 1. Protease-guided deposition of ECM-mimetic materials to genetically modified mammalian cells. ECM-mimetic biomaterials will comprise a class of protease-cleavable elastin-like polypeptides (ELPs), which elicit minimal immune responses and will form protective barriers around protease-expressing cells. ELPs are repetitive proteins with the pentapeptide sequence (VPGXG)n, where the guest residue X can be any amino acid except proline and the pentapeptide is repeated n times. ELPs have drawn interest as thermally sensitive materials due to their lower critical solution temperature (LCST) in water. Specifically, ELPs are soluble in water at temperatures below the LCST and become insoluble upon heating above the LCST (FIG.1A). ELP phase behavior can be tuned from 10 to 90 °C by modifying the identity of guest residue X and repeat number n. Generally, the LCST is lowered by increasing hydrophobicity, molecular weight, and / or protein concentration. A class of protease-cleavable ELPs that are water soluble in their full-length form and will be cleaved into water soluble and insoluble components upon exposure to proteases localized at cell surfaces is proposed (FIGs. 1B-1C). Insoluble components will assemble into physical biomaterials around genetically altered mammalian cells that display a specific protease from Tobacco Etch Virus (TEV). Protease-cleavable ELPs will have 3 key features: a charged domain (VPGEG)n (SEQ ID NO:108) that enhances ELP solubility, a cleavage site ENLYFQG that is recognized by TEV protease, and a hydrophobic domain (VPGVG)n (SEQ ID NO:109) that becomes insoluble upon cleavage. Specifically, glutamic acid and valine-rich ELPs (VPGEG)32(VPGVG)64 (SEQ ID NO:110) have LCSTs above 45 °C under most physiological solution conditions, whereas valine-only ELPs (VPGVG)60 (SEQ ID NO:13) have an LCST of 35 °C. We propose the ELP sequence (VPGEG)32ENLYFQG(VPGVG)64 (SEQ ID NO:111) will be soluble upon delivery to cells at physiological conditions (37 °C). Then, TEV proteases expressed Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 at the cell surface will trigger cleavage and subsequent ELP phase separation into a protective biomaterial surrounding the cell. The molecular design for cleavage-induced biomaterial formation defies conventional wisdom in biomaterial design, in which low molecular-weight ELPs are typically more water soluble than high molecular-weight ELPs. Approaches from recombinant protein engineering and polymer physics will be integrated to evaluate the thermal behavior of protease-cleavable ELPs. Genes encoding cleavable and non-cleavable ELPs will be assembled using recursive directional ligation, which can be used to construct repetitive protein biomaterials. Temperature- and concentration-dependent phase behaviors of cleavable and non-cleavable ELP proteins will be quantified using turbidity measurements. ELP solutions heated above the LCST undergo visible phase separation that manifests as reduced optical transmittance at 350 nm. To evaluate the influence of proteolytic cleavage on ELP behavior, both constructs will also be treated with TEV protease in vitro prior to the measurement of temperature-dependent turbidity. TEV protease treatment is anticipated to lower the LCST of the cleavable ELP below physiological temperature (37 °C); if this goal is not achieved, valine residues will be substituted with more hydrophobic leucine residues to decrease the LCST after cleavage. The optimized TEV-responsive ELP will be validated in cell culture. Human embryonic kidney (HEK) cells will be genetically engineered to display TEV protease, and administer the ELP to them. ELP phase separation only in the presence of TEV protease is proposed. To test the protective effect of the ECM-mimetic material, the HEK cells will display a common antigen (e.g., OVA) during co-culture with T cells expressing the cognate T cell receptor. The extent to which the protease-guided ELP deposition reduces T cell cytotoxicity against the HEK cells will be assessed. Finally, to better mimic a common use case where many therapeutic genes are expressed in the liver, the HEK cells will be replaced with a hepatocyte cell line and the aforementioned experiments repeated. If necessary, there will be iteration between cell culture experiments and biophysical characterization of purified ELPs to optimize their protease- dependent behavior. Aim 2. Programmed secretion of ECM-mimetic materials by genetically altered therapeutic cells. ELPs secreted by cells must remain soluble throughout the entire secretion pathway, for which the unique biochemical features of different secretory compartments and the protease- responsive ELPs developed in Aim 1 will be leveraged. Secretable ELPs will take the form of Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 (VPGKG)nRKKR (VPGHG)n (SEQ ID NO:112), where the positively charged (VPGKG)n (SEQ ID NO:113) can be removed by the Golgi-specific Furin protease at the RKKR (SEQ ID NO:114) site, and the histidine-rich (VPGHG)n (SEQ ID NO:xx)bestows pH sensitivity. Translation begins at neutral pH in the endoplasmic reticulum (pH 7.2), where (VPGKG)n (SEQ ID NO:113) prevents aggregation. As the ELP proteins pass through the Golgi apparatus (pH 6.7-6.0) and into secretory granules (pH 5.2), the protonated, charged form of (VPGHG)n (SEQ ID NO:115) will prevent aggregation. Removal of (VPGKG)n (SEQ ID NO:113) by Furin is necessary for material assembly upon secretion to extracellular environments with neutral- to-basic pH. After secretion, the uncharged, hydrophobic form of (VPGHG)n (SEQ ID NO:115 will phase separate and assemble into a protective ECM-mimetic biomaterial. The pH / Furin-responsive phase behavior of the ELPs will be initially assessed using purified proteins, and the protective effect of secretable ELPs will be evaluated using HEK cells and hepatocytes genetically engineered to secrete them, all following the approaches