Glucose-dependent droplets and supramolecular peptide depots for glucose-responsive glucagon delivery

Abstract

Described herein are peptide amphiphiles (PAs) for inclusion in droplets and hydrogels.

Description

[0001] GLUCOSE-DEPENDENT DROPLETS AND SUPRAMOLECULAR PEPTIDE DEPOTS FOR GLUCOSE-RESPONSIVE GLUCAGON DELIVERY CROSS-REFERENCE TO RELATED APPLICATION(S) This application claims priority to U.S. Provisional Patent Application No.63 / 608,410, filed on December 11, 2023, which is incorporated by reference herein in its entirety. REFERENCE TO SEQUENCE LISTING This application was filed with a Sequence Listing XML in ST.26 XML format accordance with 37 C.F.R. § 1.831 and PCT Rule 13ter. The Sequence Listing XML file submitted in the USPTO Patent Center, “092012-0036-WO01_sequence_listing_xml_10-DEC-2024.xml,” was created on December 10, 2024, contains 4 sequences, has a file size of 8.0 kilobytes (8,192 bytes), and is incorporated by reference in its entirety into the specification. BACKGROUND Living organisms respond to a variety of internal or external stimuli, sensing changes in their environment and responding through an assortment of biological functions. Blood glucose homeostasis, a control network driven by the complex signaling of a number of hormones and incretins and regulated by the central nervous system, is one such process. Toward the creation of more life-like properties, synthetic biomaterials have been similarly designed to achieve stimuli- responsive functionality and, in so doing, better interface with physiological systems. Engineering glucose-responsive biomaterials is a particularly active area of research, owing in large part to the dramatic increase in prevalence of diabetes in recent years. These systems aim to restore blood glucose homeostasis, which is dysregulated as part of the pathophysiology of diabetes, through controlled and on-demand release of key hormones like insulin and, in a less explored direction, glucagon. The emergence of supramolecular materials, prepared via specific and ordered non- covalent molecular recognition motifs, offers a useful design approach in the preparation of biomaterials and technologies for drug delivery. The underlying dynamic molecular-scale interactions give rise to advantageous bulk dynamic properties, including shear-thinning and self- healing for facile injection-centered administration. Moreover, the non-covalent constitution of these materials makes them especially susceptible to changes in their environment, regulating the extent and magnitude of their cohesive interactions and offering opportunities for design of stimuli-responsive biomaterials. While polymeric systems can achieve similar phenomena through simple or complex coacervation, liquid-liquid phase separation (LLPS) with supramolecular materials has been less commonly shown. Functional applications for synthetic LLPS systems are an expanding area of emphasis, with particular focus on capturing the transient and dynamic state of these structures for use in biomedicine. SUMMARY One embodiment described herein is a peptide amphiphile comprising: an alkyl moiety of attached to the N-terminus of a sequence of 5–12 amino acid the sequence comprising: a hydrophobic subsequence of 2–8 hydrophobic amino acid residues, wherein the N- terminus of the hydrophobic subsequence is attached to the alkyl moiety; a positively charged subsequence of 2–5 positively charged amino residues, wherein the N-terminus of the positively charged subsequence is attached to the C-terminus of the hydrophobic subsequence; and a terminal amino acid residue comprising an amine-containing side chain, wherein the N- terminus of the terminal amino acid residue is attached to the C-terminus of the positively charged subsequence; the C-terminus of the terminal amino acid residue or ; and the amine-based side chain of the terminal is attached to a boronic acid moiety, wherein the boronic acid moiety is a moiety of formula: , or an anion n is 0–4; RX, at each occurrence, is independently halo, –C1-4haloalkyl, –CN, –NO2, –C(O)H, –CO2H, –CO2C1-4alkyl, or –SO2C1-4alkyl; and X−is an anion having a net charge of −1. In another aspect, each hydrophobic amino acid residue is a non-aromatic amino acid residue. In another aspect, the peptide amphiphile is a peptide amphiphile of formula (I): Y1AA8AA7AA6AA5AA4AA3AA2AA1B1(I),wherein: Y1is the alkyl moiety; is the sequence of amino acid residues, wherein: AA1is the terminal amino acid residue; B1is the boronic acid moiety; is the positively charged subsequence; and In In another aspect, AA2, AA3, and AA4are each independently an arginine residue, a lysine residue, an ornithine residue, or a histidine residue. In another aspect, AA5, AA6, AA7, and AA8are each independently a glycine residue, an alanine residue, a valine residue, an isoleucine residue, or a leucine residue. In another aspect, the boronic acid moiety is a moiety of . In another aspect, n is 0 or 1. In another aspect, RX, at each occurrence, is independently halo or –C1-4haloalkyl. In another aspect, RX, at each occurrence, is independently –F or –C1-4fluoroalkyl. In another aspect, the peptide amphiphile is a peptide amphiphile of formula (I-a): a), wherein: or R5, R6, R7, and R8are each independently hydrogen, . In another aspect, R2, R3, and R4are . In another aspect, R5, R6, R7, and R8are each independently methyl . In another aspect, the peptide amphiphile of formula (I) is: . glucose, and optionally, glucagon and / or a glucagon analogue. In another aspect, the peptide amphiphile is present at about 0.05–4% by weight (wt%); and glucagon and / or a glucagon analogue is present at about 0.01–2 wt%. In another aspect, the glucose is present at about 1– 20 mM. In another aspect, the glucagon analogue comprises dasiglucagon and / or a depsi- glucagon analogue. In another aspect, the droplet has a diameter of about 0.2–5 µm. In another aspect, the droplet is formed by liquid-liquid phase separation. Another embodiment described herein is a hydrogel comprising: a peptide amphiphile, glucose, and a diluent peptide amphiphile, the diluent peptide amphiphile comprising: the alkyl moiety of attached to the N-terminus of a sequence of 5–12 amino acid the sequence comprising: a hydrophobic subsequence of 2–8 hydrophobic amino acid residues, wherein the N- terminus of the hydrophobic subsequence is attached to the alkyl moiety; and a positively charged subsequence of 2–5 positively charged amino residues, wherein the N-terminus of the positively charged subsequence is attached to the C-terminus of the hydrophobic subsequence; and the C-terminus of the positively charged subsequence .In another aspect, the diluent peptide amphiphile is a diluent (II): (II), wherein: Y1is the alkyl moiety; and the C- . In another aspect, the (II) is: . In another aspe 0.1–2.0 wt%; and the diluent peptide amphiphile is present in the hydrogel at about 0.1–4 wt%. In another aspect, the glucose is present in the hydrogel at about 1–20 mM. In another aspect, glucagon and / or a glucagon analogue is encapsulated within the hydrogel. In another aspect, the glucagon analogue comprises dasiglucagon and / or a depsi-glucagon analogue. In another aspect, the glucagon and / or glucagon analogue is co-formulated with a cationic polymer within the hydrogel. In another aspect, the cationic polymer is protamine. Another embodiment described herein is a pharmaceutical composition comprising a droplet or a hydrogel, and a pharmaceutically acceptable excipient. Another embodiment described herein is a method of modulating glucose levels in a subject, the method comprising: administering a therapeutically effective amount of a droplet, a hydrogel, or a pharmaceutical composition. In another aspect, the subject in need thereof is experiencing a hypoglycemic event or at risk of experiencing a hypoglycemic event. In another aspect, the subject in need thereof has diabetes. Another embodiment described herein is a kit comprising a droplet, a hydrogel, or a pharmaceutical composition; delivery or administration apparata or devices; and optionally, packaging, a label, or instructions for use. DESCRIPTION OF THE DRAWINGS FIG. 1A shows the molecular structure of an example PA-PBA (also referred to as “PAPBA”), a peptide amphiphile (PA) of sequence C10alkyl-V2A2R3Dap-PBA (SEQ ID NO: 1) wherein a phenylboronic acid (PBA) motif is presented for glucose binding (DAP = 2,3- Diaminopropanoic acid). Glucose-bound PA-PBA self-assembles into spherical structures. FIG. 1B schematically illustrates that when the net-positive PA-PBA is mixed with the net-negative dasiglucagon (SEQ ID NO: 2) therapeutic in the presence of glucose, droplets form via liquid- liquid phase separation (LLPS). The formed droplets dissolve when introduced into conditions of low glucose, releasing dasiglucagon. FIG. 2A shows turbidity (λ = 600 nm) measured over time after mixing PA-PBA, dasiglucagon, and different concentrations of glucose. FIG.2B shows quantification of turbidity (λ = 600 nm) for samples prepared at different glucose concentrations at 15 min after mixing (n = 3 / group, ± SD). FIG.2C shows brightfield microscopy images of samples prepared at different glucose concentrations at 15 min after mixing. FIG.2D is a bar graph showing droplet number at different glucose concentrations, as quantified by image analysis, measuring 9 images per sample with n = 3 samples / group for measurements (± SD). FIG. 2E is a bar graph showing droplet diameter at different glucose concentrations, as quantified by image analysis, measuring 9 images per sample with n = 3 samples / group for both measurements (± SD). FIG. 2F shows confocal laser scanning microscopy images for droplets, showing overlay (left image), fluorescein amidite (FAM)-labeled PA-PBA (middle image), and Rhodamine B (RhdB)-labeled dasiglucagon (right image). FIG. 2G shows TEM of droplets embedded, sectioned using an ultramicrotome, and stained with UranyLess. FIG.3A shows brightfield microscopy of PA-PBA and dasiglucagon droplets formed at 100 mg / dL glucose showing fusion over time. FIG. 3B shows turbidity (λ = 600 nm) of droplets prepared at 100 mg / dL glucose or samples at 0 mg / dL glucose and then supplemented 4arm- PEG-NH2over a range of polymer concentrations (0–9.52 mg / mL). FIG.3C shows confocal laser scanning microscopy of droplets 30 min after adding 5 μL deionized (DI) H2O (left) or 9.52 mg / mL PEG (right). FIG. 3D shows brightfield microscopy at 30 min after adding 5 μL DI H2O (top) or 9.52 mg / mL PEG (bottom). FIG.3E shows turbidity measurements over time for droplets samples prepared in different glucose concentrations and supplemented with 9.52 mg / mL PEG (left), as well as turbidity values compared specifically at 15 min (right, n = 3 / group, ± SD). FIG. 4A shows fluorescence recovery after photobleaching (FRAP) images for droplets showing overlay (left image), FAM-labeled PA-PBA (middle image), and RhdB-labeled dasiglucagon (right image) before bleaching (Pre) and then over time after bleaching a region of one droplet. FIG.4B shows quantification of fluorescence signal in the bleached region of interest for both FAM-labeled PA-PBA and RhdB-labeled dasiglucagon (n = 3 samples, ± SD). FIG. 5A shows the change in turbidity over time for droplets prepared at 100 mg / dL glucose and supplemented with 9.52 mg / mL 4arm-PEG-NH2before being placed into bulk buffers of different glucose concentrations. FIG.5B shows encapsulation efficiency determined for PEG- stabilized droplets prepared in different glucose concentrations, determined by measuring the soluble concentration of methoxycoumarin (MCA)-labeled dasiglucagon after formation (n = 3 / group, ± SD). FIG.5C shows the release of MCA-labeled dasiglucagon from droplets prepared at 100 mg / dL glucose and then incubated in bulk buffers of varying glucose concentrations (n = 3 / group, ± SD). FIG. 5D shows the mouse model results after prophylactic glucagon delivery prior to severe hypoglycemia was performed, with droplets injected at t = 0 min and an insulin overdose administered at t = 120 min, monitoring blood glucose throughout and FIG.5E shows specifically focusing on the region of hypoglycemia following insulin overdose. FIG. 5F shows the groups compared on the basis of the lowest (nadir) blood glucose level observed and FIG. 5G shows the final blood glucose level at 4 h (t = 360 min) after the insulin overdose (n = 9 / group, ± SEM). For FIG.5F–G, data were analyzed by one-way ANOVA and significance (*-P < 0.05) is shown for the droplets-treated group compared to the groups treated with dasiglucagon or buffer. FIG.6 shows a TEM image of PA-PBA in its glucose-bound state at 2 mg / mL peptide and 100 mg / dL glucose. FIG. 7 is a bar graph showing zeta potential measurements of PA-PBA (2 mg / mL) and dasiglucagon (0.2 mg / mL) in 10 mM HEPES buffer, with glucose varied in the buffer of PA-PBA from 0 mg / dL to 200 mg / dL. FIG. 8A shows microscopy image analysis by Python. FIG. 8B illustrates the Python microscopy image split to individual visions. FIG.9 shows the chemical structure of FAM-labeled PBA-PA. FIG.10 shows the chemical structure of RhdB-labeled dasiglucagon (SEQ ID NO: 2). FIG.11 shows fluorescent properties of FAM-PBA-PA: normalized spectra of absorbance (excitation) and fluorescence (emission). FIG. 12 shows fluorescent properties of RhdB-Dasiglucagon: normalized spectra of absorbance (excitation) and fluorescence (emission). FIG.13 shows turbidity testing results for PAA and PLGA at 0 mg / dL glucose. FIG.14 shows turbidity testing results for 4arm-PEG-NH2at 0 mg / dL glucose. FIG. 15 shows turbidity testing results for 4arm-PEG-OH, 4arm-PEG-NH2and droplets alone at 100 mg / dL glucose. FIG. 16 shows a cartoon schematic illustrating the glucose-responsive supramolecular peptide hydrogel depots for on-demand glucagon release. A peptide amphiphile (PA) was endowed with a glucose-binding phenylboronic acid (PBA) molecule (PA-PBA). To facilitate nanofiber formation and hydrogelation, a diluent peptide amphiphile (dPA) was synthesized and co-formulated with PA-PBA. When binding with glucose, these mixtures undergo a nanostructure transformation from micelles to elongated nanofibers, enabling the formation of injectable hydrogels. At low glucose conditions, the dissociation of the PBA-glucose complex allows hydrogels to swell and release glucagon. FIG.17A shows the hydrogelation of co-formulated 30% PA-PBA / dPA mixtures (2% w / v) assessed by vial inversion. FIG.17B shows an evaluation of the storage modulus (G′, solid) and loss modulus (G″, open) over time (0.5% strain, 1 rad / s) upon addition of no glucose or 100 mg / dL glucose. FIG.17C shows a rheological frequency sweep (at 0.5% strain) of co-formulated 30% PA-PA / dPA mixtures (2% w / v), where closed symbols are G′ and open symbols are G″. FIG.17D shows the storage modulus (G′, solid, left axis) and complex viscosity (η*, open, right axis) following equilibration of hydrogels (2% w / v) over time at 0.5% strain and 1 rad / s; n = 2 / sample with error bars denoting standard deviation. FIG.17E shows a shear viscosity flow ramp for 30% PA-PA / dPA hydrogel (2% w / v) at 100 mg / dL glucose to demonstrate shear-thinning. FIG. 17F shows step-strain cycling between 0.5% and 100% strain for a 30% PA-PA / dPA hydrogel (2% w / v) at 100 mg / dL glucose. FIG.18A shows circular dichroism (CD) spectroscopy of dPA and PA-PBA at 0.5% (w / v). FIG.18B shows CD spectroscopy of co-formulated 30% PA-PBA / dPA mixtures at 0.5% (w / v) with increasing concentration of glucose. FIG.18C shows Zeta potential measurements for 30% PA- PBA / dPA mixtures with increasing concentration of glucose; n = 3 / sample with error bars denoting standard deviation. FIG.18D shows transmission electron microscopy (TEM) of dPA, PA-PBA, and 30% PA-PBA / dPA mixtures at various glucose concentrations (all samples were imaged at 0.1% (w / v)). FIG. 19A shows the release profile of encapsulated MCA-dasiglucagon from 30% PA- PBA / dPA hydrogels (2% w / v) prepared in 100 mg / dL glucose and incubated in a bulk buffer containing various glucose concentrations; n = 3 / group with mean ± standard deviation shown. FIG. 19B schematically illustrates the mouse model for prophylactic glucagon delivery prior to severe hypoglycemia caused by insulin overdose. FIG. 19C shows blood glucose levels monitored throughout the study, focusing on the region following insulin overdose (gray highlighted panel) and FIG.19D shows final blood glucose levels at the end of the study. n = 9 mice / group, mean ± SEM shown. *- P < 0.05 by Student’s t-test. FIG. 20A–E show hydrogelation of PA-PBA (FIG. 20A), co-formulation of 10% PA- PBA / dPA (FIG.20B), 20% PA-PBA / dPA (FIG.20C), 30% PA-PBA / dPA (FIG.20D), and 40% PA- PBA / dPA (FIG. 20E) by gross inspection using vial inversion. Peptide concentration: 2% (w / v) and glucose concentration of 0 or 100 mg / dL, as labeled. FIG.21 shows Transmission electron microscopy (TEM) of PA, PA-PBA, 30%PA-PBA / dPA mixtures at 0.5% (w / v) peptide. FIG.22 shows the chemical structure of MCA-dasiglucagon. FIG.23 shows the chemical structure of dasiglucagon. FIG. 24A schematically illustrates the interactions between example peptide amphiphile C10alkyl-V2A2R3Dap-PBA (PAPBA) in a cartoon schematic that further includes glucose and dasiglucagon. The process in FIG.24A depicts the formation of a tetrahedral boronate complex with a negative charge upon binding with glucose. FIG. 24B schematically illustrates the mechanism of phase separation when the positively charged PAPBA interacts with the negatively charged dasiglucagon in the presence of glucose. FIG.24C show microscopy images captured at 5-minute intervals that illustrate the formation of LLPS droplets. As time progresses, the droplets increase in size, evidenced by fusion events shown in the bottom panel. This demonstrates the coalescence of multiple droplets into a larger, self-assembled phase-separated droplet. FIG. 24D shows fluorescence microscopy images of PAPBA LLPS that reveal the incorporation of PAPBA (FITC channel, left panel) and dasiglucagon (Rhodamine, middle panel) in the formation of liquid droplets. For FIG.24C–D, the LLPS component concentrations were as follows: PAPBA at 2 mg / mL, dasiglucagon at 0.2 mg / mL, and glucose at 100 mg / dL. FIG.24E schematically illustrates the different types of intermolecular interactions typically observed in systems that LLPS behavior, including pi-pi interactions, cation-pi interactions, hydrogen bonding, hydrophobic interactions, and electrostatic interactions. FIG.25A shows fluorescence microscopy images illustrating the phase regime of PAPBA liquid-liquid phase separation (LLPS) under varying concentrations of peptide PAPBA and glucose. The images show that there is no phase separation in the absence of glucose. The critical concentration for observing LLPS was determined to be 2 mg / mL PAPBA with 0.2 mg / mL dasiglucagon and a glucose concentration of 100 mg / dL. At concentrations >3 mg / mL, precipitation occurs after introducing 200 mg / dL glucose. The right panel presents a schematic representation of the phase regime, highlighting the concentration range favorable for LLPS with a fixed dasiglucagon concentration. FIG. 25B shows time-dependent turbidity measurements of the PAPBA LLPS process, with a constant PAPBA concentration of 2 mg / mL and 0.2 mg / mL dasiglucagon, while varying glucose concentrations. The profile indicates no increase in turbidity without glucose; however, both turbidity and the kinetics of LLPS increase with higher glucose concentrations. FIG.25C shows time-dependent turbidity measurements