outlined in Aim 1. Example 3 Isothermal phase-changing elastin-like polypeptides Elastin-like polypeptides (ELPs) are promising biomaterials for medical applications owing to their non-immunogenicity, scalable synthesis through recombinant protein expression, and tunable self- assembly. ELP self-assembly has been exploited to generate nanoparticles for drug delivery, injectable drug depots for sustained therapeutic release, and gel-like materials to fill cartilage defects, among others. Temperature remains the predominant stimulus for promoting ELP self-assembly, as these proteins become insoluble and aggregate above a sequence- dependent transition temperature. In therapeutic contexts, however, the relatively constant human body temperature poses a significant challenge to temperature-driven ELP self-assembly with high spatiotemporal control. Other stimuli that are typically used to induce ELP self-assembly, including pH and salt concentration, are likewise challenging to manipulate in vivo. Here an ELP is presented that self-assembles when exposed to a biological stimulus (a protease) with the potential to function in isothermal environments such as genetically engineered cells (e.g. immune-protective biomaterials), blood vessels (e.g. “smart” hemostatic materials), and cancerous tumors (e.g. local delivery of therapeutics). Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 The designed protease-responsive ELP is soluble at physiologically relevant temperatures; upon incubation with a protease, the ELP produces an insoluble ELP fragment that self assembles into a biomaterial (FIG.2A). Currently, the ELP has a tobacco etch virus (TEV) protease recognition sequence between hydrophilic and hydrophobic ELP blocks, where hydrophilicity of each block was tuned by altering the amino acid, X, in the VPGXG (SEQ ID NO:1) repeats that comprise ELPs. This recognition sequence can be substituted with any other protease recognition sequence. Successful cleavage of the TEV protease-responsive ELP is confirmed by polyacrylamide gel electrophoresis, in which lower molecular weight protein fragments correspond to each ELP block (FIG.2B, rightmost lane; See also FIGs.3A-3B). FIG. 2C demonstrates that the ELP remains soluble before cleavage, with the hydrophilic block acting as a solubility tag for the entire protein (see FIG.3C for additional controls). Upon incubation at 37 °C with TEV protease, an increase in turbidity attributed to self-assembly of the hydrophobic ELP block is observed following proteolytic removal of the hydrophilic ELP block (FIG.2C, red curve). An example of MALDI-TOF mass spectrometry of a TEV protease-responsive ELP is shown in FIG. 4. It is proposed that this protease-driven ELP self-assembly behavior will be transferrable to other compatible protease-cut site pairings, which is a current research focus. In conclusion, we demonstrate isothermal ELP self-assembly driven by proteolytic cleavage of a soluble ELP. Example 3 Introduction In this work, a protease-responsive, “cleavable” ELP that produces a phase-separating ELP fragment upon isothermal proteolytic cleavage is reported. The cleavable ELP consists of hydrophobic and hydrophilic ELP blocks separated by a protease cleavage site. With this design, the overall ELP hydrophilicity is regulated by proteolytic cleavage, thereby linking protease-driven biochemical changes to emergent phase behavior. ELP concentrations and temperatures amenable to protease-driven phase separation were identified by constructing a phase diagram of a cleavable ELP and its cleavage products. Cleavable ELP variants with responses to four unique proteases demonstrate generalizability of protease-driven phase separation of ELPs. Materials and Methods Protein Sequence Design Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 To engineer an ELP that undergoes protease-driven phase separation at constant temperature, we connected soluble and insoluble ELP fragments with a protease cleavage site. This design results in an ELP that is soluble before proteolytic cleavage and produces an insoluble fragment after cleavage (FIG.5A). ELP sequences are abbreviated based on their constituent guest residues, such that ELP[V1A8G7]nrepresents the amino acid sequence (VPGVG)(VPGAG)8(VPGGG)7(SEQ ID NO:116) repeated n times. Cleavable ELPs comprise the soluble fragment ELP[V1A8G7]6, a protease cleavage site as a linker, and the insoluble fragment ELP[V]60. Protease-driven, isothermal phase separation is designed to occur in the temperature window in which the diblock ELP[V1A8G7]6–ELP[V]60is soluble and the hydrophobic block ELP[V]60is insoluble. Cleavable ELPs contain an N-terminal ELP[V1A8G7]6hydrophilic block and C-terminal ELP[V]60hydrophobic block. These blocks are connected by a protease cleavage site, which is flanked by flexible linkers composed of glycine and serine residues. From a design perspective, as few as four ELP[V1A8G7] repeats are sufficient to increase ELP[V]60solubility. Here, the soluble block includes 6 repeats of ELP[V1A8G7] to allow for the detection of ELP blocks with distinct molecular weights using polyacrylamide gel electrophoresis (PAGE). Four cleavable ELP variants were produced by changing the cleavage site to be recognized by tobacco etch virus protease (TEVP), thrombin (Thr), enterokinase (EK), or factor Xa (FXa) (FIG.5B). As a control, we also designed ELP[V]60. All ELPs contained an N-terminal leader sequence MGGWGP (SEQ ID NO:117) and a C-terminal trailer sequence WLE(H)6 (SEQ ID NO:118). The tryptophan residues enable detection of full-length ELPs and cleavage products using Stain-Free PAGE gels. Cleavable ELP gene assembly Briefly, cleavable ELP variants were cloned using both Golden Gate assembly and directional ligation. Gene sequences encoding repetitive ELPs were generated using a codon scrambling algorithm and manual adjustments to reduce mRNA folding near the translation initiation site. Golden Gate