of the PAPBA LLPS process at different pH conditions. To generate the data shown in FIG. 25C, concentrations of the components were maintained at 2 mg / mL PAPBA, 0.2 mg / mL dasiglucagon, and 100 mg / dL glucose. The results show that turbidity increases over time at pH levels of 7, 9, and 11, whereas no turbidity increase is observed at a pH of less than 7, indicating no LLPS. FIG.25D shows a plot of turbidity as a function of pH indicating that droplet formation at pH levels below 7 are unfavorable for LLPS, while LLPS is specifically favored in the pH range above 7, aligning with the pKa of phenylboronic acid, which is ~ pH 7. FIG. 25E shows the microscopic images associated with FIG.25D. FIG.25F shows the turbidity curves of PAPBA in response to different stimuli (urea, 1,6- hexanediol, and NaCl) are presented to identify the factors responsible for LLPS. Urea disrupts hydrogen bonding, hexanediol interferes with hydrophobic interactions, and NaCl affects ionic interactions. As shown in FIG. 25F, after LLPS formation, the addition of hexanediol and urea disrupts LLPS, while NaCl promotes LLPS by inducing charge screening. FIG.25G shows the results from introducing stimuli in situ during formation. The results shown in FIG. 25G show that inhibited formation correlates with the data for droplet disruption shown in the panel (FIG.25F). FIG. 25H shows the turbidity results from addition of varying concentrations of each individual stimulus during the formation process. The results shown in FIG.25H indicate that both hexanediol and urea significantly disrupt LLPS assembly, while NaCl promote it, confirming that the LLPS system is majorly driven by hydrogen bonding and hydrophobic interactions. FIG.25I shows microscopy images before and after the addition of stimuli. FIG. 26A shows fluorescence microscopy images that illustrate the phase behavior of PAPBA liquid-liquid phase separation (LLPS) at a fixed glucose concentration of 100 mg / dL, with varying concentrations of dasiglucagon and PAPBA. As shown in FIG. 26A, the critical concentration required to observe LLPS was determined to be 1 mg / mL of PAPBA combined with 0.4 mg / mL of dasiglucagon at the same glucose level. The right side of FIG. 26A features a schematic representation of the phase regime, highlighting the concentration range conducive to LLPS. It also illustrates a trend showing an increase in droplet size as the concentration of dasiglucagon rises. FIG.26B shows a droplet size distribution profile indicating that the PAPBA LLPS droplets formed without dasiglucagon have smaller diameters compared to those formed in the presence of dasiglucagon, which resulted in larger droplet diameters. Inset microscopy images are included in FIG.26B for visual reference. FIG.26C demonstrates the possibility to form smaller droplets from PAPBA and glucose without the addition of dasiglucagon. FIG.26D shows zeta potential measurements of the LLPS components indicating that PAPBA exhibits a high zeta potential of ~ +15 mV, which decreases to ~ +11 mV upon the addition of net-negative dasiglucagon. This charge further shifts toward a less positive equilibrium when glucose is introduced, as the negative charge from boronic acid reduces the overall charge of the LLPS system. Zeta potential analysis was performed at pH 7, based on three independent measurements. FIG. 26E shows time-dependent dynamic light scattering (DLS) analysis demonstrating that as time progresses, the droplet diameter increases, supporting the droplet coalescence event associated with the LLPS mechanism. Initial measurements indicate that droplet micelles are approximately 1 µm, which grow to about 3–5 µm after approximately 9 minutes. FIG. 26F shows temperature-dependent DLS studies revealing that LLPS droplets are disrupted after a 3-minute incubation at 40 °C. However, maintaining the temperature around 25 °C allows the LLPS droplets to reform. This behavior indicates that the PAPBA LLPS system is dynamic and exhibits temperature reversibility. FIG. 27A shows the kinetics of liquid-liquid phase separation (LLPS) measured using a turbidity assay at 600 nm at 5 °C, followed by a thermal ramp from 5 °C to 40 °C. The results indicate that an initial increase in temperature promotes LLPS (5–10°C). As the temperature rises further to around 25 °C, stable droplets are observed, but disruption occurs at temperatures above 25 °C. This trend suggests a behavior similar to that of UCST (Upper Critical Solution Temperature), attributed to the enthalpy-driven self-assembly of the LLPS system. The inset microscopy images illustrate the before and after states of thermal melting. FIG.27B shows the kinetics of PAPBA LLPS at varying temperatures indicate that as the temperature increases, the droplets become disrupted, further supporting the UCST-like behavior. FIG. 27C shows the LLPS kinetics examined at different concentrations of PAPBA, followed by thermal ramp from 5 °C to 40 °C. FIG.27D shows that as concentration of PAPBA increases, turbidity levels rise. Initially, increasing the temperature promotes LLPS (5–10 °C) before showing a transition melting temperature (Tm) at various temperatures. The transition melting observed in this profile was plotted as a function of PAPBA concentration, illustrated in panel (FIG.27E). FIG. 27F shows microscopic images taken after 5 minutes of thermal melting at 40 °C from experiments with different PAPBA concentrations show a trend: as the concentration of PAPBA increases, the size of the droplets recovered after thermal melting also increases. The size distribution of droplets is plotted in the right side of FIG.27F. FIG. 28A shows that the net-positive PAPBA, consisting of the modified sequence C10alkylG4R3Dap-PBA, interacts with the net-negative dasiglucagon in the presence of 100 mg / dL glucose, leading to the formation of liquid-liquid phase separation (LLPS). FIG.28B illustrates the phase regime with varying concentrations of PA. This panel shows that the critical concentration required for the modified C10alkylG4R3Dap-PBA to achieve LLPS is 2 mg / mL, accompanied by 0.2 mg / mL dasiglucagon and 100 mg / dL glucose. FIG. 28C illustrates the kinetics of droplet formation were assessed using a turbidity measurement at 600 nm. The results indicate slower kinetics for C10alkylG4R3Dap-PBA compared to C10alkyl-V2A2R3Dap-PBA. The corresponding microscopy images are shown in the inset, providing a visual reference for the findings. This suggests that hydrophobic valine and alanine play a crucial role in promoting LLPS. FIG. 28D shows the mutated dasiglucagon designed to be net-positive that was synthesized by replacing negatively charged amino acid residues with lysine and arginine. The modified residues are highlighted in boxes in FIG. 28D. As further depicted in the microscopy images of FIG.28D, when mixed with the positively charged dasiglucagon, PAPBA did not self- assemble to form LLPS after glucose triggering, even with varying concentrations of the positively charged dasiglucagon. This highlights the importance of charge screening induced by the negatively charged dasiglucagon in facilitating LLPS. DETAILED DESCRIPTION Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. For example, any nomenclatures used in connection with, and techniques of biochemistry, molecular biology, immunology, microbiology, genetics, cell and tissue culture, and protein and nucleic acid chemistry described herein are well known and commonly used in the art. In case of conflict, the present disclosure, including definitions, will control. Exemplary methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the embodiments and aspects described herein. As used herein, the terms “amino acid,” “nucleotide,” “polynucleotide,” “vector,” “polypeptide,” and “protein” have their common meanings as would be understood by a biochemist of ordinary skill in the art. Standard single letter nucleotides (A, C, G, T, U) and standard single letter amino acids (A, C, D, E, F, G, H, I, K, L, M, N, P, Q, R, S, T, V, W, or Y) are used herein. As used herein, terms such as “include,” “including,” “contain,” “containing,” “having,” and the like mean “comprising.” The present disclosure also contemplates other embodiments “comprising,” “consisting essentially of,” and “consisting of” the embodiments or elements presented herein, whether explicitly set forth or not. As used herein, “comprising,” is an “open- ended” term that does not exclude additional, unrecited elements or method steps. As used herein, “consisting essentially of” limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristics of the claimed invention. As used herein, “consisting of” excludes any element, step, or ingredient not specified in the claim. As used herein, the term “a,” “an,” “the” and similar terms used in the context of the disclosure (especially in the context of the claims) are to be construed to cover both the singular and plural unless otherwise indicated herein or clearly contradicted by the context. In addition, “a,” “an,” or “the” means “one or more” unless otherwise specified. As used herein, the term “or” can be conjunctive or disjunctive. As used herein, the term “and / or” refers to both the conjunctive and disjunctive. As used herein, the term “substantially” means to a great or significant extent, but not completely. As used herein, the term “about” or “approximately” as applied to one or more values of interest, refers to a value that is similar to a stated reference value, or within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, such as the limitations of the measurement system. In one aspect, the term “about” refers to any values, including both integers and fractional components that are within a variation of up to ± 10% of the value modified by the term “about.” Alternatively, “about” can mean within 3 or more standard deviations, per the practice in the art. Alternatively, such as with respect to biological systems or processes, the term “about” can mean within an order of magnitude, in some embodiments within 5-fold, and in some embodiments within 2-fold, of a value. As used herein, the symbol “~” means “about” or “approximately.” All ranges disclosed herein include both end points as discrete values as well as all integers and fractions specified within the range. For example, a range of 0.1–2.0 includes 0.1, 0.2, 0.3, 0.4 . . . 2.0. If the end points are modified by the term “about,” the range specified is expanded by a variation of up to ±10% of any value within the range or within 3 or more standard deviations, including the end points, or as described above in the definition of “about.” As used herein, the terms “room temperature,” “RT,” or “ambient temperature” refer to the typical temperature in an indoor laboratory setting. In one aspect, the laboratory setting is climate controlled to maintain the temperature at a substantially uniform temperature or with a specific range of temperatures. In one aspect, “room temperature” refers a temperature of about 15–30 °C, including all integers and endpoints within the specified range. In another aspect, “room temperature” refers a temperature of about 15–30 °C; about 20–30 °C; about 22–30 °C; about 25–30 °C; about 27–30 °C; about 15–22 °C; about 15–25 °C; about 15–27 °C; about 20–22 °C; about 20–25 °C; about 20–27 °C; about 22–25 °C; about 22–27 °C; about 25–27 °C; about 15 °C ± 10%; about 20 °C ± 10%; about 22 °C ± 10%; about 25 °C ± 10%; about 27 °C ± 10%; ~20 °C, ~22 °C, ~25 °C, or ~27 °C, at standard atmospheric pressure. As used herein, the terms “active ingredient” or “active pharmaceutical ingredient” refer to a pharmaceutical agent, active ingredient, compound, or substance, compositions, or mixtures thereof, that provide a pharmacological, often beneficial, effect. As used herein, the terms “control,” or “reference” are interchangeable. A “reference” or “control” level may be a predetermined value or range, which is employed as a baseline or benchmark against which to assess a measured result. “Control” also refers to control experiments or control cells. As used herein, the term “dose” denotes any form of an active ingredient formulation or composition, including cells, that contains an amount sufficient to initiate or produce a therapeutic effect with at least one or more administrations. “Formulation” and “composition” are used interchangeably herein. As used herein, the term “prophylaxis” refers to preventing or reducing the progression of a disorder, either to a statistically significant degree or to a degree detectable by a person of ordinary skill in the art. As used herein, the terms “effective amount” or “therapeutically effective amount,” refers to a substantially non-toxic, but sufficient amount of an action, agent, composition, or cell(s) being administered to a subject that will prevent, treat, or ameliorate to some extent one or more of the symptoms of the disease or condition being experienced or that the subject is susceptible to contracting. The result can be the reduction or alleviation of the signs, symptoms, or causes of a disease, or any other desired alteration of a biological system. An effective amount may be based on factors individual to each subject, including, but not limited to, the subject’s age, size, type or extent of disease, stage of the disease, route of administration, the type or extent of supplemental therapy used, ongoing disease process, and type of treatment desired. As used herein, the term “subject” refers to an animal. Typically, the subject is a mammal. A subject also refers to primates (e.g., humans, male or female; infant, adolescent, or adult), non- human primates, rats, mice, rabbits, pigs, cows, sheep, goats, horses, dogs, cats, fish, birds, and the like. In one embodiment, the subject is a primate. In one embodiment, the subject is a human. As used herein, a subject is “in need of treatment” if such subject would benefit biologically, medically, or in quality of life from such treatment. A subject in need of treatment does not necessarily present symptoms, particular in the case of preventative or prophylaxis treatments. As used herein, the terms “inhibit,” “inhibition,” or “inhibiting” refer to the reduction or suppression of a given biological process, condition, symptom, disorder, or disease, or a significant decrease in the baseline activity of a biological activity or process. As used herein, “treatment” or “treating” refers to prophylaxis of, preventing, suppressing, repressing, reversing, alleviating, ameliorating, or inhibiting the progress of biological process including a disorder or disease, or completely eliminating a disease. A treatment may be either performed in an acute or chronic way. The term “treatment” also refers to reducing the severity of a disease or symptoms associated with such disease prior to affliction with the disease. “Repressing” or “ameliorating” a disease, disorder, or the symptoms thereof involves administering a cell, composition, or compound described herein to a subject after clinical appearance of such disease, disorder, or its symptoms. “Prophylaxis of” or “preventing” a disease, disorder, or the symptoms thereof involves administering a cell, composition, or compound described herein to a subject prior to onset of the disease, disorder, or the symptoms thereof. “Suppressing” a disease or disorder involves administering a cell, composition, or compound described herein to a subject after induction of the disease or disorder thereof but before its clinical appearance or symptoms thereof have manifest. Definitions of specific functional groups and chemical terms are described in more detail herein. The chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 75thed., inside cover, and specific functional groups are generally defined as described therein. Additionally, general principles of organic chemistry, as well as specific functional moieties and reactivity, are described in Thomas Sorrell, Organic Chemistry, University Science Books, Sausalito, 1999; Smith and March, March’s Advanced Organic Chemistry, 5thed, John Wiley & Sons, Inc., New York, 2001; Larock, Comprehensive Organic Transformations, VCH Publishers, Inc., New York, 1989; and Carruthers, Some Modern Methods of Organic Synthesis, 3rded, Cambridge University Press, Cambridge, 1987. The term “alkyl,” as used herein, means a straight or branched, saturated hydrocarbon chain. The term “lower alkyl” or “C1-6alkyl” means a straight or branched chain hydrocarbon containing from 1 to 6 carbon atoms. The term “C1-4alkyl” means a straight or branched chain hydrocarbon containing from 1 to 4 carbon atoms. Representative examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, n- pentyl, isopentyl, neopentyl, n-hexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n- heptyl, n-octyl, n-nonyl, and n-decyl. The term “halogen” or “halo,” as used herein, means Cl, Br, I, or F. The term “haloalkyl,” as used herein, means an alkyl group, as defined herein, in which one, two, three, four, five, six, seven or eight hydrogen atoms are replaced by a halogen. The term “haloalkoxy,” as used herein, means at least one haloalkyl group, as defined herein, is appended to the parent molecular moiety through an oxygen atom. The term “substituted” refers to a group that may be further substituted with one or more non-hydrogen substituent groups. Substituent groups include, but are not limited to, halogen, =O (oxo), =S (thioxo), cyano, nitro, fluoroalkyl, alkoxyfluoroalkyl, fluoroalkoxy, alkyl, alkenyl, alkynyl, haloalkyl, haloalkoxy, heteroalkyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocycle, cycloalkylalkyl, heteroarylalkyl, arylalkyl, hydroxy, hydroxyalkyl, alkoxy, alkoxyalkyl, alkylene, aryloxy, phenoxy, benzyloxy, amino, alkylamino, acylamino, aminoalkyl, arylamino, sulfonylamino, sulfinylamino, sulfonyl, alkylsulfonyl, arylsulfonyl, aminosulfonyl, sulfinyl, -COOH, ketone, amide, carbamate, and acyl. For compounds described herein, groups and substituents thereof may be selected in accordance with permitted valence of the atoms and the substituents, such that the selections and substitutions result in a stable compound, e.g., which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. The term “peptide,” as used herein, means a compound comprising two or more amino acids. As used herein, the term “peptide” encompasses peptides terminated with a carboxyl group and peptides terminated with a free amide group (–C(O)NH2). The term “amino acid,” as used herein, means an organic compound that contains both amino and carboxyl functional group. As used herein, the term “amino acid” may refer to a native amino acid residue (i.e., a proteogenic amino acid residue) or a non-native amino acid residue (i.e., a non-proteogenic amino acid residue). The term “amino acid residue,” as used herein, means the part of an amino acid that remains after two or more amino acids combine to form a peptide. As used herein, the term “amino acid residue” may refer to a native amino acid residue (i.e., a proteogenic amino acid residue) or a non-native amino acid residue (i.e., a non-proteogenic amino acid residue). The term “N-terminus,” as used herein, means the nitrogen terminus of an amino acid, peptide, or protein. The term “C-terminus,” as used herein, means the carbon terminus of an amino acid, peptide, or protein. Herein, a peptide amphiphile (PA) bearing a phenylboronic acid (PBA) is explored in conjunction with a therapeutic glucagon analogue (dasiglucagon) for glucose directed LLPS (FIG. 1A–B). PBAs are Lewis acids that have been frequently explored as synthetic glucose sensors in material design due to their ability to form dynamic-covalent bonds with glucose and related diols. Interestingly, when the net-positive PA is combined with the net-negative dasiglucagon protein in the presence of glucose, a droplet phase emerges comprised of both PA and protein (FIG.1B). These droplets are dynamic and readily coalesce, though interfacial stabilization using another polymer improves stability. Furthermore, the dependence of droplet formation on the presence of glucose to modulate PA electrostatics results in their dissolution under conditions of low glucose, leading to release of a dasiglucagon payload that itself is the therapeutic remedy for low blood glucose. Accordingly, dasiglucagon release from the droplets is accelerated in the absence of glucose, offering a functional strategy to mitigate the severity of hypoglycemia in a rodent model of insulin overdose. As further described herein, upon mixing the PA bearing a terminal PBA motif (PA-PBA) with a diluent PA (dPA) in the presence of glucose, self-assembled nanofibers may form that further elongate and entangle to form self-supporting hydrogels (FIG.16). Glucose is essential for high aspect-ratio nanofiber formation and hydrogelation, and in the absence of glucose smaller nanostructures arise that do not form hydrogels. Accordingly, hydrogels formed from these materials in the presence of glucose can become destabilized under low glucose conditions to release encapsulated glucagon. In an animal model of insulin overdose and hypoglycemia, the administration of the PA-PBA / dPA hydrogels offers some protection and improved blood glucose recovery. Peptide Amphiphiles (PAs) In one aspect, the present disclosure provides peptide amphiphiles (PAs). As used herein, the term “peptide amphiphile” refers to a peptide or peptide conjugate having distinct hydrophilic (e.g., polar) and hydrophobic (e.g., nonpolar) domains. The peptide amphiphiles (PAs) disclosed herein comprise: an alkyl moiety of attached to the N-terminus of a sequence of 5–12 amino acid the sequence comprising: a hydrophobic subsequence of 2–8 hydrophobic amino acid residues, wherein the N- terminus of the hydrophobic subsequence is attached to the alkyl moiety; a positively charged subsequence of 2–5 positively charged amino residues, wherein the N-terminus of the positively charged subsequence is attached to the C-terminus of the hydrophobic subsequence; and a terminal amino acid residue comprising an amine-containing side chain, wherein the N- terminus of the terminal amino acid residue is attached to the C-terminus of the positively charged subsequence; the C-terminus of the terminal amino acid residue ; and the amine-based side chain of the terminal to a boronic acid moiety, wherein the boronic acid moiety is a moiety of formula: , or an n is 0–4; RX, at each occurrence, is independently halo, –C1-4haloalkyl, –CN, –NO2, –C(O)H, –CO2H, –CO2C1-4alkyl, or –SO2C1-4alkyl; and X−is an anion having a net charge of −1. In some instances, each hydrophobic amino acid residue is a non-aromatic amino acid residue. In some instances, the peptide amphiphile is a peptide of formula (I): Y1AA8AA7AA6AA5AA4AA3AA2AA1B1(I),wherein: Y1is the alkyl moiety; is the sequence of amino acid residues, wherein: AA1is the terminal amino acid residue; B1is the boronic acid moiety; is the positively charged subsequence; and is the hydrophobic subsequence. In non-native amino acid residue. In AA4each independently may be an arginine residue, a lysine residue, an ornithine residue, or a histidine residue. In various instances, AA5, AA6, AA7, and AA8each independently may be a glycine residue, an alanine residue, a valine residue, an isoleucine residue, or a leucine residue. In various instances, the boronic acid moiety may be a moiety of formula: . In various instances, n may be 0 or 1. In various instances, RX, at each occurrence, independently may be halo or –C1-4haloalkyl. In various instances, RX, at each occurrence, independently may be –F or –C1-4fluoroalkyl. In various instances, the peptide amphiphile may be a peptide amphiphile of formula (I-a): , or R5, R6, R7, and R8are each independently hydrogen, . 2 3 42In various instances, R , R , and R each ma . In various instances, R5, R6, R7, and R8each n epen en y may be methyl or . In various instances, the peptide amphiphile of formula (I) may be: . Diluent Peptide Amphiphiles (dPAs) The present disclosure provides further diluent peptide amphiphiles (dPAs). As used herein, the term “diluent peptide amphiphile” refers to a non-bioactive peptide amphiphile (PA) that acts to co-assemble alongside the active PA to facilitate molecular spacing within an assembled structure. Exemplary diluent peptide amphiphiles (dPAs) may be used in conjunction with a peptide amphiphile (PA) described above, e.g., a peptide amphiphile (PA) of formula (I). The diluent peptide amphiphiles (dPAs) disclosed herein comprise: an alkyl moiety of attached to the N-terminus of a sequence of 5–12 amino acid a sequence comprising: a hydrophobic subsequence of 2–8 hydrophobic amino acid residues, wherein the N- terminus of the hydrophobic subsequence is attached to the alkyl moiety; and a positively charged subsequence of 2–5 positively charged amino residues, wherein the N-terminus of the positively charged subsequence is attached to the C-terminus of the hydrophobic subsequence; and the C-terminus of the positively charged subsequence .In various instances, the diluent peptide amphiphile may of formula (II): (II), wherein: Y1is the alkyl is the positively charged subsequence; and the C- . The peptide wherein asymmetric or chiral centers are present. The stereoisomer is “R” or “S” depending on the configuration of substituents around the chiral carbon atom. The terms “R” and “S” used herein are configurations as defined in IUPAC 1974 Recommendations for Section E, Fundamental Stereochemistry, in Pure Appl. Chem., 1976, 45: 13-30. The disclosure contemplates various stereoisomers and mixtures thereof and these are specifically included within the scope of this invention. Stereoisomers include enantiomers and diastereomers, and mixtures of enantiomers or diastereomers. Individual stereoisomers of the compounds may be prepared synthetically from commercially available starting materials, which contain asymmetric or chiral centers or by preparation of racemic mixtures followed by methods of resolution well-known to those of ordinary skill in the art. These methods of resolution are exemplified by (1) attachment of a mixture of enantiomers to a chiral auxiliary, separation of the resulting mixture of diastereomers by recrystallization or chromatography and optional liberation of the optically pure product from the auxiliary as described in Furniss, Hannaford, Smith, and Tatchell, “Vogel’s Textbook of Practical Organic Chemistry”, 5th edition (1989), Longman Scientific & Technical, Essex CM202JE, England, or (2) direct separation of the mixture of optical enantiomers on chiral chromatographic columns or (3) fractional recrystallization methods. It should be understood that the peptide amphiphile may possess tautomeric forms, as well as geometric isomers, and that these also constitute an aspect of the invention. In the peptide amphiphiles, e.g., peptide amphiphiles of formula (I), diluent peptide amphiphiles of formula (II), and any subformulas thereof, any “hydrogen” or “H,” whether explicitly recited or implicit in the structure, encompasses hydrogen isotopes1H (protium) and2H (deuterium). The present disclosure also includes isotopically-labeled peptide amphiphiles (e.g., deuterium labeled), where an atom in the isotopically-labeled peptide amphiphiles is specified as a particular isotope of the atom. Examples of isotopes suitable for inclusion in the peptides of the invention are hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, fluorine, and chlorine, such as, but not limited to2H,3H,13C,14C,15N,18O,17O,31P,32P,35S,18F, and36Cl, respectively. Isotopically-enriched forms of peptide amphiphiles of formula (I), or any subformulas, may generally be prepared by conventional techniques known to those skilled in the art or by processes analogous to those described in the accompanying Examples using an appropriate isotopically-enriched reagent in place of a non-isotopically-enriched reagent. The extent of isotopic enrichment can be characterized as a percent incorporation of a particular isotope at an isotopically-labeled atom (e.g., % deuterium incorporation at a deuterium label). Pharmaceutical Salts The disclosed peptide amphiphiles may exist as pharmaceutically acceptable salts. The term “pharmaceutically acceptable salt” refers to salts or zwitterions of the compounds which are water or oil-soluble or dispersible, suitable for treatment of disorders without undue toxicity, irritation, and allergic response, commensurate with a reasonable benefit / risk ratio and effective for their intended use. The salts may be prepared during the final isolation and purification of the peptide amphiphiles or separately by reacting an amino group of the peptide amphiphiles with a suitable acid. For example, a peptide amphiphile may be dissolved in a suitable solvent, such as but not limited to methanol and water and treated with at least one equivalent of an acid, like hydrochloric acid. The resulting salt may precipitate out and be isolated by filtration and dried under reduced pressure. Alternatively, the solvent and excess acid may be removed under reduced pressure to provide a salt. Representative salts include acetate, adipate, alginate, citrate, aspartate, benzoate, benzenesulfonate, bisulfate, butyrate, camphorate, camphorsulfonate, digluconate, glycerophosphate, hemisulfate, heptanoate, hexanoate, formate, isethionate, fumarate, lactate, maleate, methanesulfonate, naphthylenesulfonate, nicotinate, oxalate, pamoate, pectinate, persulfate, 3-phenylpropionate, picrate, oxalate, maleate, pivalate, propionate, succinate, tartrate, thrichloroacetate, trifluoroacetate, glutamate, para- toluenesulfonate, undecanoate, hydrochloric, hydrobromic, sulfuric, phosphoric and the like. The amino groups of the compounds may also be quaternized with alkyl chlorides, bromides, and iodides such as methyl, ethyl, propyl, isopropyl, butyl, lauryl, myristyl, stearyl and the like. Basic addition salts may be prepared during the final isolation and purification of the disclosed peptide amphiphiles by reaction of a carboxyl group with a suitable base such as the hydroxide, carbonate, or bicarbonate of a metal cation such as lithium, sodium, potassium, calcium, magnesium, or aluminum, or an organic primary, secondary, or tertiary amine. Quaternary amine salts can be prepared, such as those derived from methylamine, dimethylamine, trimethylamine, triethylamine, diethylamine, ethylamine, tributylamine, pyridine, N,N-dimethylaniline, N-methylpiperidine, N-methylmorpholine, dicyclohexylamine, procaine, dibenzylamine, N,N-dibenzylphenethylamine, 1-ephenamine and N,N′-dibenzylethylenediamine, ethylenediamine, ethanolamine, diethanolamine, piperidine, piperazine, and the like. General Synthesis The peptide amphiphiles disclosed herein may be prepared according to peptide synthesis methods known in the art. In some instances, the peptide amphiphiles may be prepared using solid-phase synthesis. Optimum reaction conditions and reaction times for each individual step can vary depending on the particular reactants employed and substituents present in the reactants used. Specific procedures are provided in the Examples section. Reactions can be worked up in the conventional manner, e.g., by eliminating the solvent from the residue and further purified according to methodologies generally known in the art such as, but not limited to, crystallization, distillation, extraction, trituration, and chromatography. Unless otherwise described, the starting materials and reagents are either commercially available or can be prepared by one skilled in the art from commercially available materials using methods described in the chemical literature. Starting materials, if not commercially available, can be prepared by procedures selected from standard organic chemical techniques, techniques that are analogous to the synthesis of known, structurally similar peptide amphiphiles, or techniques that are analogous to the procedures described in the Examples below. Routine experimentations, including appropriate manipulation of the reaction conditions, reagents and sequence of the synthetic route, protection of any chemical functionality that cannot be compatible with the reaction conditions, and deprotection at a suitable point in the reaction sequence of the method are included in the scope of the invention. Suitable protecting groups and the methods for protecting and deprotecting different substituents using such suitable protecting groups are well known to those skilled in the art; examples of which can be found in PGM Wuts and TW Greene, in Greene’s book titled Protective Groups in Organic Synthesis (4thed.), John Wiley & Sons, NY (2006), which is incorporated herein by reference in its entirety. Synthesis of the compounds of the invention can be accomplished by methods analogous to those described in the synthetic schemes described hereinabove and in specific examples. When an optically active form of a disclosed peptide amphiphile is required, it can be obtained by carrying out one of the procedures described herein using an optically active starting material (prepared, for example, by asymmetric induction of a suitable reaction step), or by resolution of a mixture of the stereoisomers of the peptide amphiphile or intermediates using a standard procedure (such as chromatographic separation, recrystallization, or enzymatic resolution). Similarly, when a pure geometric isomer of a peptide amphiphile is required, it can be obtained by carrying out one of the above procedures using a pure geometric isomer as a starting material, or by resolution of a mixture of the geometric isomers of the peptide amphiphile or intermediates using a standard procedure such as chromatographic separation. It can be appreciated that the synthetic schemes and specific examples as described are illustrative and are not to be read as limiting the scope of the invention as it is defined in the appended claims. All alternatives, modifications, and equivalents of the synthetic methods and specific examples are included within the scope of the claims. Droplets In another aspect, the present disclosure provides droplets comprising a peptide amphiphile and glucose. Optionally, the droplets may further comprise glucagon and / or a glucagon analogue. In various instances, the glucagon analogue may comprise dasiglucagon and / or a depsi-glucagon analogue. In various instances, the droplet may be formed by liquid- liquid phase separation (LLPS). In various instances, the peptide amphiphile may be present in the droplet at about 0.05– 4% by weight (wt%). In various instances, the peptide amphiphile may be present in the droplet at about 0.1–3.9 wt%; about 0.2–3.8 wt%; about 0.3–3.7 wt%; about 0.4–3.6 wt%; about 0.5–3.5 wt%; about 0.6–3.4 wt%; about 0.7–3.3 wt%; about 0.8–3.2 wt%; about 0.9–3.1 wt%; about 1.0– 3.0 wt%; about 1.1–2.9 wt%; about 1.2–2.8 wt%; about 1.3–2.7 wt%; about 1.4–2.6 wt%; or about 1.5–2.5 wt%. In various instances, the peptide amphiphile may be present in the droplet at no greater than about 4.0 wt%; no greater than about 3.8 wt%; no greater than about 3.5 wt%; no greater than about 3.3 wt%; no greater than about 3.0 wt%; no greater than about 2.8 wt%; no greater than about 2.5 wt%; no greater than about 2.3 wt%; no greater than about 2.0 wt%; no greater than about 1.8 wt%; no greater than about 1.5 wt%; no greater than about 1.3 wt%; no greater than about 1.0 wt%; no greater than about 0.8 wt%; or no greater than about 0.5 wt%. In various instances, the peptide amphiphile may be present in the droplet at no less than about 0.05 wt%; no less than about 0.1 wt%; no less than about 0.2 wt%; no less than about 0.5 wt%; no less than about 0.7 wt%; no less than about 1.0 wt%; no less than about 1.2 wt%; no less than about 1.5 wt%; no less than about 1.7 wt%; no less than about 2.0 wt%; no less than about 2.2 wt%; no less than about 2.5 wt%; no less than about 2.7 wt%; no less than about 3.0 wt%; no less than about 3.2 wt%; or no less than about 3.5 wt%. In various instances, glucagon and / or a glucagon analogue may be present in the droplet at about 0.01–2 wt%. In various instances, glucagon and / or a glucagon analogue may be present in the droplet at about 0.05–2 wt%; about 0.1–1.9 wt%; about 0.2–1.8 wt%; about 0.3–1.7 wt%; about 0.4–1.6 wt%; about 0.5–1.5 wt%; about 0.6–1.4 wt%; about 0.7–1.3 wt%; about 0.8–1.2 wt%; or about 0.9–1.1 wt%. In various instances, glucagon and / or a glucagon analogue may be present in the droplet at no greater than about 2.0 wt%; no greater than about 1.8 wt%; no greater than about 1.5 wt%; about 1.3 wt%; no greater than about 1.0 wt%; no greater than about 0.8 wt%; no greater than about 0.5 wt%; no greater than about 0.1 wt%; or no greater than about 0.05 wt%. In various instances, glucagon and / or a glucagon analogue may be present in the droplet at no less than about 0.01 wt%; no less than about 0.05 wt%; no less than about 0.1 wt%; no less than about 0.2 wt%; no less than about 0.5 wt%; no less than about 0.7 wt%; no less than about 1.0 wt%; no less than about 1.2 wt%; or no less than about 1.5 wt%. In various instances, the glucose may be present in the droplet at about 1–20 mM. In various instances, the glucose may be present in the droplet at about 2–18 mM; about 2–17 mM; about 4–16 mM; about 5–15 mM; about 6–14 mM; about 7–13 mM; about 8–12 mM; or about 9–11 mM. In various instances, the glucose may be present in the droplet at no greater than about 20 mM; no greater than about 18 mM; no greater than about 15 mM; no greater than about 13 mM; no greater than about 10 mM; no greater than about 8 mM; or no greater than about 5 mM. In various instances, the glucose may be present in the droplet at no less than about 1 mM; no less than about 2 mM; no less than about 5 mM; no less than about 7 mM; no less than about 10 mM; no less than about 12 mM; or no less than about 15 mM. In various instances, the droplet may have a diameter of about 0.2–5 µm. In various instances, the droplet may have a diameter of about 0.5–5 µm; about 1–4.5 µm; about 1.5–4 µm; about 2–3.5 µm; or about 2.5–3 µm. In various instances, the droplet may have a diameter of no greater than about 5 µm; no greater than about 4.5 µm; no greater than about 4 µm; no greater than about 3.5 µm; no greater than about 3 µm; no greater than about 2.5 µm; no greater than about 2 µm; no greater than about 1.5 µm; or no greater than about 1 µm. In various instances, the droplet may have a diameter of no less than about 0.5 µm; no less than about 1.5 µm; no less than about 2.0 µm; no less than about 2.5 µm; no less than about 3 µm; no less than about 3.5 µm; no less than about 4 µm; or no less than about 4.5 µm. Hydrogels In another aspect, the present disclosure provides hydrogels comprising a peptide amphiphile, glucose, and a diluent peptide amphiphile. In various instances, the glucose, and the glucagon and / or glucagon analogue interact to form a complex. In various instances, the peptide amphiphile may be present in the hydrogel at about 0.1– 2.0 wt%. In various instances, the peptide amphiphile may be present in the hydrogel at about 0.1–1.9 wt%; about 0.2–1.8 wt%; about 0.3–1.7 wt%; about 0.4–1.6 wt%; about 0.5–1.5 wt%; about 0.6–1.4 wt%; about 0.7–1.3 wt%; about 0.8–1.2 wt%; or about 