assembly overhangs were designed using the NEBridge Golden Gate online resource. First, each ELP block was assembled separately using Golden Gate assembly through BsmBI sites. Then, the blocks were combined and subcloned into a modified pET-22b(+) expression vector (SI) using directional ligation. Finally, annealed oligos (data not shown) encoding protease cleavage sites were inserted between the blocks in a second Golden Gate assembly reaction using BsaI. DNA sequences for TEVP-, Thr-, EK-, and FXa-cleavable ELP variants were validated with whole-plasmid sequencing (Primordium Labs) and are reported in Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 the supplementary information. Plasmids encoding these four cleavable ELP variants, along with a precursor plasmid to generate variants with other protease cleavage sites, are deposited in Addgene with catalog numbers (data not shown). ELP[V]60 gene synthesis ELP[V]60was cloned using a single Golden Gate assembly reaction with BsmBI sites, followed by directional ligation into the modified pET-22b(+) expression vector. The gene sequence was designed similarly to the variants described above. The DNA sequence was validated by whole-plasmid sequencing and deposited in Addgene (data not shown). The protein sequence is included in Supplementary Information. Protein expression, purification, and validation ELPs were produced by recombinant protein expression in the BLR(DE3) (Novagen) strain of Escherichia coli. Single transformed colonies were selected from agar plates and grown at 37 °C in Luria-Bertani (LB) media overnight cultures supplemented with 200 µg ampicillin / mL. Beta-lactamase was removed from the overnight culture by pelleting cells via centrifugation and gently resuspending in an equal volume of fresh LB. One liter of Terrific broth (TB) supplemented with 200 µg ampicillin / mL was inoculated with 10 mL of overnight culture in fresh LB media. Cultures were incubated at 30 °C with orbital shaking between 200–250 rpm. Following a hyperexpression protocol, cultures were grown for 24 hr without isopropyl ^-D-1- thiogalactopyranoside (IPTG) induction. Cultures were harvested by centrifugation; were resuspended in 35 mL of lysis buffer (3 mM MgCl2, 1 mM ethylenediaminetetraacetic acid (EDTA), 100 mM NaCl, 10 mM Tris, pH 7.5) and frozen overnight at -80 °C. Lysates were thawed and incubated at 4 °C with stirring for at least one hour with lysozyme (0.5–1 mg / mL lysate), DNase I (0.5–1 µL / 10 mL lysate), and RNase A (spatula tip). Lysates were further processed with probe sonication, followed by lysate clarification via centrifugation (4 °C, 14635 ×g, 1 hr). ELPs were isolated with inverse transition cycling (ITC), with each ITC cycle comprising a hot spin followed by a cold spin. For cleavable ELP variants, solid NaCl was added to a final concentration of 1.5 M, and solutions were warmed to 37 °C for at least 2 hr and until all NaCl dissolved to drive selective coacervation of the ELP. ELP-enriched pellets were obtained via centrifugation in a pre-heated centrifuge (37 °C, 14635 ×g, 1 hr). Pellets were resuspended in 1× phosphate-buffered saline (PBS, 137 mM NaCl) or ultrapure water and placed on a rotisserie rotator at 4 °C for at least 2 hr to solubilize the pellets. Insoluble contaminants were removed via centrifugation in a subsequent cold spin in a pre-chilled centrifuge (4 °C, 14635 ×g, 1 hr). Two Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 additional ITC cycles were performed for cleavable ELP variants; in these subsequent cycles, 4.5 M NaCl solution was added to reach a final concentration of 1.5 M NaCl. Similarly, ELP[V]60was purified using three ITC cycles. For ELP[V]60, coacervation was induced by adding solid NaCl to a final concentration of 3 M for the first cycle and 4.5 M NaCl solution to reach 1.5 M NaCl for the following two cycles. After the third cold spin, all ELPs were dialyzed against ultrapure water (Milli- Q, 18.2 MΩ-cm, 4 L, 4 °C, 5–6 cycles, at least 3 hr / cycle) in 14000 Da cutoff cellulose dialysis tubing. Samples were subsequently lyophilized to yield a white, fluffy material. Cleavable ELP variants yielded between 20–40 mg / L, and ELP[V]60yielded between 60–140 mg / L. Successful expression of each ELP was validated with 12% sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS, Protein and Nucleic Acid Facility, Stanford University). Sample preparation Protein stock solutions were produced by weighing and resuspending lyophilized protein in buffer. Stock solutions were mixed overnight at 4 °C in a rotisserie rotator. Final protein solutions were prepared by dilution of protein stock solutions, and final protein concentrations were confirmed by UV absorbance at 280 nm (data not shown). For turbidimetry measurements, protein solutions with concentrations below 100 µM were generated by serial dilution. For all experiments, replicates were performed using freshly prepared protein stock solutions. Time-resolved turbidimetry To demonstrate isothermal phase separation of TEVP-cleavable ELP, changes in optical density were monitored at 350 nm (OD350). Measurements were collected using a Tecan Infinite 200 Pro M Nano+plate reader in a flat bottom, clear 96-well plate. Prior to starting experiments, the plate reader sample chamber, well plate, and sample solutions were equilibrated to the measurement temperature for at least 30 minutes. At the start of the experiment, 200 µL of 30 µM TEVP-cleavable ELP in PBS were mixed with 8 µL of either TEVP (10 units / µL) or PBS (negative control). TEVP-only controls contained 200 µL of PBS and 8 µL TEVP. OD350 was recorded every 5 minutes, with each reported measurement corresponding to the mean of 25 reads per well. Each measurement was preceded by 5 s of orbital shaking. Following the experiments, reaction products were analyzed using SDS-PAGE. A sample containing the TEVP-cleavable ELP and TEVP was cooled to 4 °C to resolubilize the