0.9–1.1 wt%. In various instances, the peptide amphiphile may be present in the hydrogel at no greater than about 2.0 wt%; no greater than about 1.8 wt%; no greater than about 1.5 wt%; about 1.3 wt%; no greater than about 1.0 wt%; no greater than about 0.8 wt%; or no greater than about 0.5 wt%. In various instances, the peptide amphiphile may be present in the hydrogel at no less than about 0.1 wt%; no less than about 0.2 wt%; no less than about 0.5 wt%; no less than about 0.7 wt%; no less than about 1.0 wt%; no less than about 1.2 wt%; or no less than about 1.5 wt%. In various instances, the diluent peptide amphiphile may be present in the hydrogel at about 0.1–4 wt%. In some instances, the diluent peptide amphiphile may be present in the hydrogel at about 0.1–3.9 wt%; about 0.2–3.8 wt%; about 0.3–3.7 wt%; about 0.4–3.6 wt%; about 0.5–3.5 wt%; about 0.6–3.4 wt%; about 0.7–3.3 wt%; about 0.8–3.2 wt%; about 0.9–3.1 wt%; about 1.0–3.0 wt%; about 1.1–2.9 wt%; about 1.2–2.8 wt%; about 1.3–2.7 wt%; about 1.4–2.6 wt%; or about 1.5–2.5 wt%. In various instances, the diluent peptide amphiphile may be present in the hydrogel at no greater than about 4.0 wt%; no greater than about 3.8 wt%; no greater than about 3.5 wt%; no greater than about 3.3 wt%; no greater than about 3.0 wt%; no greater than about 2.8 wt%; no greater than about 2.5 wt%; no greater than about 2.3 wt%; no greater than about 2.0 wt%; no greater than about 1.8 wt%; no greater than about 1.5 wt%; no greater than about 1.3 wt%; no greater than about 1.0 wt%; no greater than about 0.8 wt%; or no greater than about 0.5 wt%. In various instances, the diluent peptide amphiphile may be present in the hydrogel at no less than about 0.1 wt%; no less than about 0.2 wt%; no less than about 0.5 wt%; no less than about 0.7 wt%; no less than about 1.0 wt%; no less than about 1.2 wt%; no less than about 1.5 wt%; no less than about 1.7 wt%; no less than about 2.0 wt%; no less than about 2.2 wt%; no less than about 2.5 wt%; no less than about 2.7 wt%; no less than about 3.0 wt%; no less than about 3.2 wt%; or no less than about 3.5 wt%. In various instances, the glucose may be present in the hydrogel at about 1–20 mM. In various instances, the glucose may be present in the hydrogel at about 2–18 mM; about 2–17 mM; about 4–16 mM; about 5–15 mM; about 6–14 mM; about 7–13 mM; about 8–12 mM; or about 9–11 mM. In various instances, the glucose may be present in the hydrogel at no greater than about 20 mM; no greater than about 18 mM; no greater than about 15 mM; no greater than about 13 mM; no greater than about 10 mM; no greater than about 8 mM; or no greater than about 5 mM. In various instances, the glucose may be present in the hydrogel at no less than about 1 mM; no less than about 2 mM; no less than about 5 mM; no less than about 7 mM; no less than about 10 mM; no less than about 12 mM; or no less than about 15 mM. In various instances, glucagon and / or a glucagon analogue may be encapsulated within the hydrogel. The glucagon analogue may comprise dasiglucagon and / or a depsi-glucagon analogue. In various instances, the glucagon and / or glucagon analogue may be co-formulated with a cationic polymer within the hydrogel. The cationic polymer may be protamine. Glucagon and Glucagon Analogues Glucagon administered at low doses may prevent insulin-induced hypoglycemia or improve the ability to recover from hypoglycemia. However, glucagon is of limited use in pharmaceuticals due to fast clearance from circulation with a half-life of approximately 5 min. Compared to glucagon, glucagon-like analogues (i.e., “glucagon analogues”) may demonstrate improved physical stability toward gel and fibril formation, improved chemical stability and increased half-life, while also showing improved aqueous solubility at neutral pH or slightly basic pH. Glucagon analogues mimic the endogenous hormone glucagon-like peptide 1 (GLP-1), a gastrointestinal hormone that is released into the circulation in response to ingested nutrients. Various exemplary glucagon-based analogues are described in U.S. Patent No.9,486,506 B2. In various instances, the glucagon analogue comprises one or more of: dasiglucagon and / or a depsi- glucagon analogue. Various exemplary depsi-glucagon analogues are described in international patent publication WO 2017 / 210168 A1. Pharmaceutical Compositions Pharmaceutical compositions of the present invention may comprise glucagon and / or a glucagon analogue encapsulated within the hydrogels disclosed herein (i.e., “hydrogel- encapsulated glucagon and / or glucagon analogue”). The hydrogel-encapsulated glucagon / glucagon analogue may be incorporated into pharmaceutical compositions suitable for administration to a subject (such as a patient, which may be a human or non-human). The pharmaceutical compositions may include a “therapeutically effective amount” or a “prophylactically effective amount” of the active agent (glucagon and / or glucagon analogue). A “therapeutically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic result. A therapeutically effective amount of the composition may be determined by a person skilled in the art and may vary according to factors such as the disease state, age, sex, and weight of the individual, and the ability of the composition to elicit a desired response in the individual. A “therapeutically effective amount” is also one in which any toxic or detrimental effects are outweighed by the therapeutically beneficial effects. A “prophylactically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired prophylactic result. Typically, since a prophylactic dose is used in subjects prior to or at an earlier stage of disease, the prophylactically effective amount will be less than the therapeutically effective amount. The pharmaceutical compositions may include pharmaceutically acceptable carriers. The term “pharmaceutically acceptable carrier,” as used herein, means a non-toxic, inert solid, semi- solid or liquid filler, diluent, encapsulating material, or formulation auxiliary of any type. Some examples of materials which can serve as pharmaceutically acceptable carriers are sugars such as, but not limited to, lactose, glucose and sucrose; starches such as, but not limited to, corn starch and potato starch; cellulose and its derivatives such as, but not limited to, sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; powdered tragacanth; malt; gelatin; talc; excipients such as, but not limited to, cocoa butter and suppository waxes; oils such as, but not limited to, peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil and soybean oil; glycols; such as propylene glycol; esters such as, but not limited to, ethyl oleate and ethyl laurate; agar; buffering agents such as, but not limited to, magnesium hydroxide and aluminum hydroxide; alginic acid; pyrogen-free water; isotonic saline; Ringer’s solution; ethyl alcohol, and phosphate buffer solutions, as well as other non-toxic compatible lubricants such as, but not limited to, sodium lauryl sulfate and magnesium stearate, as well as coloring agents, releasing agents, coating agents, sweetening, flavoring and perfuming agents, preservatives and antioxidants can also be present in the composition, according to the judgment of the formulator. Thus, the hydrogels and their physiologically acceptable salts and solvates may be formulated for administration by, for example, solid dosing, eyedrop, in a topical oil-based formulation, injection, inhalation (either through the mouth or the nose), implants, or oral, buccal, parenteral, or rectal administration. Techniques and formulations may generally be found in “Remington’s Pharmaceutical Sciences,” (Meade Publishing Co., Easton, Pa.). Therapeutic compositions must typically be sterile and stable under the conditions of manufacture and storage. The route by which the hydrogel-encapsulated glucagon / glucagon analogue is administered, and the form of the composition will dictate the type of carrier to be used. The composition may be in a variety of forms, suitable, for example, for systemic administration (e.g., oral, rectal, nasal, sublingual, buccal, implants, or parenteral) or topical administration (e.g., dermal, pulmonary, nasal, aural, ocular, liposome delivery systems, or iontophoresis). Carriers for systemic administration typically include at least one of diluents, lubricants, binders, disintegrants, colorants, flavors, sweeteners, antioxidants, preservatives, glidants, solvents, suspending agents, wetting agents, surfactants, combinations thereof, and others. All carriers are optional in the compositions. Suitable diluents include sugars such as glucose, lactose, dextrose, and sucrose; diols such as propylene glycol; calcium carbonate; sodium carbonate; sugar alcohols, such as glycerin; mannitol; and sorbitol. The amount of diluent(s) in a systemic or topical composition is typically about 50 to about 90%. Suitable lubricants include silica, talc, stearic acid and its magnesium salts and calcium salts, calcium sulfate; and liquid lubricants such as polyethylene glycol and vegetable oils such as peanut oil, cottonseed oil, sesame oil, olive oil, corn oil and oil of theobroma. The amount of lubricant(s) in a systemic or topical composition is typically about 5 to about 10%. Suitable binders include polyvinyl pyrrolidone; magnesium aluminum silicate; starches such as corn starch and potato starch; gelatin; tragacanth; and cellulose and its derivatives, such as sodium carboxymethylcellulose, ethyl cellulose, methylcellulose, microcrystalline cellulose, and sodium carboxymethylcellulose. The amount of binder(s) in a systemic composition is typically about 5 to about 50%. Suitable disintegrants include agar, alginic acid and the sodium salt thereof, effervescent mixtures, croscarmellose, crospovidone, sodium carboxymethyl starch, sodium starch glycolate, clays, and ion exchange resins. The amount of disintegrant(s) in a systemic or topical composition is typically about 0.1 to about 10%. Suitable colorants include a colorant such as an FD&C dye. When used, the amount of colorant in a systemic or topical composition is typically about 0.005 to about 0.1%. Suitable flavors include menthol, peppermint, and fruit flavors. The amount of flavor(s), when used, in a systemic or topical composition is typically about 0.1 to about 1.0%. Suitable sweeteners include aspartame and saccharin. The amount of sweetener(s) in a systemic or topical composition is typically about 0.001 to about 1%. Suitable antioxidants include butylated hydroxyanisole (“BHA”), butylated hydroxytoluene (“BHT”), and vitamin E. The amount of antioxidant(s) in a systemic or topical composition is typically about 0.1 to about 5%. Suitable preservatives include benzalkonium chloride, methyl paraben and sodium benzoate. The amount of preservative(s) in a systemic or topical composition is typically about 0.01 to about 5%. Suitable glidants include silicon dioxide. The amount of glidant(s) in a systemic or topical composition is typically about 1 to about 5%. Suitable solvents include water, isotonic saline, ethyl oleate, glycerine, hydroxylated castor oils, alcohols such as ethanol, and phosphate buffer solutions. The amount of solvent(s) in a systemic or topical composition is typically from about 0 to about 100%. Suitable suspending agents include AVICEL RC-591 (from FMC Corporation of Philadelphia, PA) and sodium alginate. The amount of suspending agent(s) in a systemic or topical composition is typically about 1 to about 8%. Suitable surfactants include lecithin, Polysorbate 80, and sodium lauryl sulfate, and the TWEENs from Atlas Powder Company of Wilmington, Delaware. Suitable surfactants include those disclosed in the C.T.F.A. Cosmetic Ingredient Handbook, 1992, pp.587-592; Remington’s Pharmaceutical Sciences, 15th Ed.1975, pp.335–337; and McCutcheon’s Volume 1, Emulsifiers & Detergents, 1994, North American Edition, pp. 236–239. The amount of surfactant(s) in the systemic or topical composition is typically about 0.1% to about 5%. Although the amounts of components in the systemic compositions may vary depending on the type of systemic composition prepared, in general, systemic compositions include 0.01% to 50% of actives and 50% to 99.99% of one or more carriers. Compositions for parenteral administration typically include 0.1% to 10% of actives and 90% to 99.9% of a carrier including a diluent and a solvent. Compositions for oral administration can have various dosage forms. For example, solid forms include tablets, capsules, granules, and bulk powders. These oral dosage forms include a safe and effective amount, usually at least about 5%, and more particularly from about 25% to about 50% of actives. The oral dosage compositions include about 50% to about 95% of carriers, and more particularly, from about 50% to about 75%. Tablets can be compressed, tablet triturates, enteric-coated, sugar-coated, film-coated, or multiple-compressed. Tablets typically include an active component, and a carrier comprising ingredients selected from diluents, lubricants, binders, disintegrants, colorants, flavors, sweeteners, glidants, and combinations thereof. Specific diluents include calcium carbonate, sodium carbonate, mannitol, lactose, and cellulose. Specific binders include starch, gelatin, and sucrose. Specific disintegrants include alginic acid and croscarmellose. Specific lubricants include magnesium stearate, stearic acid, and talc. Specific colorants are the FD&C dyes, which can be added for appearance. Chewable tablets preferably contain sweeteners such as aspartame and saccharin, or flavors such as menthol, peppermint, fruit flavors, or a combination thereof. Capsules (including implants, time release and sustained release formulations) typically include an active and a carrier including one or more diluents disclosed above in a capsule comprising gelatin. Granules typically comprise an active, and preferably glidants such as silicon dioxide to improve flow characteristics. Implants can be of the biodegradable or the non- biodegradable type. The selection of ingredients in the carrier for oral compositions depends on secondary considerations like taste, cost, and shelf stability, which are not critical for the purposes of this invention. Solid compositions may be coated by conventional methods, typically with pH or time- dependent coatings, such that the hydrogel-encapsulated glucagon / glucagon analogue is released in the gastrointestinal tract in the vicinity of the desired application, or at various points and times to extend the desired action. The coatings typically include one or more components selected from the group consisting of cellulose acetate phthalate, polyvinyl acetate phthalate, hydroxypropyl methyl cellulose phthalate, ethyl cellulose, EUDRAGIT coatings (available from Rohm & Haas G.M.B.H. of Darmstadt, Germany), waxes and shellac. Compositions for oral administration can have liquid forms. For example, suitable liquid forms include aqueous solutions, emulsions, suspensions, solutions reconstituted from non- effervescent granules, suspensions reconstituted from non-effervescent granules, effervescent preparations reconstituted from effervescent granules, elixirs, tinctures, syrups, and the like. Liquid orally administered compositions typically include the hydrogel-encapsulated glucagon / glucagon analogue and a carrier, namely, a carrier selected from diluents, colorants, flavors, sweeteners, preservatives, solvents, suspending agents, and surfactants. Peroral liquid compositions preferably include one or more ingredients selected from colorants, flavors, and sweeteners. Other compositions useful for attaining systemic delivery of the subject compounds include sublingual, buccal and nasal dosage forms. Such compositions typically include one or more of soluble filler substances such as diluents including sucrose, sorbitol, and mannitol; and binders such as acacia, microcrystalline cellulose, carboxymethyl cellulose, and hydroxypropyl methylcellulose. Such compositions may further include lubricants, colorants, flavors, sweeteners, antioxidants, and glidants. The disclosed compositions can be topically administered. Topical compositions that can be applied locally to the skin may be in any form including solids, solutions, oils, creams, ointments, gels, lotions, shampoos, leave-on and rinse-out hair conditioners, milks, cleansers, moisturizers, sprays, skin patches, and the like. Topical compositions include: a disclosed hydrogel and a carrier. The carrier of the topical composition preferably aids penetration of the hydrogels into the skin. The carrier may further include one or more optional components. The amount of the carrier employed in conjunction with the hydrogel-encapsulated glucagon / glucagon analogue is sufficient to provide a practical quantity of composition for administration per unit dose of the medicament. Techniques and compositions for making dosage forms useful in the methods of this invention are described in the following references: Modern Pharmaceutics, Chapters 9 and 10, Banker & Rhodes, eds. (1979); Lieberman et al., Pharmaceutical Dosage Forms: Tablets (1981); and Ansel, Introduction to Pharmaceutical Dosage Forms, 2nded., (1976). A carrier may include a single ingredient or a combination of two or more ingredients. In the topical compositions, the carrier includes a topical carrier. Suitable topical carriers include one or more ingredients selected from phosphate buffered saline, isotonic water, deionized water, monofunctional alcohols, symmetrical alcohols, aloe vera gel, allantoin, glycerin, vitamin A and E oils, mineral oil, propylene glycol, PPG-2 myristyl propionate, dimethyl isosorbide, castor oil, combinations thereof, and the like. More particularly, carriers for skin applications include propylene glycol, dimethyl isosorbide, and water, and even more particularly, phosphate buffered saline, isotonic water, deionized water, monofunctional alcohols, and symmetrical alcohols. The carrier of a topical composition may further include one or more ingredients selected from emollients, propellants, solvents, humectants, thickeners, powders, fragrances, pigments, and preservatives, all of which are optional. Suitable emollients include stearyl alcohol, glyceryl monoricinoleate, glyceryl monostearate, propane-1,2-diol, butane-1,3-diol, mink oil, cetyl alcohol, isopropyl isostearate, stearic acid, isobutyl palmitate, isocetyl stearate, oleyl alcohol, isopropyl laurate, hexyl laurate, decyl oleate, octadecan-2-ol, isocetyl alcohol, cetyl palmitate, di-n-butyl sebacate, isopropyl myristate, isopropyl palmitate, isopropyl stearate, butyl stearate, polyethylene glycol, triethylene glycol, lanolin, sesame oil, coconut oil, arachis oil, castor oil, acetylated lanolin alcohols, petroleum, mineral oil, butyl myristate, isostearic acid, palmitic acid, isopropyl linoleate, lauryl lactate, myristyl lactate, decyl oleate, myristyl myristate, and combinations thereof. Specific emollients for skin include stearyl alcohol and polydimethylsiloxane. The amount of emollient(s) in a skin-based topical composition is typically about 5% to about 95%. Suitable propellants include propane, butane, isobutane, dimethyl ether, carbon dioxide, nitrous oxide, and combinations thereof. The amount of propellant(s) in a topical composition is typically about 0% to about 95%. Suitable solvents include water, ethyl alcohol, methylene chloride, isopropanol, castor oil, ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, dimethylsulfoxide, dimethyl formamide, tetrahydrofuran, and combinations thereof. Specific solvents include ethyl alcohol and homotopic alcohols. The amount of solvent(s) in a topical composition is typically about 0% to about 95%. Suitable humectants include glycerin, sorbitol, sodium 2-pyrrolidone-5-carboxylate, soluble collagen, dibutyl phthalate, gelatin, and combinations thereof. Specific humectants include glycerin. The amount of humectant(s) in a topical composition is typically 0% to 95%. The amount of thickener(s) in a topical composition is typically about 0% to about 95%. Suitable powders include beta-cyclodextrins, hydroxypropyl cyclodextrins, chalk, talc, fullers earth, kaolin, starch, gums, colloidal silicon dioxide, sodium polyacrylate, tetra alkyl ammonium smectites, trialkyl aryl ammonium smectites, chemically-modified magnesium aluminum silicate, organically- modified Montmorillonite clay, hydrated aluminum silicate, fumed silica, carboxyvinyl polymer, sodium carboxymethyl cellulose, ethylene glycol monostearate, and combinations thereof. The amount of powder(s) in a topical composition is typically 0% to 95%. The amount of fragrance in a topical composition is typically about 0% to about 0.5%, particularly, about 0.001% to about 0.1%. Suitable pH adjusting additives include HCl or NaOH in amounts sufficient to adjust the pH of a topical pharmaceutical composition. Methods of Treatment The disclosed compositions may be used to modulate glucose levels in a subject. The method may comprise administering a therapeutically effective amount of a pharmaceutical composition comprising glucagon and / or a glucagon analogue encapsulated within a hydrogel, as described herein, to a subject in need thereof. In various instances, the subject in need thereof may have an insulin disorder, such as diabetes. In various instances, the subject in need thereof may be at risk of experiencing a hypoglycemic event. In various instances, the subject in need thereof may be experiencing a hypoglycemic event. In some instances, when the subject is hypoglycemic, the glucagon and / or glucagon analogue may be released from the hydrogel, however, conversely, when the subject is normoglycemic or hyperglycemic, the glucagon and / or glucagon analogue will not be released from the hydrogel. In various instances, the therapeutically effective amount comprises 0.1–10 mg. In various instances, the therapeutically effective amount comprises 0.2–9.8 mg; 0.5–9.5 mg; 1.0– 9.0 mg; 2.0–8.0 mg; 3.0–7.0 mg; or 4.0–6.0 mg. In various instances, the therapeutically amount comprises no greater than 10 mg; no greater than 9.0 mg; no greater than 8.0 mg; no greater than 7.0 mg; no greater than 6.0 mg; no greater than 5.0 mg; no greater than 4.0 mg; no greater than 3.0 mg; no greater than 2.0 mg; no greater than 1.0 mg; no greater than 0.5 mg; or no greater than 0.2 mg; or no greater than 0.1 mg. In various instances, the therapeutically amount comprises no less than 0.1 mg; no less than 0.2 mg; no less than 0.5 mg; no less than 1.0 mg; no less than 2.0 mg; no less than 3.0 mg; no less than 4.0 mg; no less than 5.0 mg; no less than 6.0 mg; no less than 7.0 mg; no less than 8.0 mg; no less than 9.0 mg; or no less than 10 mg. In various instances, following administration of the pharmaceutical composition, the subject has blood glucose levels of about 20–600 mg / dL. In various instances, following administration of the pharmaceutical composition, the subject has blood glucose levels of about 30–500 mg / dL; about 40–400 mg / dL; about 50–300 mg / dL; about 60–200 mg / dL; or about 70– 200 mg / dL. In various instances, following administration of the pharmaceutical composition, the subject has blood glucose levels of no greater than about 600 mg / dL; no greater than about 500 mg / dL; no greater than about 400 mg / dL; no greater than about 300 mg / dL; no greater than about 200 mg / dL; no greater than about 100 mg / dL; no greater than about 90 mg / dL; no greater than about 80 mg / dL; no greater than about 70 mg / dL; no greater than about 60 mg / dL; no greater than about 50 mg / dL; or no greater than about 40 mg / dL. It will be apparent to one of ordinary skill in the relevant art that suitable modifications and adaptations to the compositions, formulations, methods, processes, and applications described herein can be made without departing from the scope of any embodiments or aspects thereof. The compositions and methods provided are exemplary and are not intended to limit the scope of any of the specified embodiments. All of the various embodiments, aspects, and options disclosed herein can be combined in any variations or iterations. The scope of the compositions, formulations, methods, and processes described herein include all actual or potential combinations of embodiments, aspects, options, examples, and preferences herein described. The exemplary compositions and formulations described herein may omit any component, substitute any component disclosed herein, or include any component disclosed elsewhere herein. The ratios of the mass of any component of any of the compositions or formulations disclosed herein to the mass of any other component in the formulation or to the total mass of the other components in the formulation are hereby disclosed as if they were expressly disclosed. Should the meaning of any terms in any of the patents or publications incorporated by reference conflict with the meaning of the terms used in this disclosure, the meanings of the terms or phrases in this disclosure are controlling. Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments. All patents and publications cited herein are incorporated by reference herein for the specific teachings thereof. Various embodiments and aspects of the inventions described herein are summarized by the following clauses: Clause 1. A peptide amphiphile comprising: an alkyl moiety of attached to the N-terminus of a sequence of 5–12 amino acid the sequence comprising: a hydrophobic subsequence of 2–8 hydrophobic amino acid residues, wherein the N- terminus of the hydrophobic subsequence is attached to the alkyl moiety; a positively charged subsequence of 2–5 positively charged amino residues, wherein the N-terminus of the positively charged subsequence is attached to the C-terminus of the hydrophobic subsequence; and a terminal amino acid residue comprising an amine-containing side chain, wherein the N- terminus of the terminal amino acid residue is attached to the C-terminus of the positively charged subsequence; the C-terminus of the terminal amino acid residue the amine-based side chain of the terminal a boronic acid moiety, wherein the boronic acid moiety is a moiety of formula: , or an n is 0–4; RX, at each occurrence, is independently halo, –C1-4haloalkyl, –CN, –NO2, –C(O)H, –CO2H, –CO2C1-4alkyl, or –SO2C1-4alkyl; and X−is an anion having a net charge of −1. Clause 2. The peptide amphiphile of clause 1, wherein each hydrophobic amino acid residue is a non-aromatic amino acid residue. Clause 3. The peptide amphiphile of clause 1 or 2, wherein the peptide amphiphile is a peptide amphiphile of formula (I): Y1AA8AA7AA6AA5AA4AA3AA2AA1B1(I),wherein: Y1is the alkyl moiety; is the sequence of amino acid residues, wherein: AA1is the terminal amino acid residue; B1is the boronic acid moiety; is the and Clause a non-native amino acid residue. Clause 5. The peptide amphiphile of clause 3 or 4, wherein AA2, AA3, and AA4are each independently an arginine residue, a lysine residue, an ornithine residue, or a histidine residue. Clause 6. The peptide amphiphile of any one of clauses 3–5, wherein AA5, AA6, AA7, and AA8are each independently a glycine residue, an alanine residue, a valine residue, an isoleucine residue, or a leucine residue. Clause 7. The peptide amphiphile of any one of clauses 1–6, wherein the boronic acid moiety . of clauses 1–7, wherein n is 0 or 1. Clause 9. The peptide amphiphile of any one of clauses 1–8, wherein RX, at each occurrence, is independently halo or –C1-4haloalkyl. Clause 10. The peptide amphiphile of clause 9, wherein RX, at each occurrence, is independently –F or –C1-4fluoroalkyl. Clause 11. The peptide amphiphile of any one of clauses 1–10, wherein the peptide amphiphile is a peptide amphiphile of formula (I-a): a), R2, R3, or R4are each independently , or ; and R5, R6, R7, and R8are each independently hydrogen, . Clause 12. The peptide amphiphile of clause 11, wherein each . Clause amphiphile of clause 11 or 12, wherein R5, R6, R7, and R8are each independently . Clause 14. The peptide of any one of clauses 1–13, wherein the peptide amphiphile of formula (I) is:

[0002] . C the peptide amphiphile of any one of clauses 1–14; glucose; and optionally, glucagon and / or a glucagon analogue. Clause 16. The droplet of clause 15, wherein: the peptide amphiphile of any one of clauses 1–14 is present at about 0.05–4% by weight (wt%); and glucagon and / or a glucagon analogue is present at about 0.01–2 wt%. Clause 17. The droplet of clause 15 or 16, wherein the glucose is present at about 1–20 mM. Clause 18. The droplet of clause 15, wherein the glucagon analogue comprises dasiglucagon and / or a depsi-glucagon analogue. Clause 19. The droplet of any one of clauses 15–18, wherein the droplet has a diameter of about 0.2–5 µm. Clause 20. The droplet of any one of clauses 15–19, wherein the droplet is formed by liquid- liquid phase separation. Clause 21. A hydrogel comprising: the peptide amphiphile of any one of clauses 1–14; glucose; and a diluent peptide amphiphile, the diluent peptide amphiphile comprising: the alkyl moiety of attached to the N-terminus of a sequence of 5–12 amino acid residues; the sequence comprising: a hydrophobic subsequence of 2–8 hydrophobic amino acid residues, wherein the N- terminus of the hydrophobic subsequence is attached to the alkyl moiety; and a positively charged subsequence of 2–5 positively charged amino residues, wherein the N-terminus of the positively charged subsequence is attached to the C-terminus of the hydrophobic subsequence; and the C-terminus of the positively charged subsequence .Clause 22. The hydrogel of clause 21, wherein the is a diluent peptide amphiphile of formula (II): (II), wherein: 1 Y is the alkyl is the positively charged subsequence; and the C- . Clause 23. The the diluent peptide amphiphile of formula (II) is: . Clause 24. the peptide amphiphile of any one of clauses 1–14 is present at about 0.1–2.0 wt%; and the diluent peptide amphiphile is present at about 0.1–4 wt%. Clause 25. The hydrogel of any one of clauses 21–24, wherein the glucose is present at about 1–20 mM. Clause 26. The hydrogel of any one of clauses 21–25, wherein glucagon and / or a glucagon analogue is encapsulated within the hydrogel. Clause 27. The hydrogel of clause 26, wherein the glucagon analogue comprises dasiglucagon and / or a depsi-glucagon analogue. Clause 28. The hydrogel of clause 26 or 27, wherein the glucagon and / or glucagon analogue is co-formulated with a cationic polymer within the hydrogel. Clause 29. The hydrogel of clause 28, wherein the cationic polymer is protamine. Clause 30. A pharmaceutical composition comprising: the droplet of any one of clauses 15–20 or the hydrogel of any one of clauses 21–29; and a pharmaceutically acceptable excipient. Clause 31. A method of modulating glucose levels in a subject, the method comprising: administering a therapeutically effective amount of the droplet of any one of clauses 15– 20, the hydrogel of any one of clauses 21–29, or the pharmaceutical composition of clause 30. Clause 32. The method of clause 31, wherein the subject in need thereof is experiencing a hypoglycemic event or at risk of experiencing a hypoglycemic event. Clause 33. The method of clause 31 or 32, wherein the subject in need thereof has diabetes. Clause 34. A kit comprising the droplet of any one of clauses 15–20, the hydrogel of any one of clauses 21–29, or the pharmaceutical composition of clause 30; delivery or administration apparata or devices; and optionally, packaging, a label, or instructions for use. Clause 35. Use of the droplet of any one of clauses 15–20, the hydrogel of any one of clauses 21–29, or the pharmaceutical composition of clause 30 to deliver glucagon and / or a glucagon analogue to a subject in need thereof. EXAMPLES Example 1 PA-PBA Synthesis and Purification C10alkyl-V2A2R3-Dap(Mtt) was synthesized by solid-phase methods using a CEM Liberty Blue synthesizer. Fmoc-protected amino acids and Rink amide resin (0.94 emq / g, 100–200 mesh) were purchased from ChemImpex. PBA was purchased from VWR International. Resins were immersed in dimethylformamide (DMF) to swell for 5 mins. Fmoc was first removed by 20% piperidine in DMF, followed by a coupling reaction with diisopropylcarbodiimide (DIC) and Oxyma in DMF under microwave heating. The synthesized C10alkyl-V2A2R3-Dap(Mtt) peptide was first treated with an Mtt deprotection cocktail of 3% trifluoroacetic acid (TFA) and 3% triisopropylsilane (TIPS) in Dichloromethane (DCM) and shaken for 5 min, washed twice with DCM, and the cycle was then repeated for 5 additional times until the bright yellow color of the removed Mtt had disappeared. The resin was then immersed in an activation cocktail of 2% diisopropylethylamine in DMF and shaken for 10 min, with this step repeated two times. The resin was then subjected to a Kaiser test to verify the amine group on Dap was fully deprotected. PBA was coupled to Dap by hand using 4 eq. PBA mixed with 3.95 eq. DIC and 6 eq. HBTU in 15 mL DMF, with the mixture added into the peptide reaction vessel and shaken for 2 h. The synthesized PA-PBA peptide was cleaved from the resin by the treatment with TFA / TIPs / H2O (95:2.5:2.5 v / v / v) for 2 h at room temperature. The cleavage solution was then concentrated under vacuum to remove TFA and recovered by precipitation in cold diethyl ether. Crude material was collected after centrifugation and air-dried overnight before purification. The dried crude peptide was dissolved in hexafluoro- 2-propanol (HFIP) at a concentration of 100–150 mg / mL. Separation was performed on a reversed-phase bio-C18flash cartridge (25 g) at a flow rate of 40 mL / min with a linear gradient from 0 to 100% (v / v) acetonitrile (+ 0.1% TFA) in water and monitored at 220 and 280 nm for fraction collection on a Biotage Isolera system. The collected fractions were then verified by electrospray ionization mass spectrometry (ESI-MS, Advion, Expected Mass: 1214 [M]; Observed Mass: 405.8[M+3H]3+, 608.1[M+2H]2+) and analytical high-performance liquid chromatography (HPLC) on a C18 Gemini (Phenomenex) column. Fractions verified as pure products were combined and lyophilized, yielding a slightly yellowish powder product. The identity of the final product was finally verified by1H NMR and1H-1H COSY NMR. Fluorescein Amidite (FAM)-labeled PA-PBA Synthesis and Purification A peptide of sequence R3-Dap(Mtt) was synthesized, and PBA was coupled to the deprotected amine group on the Dap side chain, as described above. The resins were returned to the peptide synthesizer to complete the sequence with addition of C10alkyl-V2A2-Dap(Mtt) to the resin. The C10alkyl-V2A2-Dap(Mtt)-R3-Dap(PBA) was Mtt-deprotected and activated following the same steps as described above; 8 eq FAM mixed with 3.95 eq DIC and 6 eq HBTU in 15 mL DMF was added into the peptide reaction vessel, shaking overnight. The reacted resin was cleaved, isolated, and purified as described above. The purified FAM-labeled PA-PBA was verified by ESI-MS (Expected Mass: 1657.8 [M]; Observed Mass: 578.7 [M+3H-2H+2K]3+) and analytical HPLC. Dasiglucagon, MCA-dasiglucagon and RhdB-dasiglucagon Synthesis and Purification Dasiglucagon was synthesized according to a previous report, with molecular structure verified by ESI-MS and HPLC (Expected Mass: 3382 [M]; Observed Mass: 1692.9 [M+2H]2+, 1129.2 [M+3H]3+, 846.9[M+4H]4+) and analytical HPLC. The secondary structure was confirmed by circular dichroism (CD) spectroscopy. Methoxycoumarin (MCA)-labeled dasiglucagon was also synthesized according to this same prior report,1 with molecular structure verified by ESI- MS (Expected Mass: 3539 [M]; Observed Mass: 1770.5 [M+2H]2+, 1180.7 [M+3H]3+, 885.7[M+4H]4+) and analytical HPLC. RhdB-dasiglucagon was synthesized and purified using similar methods with the replacement of 25th amino acids with Dap (RhdB). The purified RhdB- dasiglucagon was verified by ESI-MS (Expected Mass: 3706 [M]; Observed Mass: 1855.5 [M+2H]2+, 1237.3 [M+3H]3+, 928[M+4H]4+, 742.5[M+5H]5+) and analytical HPLC. Formation of PA-PBA & Dasiglucagon Droplets A stock solution of PA-PBA was prepared by dissolving in deionized (DI) water and adjusting to pH 7 with 0.1 M NaOH to a final PA-PBA concentration of 10 mg / mL. A stock solution of dasiglucagon was prepared by dissolving the dasiglucagon in DI water and adjusting to pH 7 at a final concentration of 2 mg / mL. Stock solutions of PBA-PA peptide and dasiglucagon were then mixed and diluted to the final concentration of PA-PBA peptide of 4 mg / mL and dasiglucagon of 0.4 mg / mL in DI water in 96-well plates. Droplets were induced by adding an equal volume of 2× HEPES buffer (20 mM HEPES + 280 mM NaCl) containing glucose at different concentrations ( 0, 50, 100, 200, 400 mg / dL) to the mixed solution, for a final concentration of 2 mg / mL PA-PBA, 0.2 mg / mL dasiglucagon, and glucose that was one-half that in the 2× HEPES stock buffers. Droplets were observed in the next 5 min by eye as the solution turned milky. Zeta Potential The zeta potential was measured using a Malvern Zetasizer. Solutions of PA-PBA at a concentration of 2 mg / mL were prepared in a HEPES buffer (10 mM) at pH 7.4, containing varying glucose levels of 0, 25, 50, 100, and 200 mg / dL. Dasiglucagon was prepared at 0.2 mg / mL in HEPES buffer (10 mM) at pH 7.4. For the measurement process, 800 μL of each sample was placed into a clear folded cuvette. These samples were then analyzed at 25 °C using the Huckel model. To ensure accuracy and reproducibility, each sample was prepared and measured three times. Procedure for 4arm-PEG-NH2(MW: 2K) Stabilized Droplet Formation A stock solution of 4arm-PEG-NH2(MW 2 kDa) was prepared by dissolving the PEG powder in DI water at the concentration of 200 mg / mL. PA-PBA / dasiglucagon droplets were prepared according to the above process. After incubating the droplets for 15 mins, 4arm-PEGs- NH2was added to the droplets at final concentrations 0, 2.38, 4.76, 9.52 mg / mL. Determination of MCA-dasiglucagon Encapsulation Efficiency The prepared droplet solutions at 100 μL were centrifuged at the speed of 800 × g for 5 min, and 50 μL supernatant was taken, diluted 2×, and MCA fluorescence was recorded to determine the unencapsulated MCA-dasiglucagon and calculate the encapsulation efficiency by fitting to a standard curve. Evaluation of the Droplet Formation Process Solutions of 100 μL droplets were prepared as described above at different final glucose concentrations of 0, 25, 50, 100, 200 mg / dL. Measurements were immediately performed at 600 nm using a plate reader, with data collected continuously for 20 min. A background of 1× HEPES buffer was subtracted for all samples. The experiments for each glucose concentration were performed 3 times and averaged for each group. To compare the turbidity at different glucose levels, freshly prepared droplets were incubated for 15 mins and absorbance was measured at 600 nm. Evaluation of Different Polymers in Stabilizing Droplets Solutions of 100 μL droplets were prepared as described above at glucose concentrations of 0 and 100 mg / dL. After incubating for 15 mins, 5 μL stock solutions (50 mg / mL) of 4arm-PEG- NH2(2 kDa), polyacrylic acid (PAA, 2 kDa), PLGA (10–50 kDa) were added into the droplet