phase- separated component. An aliquot was reserved for further analysis. To analyze the composition of the insoluble and soluble phases at 37 °C, the insoluble phase was separated from the soluble Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 phase via centrifugation. Briefly, the remaining sample was heated to 37 °C in a thermocycler and centrifuged to separate the insoluble component (37 °C, 21100 ×g, 15 mins). The supernatant was removed, and the pellet was dried upside down before resuspending it in an equal volume of PBS at 4 °C. Samples were analyzed using a 12% SDS-PAGE Stain-Free gel under reducing conditions following the manufacturer’s instructions (Bio-Rad). Coomassie Brilliant Blue staining of samples was unsuccessful due to poor visualization of the hydrophilic cleavage product (FIG. 10). Poor visualization of the hydrophilic ELP cleavage product likely arises from its low content of basic and aromatic residues that are typically bound by Coomassie Brilliant Blue. Unsuccessful staining of ELP fragments with Coomassie Brilliant Blue has been previously reported. Turbidimetry Transition temperatures of ELP[V]60, TEVP-cleavable ELP, and cleavage products were determined using turbidimetry. Cleavage products were obtained by incubating 100 µM TEVP- cleavable ELP with TEVP (10 units / µL) at a 60:1 volume ratio for at least 3 hours at 34 °C with 150 rpm orbital shaking. Temperature-dependent OD350was measured in a 1 mm path length quartz cuvette that was capped to prevent evaporation using a Jasco J-815 spectrometer. Samples were placed in the pre-cooled sample chamber and equilibrated for one minute before starting the measurement. The sample chamber temperature was increased from 20 °C to 55 °C by 1 °C / min, and OD350 was measured every 0.5 °C. For each ELP construct and concentration, the transition temperature was determined by calculating the inflection point of the temperature- dependent OD350curve as detailed in the Supplementary Information. Transition temperatures are reported as the average and standard deviation of triplicate measurements. Combinatorial screening of isothermal phase separation Generalizability of protease-driven phase separation of ELPs was demonstrated via time- resolved turbidimetry with cleavable ELP variants. Cleavable ELP variant stock solutions were prepared as described above using either PBS for reactions with TEVP or a general reaction buffer (20 mM Tris, 100 mM NaCl, 2 mM CaCl2, pH 8.0) for reactions with thrombin, factor Xa, and enterokinase. The plate reader sample chamber and 30 µM cleavable ELP solutions were equilibrated at 37 °C for at least 30 minutes prior to starting measurements. Enzymes (6 µL TEVP at 10 units / µL, 3 µL thrombin at 1 unit / µL, 3 µL factor Xa at 1 mg / mL, 3 µL enterokinase at 16 units / µL) were added to a second 96-well plate held at 4 °C to preserve enzymatic activity. Solutions containing 30 µM cleavable ELP variants (150 µL) were transferred to the enzyme 96- well plate, and the entire plate was placed in the plate reader. OD350 was taken every 10 minutes, Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 with each reported measurement corresponding to the mean of 25 reads per well. Each measurement was preceded by 5 s of orbital shaking. Reaction products were analyzed with SDS- PAGE Stain-Free gels (Bio-Rad). Results and Discussion Isothermal phase separation of TEVP-cleavable ELP Incubation of TEVP-cleavable ELP with TEVP at 37 °C led to isothermal phase separation. Isothermal phase separation was monitored with time-resolved turbidimetry during a 3-hour reaction between TEVP-cleavable ELP and TEVP (FIG.6A). After 15 minutes, increased turbidity was attributed to light scattering by ELP aggregates. Turbidity was non-monotonic, reaching a maximum before decreasing. The decrease resulted from ELP coalescence into larger aggregates, which scatter light weakly when compared to smaller aggregates. Solutions containing only TEVP-cleavable ELP did not demonstrate changes in turbidity, suggesting that a cleavage product was responsible for isothermal phase separation. At the end of the time-resolved turbidimetry experiment, TEVP reactivity with TEVP- cleavable ELP was verified with SDS-PAGE (FIG.6B). Lane 1 contained the full-length TEVP- cleavable ELP, which appeared as a single high molecular weight band near 75 kDa. The expected protein molecular weight of 64.0 kDa was validated with MALDI-TOF MS (FIG.12A). ELPs and other proline-rich proteins tend to exhibit anomalous electrophoretic migration that results in a higher apparent molecular weight than the true molecular weight. This anomalous migration likely stems from conformations introduced by high proline content. Lane 2 contained the TEVP and cleavable ELP reaction mixture, which appeared as three distinct bands between 25 kDa and 50 kDa. These bands corresponded to the hydrophilic ELP block (expected 37.9 kDa), the hydrophobic ELP block (expected 26.2 kDa), and TEVP (28 kDa). Importantly, the high molecular weight band corresponding to the TEVP-cleavable ELP was no longer present. Lane 3 contained TEVP only as a control. To identify the cleavage product responsible for isothermal phase separation, the insoluble fraction of the reaction mixture was separated via centrifugation at 37 °C. Lanes 4 and 5 contained the resulting pellet and supernatant, respectively. Lane 4 indicated that the hydrophobic ELP block was enriched in the insoluble pellet. In contrast, lane 5 contained only the hydrophilic ELP block Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 and TEVP. Lane 6 contained recombinant ELP[V]60to validate the depletion of the hydrophobic ELP block from the supernatant. Overall, this endpoint analysis demonstrates that increased turbidity emerges due to phase separation of the hydrophobic ELP[V]60 cleavage product. Thermodynamic behavior of TEVP-cleavable ELP reveals conditions for protease-driven, isothermal phase