solutions. Similar measurements were immediately performed as described above over 600 mins. The experiments for each polymer were performed 3 times and averaged for each group. Evaluation of 4arm-PEG-NH2in Stabilizing Droplets at Different Glucose Concentrations Solutions of 100 μL droplets were prepared as described above at different glucose concentrations of 0, 25, 50, 100, 200 mg / dL. After 15 min incubation, 5 μL of stock solutions (200 mg / mL) of 4arm-PEG-NH2 was added to the droplet solutions, with absorbance measurements beginning immediately and extending for 600 min. Evaluation of 4arm-PEG-OH in Stabilizing Droplets Solutions of 100 μL droplets were prepared as described above at glucose concentration 100 mg / dL. After 15 min incubation, 5 μL of stock solutions (200 mg / mL) of 4arm-PEG-OH was added to the droplet solutions, with absorbance measurements beginning immediately and extending for 600 min. Optical Microscopy of PA-PBA & Dasiglucagon Droplets at Different Glucose Levels Droplets at glucose concentrations of 0, 25, 50, 100, 200 mg / dL were prepared as described above 96-well plates. After equilibrating for 15 mins, microscope images were taken using an inverted EVOS-Auto microscope with 100× oil lens. Images were taken under a semi- automated mode to collect 9 images of each sample, which were then analyzed by the depicted Python workflow (FIG. 8A–B). Each experiment was replicated 3 times and results were averaged. Data Analysis A Python-based method was developed using OpenCV for image analysis. This involves converting images to grayscale, applying Gaussian blur and adaptive thresholding for noise reduction, and then using the watershed algorithm for segmentation. Small contours were filtered out based on a preset area threshold. The statistical attributes were subsequently calculated such as count, mean, median, and mode for both area and diameter. Results were written into a CSV file, and histograms were generated to visualize the distribution of the areas and diameters of the detected objects. Optical Microscopy for Observation of Droplet Stability Fresh droplets were prepared in 96-well transparent plates. To verify the stabilization of 4arm-PEG-NH2, 100 μL droplets samples at glucose concentration of 100 mg / dL were treated with 5 μL of either DI water or 4arm-PEG-NH2(MW: 2K, Conc.: 200 mg / mL). Microscopy images were taken after 2 h. Transmission Electron Microscopy (TEM) TEM of PA-PBA Alone: PA-PBA was prepared at 2 mg / mL in 1× HEPES buffer containing 100 mg / dL glucose before TEM sample preparation. TEM samples were prepared by depositing a volume of 5 μL peptide solutions onto copper grids with a carbon film (Ted Pella, 200 mesh) for 45 s. After wicking away excess fluid, the grids were washed 2× with DI H2O and allowed to dry in air. Negative staining was applied using 2% uranyl acetate. TEM visualization was performed at an accelerating voltage of 80 keV using a Talos F200i (Thermo Fisher). TEM of PBA-PA-Dasiglucagon Droplets PA-PBA and dasiglucagon droplets were prepared as previously described. After stabilizing for 15 mins, 1 mL prepared droplets solution were centrifuged at the speed of 400 × g for 15 min. The supernatant was taken and replaced with 1 mL 2.5% glutaraldehyde (Electron Microscopy Sciences) in 1× HEPES buffer containing 100 mg / dL glucose for 2 h at room temperature. Samples were then centrifuged at the speed of 400 × g for 5 min and rinsed 3 times with 1× HEPES buffer. After rinsing, the samples were submerged in 4% Osmium Tetroxide (EMS) in a buffer for one hour. The samples were then rinsed twice and dehydrated through a graded series of ethyl alcohols, 25–100%, for 5–10 min intervals at each step. After two changes of 100% EtOH the alcohol was replaced with propylene oxide (EMS). The series of infiltration using PO is as follows: two incubations in 100% PO for 15 min each followed by a 3:1 mixture of PO / epoxy (EMbed 812 Embedding Kit, EMS), 1:1 PO / epoxy, and 1:3 PO / epoxy, for 30 min each. Samples were then submerged two times in 100% epoxy for 30 min followed by a change in epoxy and then overnight incubation at room temperature. Finally, the samples are embedded in fresh epoxy and placed in an oven at 62 °C for 24 h. Once samples had hardened, they were trimmed using a glass knife to expose the cutting surface for loading onto grids (200 mesh copper grids, EMS). A UC7 ultramicrotome (Leica) was used to section the samples at 70 nm thickness using a diamond knife (Diatome). Grids were allowed to dry overnight and then stained using a secondary staining protocol with UranyLess (EMS) for 2 min, rinsed with DI H2O and lead citrate (EMS) for 2 min, and then thoroughly rinsed, blotted, and placed in a grid box for drying. After 24 h of drying, the grids were then imaged using a Talos F200i (Thermo Fisher). Confocal Imaging All confocal fluorescence images were collected with a Nikon A1R inverted confocal microscope equipped with a 100x immersion oil lens. The excitation / emission of FAM labeled PA-PBA was measured by plate reader to be 495 / 525 nm and Rhodamine B (RhdB) labeled dasiglucagon to be 570 / 585 nm. 1 wt% FAM labeled PBA-PA peptides and 5 wt% RhdB labeled dasiglucagon were used for the preparation of droplets at glucose concentration of 100 mg / mL following the same procedures above. 150 μL droplets were prepared in an 8 well chamber slide and incubated for 10 mins. Fluorescence images were collected using GFP and TRITC channel settings. Fluorescence Recovery after Photobleaching (FRAP) FRAP was performed by the same Nikon A1R confocal microscope with a 100× immersion oil lens. Droplet samples were prepared in 8 well chamber slides as before with fluorescent components. Three circular regions of interest (ROI) were monitored in the field of view: ROI-1 was set at the center of the droplets with a diameter of 0.1 μm for the active photobleaching; ROI- 2 was set to a reference droplet with a diameter of 0.1 μm to monitor the influence of broad bleaching during the study; ROI3 was set to the background with a diameter of 0.2 μm. Photobleaching was performed using 488 and 561 nm laser light at a power setting of 5% and 10%, respectively, to achieve a 90% decrease in signal intensity. The fluorescence recovery was monitored by imaging every 15 s for 880 s after photobleaching. The normalized fluorescence intensity, I(n), for both FAM and RhdB were corrected with passive bleaching and background subtraction following previous protocols. I(n) was calculated using the following equations: ^^^^^^^ ൌ ^^^^^^^^ െ ^^^^^^^ െ ^^^^^^^^^^^^^^ െ ^^^^^^^^^^^^^^ ^^^^^^^ where n1and n2refers to fluorescence intensity; and I(nbleach1) and I(nbleach2) refers to the time point of photobleaching. ^^^^^^^ ൌ ଶ^^^ In vitro Release Assay PA-PBA & Dasiglucagon droplets were prepared separately for each time point in 96 well plates at glucose concentration of 100 mg / dL (100 μL / well) as described above. The plates were centrifuged at a speed of 800 × g for 5 min. Supernatants from each well were discarded to remove free dasiglucagon. Another 100 μL 1× HEPES buffer containing different glucose concentrations of 0, 25, 50, 100, 200 mg / dL were immediately added back. At each time, the plate was centrifuged at 800 × g for 5 min.50 μL supernatant was taken and diluted 2× for MCA fluorescence measurement by a plate reader. For each time point, the droplets were prepared individually. In vitro Droplets Disassembly Process Monitoring Droplets were prepared as described above and after adding the buffer, the disassembly process of droplets for each glucose concentration was monitored by immediately performing the turbidity measurements over time for 180 min. In vivo Hypoglycemia Mouse Model Droplets were evaluated on the previously established hypoglycemia mouse model to assess the preventive application of this material in reducing the severity of hypoglycemia. Briefly, male C57BL6 / J mice, aged 8 weeks, were induced to diabetes by streptozotocin (STZ) and those with non-fasted blood glucose (BG) levels of 600 + mg / dL were selected for study. After fasting for 8 h, mice with BG > 450 mg / dL were dosed with 0.5 IU / kg basal insulin detemir (Levemir, Novo Nordisk) via subcutaneous (s.c.) injection in a total volume of 100 μL. After 4 h, as BG levels returned to a normal range (~180 mg / dL), mice were randomly divided into 3 groups and treated with buffer, dasiglucagon alone (6 μg), the PA-PBA and dasiglucagon droplets (loaded with 6 μg dasiglucagon), via a 30 μL s.c. injection. All samples were administered in a 1× HEPES buffer (10 mM HEPES + 140 mM NaCl); the droplets group was prepared using an additional 100 mg / dL glucose to induce droplet formation. This amount of glucose was assumed to have a negligible influence on BG levels in mice, as if even it was instantly and completely distributed into the total blood volume of a mouse (0.8 mL / g × 25 g mouse = 2 mL) the amount of glucose in the 30 μL injection would account for a blood glucose increase of only 1.5 mg / dL. Realistically, however, any glucose that is not PBA-bound would actually distribute into both interstitial and blood volumes, making any resulting increase even lower. BG levels were monitored after the treatment (t = 0 min). To trigger hypoglycemia, after 2 h mice were injected i.p. with AOF recombinant human insulin (Gibco) at a dose of 3 IU / kg in 100 μL saline. BG levels were monitored for another 4 h. During the process, mice exhibiting “high” readings were noted as a BG value of 600 mg / dL, while “low” readings were noted as a BG value of 20 mg / dL (also indicated dead). n = 9 mice per Molecular Design The classical PA motif consists of a saturated alkyl chain providing a hydrophobic driving force for self-assembly and micellization in water that is covalently attached to the terminus of a peptide comprising at least two domains: a fibrilizing domain promoting parallel intermolecular β- sheet formation for directional hydrogen bonding and one-dimensional assembly, and a charged headgroup facilitating solubility and favorable solvent interactions on the micelle surface.20 Further, the surface of the resulting nanostructures enables high-density presentation of bioactive signals to recreate functions and structures of native extracellular matrix, with uses in an assortment of biomedical applications. In an initial effort that was intended to make glucose- responsive hydrogels, here a PA was designed for surface-presentation of an amide-linked PBA motif. The sequence of the specific PA studied (PA-PBA) was C10alkyl–V2A2R3-Dap(PBA) (FIG. 1A). The C10saturated alkyl segment (“C10alkyl”) was selected to reduce the hydrophobic driving force for self-assembly so as to enhance the eventual glucose-responsiveness of the system and followed a design from prior work exploring enzymatically driven PA hydrogelation. Similarly, an established short β-sheet sequence of two valine residues followed by two alanine residues (V2A2) was also inserted with the intention to promote peptide hydrogelation while at the same time not having the same high cohesive interactions of traditionally longer β-sheet segments. A segment of three arginines (R3) offered a hydrophilic head group to promote solubility and order self- assembly of the molecule in water. On the C-terminal end of the molecule opposite the alkyl tail, a diaminopropionic acid (Dap) residue was included; synthetically this was inserted on-resin with its β-amine protected with a 4-methyltrityl (Mtt) protecting group, for selective on-resin deprotection using mild acidic conditions to enable side-chain functionalization with a PBA motif through amide bond formation. This amide-linked PBA would be expected to have a pKaof ~8.4; this would not typically lead to a significant amount of the tetrahedral boronate species necessary for glucose binding under physiological conditions. However, the positioning of this PBA next to cationic arginine residues was expected to significantly reduce its effective pKa, a phenomenon also observed in PBA-modified cationic polymers. The design of PA-PBA was initially intended for a goal of glucose-directed hydrogelation. Specifically, glucose binding to a PBA group at pH conditions near to its pKais known to shift the equilibrium to the negatively charged tetrahedral boronate ester species. As such, in the presence of glucose, the PBA group on the molecule should become more negatively charged, in turn reducing the net charge on the PA-PBA headgroup. The reduced electrostatic repulsion upon glucose binding would then be expected to enhance self-assembly and hydrogelation, as is also seen for other PA designs upon introduction of charge-screening ionic species or changes in pH. As an alternative to a prior report exploring enzymatically driven hydrogelation in the presence of glucose through the actuation of xenogeneic glucose oxidase, the current approach envisioned with PA-PBA was thought to offer a more biocompatible and direct way to achieve a glucose- stabilized hydrogel for release of glucagon upon hypoglycemia. PBA-modified oligopeptides were previously shown to self-assemble into nanocoils that then became entangled into a hydrogel network upon PBA–glucose binding. However, initial efforts with the platform here failed to realize formation of a self-supporting hydrogel upon addition of glucose. TEM of PA-PBA in its glucose- bound state instead revealed formation of spherical micellar structures (FIG.6), likely explaining the inability of this molecule to form the nanofibrillar hydrogels of a typical PA material. Accordingly, cohesive interactions in this relatively short β-sheet segment were not sufficient to overcome the electrostatic repulsion and hydrated volume of its charged and glucose-bound headgroup. Observation of Droplet Formation Here, a stabilized and water-soluble glucagon analogue, dasiglucagon, was explored for formulation and delivery with PA-PBA. It was initially reasoned that though PA-PBA did not gel on its own, the added electrostatic screening from the negatively charged dasiglucagon could contribute to nanofibril formation and hydrogelation of PA-PBA, as had been shown for other arginine-rich cationic PAs when mixed with negatively charged biomolecules. Upon mixing PA- PBA at 2 mg / mL with synthesized dasiglucagon at 0.2 mg / mL in glucose conditions of 200 mg / dL resembling a glucose concentration on the high end of the normal physiological range, the resulting mixture appeared cloudy, having the appearance of a colloidal suspension rather than a self-supporting hydrogel. To further probe this phenomenon, the components were mixed under different glucose concentrations ranging from 0–200 mg / dL and sample turbidity was monitored in real time (FIG.2A) by measuring absorbance (i.e., light scattering) at λ = 600 nm, where the individual components have negligible molecular absorbance. These data point to a rapid increase in sample turbidity shown by greater overall light scattering in samples prepared at higher glucose concentrations, whereas samples remained translucent at low glucose concentrations (FIG. 2B). Optical microscopy of these samples revealed the presence of spherical droplets, with the number generally increasing with increases in glucose concentration of the mixture (FIG.2C). Zeta potential measurements were collected to study the charge state of PA-PBA at 2 mg / mL across a range of different glucose concentrations (FIG.7). These data show a steady reduction in the zeta potential of PA-PBA as glucose level is increased, from 34.1 ± 1.7 mV at 0 mg / dL glucose to 18.9 ± 1.7 mV at 200 mg / dL. Comparatively, dasiglucagon at 0.2 mg / mL had a zeta potential of −19.9 ± 0.3 mV. Accordingly, as PA-PBA binds to glucose, the charged tetrahedral boronate of its PBA motif is stabilized, leading to a reduction in the overall extent of positive charge of the PA-PBA. Interestingly, at these higher glucose levels the charge of PA-PBA at 2 mg / mL is effectively equal in magnitude as the opposing negative charge on dasiglucagon at 0.2 mg / mL. Accordingly, addition of glucose may promote greater charge- balance between the two components, thereby promoting complexation and droplet formation. To systematically quantify both droplet number and diameter as a function of glucose concentration, microscopy images of droplets prepared in 96-well plates were analyzed with a Python-based automated method (FIG. 8A–B), collecting nine images per sample with three sample replicates. This analysis confirms negligible droplet formation in the absence of glucose. As glucose level was increased from 25 to 200 mg / dL, the total number of droplets correspondingly increased (FIG. 2D). Accordingly, droplet formation was highly impacted by glucose concentration. However, the diameter of formed droplets remained relatively constant, in a range of 0.9–1 µm, showing limited impact from glucose concentration (FIG.2E). The highly spherical nature of the resulting droplets supports their existence as a type of coacervate phase, versus a micron-scale aggregate or precipitate. The formation of peptide- based droplet phases is an area of increasing interest in the field of drug delivery, with several examples of peptide and peptide-polymer hybrid droplets reported thus far. Of note here, PA- PBA is net-positive while dasiglucagon is net-negative. The emergence of a droplet phase through complex coacervation has been reported when mixing (poly)peptides of opposite charges. The role of glucose in binding to PA-PBA is likewise interesting; glucose binding is seemingly necessary to reduce the extent of positive charge of PA-PBA and ensure effective electrostatic complex formation when mixed with the negatively charged dasiglucagon. Previous work describing glucose-induced peptide droplet formation achieved function through combining a pH-sensitive coacervate-forming peptide derived from a type of squid beak with glucose oxidase to afford a means of converting glucose level to pH change. Comparatively, the system here offers a direct response to glucose through use of a synthetic binder and droplet formation specifically arises from combination of a PA-based supramolecular material with a therapeutic hormone remedy for dangerously low blood glucose. Next, to verify that droplets were composed of both PA-PBA and dasiglucagon, PA-PBA was selectively labeled with 5,6-carboxyfluorescein (FAM, FIG.9) and dasiglucagon was labeled with rhodamine B (RhdB, FIG.11). The excitation and emission of these labeled peptides was also verified (FIG.11–12). FAM-labeled PA-PBA was doped into PA-PBA at 1% of the total PA amount while RhdB-labeled dasiglucagon was doped in at 5% of the total dasiglucagon. After mixing these samples containing labeled constituents in the presence of 100 mg / dL glucose as described above and equilibrating for 15 minutes, confocal laser scanning microscopy (CLSM) was used to image samples (FIG.2F). All droplets showed signals from both FAM and RhdB with complete spatial overlap and homogeneous fluorescence signal within the droplets, supporting formation of a continuous phase rather than a heterogeneous precipitate. Further, these results demonstrate that both PA-PBA and dasiglucagon contribute to droplet formation. Stained TEM was then performed on droplets embedded and sectioned using an ultramicrotome (FIG. 2G). These images suggested that the droplets exist as a continuous phase with some subtle texture visible under higher magnification. The form of the underlying nanostructure, and specifically whether PA-PBA forms the originally intended supramolecular fibrils or remains as spherical micelles in the presence of dasiglucagon, is not clear from these images. Droplet Interfacial Stabilization As further evidence of their fluid-like character, droplets were observed to coalesce over short times under observation (FIG.3A). This effect was evident in absorbance data for droplets prepared in the presence of glucose, with a reduction in absorbance corresponding to coalescence over ~1–2 h (FIG. 3B). Such behavior is common in LLPS systems with low to moderate surface tension, as the system seeks to minimize its interfacial surface area through droplet fusion. In exploring these droplets for applications in therapeutic glucagon delivery, particle instability and rapid fusion are not desirable characteristics. Hydrophilic and amphiphilic polymers have been explored as interfacial stabilizers for their role in enhancing droplet surface tension and preventing coalescence. Accordingly, the exploration of polymers as interfacial stabilizers was further assessed here. Various polymers were tested for their role in droplet stabilization. These included a branched polyethylene glycol (PEG, 2 kDa, 4-arm NH2-terminated), polyacrylic acid (PAA, 2 kDa) and poly(lactic-co-glycolic)acid (PLGA, 10–50 kDa). For screening purposes, polymer stock solutions (50 mg / mL) were added in a volume of 5 µL to a 100 µL pre-prepared samples of PA- PBA and dasiglucagon at a glucose concentration of either 0 mg / dL, which did not have droplets, or 100 mg / dL where the droplets were formed and had been allowed to equilibrate for 15 min prior to polymer addition. Absorbance at 600 nm was monitored for these mixtures over time, as before, to determine if the glucose-driven droplet phase was stabilized by the polymer. PAA and PLGA caused an increase in absorbance in the glucose-free case, presumably due to electrostatic interactions and aggregation between these anionic polymers and the net-positive PA-PBA (FIG. 14). Accordingly, PAA and PLGA were not further explored here for use in stabilizing these droplets. The branched PEG did not lead to an increase in absorbance in the glucose-free case (FIG.15), indicating no aggregation, and thus behaved comparably to the original mixtures in the absence of glucose. In the presence of 100 mg / dL glucose with addition of branched PEG, the same droplets were observed as before yet the rate of reduction of absorbance due to droplet coalescence was slowed as polymer concentration increased from 0, 2.38, 4.76, and 9.52 mg / mL (FIG.3B). Morphological comparisons of droplets 30 min after addition of branched PEG at 9.52 mg / mL compared to a control diluted with an equivalent volume of water revealed less droplet fusion and improved stability, as observed by CLSM (FIG.3C) and brightfield microscopy (FIG. 3D). These studies also revealed likely fusion and spreading onto the glass substrate occurring in the case of the unstabilized droplets. The PEG-stabilized droplets also showed some evidence of glucose-directed increase in droplet formation on the basis of turbidity (FIG. 3E), though the glucose-specific differences were not as pronounced as in the case where no PEG stabilizer was added (FIG. 2B). The terminal amino groups on the 4-arm PEG-NH2were critical to droplet stabilization, as a 4-arm PEG-OH of identical molecular weight provided no enhancement in droplet stability. These results suggest electrostatic contributions from the cationic end-groups of the 4-arm PEG-NH2enable stabilization through association at the droplet interface. Droplet Dynamics Following efforts to prepare stabilized droplets, the dynamics of droplet constituents was of interest. Fluorescence recovery after photobleaching (FRAP) enables monitoring and quantification of molecular diffusion for fluorescently labeled constituents within droplets by photobleaching a region and monitoring fluorescence recovery over time. Droplets doped with FAM- and RhdB-labeled constituents were prepared in 100 mg / dL glucose with a 15-minute incubation time, followed by the addition of the 4-arm PEG-NH2stabilizer. A three-dimensional reconstructed z-stack of the droplets performed via CLSM revealed the existence of a homogenous fluorescent field throughout the droplet for both constituents, pointing to a continuous phase and lack of interfacial concentration of either component. The droplet center was then bleached using 488 nm and 561 nm lasers and the fluorescence of the bleached region of interest was monitored for fluorescence recovery. Though recovery was evident for both the PA-PBA (28.5%) and dasiglucagon (25.5%) constituents, in general it was quite limited (FIG.4A– B). The limited volume of the droplet relative to the volume of the region bleached makes complete recovery unlikely, though the bleached region was clearly evident at the endpoint. This result showing slow recovery dynamics supports a more gel-like character of the droplets rather than a highly dynamic liquid-like character; this could be related to the relative size and stability of these PA-PBA–dasiglucagon supramolecular complexes in the context of the time over which diffusion was observed. In related protein-based droplets, structural maturation and interaction of components is similarly known to reduce diffusion within the droplet. Functional Dasiglucagon Delivery To assess the performance of the PA-PBA and dasiglucagon droplets in glucose-directed therapeutic delivery, responsiveness to different glucose levels was further assessed. Droplets were formed at 100 mg / dL glucose in all cases and then incubated in a buffer ranging in glucose level from 0-200 mg / dL. The pre-formed droplets completely dissipated over the course of 60– 90 minutes in glucose concentrations of 0 mg / dL and 25 mg / dL (FIG. 5A). However, at higher glucose concentrations of 50, 100, and 200 mg / dL, the droplets only exhibited partial dissolution of their structure in this time, with absorbance reduced to 45%, 60%, and 72% of its initial values, respectively. Droplet stability was thus enhanced as a function of bulk glucose levels. In order to assess glucose-responsive release of dasiglucagon, a previously reported variant labeled with methylcoumarin (MCA) was used. The presence of glucose dramatically increased the dasiglucagon encapsulation efficiency, as determined from the amount of dasiglucagon that remained soluble following mixing with PA-PBA (FIG.5B). In agreement with the data on droplet stability, the free dasiglucagon that was released also exhibited an inverse relationship to glucose level (FIG. 5C). After 8 h, 80% of glucagon was released from droplets formed at 100 mg / dL glucose and then transferred into a glucose-free bulk; this indicated an improvement in the rate of glucagon release compared to a previously reported PA platform that relied on glucose oxidase for pH-directed hydrogel stability. The glucose-stabilized nature of these LLPS droplets was of interest to explore as a glucagon delivery technology in the context of hypoglycemia prevention. A previously established model in STZ-induced diabetic mice simulating prophylactic delivery prior to application of an insulin overdose was employed (FIG. 5D). Following a period of fasting and blood glucose normalization, droplets prepared in 100 mg / dL glucose-containing buffer were injected subcutaneously at a total dasiglucagon dose of 6 µg. Controls of buffer or dasiglucagon alone (6 µg) were also administered. Immediately following injection, groups treated with the dasiglucagon droplets or dasiglucagon alone showed an increase in blood glucose. This confirms activity of the therapeutic, but also suggests some extent of undesirable dasiglucagon leakage from the droplets. After 2 h, mice were given an insulin dose of 3 IU / kg to induce hypoglycemia; blood glucose levels following this overdose were more closely inspected (FIG. 5E). Specifically, the average nadir (i.e., lowest) value observed in mice (FIG.5F) treated with the LLPS droplets (62 ± 3 mg / dL) was significantly higher than that for mice treated with dasiglucagon alone (46 ± 4 mg / dL) or buffer (43 ± 6 mg / dL). Mortality offered another measure of the severity of hypoglycemia, with 0% (0 / 9 mice) dying in the group treated with droplets compared to 11% (1 / 9) in the group treated with dasiglucagon and 33% (3 / 9) in the group treated with buffer. The final blood glucose values at 4 h following insulin overdose (FIG.5G) were also significantly higher for mice treated with the LLPS droplets (95 ± 4 mg / dL) compared to that for mice treated with dasiglucagon alone (68 ± 7 mg / dL) or buffer (62 ± 11 mg / dL). Overall, the performance of these LLPS droplets in delivering glucagon was comparable to that of the previously reported hydrogel platform using glucose oxidase for glucose sensing in this same animal model. As such, glucose- driven LLPS droplet formation offers function in the delivery of dasiglucagon that may be relevant in the context of a corrective therapeutic strategy to mitigate the effects of hypoglycemia. The remarkable function from LLPS systems, including membraneless organelles in cell biology, has offered inspiration in designing an array of functional soft materials. A number of bio- inspired synthetic polymers, recombinant proteins, and peptide-based building blocks have been found to demonstrate LLPS phenomena in water. However, in spite of their similarity to natural polymers, there is limited evidence for supramolecular materials participating in LLPS. Herein, the combination of a net-positive peptide amphiphile with a net-negative protein therapeutic, dasiglucagon, underwent LLPS to form gel-like droplets specifically in the presence of glucose. The formation and stability of the droplets here was enhanced under conditions of physiologically relevant glucose concentration. Though the droplets formed upon initial mixture were prone to coalescence, the interface could be stabilized through addition of a hydrophilic branched PEG polymer. Prepared droplets rapidly dissolved when placed into conditions of low glucose yet remained more stable and dissolved more slowly under conditions of normal to high glucose levels. A therapeutic hormone that corrects low blood glucose, dasiglucagon, was one of the two biomolecular components participating in the complexation driving the initial droplet formation. As such, the observation for both glucose-driven droplet formation and rapid dissolution in the absence of glucose pointed to the possibility of using these droplets for therapeutic delivery of dasiglucagon. These droplets indeed exhibited dasiglucagon release that was reduced on exposure to increased glucose levels and demonstrated a functional benefit in mitigating the most severe effects of hypoglycemia arising from insulin overdose in a mouse model. Accordingly, beyond reporting an uncommon phenomenon for a supramolecular building block to participate in glucose-driven LLPS and gel-like droplet formation, this current work also points to a functional role for this system in the therapeutic delivery of dasiglucagon toward improved diabetes management. Example 2 Peptide Synthesis & Purification Peptides were synthesized by solid-phase Fmoc synthesis procedures using a CEM Liberty Blue microwave synthesizer. Fmoc groups on Rink amide resin (0.72 mmeq / g, 100–200 mesh) were removed by 20% (v / v) piperidine in N,N-dimethylformamide (DMF), followed by a coupling reaction with diisopropylcarbodiimide (DIC) and Oxyma in DMF under microwave heating. For C10alkyl-V2A2R3-Dap(Mtt) peptide, removal of a selectively labile Mtt protecting group was performed using 5% TFA in dichloromethane (DCM), followed by conjugation of 4- carboxyphenylboronic acid to the free amine on the side chain of Dap residue. After completion of synthesis, peptides were cleaved from resin using a mixture of trifluoroacetic acid (TFA), triisopropanolsilane (TIS), and H2O (95:2.5:2.5, v / v / v) for 3 h at room temperature. The resin was washed with DCM and the mixture of TFA and DCM was concentrated under vacuum to remove most solvent. The residual peptide solution was precipitated in cold diethyl ether, followed by centrifugation and diethyl ether washing and drying under vacuum overnight. The crude peptides were dissolved in hexafluoro-2-propanol (HFIP) and purified on a Biotage Isolera using a reversed-phase bio-C18flash cartridge (25 g) with a linear gradient of water to acetonitrile (ACN), each containing 0.1% TFA. The elution was monitored at 220 and 260 nm. The purity of collected fractions were verified by electrospray ionization mass spectrometry (ESI-MS, Advin) and high performance-liquid chromatography (HPLC) using a C18Gemini (Phenomenex) column. Dasiglucagon and MCA-labeled dasiglucagon were synthesized and purified. Preparation of PA-PBA / dPA Hydrogels PA-PBA and PA peptides were individually dissolved at 10 mg / mL in an ACN / H2O (1:1 v / v) mixture and mixed at a mass fraction of PA-PBA to dPA of 10%, 20%, 30%, or 40%. The mixed samples were then frozen in liquid nitrogen and dried by lyophilization to remove all solvent. The co-formulated peptide powders were then dissolved in deionized water at a concentration of 4% (w / v), and after solubilized were mixed with 2× HEPES buffer (pH 7.4, 10 mM) and diluted to a final a concentration of 2% (w / v) and glucose concentrations of 0, 25, 50, 100, or 200 mg / dL. Circular Dichroism (CD) Spectroscopy CD spectroscopy was performed on a Jasco 710 CD spectrometer. PA-PBA / dPA samples were mixed and prepared as described above and diluted in HEPES buffer (pH 7.4, 10 mM) at various glucose concentrations (0, 25, 50, 100, or 200 mg / dL) to a concentration of 0.5% (w / v). CD spectra were collected from 250 nm to 195 nm at room temperature using a 0.1 mm cuvette, a bandwidth at 0.1 nm, scan rate at 50 nm / min, and a response time of 2 s. The spectrum of HEPES buffer (pH 7.4, 10 mM) was measured as background and subtracted from all samples. The raw data was converted to mean residue ellipticity (MRE) by using the formula θ =(1000⋅mDeg) / (c⋅n⋅l) where c is the peptide concentration in mM, n is the number of amino acids, and l is the pathlength of the cell used in millimeters. Transmission Electron Microscopy (TEM) PA-PBA / dPA samples were prepared as described above at 2% (w / v) in HEPES buffer with varying glucose levels. Immediately before preparing grids, samples were further diluted in the same HEPES buffer containing 0, 25, 50, 100, 200 mg / dL glucose to a final concentration of 0.1% (w / v). A 10 μL sample was pipetted onto a lacey carbon grid (Ted Pella 01824). After 2 min, the sample solution was removed by filter paper and 10 μL of 2% (w / v) uranyl acetate solution was pipetted onto the grid for negative staining. After 2 min, the excess uranyl acetate solution was removed by filter paper and grids were dried overnight before imaging on the Talos F200i (S)TEM 20-200 kV field emission (scanning) TEM. Zeta Potential PA-PBA / dPA samples were prepared as described above in HEPES buffer (pH 7.4, 10 mM, 150 mM NaCl) at concentration of 0.5% (w / v) with addition of 0, 25, 50, 100, or 200 mg / dL glucose. The zeta potential was measured using a Malvern Zetasizer with a Huckel model at 25 °C. The zeta potential measurements were collected in triplicate. Rheological Characterization PA-PBA / dPA samples were prepared as described above in HEPES buffer (pH 7.4, 10 mM, 150 mM NaCl) at 2% (w / v) within addition of glucose concentrations of 0, 25, 50, 100, or 200 mg / dL and their rheological properties were evaluated using TA Instruments Discovery HR-2 rheometer. The linear viscoelastic range was determined by an amplitude sweep performed at 1 rad / s. A frequency sweep was then performed at constant strain of 0.5%. The gelation over time was evaluated via a time sweep at a constant 0.5% strain and 1 rad / s. Recovery following high strain for PA-PBA / dPA hydrogel at glucose 100 mg / dL was evaluated by a step-strain cycling between 0.5% strain for 2 min and 100% strain for 30 s at a constant angular frequency of 1 rad / s. The shear-thinning property of PA-PBA / PA hydrogel at glucose 100 mg / dL was studied under steady shear flow over a shear rate range from 0.001 to 88 s−1. Glucagon Release PA-PBA / dPA hydrogels were prepared as described above at 2% (w / v) in HEPES buffer at glucose concentration of 100 mg / dL and included 0.1 mg / mL MCA-dasiglucagon. MCA- dasiglucagon was synthesized as previously described. See Yu et al., J. Am. Chem. Soc.143: 12578-12589 (2021). Following preparation, 50 μL hydrogels were incubated within 12-well plates in 2 mL of bulk HEPES buffer containing 0, 25, 50, 100, or 200 mg / dL glucose. At each time point, a sample of half of the bulk buffer was removed and subjected to fluorescence analysis (Ex: 324 nm, Em: 380 nm) on a Tecan M200 plate reader. At each time point, after removing half of the volume of the bulk buffer (1 mL), fresh buffer of equal volume was added to simulate conditions of bulk dilution. In vivo Hypoglycemia Protection Animal studies were performed in accordance with guidelines for the care and use of laboratory animals and protocols were approved by the University of Notre Dame Institutional Animal Care and Use Committee (IACUC). A previously established hypoglycemic rescue model in mice was performed as described. See Yu et al., J. Am. Chem. Soc.143: 12578-12589 (2021). Male C57BL6 / J mice (8 weeks) were administered streptozotocin (STZ) i.p. at a dose of 150 mg / kg to induce an insulin-deficient phenotype. After 10–12 d, non-fasting blood glucose levels reached 600 + mg / dL and the in vivo study was initiated. After 8 h fasting, mice with blood glucose levels (BGL) higher than 450 mg / dL were treated with 0.5 IU / kg basal insulin detemir via s.c. injection. Once the BGL was reduced to 180 mg / dL, mice were randomized into two groups (n = 9) and treated with single s.c. injection of 0.1 mL PA-PBA / dPA hydrogel containing 5 μg dasiglucagon and compared to a single s.c. injection of 5 μg dasiglucagon. After 2 h, AOF recombinant human insulin was administered at a dose of 2.8 IU / kg via i.p. injection to induce severe hypoglycemia. BGL was measured by handheld blood glucose monitor throughout the study. Mice with “high” BGL readings were noted with a 600 mg / dL, while “low” BGL readings were noted with a 20 mg / dL and triaged from the study due to severe morbidity or mortality. Molecular Design of Peptides Peptide amphiphiles (PAs) are a versatile and well-studied platform for the preparation of hydrogel biomaterials. The design of PA-PBA (C10alkyl–V2A2R3Dap(PBA), SEQ ID NO: 1, FIG. 16) was used. A saturated alkyl (C10alkyl) tail providing a hydrophobic driving force for self- assembly in water was functionalized with two valine (V2) and two alanine (A2) residues to promote intermolecular parallel β-sheet structures, while three positively charged arginine (R3) residues offered hydrophilic motifs to impart amphiphilicity. A diaminopropionic acid (Dap) was included at the C-terminus and coupled on-resin with 4-carboxyphenylboronic acid (PBA) via selective deprotection and orthogonal amide bond formation. The position of the PBA motif was intended to afford glucose binding on the surface of the assembly. PBAs are capable of forming stable bonds with glucose in water at pH levels at or above their pKa. Although the pKa of this amide- linked PBA is around 8.4, the positively charged arginine residues near to the PBA are expected to reduce its pKawithin the range of physiological pH. When designing PA-PBA it was believed that glucose binding to its PBA motif would stabilize the negatively charged tetrahedral boronate and reduce the net-charge of