separation To predict conditions for protease-driven phase separation, the phase behaviors of TEVP- cleavable ELP and its cleavage products were mapped using temperature-dependent turbidimetry. The transition temperatures of TEVP-cleavable ELP were 4 to 5 °C higher than its cleavage products at all concentrations investigated (FIG.7). For the cleavage products, transition temperatures reflect those of the ELP[V]60hydrophobic block, consistent with its selective phase separation at 30 µM and 37 °C (FIG.6B, FIG.16A-16B). The higher transition temperatures of TEVP-cleavable ELP suggest that its hydrophilic ELP[V1A8G7]6block functions as a solubility tag. Prior work by Dreher et al. similarly found that ELP[V1A8G7]nenhances the solubility of ELP[V]60in a diblock ELP. Protease-driven phase separation was observed above the transition temperature of the hydrophobic cleavage product. Solutions of 30 µM TEVP-cleavable ELP underwent dramatic increases in turbidity when incubated with TEVP at 37 °C (FIG. 6A). At the beginning of the reaction, 30 µM TEVP-cleavable ELP was below its transition temperature and therefore soluble (open triangle, FIG.7). At the end of the reaction, the solution contained 30 µM hydrophobic and 30 µM hydrophilic cleavage products (FIG.6B). At 37 °C, the hydrophobic cleavage product was above its transition temperature (34 °C at 30 µM) and underwent phase separation. More generally, phase separation is expected to occur for reaction conditions bounded by the transition temperatures of the cleavable ELP and its cleavage products (Region I, FIG.7). Below the transition temperature of the cleavage products, protease-driven phase separation was not observed. At 32 °C, solutions of 30 µM TEVP-cleavable ELP underwent only minor increases in turbidity when incubated with TEVP (FIG.14A-14B). Nearly constant turbidity was observed throughout the reaction because both reactants and products remain soluble at 30 µM and 32 °C (closed triangle, FIG. 7). After the reaction, gel electrophoresis confirmed the complete conversion of cleavable ELP to its cleavage products (FIG. 14A-14B). Complete conversion was achieved despite different protease kinetics at 32 °C and 37 °C. Therefore, Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 protease-driven phase separation does not occur using reaction conditions below the cleavage product transition temperature (Region II, FIG.7). The transition temperatures of recombinant ELP[V]60were 3 to 4 °C lower than those of the cleavage products. This discrepancy in transition temperatures is not attributable to the presence of TEVP or its storage buffer in solution with the cleavage product (FIG.15). Likewise, the presence of hydrophilic ELP[V1A8G7]6cleavage product in solution does not influence the transition temperature of the hydrophobic cleavage product (FIG. 16A-16B). Rather, the suppression in transition temperature of recombinant ELP[V]60likely arises from the hydrophobicity of the leader sequence tag (MGGWGP) (SEQ ID NO:117), which is not included in the ELP[V]60cleavage product sequence (data not shown). Time-resolved turbidimetry of 30 µM TEVP-cleavable ELP incubated with TEVP at 32 °C (above the recombinant ELP[V]60transition temperature) did not result in substantial phase separation. Therefore, the suppression of transition temperatures in the recombinant ELP[V]60generated an incorrect boundary between regions I and II in the TEVP-cleavable ELP phase diagram. Generalization of isothermal phase behavior to diverse proteases Protease-driven ELP phase separation was extended to proteases beyond TEVP by incorporating alternative protease cleavage sequences between the hydrophilic and hydrophobic ELP blocks. Three additional cleavable ELP variants with responses to thrombin, factor Xa, and enterokinase were designed, cloned, expressed, and purified, with molecular weights validated by MALDI-TOF MS (FIG.12B-12D). These proteases were chosen as stimuli for isothermal ELP phase separation because of their common use in recombinant protein affinity tag removal. Reactions of all unique cleavable ELP-protease pairings were monitored with time-resolved turbidimetry (FIG.17), and final OD350 measurements for one replicate are reported in FIG.8. Protease quantities used in reactions were selected to ensure near-complete cleavage of intended cleavable ELP variants within 6 hours at 37 °C (FIG.18). All cleavable ELP variants demonstrated elevated turbidity only when incubated with their intended compatible protease. These results suggest that elevated turbidity results from phase separation of hydrophobic cleavage products. In reactions demonstrating elevated turbidity, monotonic increases in OD350 were typically observed during time-resolved turbidimetry (FIG.17). An exception was the reaction between TEVP-cleavable ELP and TEVP, which produced a local maximum in turbidity. Turbidity profiles are strongly dependent on ELP cleavage kinetics, with faster cleavage producing a local maximum in the turbidity profile (FIG.19A-19F). Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 Near complete conversion of cleavable ELPs to the hydrophobic and hydrophilic cleavage products was confirmed with SDS-PAGE (FIG. 18). However, off-target cleavage occurred between factor Xa and Thr-cleavable ELP as well as enterokinase and FXa-cleavable ELP. For each off-target pairing, SDS-PAGE resolved a high intensity band corresponding to the cleavable ELP as well as two lower intensity bands that migrated similarly to the intended cleavage products. The lower molecular weight bands suggest that off-target cleavage occurred within the ELP’s protease cleavage sequence. The proteases with off-target reactivity (factor Xa and enterokinase) are trypsin-like proteases, which promiscuously cleave after lysine or arginine. This activity is consistent with off-target cleavage occurring within the cleavage sequence (Scheme 1), thereby producing the intended ELP cleavage products. Off-target cleavage activity is relatively weak, as indicated by the low intensity of cleavage product bands and high intensity of starting material bands. Despite producing hydrophobic cleavage products, off-target reactivity did not result in elevated turbidity (FIG.8). Turbidity of the two off-target cleavable ELP–protease pairings nearly matched that of ELP-only controls, indicating that no ELP phase separation occurred in these reactions. At 37 °C, phase separation of the hydrophobic cleavage product only occurred above a critical concentration of approximately 10 µM for the TEVP-cleavable ELP variant (FIG. 7). Therefore, at least one third of the initial 30 µM TEVP-cleavable ELP must be converted to its cleavage products to observe phase separation. Low conversion of cleavable ELPs in off-target reactions resulted in prohibitively low concentrations of hydrophobic cleavage products to drive phase separation. In some scenarios, higher levels of off-target reactivity might produce unintended phase separation responses; however, off-target reactivity could be leveraged beneficially to engineer broad-spectrum protease-cleavable ELPs that respond to families of similar proteases. Conclusions In summary, we report protease-driven phase separation of ELPs. Manipulating ELP phase separation with a biological cue relaxes the requirement for external stimuli to regulate ELP behavior. Protease-responsive “cleavable” ELPs were designed by placing a protease cleavage site between hydrophobic and hydrophilic ELP blocks. The hydrophilic ELP block enhances the solubility of the hydrophobic ELP block, thereby producing a temperature window in which protease-driven phase separation proceeds during an isothermal reaction. The hydrophilic block sequence design space is vast: hydrophilic ELP blocks containing polar or charged guest residues Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 can increase the solubility of hydrophobic ELPs, as can hydrophilic tags or protein domains beyond ELPs. As a technology, protease-driven ELP phase separation will benefit from systematic understanding of the role of the hydrophilic block sequence on the temperature window for protease-driven ELP phase separation. We further report four cleavable ELP variants responsive to tobacco etch virus protease, thrombin, factor Xa, and enterokinase, each of which undergoes isothermal phase separation upon incubation with the intended protease. These findings provide a generalizable tool to drive ELP phase separation in biological systems with proteases. References 1. Jenkins, I. C.; Milligan, J. J.; Chilkoti, A. Genetically Encoded Elastin-Like Polypeptides for Drug Delivery. Adv. Healthcare Mater. 2021, 10 (13), e2100209. 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Hsu, H.-J.; Tsai, K.-C.; Sun, Y.-K.; Chang, H.-J.; Huang, Y.-J.; Yu, H.-M.; Lin, C.-H.; Mao, S.- S.; Yang, A.-S. Factor Xa Active Site Substrate Specificity with Substrate Phage Display and Computational Molecular Modeling. J. Biol. Chem. 2008, 283 (18), 12343-12353. DOI: 10.1074 / jbc.M708843200 50. Jenny, R. J.; Mann, K. G.; Lundblad, R. L. A critical review of the methods for cleavage of fusion proteins with thrombin and factor Xa. Protein Expression Purif.2003, 31 (1), 1-11. DOI: 10.1016 / S1046-5928(03)00168-2 51. Choi, J.-W.; Won, J.-I. Self-assembly behavior of elastin-like polypeptides composed of charged and neutral blocks with different block ratio. J. Appl. Polym. Sci. 2023, 140 (44), e54621. DOI: 10.1002 / app.54621 52. Le Fer, G.; Wirotius, A.-L.; Brûlet, A.; Garanger, E.; Lecommandoux, S. Self-Assembly of Stimuli-Responsive Biohybrid Synthetic-b-Recombinant Block Copolypeptides. Biomacromolecules 2019, 20 (1), 254-272. DOI: 10.1021 / acs.biomac.8b01390 53. Horn, J. M.; Zhu, Y.; Ahn, S. Y.; Obermeyer, A. C. Self-assembly of globular proteins with intrinsically disordered protein polyelectrolytes and block copolymers. Soft Matter 2022, 18 (31), 5759-5769, DOI: 10.1039 / D2SM00415A 54. Chang, M. P.; Huang, W.; Mai, D. J. Monomer-scale design of functional protein polymers using consensus repeat sequences. J. Polym. Sci. 2021, 59 (22), 2644-2664. DOI: 10.1002 / pol.20210506 In at least some of the previously described embodiments, one or more elements used in an embodiment can interchangeably be used in another embodiment unless such Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 a replacement is not technically feasible. It will be appreciated by those skilled in the art that various other omissions, additions and modifications may be made to the methods and structures described above without departing from the scope of the claimed subject matter. All such modifications and changes are intended to fall within the scope of the subject matter, as defined by the appended claims. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and / or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 together, B and C together, and / or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like include the number recited and refer to ranges which can be subsequently broken down into sub-ranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 articles refers to groups having 1, 2, or 3 articles. Similarly, a group having 1-5 articles refers to groups having 1, 2, 3, 4, or 5 articles, and so forth. Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 changes and modifications may be made thereto without departing from the spirit or scope of the appended claims. Accordingly, the preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims. In the claims, 35 U.S.C. §112(f) or 35 U.S.C. §112(6) is expressly defined as being invoked for a limitation in the claim only when the exact phrase "means for" or the exact phrase "step for" is recited at the beginning of such limitation in the claim; if such exact phrase is not used in a limitation in the claim, then 35 U.S.C. § 112 (f) or 35 U.S.C. §112(6) is not invoked.

Claims

Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 WHAT IS CLAIMED IS: ally phase-separable elastin-like polypeptide (ELP), the ELP comprising: i) a first ELP domain having a first lower critical solution temperature (LCST); and ii) a second ELP domain having a second LCST that is different from the first LCST, wherein the first and second ELP domains are separated by an enzymatic cleavage site.

2. The ELP of Claim 1, wherein the first LCST is greater than the second LCST.

3. The ELP of Claim 1 or 2, wherein the first and second ELP domain each comprises one or more pentapeptide repeats.

4. The ELP of Claim 3, wherein each pentapeptide repeat comprises an amino acid sequence VPGXG (SEQ ID NO:1), wherein X is any amino acid other than proline.

5. The ELP of Claim 4, wherein each pentapeptide repeat comprises an amino acid sequence VPGXG (SEQ ID NO:2), wherein X is selected from valine, alanine, glycine, lysine, histidine, serine, and glutamate.

6. The ELP of Claim 5, wherein: i) The first ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5), VPGAG (SEQ ID NO:6), VPGGG (SEQ ID NO:7), VPGKG (SEQ ID NO:8), VPGSG (SEQ ID NO:9), and VPGEG (SEQ ID NO:10); and ii) The second ELP domain comprises one or more pentapeptide repeats, each pentapeptide repeat comprising an amino acid sequence selected from: VPGVG (SEQ ID NO:5) and VPGHG (SEQ ID NO:11).

7. The ELP of any one of Claims 3-6, wherein the first and second ELP domain each comprises from 1 to 250 pentapeptide repeats.

8. The ELP of Claim 7, wherein:Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 i) the first ELP domain comprises from 50 to 150 pentapeptide repeats; and ii) the second ELP domain comprises 30 to 90 pentapeptide repeats.

9. The ELP of Claim 8, wherein: i) the first ELP domain comprises from 75 to 125 pentapeptide repeats; and ii) the second ELP domain comprises 45 to 75 pentapeptide repeats.

10. The ELP of any one of Claims 4-9, wherein: i) the first ELP domain comprises an amino acid sequence having at least 80% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:12; and ii) the second ELP domain comprises an amino acid sequence having at least 80% amino acid sequence identity to the amino acid sequence set forth in SEQ ID NO:

13.

11. The ELP of any one of Claims 4-10, wherein: i) the first ELP domain comprises the amino acid sequence set forth in SEQ ID NO:12; and ii) the second ELP domain comprises the amino acid sequence set forth in SEQ ID NO:

13.

12. The ELP of any one of Claims 1-11, wherein the first and second ELP domains are separated by two or more enzymatic cleavage sites.

13. The ELP of any one of Claims 1-12, wherein the enzymatic cleavage site is a protease cleavage site.

14. The ELP of Claim 13, wherein the protease cleavage site is a cleavage site for a eukaryotic protease, a prokaryotic protease, or a viral protease.

15. The ELP of Claim 14, wherein the protease cleavage site is selected from: a TEV protease cleavage site, an enterokinase cleavage site a thrombin cleavage site, a factor Xa cleavage site, a factor VIIa cleavage site, a factor IXa cleavage site, a factor XIa cleavage site, a factor XIIa cleavage site, a kallikrein cleavage site, a plasmin cleavage site, a furin cleavage site, a matrix metalloproteinase cleavage site, a caspase cleavage site, a paracaspase cleavage site, a granzyme B cleavage site, and a proline-endopeptidase cleavage site.Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 16. The ELP of any one of Claims 1-15, wherein the ELP further comprises: i) a first linker between the first ELP domain and the enzymatic cleavage site; and / or ii) a second linker between the second ELP domain and the enzymatic cleavage site.

17. The ELP of Claim 16, wherein the first and second linkers each comprise an amino acid sequence comprising: a) the amino acid sequence set forth in SEQ ID NO: 14; or b) the amino acid sequence set forth in SEQ ID NO: 15, wherein n is an integer equal to or greater than 1.

18. The ELP of Claim 16 or 17, wherein the ELP comprises, in order from N-terminus to C- terminus: a1) the first ELP domain; b1) the first linker; c1) the enzymatic cleavage site; d1) the second linker; and e1) the second ELP domain, or a2) the second ELP domain; b2) the second linker; c2) the enzymatic cleavage site; d2) the first linker; and e2) the first ELP domain.

19. The ELP of any one of Claims 1-18, wherein the ELP further comprises a payload polypeptide.

20. The ELP of Claim 19, wherein the payload polypeptide comprises a single-chain antibody, a cytokine, a growth factor, a peptide hormone, or a therapeutic peptide.Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 21. The ELP of Claim 19 or 20, wherein the payload polypeptide is fused to the second ELP domain via a linker.

22. The ELP of Claim 21, wherein the payload polypeptide: a) is fused N-terminally to the second ELP domain; or b) is fused C-terminally to the second ELP domain.

23. The ELP of any one of Claims 1-22, wherein the ELP further comprises an N-terminal leader domain.

24. The ELP of Claim 23, wherein the N-terminal leader domain encodes a signal peptide.

25. The ELP of any one of Claims 1-24, wherein the ELP is non-immunogenic.

26. The ELP of any one of Claims 1-25, wherein the ELP is conjugated to a payload molecule.

27. The ELP of Claim 26, wherein the payload molecule is a nucleic acid, a polypeptide, a carbohydrate, or a small molecule.

28. The ELP of Claim 26 or 27, wherein the payload molecule is conjugated to the second ELP domain.

29. A nucleic acid encoding the ELP of any one of Claims 1-25.

30. An expression vector comprising the nucleic acid of Claim 29.

31. The expression vector of Claim 30, wherein the expression vector further comprises a nucleic acid sequence encoding a transgene.Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 32. A cell comprising the expression vector of Claim 31.

33. The cell of Claim 32, wherein the cell is a eukaryotic cell.

34. The cell of Claim 33, wherein the eukaryotic cell is a mammalian cell.

35. The cell of Claim 34, wherein the mammalian cell is a human cell.

36. The cell of any one of Claims 32-35, wherein the cell is in vivo.

37. An ELP composition comprising: a) an ELP of any one of Claims 1-28; and b) a pharmaceutically acceptable excipient.

38. A method for assembling a cell-protective biopolymer on the surface of a target cell, the method comprising: contacting the surface of a target cell with an ELP of any one of Claims 1-25 to assemble a cell- protective biopolymer, wherein the surface of the target cell comprises an enzyme that can cleave the enzymatic cleavage site of the ELP.

39. A method for assembling a cell-protective biopolymer on the surface of a target cell, the method comprising: expressing an ELP of any one of Claims 1-25 in the target cell to assemble a cell-protective biopolymer on the surface of said cell, wherein the ELP is secreted by the target cell, and wherein the target cell comprises an enzyme that can cleave the enzymatic cleavage site of the ELP.

40. The method of Claim 39, wherein the target cell comprises the expression vector of Claim 30 or 31.Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 41 The method of Claim 39 or 40, wherein the enzyme is present on the surface of the target cell.

42. The method of Claim 39 or 40, wherein the enzyme is present inside of the target cell.

43. The method of any one of Claims 38-42, wherein the target cell is a eukaryotic cell.

44. The method of Claim 43, wherein the eukaryotic cell is a mammalian cell.

45. The method of Claim 44, wherein the mammalian cell is a human cell.

46. The method of any one of Claims 43-45, wherein the target cell is in vivo.

47. The method of any one of Claims 38-46, wherein the target cell expresses a transgene.

48. A method for reducing blood loss at a hemorrhage site in a subject, the method comprising: administering to a hemorrhage site in a subject an effective amount of an ELP composition according to Claim 37 to reduce blood loss at the hemorrhage site, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the hemorrhage site.

49. The method of Claim 48, wherein the enzymatic cleavage site of the ELP is a protease cleavage site.

50. The method of Claim 49, wherein the protease cleavage site is a thrombin cleavage site or a factor Xa cleavage site.

51. The method of any one of Claims 48-50, wherein the hemorrhage site is an external hemorrhage site.Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 52. The method of Claim 51, wherein the administering comprises applying the ELP composition to the external hemorrhage site.

53. The method of any one of Claims 48-50, wherein the hemorrhage site is an internal hemorrhage site.

54. The method of Claim 53, wherein the administering comprises intravenously administering the ELP composition to the subject.

55. A method for delivering a therapeutic agent to a target site in a subject, the method comprising: administering an ELP composition according to Claim 37 to a subject, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the target site.

56. The method of Claim 55, wherein the administering comprises intravenously administering the ELP composition to the subject.

57. The method of Claim 55 wherein the administering comprises intramuscular injection, intradermal injection, or subcutaneous injection of the ELP composition in a subject.

58. The method of any one of Claims 55-57, wherein the target site is a tumor.

59. The method of Claim 58, wherein the enzymatic cleavage site of the ELP is a protease cleavage site.

60. The method of Claim 59, wherein protease cleavage site is a matrix metalloproteinase cleavage site.

61. A method for producing a tissue scaffold at a site of injury in a subject, the method comprising: administering an ELP composition according to Claim 37 to a subject, wherein an enzyme that can cleave the enzymatic cleavage site of the ELP is present in or around the site of injury.Attorney Docket No.: STAN-2151WO Stanford No.: S23-364 62. The method of Claim 61, wherein the administering comprises applying the ELP composition to the site of injury.

63. The method of Claim 61, wherein the administering comprises intramuscular injection, intradermal injection, or subcutaneous injection of the ELP composition in a subject.

64. A kit comprising: a) an ELP according to any one of Claims 1-28; and b) a pharmaceutical excipient.

65. The kit of Claim 64, wherein the ELP is lyophilized.

66. The kit of Claims 64 or 65, wherein the kit further comprises a substrate material.

67. The kit of Claim 66, wherein the substrate material comprises a gauze.

68. The kit of any one of Claims 64-67, wherein the kit further comprises a syringe.

69. A kit comprising: a) an expression vector according to Claim 30; b) an endonuclease; and c) a ligase.

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