this otherwise cationic PA to drive nanofiber assembly. However, in its previous use PA-PBA surprisingly formed nanoscale spherical assemblies in the presence of glucose, with these transitioning into liquid– liquid phase-separated droplets upon addition of dasiglucagon (SEQ ID NO: 2). It was therefore hypothesized that PA-PBA did not form the typical high aspect-ratio nanofibers seen for other PAs due to both its relatively short alkyl and β-sheet segments and substantial electrostatic repulsion from its charged and glucose-bound headgroup. With the goal of producing nanofibrillar hydrogels in this work, a diluent PA (dPA, FIG.16) with peptide sequence of C10alkyl–V2A2R3was synthesized for co-formulation with PA-PBA to promote intermolecular β-sheet formation and nanofibrillar assembly. The conserved core, β-sheet, and charged regions of the two PAs were intended to facilitate mixing and co-assembly of dPA and PA-PBA. Glucose-Dependent Hydrogelation The goal was to prepare a peptide assembly that was stabilized in the presence of physiologically normal glucose levels but destabilized under conditions of low glucose to release encapsulated glucagon (FIG.16). This follows from other works that used GOx or PBA–glucose binding to enable glucose-stabilized supramolecular peptide assemblies. The molecular design rationale here was to use dPA to facilitate nanofibrillar assembly and hydrogelation, while PA-PBA imparts glucose-responsiveness to the resulting assemblies through modulating electrostatic interactions as a function of glucose level. Accordingly, different mixing ratios were first explored for glucose-dependent hydrogelation (FIG. 20). Samples were prepared in HEPES buffer (10 mM, 150 mM NaCl) at a peptide concentration of 2% (w / v) with the addition of either 0 or 100 mg / dL glucose. By itself, PA-PBA formed a clear solution without glucose, becoming a cloudy suspension when glucose was added. This result confirms previous findings that PA-PBA does not gel upon glucose binding. The addition of dPA was next explored to improve β-sheet cohesion and drive nanofiber formation and hydrogelation. PA-PBA and dPA were individually dissolved in 1:1 ACN / H2O and mixed at a desired mass ratio prior to freeze-drying in order to ensure mixing, with subsequent rehydration under the desired buffer and glucose conditions. Samples were prepared at a total peptide concentration of 2% (w / v) at weight ratios of PA-PBA to dPA of 10%, 20%, 30%, or 40% (FIG. 20). Samples prepared with 10% or 20% PA-PBA in dPA did not demonstrate any glucose-triggered gelation; though samples became less translucent upon addition of glucose, they did not form self-supporting hydrogels. Interestingly, samples prepared with 30% PA-PBA in dPA exhibited the desired characteristics of a transition from a flowing solution with no glucose to a stable and self-supporting hydrogel at 100 mg / dL glucose. When the ratio was further increased to 40% PA-PBA in dPA, samples formed self-supporting hydrogels with or without glucose. Supposing that the pKaof the boronate is within the physiologically relevant range, this result implies that some extent of charged boronic acid contributes to reducing the electrostatic repulsion among the headgroups in the mixed PA system to facilitate gelation when present at a high relative amount in the mixture, even in the absence of glucose. Accordingly, the PA-PBA / dPA mixture consisting of 30% PA-PBA was used for all subsequent studies as it displayed the desired gelation properties in this initial screen. The properties of hydrogels formed by mixing 30% PA-PBA in dPA were further evaluated over a more detailed and broader range of glucose concentrations, from 0 to 200 mg / dL (FIG. 17A). Self-supporting hydrogels were observed in samples prepared at 50, 100, and 200 mg / dL glucose. The sample prepared with 25 mg / dL glucose formed a very viscous material that flowed slowly following vial inversion, while the sample prepared with 0 mg / dL glucose again formed a clear solution. To further quantify rheological properties of the 30% PA-PBA / dPA hydrogels upon addition of glucose, a rheological time-course study was next performed (FIG. 17B). Samples were prepared as described above in either 0 or 100 mg / dL glucose and immediately placed onto the rheometer stage. The storage modulus (G′) and loss modulus (G″) were then monitored over the course of 30 min. Both samples began with moduli near to the limit of instrument sensitivity (~1 Pa). However, over the course of the next 10 min, the sample prepared with 100 mg / dL showed a rapid increase in both G′ and G″ to approximately 1000 Pa and 100 Pa, respectively. At the endpoint of analysis, plateau values of G′ and G’’ were measured at 1400 Pa and 200 Pa, respectively. Conversely, the sample prepared without the addition of glucose showed a limited increase in both G′ (1.5 Pa) and G″ (0.6 Pa) over the course of evaluation. Though surpassing the rheological threshold for hydrogelation (G′ > G″), these values are near to the lower limits of instrument sensitivity and thus are not a reliable indicator of gel formation. Regardless, these data point to significant stabilization and hydrogel stiffening of 3 orders of magnitude upon introduction of a physiologically relevant level of glucose. To further probe the effects of glucose concentration on mechanical properties of PA- PBA / dPA hydrogels, a frequency sweep was performed on gels prepared in various glucose concentrations of 25, 50, 100, and 200 mg / dL (FIG. 17C). In spite of their supramolecular and dynamic character, there was limited frequency-dependent behavior observed for these hydrogels over the frequency range evaluated, as G′ was in excess of the G″ for the entire range. This feature suggests very slow dynamics and slow stress relaxation for these non-covalent and entangled nanofiber networks. Comparing G′ as a function of glucose level revealed trends of increasing hydrogel stiffness as glucose level increased (FIG. 17D). Samples without glucose were at the lower limits of instrument sensitivity (<1 Pa), while the addition of even a low level of glucose (25 mg / dL) resulted in a G′ value of about 40 Pa, further increasing to 180 Pa at 50 mg / dL; these constitute fairly weak hydrogel networks at glucose levels within the physiological range of hypoglycemia. However, at a normal glucose level of 100 mg / dL, hydrogels stiffened to 1200 Pa, with the trend of increasing stiffness continuing to a value of 1800 Pa for moderately high glucose levels of 200 mg / dL. As another measure of glucose-induced change in these materials, the complex viscosity (η*) provides a measure of the total resistance to flow as a function of angular frequency (FIG. 17D). These values showed a similar trend to those for G′, with η* increasing dramatically to 40 Pa⋅s as glucose levels were increased from 0 to 25 mg / dL. The η* values continued to increase to 200 Pa⋅s at 50 mg / dL, 1400 Pa⋅s at 100 mg / dL, and 1900 Pa⋅s at 200 mg / dL. Accordingly, the addition of glucose drives hydrogelation and increased viscosity in the PA-PBA / dPA mixture, confirming observations from vial inversion. To probe the potential of these PA-PBA / PA hydrogels to be applied in injection-relevant applications, their ability to shear-thin to pass through a syringe and recover their mechanical properties following the high strain of injection were evaluated. Hydrogels of PA-PBA / dPA prepared at 2% (w / v) and 100 mg / dL glucose were assessed by a shear-ramp experiment (FIG. 17E) and demonstrated a reduction in viscosity as shear rate increased from an initial “zero-shear” level of 10000 Pa⋅s to <0.1 Pa⋅s at 88 s−1. To evaluate their strain recovery, a step-strain experiment was performed by cycling strain between 0.5% and 100% at a frequency of 1 rad / s (FIG. 17F). With application of high strain, G′ was below G″; this indicates disruption of the hydrogel network. However, when returning to a low strain condition, the hydrogel network was immediately recovered (G′ > G″). This behavior was maintained for multiple strain cycles with no evidence of deterioration in the structure of the gel network. Glucose-Dependent Nanostructure PA assemblies typically adopt a parallel β-sheet secondary structure with this z-axial hydrogen bonding network underlying high aspect-ratio nanofibrillar assembly. These interactions can be tuned through β-sheet sequence selection to alter the rigidity of the resulting nanofibrillar hydrogels. To assess the impact of molecular design and PA mixing on secondary structure in the PA-PBA / dPA system, CD spectroscopy was performed (FIG.18A). By this analysis, dPA had a negative peak at 222 nm and a positive peak at 206 nm; this red-shifted signature is generally indicative of a twisted β-sheet secondary structure. However, PA-PBA exhibited pronounced negative peaks at both 222 nm and 204 nm. Though the additional minima at 204 nm is not a characteristic feature of classical β-sheet structures, it has been reported that this signature can arise from aromatic or distorted β-sheet effects in self-assembling peptides. Here, the aromatic PBA group may impart a similar distorting effect as the native phenylalanine residues used in this prior work. The effect of mixing and addition of glucose was next evaluated for the PA-PBA / dPA mixture prepared at a mass ratio of 30% PA-PBA (FIG.18B). The spectra for the co-formulated PA-PBA / dPA mixture in the absence of glucose, as well as under low glucose conditions of 25 and 50 mg / dL, was similar to PA-PBA sample alone with minima at 222 nm and 203 nm. As glucose was increased to 100 mg / dL, a dramatic shift in the profile of these two minima was observed, with the 203 nm signal becoming more prominent while the intensity of the 222 nm signal decreased. The spectra at 200 mg / dL were generally comparable, though showed additional shifting in the intensity of these two peaks along with a blue-shift of its signal to 201 nm. PBA–glucose binding thus appears to contribute to further distorting the β-sheet structure of the co-formulated PA-PBA / dPA mixtures. The design of this system envisioned PBA–glucose binding to stabilize the charged tetrahedral boronate species and reduce the magnitude of positive charge in the co-formulated PA-PBA / dPA assemblies. This effect was previously observed for PA-PBA alone, where a steady reduction in positive zeta potential was observed as glucose level increased. Zeta potential measurements were also recorded here for the co-formulated PA-PBA / dPA mixture with glucose varied from 0 to 200 mg / dL (FIG.18C). In the absence of glucose, PA-PBA / dPA had a positive zeta potential of 22.5 mV, which showed limited change upon addition of either 25 or 50 mg / dL glucose. A reduction in zeta potential was observed when glucose concentration was increased to 100 mg / dL, measuring 18 mV; increasing glucose to 200 mg / dL offered a slight reduction from this level. These results align with observations from CD, with the increase in glucose from 50 to 100 mg / dL resulting in a clear structural and electrostatic transition in the assemblies. Samples of each PA alone as well as the co-formulated PA-PBA / dPA mixture at different glucose levels were next investigated for their nanostructure by TEM (FIG. 18D). All samples were imaged at 0.1% (w / v). In the sample of dPA alone, heterogeneous populations of spherical particles with sizes of 10–40 nm were observed. In the sample of PA-PBA alone, homogeneous spherical assemblies with a diameter of approximately 10 nm were observed; this confirmed a prior report on PA-PBA that showed a preference for nano-spherical rather than traditional nanofibrillar assembly. In the absence of glucose, the co-formulated PA-PBA / dPA mixture also formed spherical nanoparticles of about 10 nm diameter. This nanostructure had no detectable change upon addition of 25 mg / dL glucose. However, when glucose concentration was increased to 50 mg / dL, short fibrillar nanostructures began to appear alongside the spherical nanostructures. Further increasing glucose concentration to 100 or 200 mg / dL led to elongated and entangled nanofiber structures. The emergence of longer nanofibers upon addition of glucose is thus correlated with the glucose-triggered hydrogelation of this material, supporting a mechanism of nanofiber elongation and entanglement leading to hydrogel formation upon PBA– glucose binding. Of note, samples prepared at 0.5% (w / v) and imaged by TEM showed some difference in nanostructure, with very short fibrillar structures observed for both dPA and PA-PBA alone (FIG. 21). For the PA-PBA / dPA mixture, as glucose increased the nanostructures again demonstrated glucose-dependent nanofiber elongation and entanglement. Glucose-Responsive Glucagon Delivery The performance of co-formulated PA-PBA / dPA hydrogels in the glucose-responsive therapeutic delivery of glucagon was further evaluated. Similar to prior reports, the objective here was to use these glucose-stabilized materials for glucose-directed delivery of the glucagon hormone that offers a corrective measure for treating low blood glucose. The dasiglucagon analog, which was recently approved by the FDA, is a stabilized modified glucagon used to treat severe hypoglycemia by stimulating the depolymerization and release of stored glycogen to correct blood glucose levels. For ease in quantifying encapsulation and release from co- formulated PA-PBA / dPA hydrogels, a fluorescent methoxycoumarin-4-acetic acid (MCA) conjugated dasiglucagon was synthesized according to prior methods (FIG. 22). The PA- PBA / dPA hydrogels were mixed with MCA-dasiglucagon in HEPES buffer at physiological glucose levels of 100 mg / dL. These hydrogels were then placed in wells with a bulk buffer of varying glucose level and MCA fluorescence intensity was monitored over time in the bulk phase to quantify release (FIG.19A). In the absence of glucose, hydrogels showed very fast drug release, as 54% of MCA-dasiglucagon was released after 5 h incubation. With the addition of low levels of glucose, 25 and 50 mg / dL, the total release amount decreased to 45% and 35% at 5 h, respectively. Further increase in glucose level to a normal level of 100 mg / dL or a hyperglycemic level of 200 mg / dL resulted in 25% and 22% of encapsulated dasiglucagon released, respectively. Taken together with material characterization data, the stabilization of these materials in the presence of glucose facilitated by PBA–glucose binding, enables their use in the responsive delivery of a dasiglucagon therapeutic that itself is a corrective agent for low blood glucose conditions. Glucose-responsive dasiglucagon delivery from PA-PBA / dPA hydrogels was further validated in a previously established streptozotocin (STZ)-induced type 1 diabetic mouse model recreating hypoglycemia brought about by an insulin overdose (FIG.19B). Fasted diabetic mice were corrected to normoglycemia (180-200 mg / dL for mice) by administration of Insulin Detemir; after 4 h, 100 μL PA-PBA / dPA hydrogels containing 5 μg dasiglucagon were injected subcutaneously and compared to a control of 5 μg dasiglucagon. Blood glucose levels were monitored throughout the study (FIG.19C). Mice treated with both the PA-PBA / dPA hydrogel and free dasiglucagon exhibited a dramatic increase in blood glucose following administration; though expected for the free drug, this increase following administration of the hydrogel indicates burst release of some fraction of the therapeutic following injection. This result is consistent with past findings for other glucose-stabilized materials, pointing to one drawback of using glucose- stabilized hydrogels in this role. Burst release is likewise consistent with the release behavior seen in vitro showing some early release into the bulk phase (FIG. 19A). After 2 h, severe hypoglycemia was induced by intraperitoneal injection of insulin. The hypoglycemic onset was then assessed over 4 h following this insulin overdose (FIG.19C). When comparing final blood glucose levels (FIG. 19D), mice treated with the PA-PBA / dPA hydrogel had significantly higher glucose levels (111 mg / dL) than the free dasiglucagon control (84 mg / dL). This finding suggests some protective function of the PA-PBA / dPA hydrogel in facilitating recovery following hypoglycemia. As another measure of protection, no mortality was observed in the group treated with the PA-PBA / dPA hydrogel, while one animal did not survive in the control group. The performance of the PA-PBA / dPA hydrogel was generally consistent with the results of other glucose-stabilized materials in this same animal model. Accordingly, the current study lends further support to the concept of using glucose-stabilized materials to provide preventative support in advance of a hypoglycemic episode yet does not address the repeated issue of dasiglucagon leakage following administration that remains a drawback of this approach that would confound insulin-centered blood glucose control in treating type 1 diabetes. This work successfully demonstrates the development of a glucose-responsive supramolecular PA-PBA hydrogel system for glucagon delivery. The design strategy exploits glucose as a molecular trigger to drive nanofiber assembly and gelation at physiological glucose levels, which then disassembles under hypoglycemic conditions to release the encapsulated therapeutic. The tunable nature of the assembly, characterized by changes in electrostatic interactions and nanostructure morphology, provides a means of controlling glucagon release at rates inversely related to glucose level. Studie in vitro highlight responsiveness to varying glucose concentrations, while the in vivo results in a Type 1 diabetic mouse model demonstrate the protective effect of the PA-PBA hydrogel in mitigating hypoglycemia. However, while the hydrogel system showed potential for controlled glucagon delivery, the observed burst release following initial injection suggests that further refinement is required to achieve a more sustained release profile. Modifications to reduce the initial burst while maintaining responsiveness to low glucose could further improve the therapeutic efficacy of the system. Future studies should explore alternative formulations and co-delivery strategies to optimize glucagon release under hypoglycemic conditions. Overall, this study provides valuable insights into the design of glucose-responsive materials and highlights the broader application of supramolecular systems for therapeutic delivery. The ability to modulate drug release in response to environmental cues, such as glucose levels, presents exciting possibilities for precision medicine approaches, especially in the treatment of diabetes. The PA-PBA system offers a platform for further development and could be adapted for other therapeutic delivery applications where responsive, on-demand, glucose- responsive drug release is required. Example 3 Phase Regime of PAPBA LLPS and Factors Associated with the Self-Assembly of Peptide Amphiphiles into Liquid Droplets Fluorescence microscopy was performed to elucidate the phase regime of PAPBA liquid- liquid phase separation (LLPS) under varying concentrations of peptide PAPBA and glucose (FIG. 25A). The images show that there is no phase separation in the absence of glucose (FIG.25A). The critical concentration for observing LLPS was determined to be 2 mg / mL PAPBA with 0.2 mg / mL dasiglucagon and a glucose concentration of 100 mg / dL. At concentrations >3 mg / mL, precipitation occurs after introducing 200 mg / dL glucose. Time-dependent turbidity measurements of the PAPBA LLPS process were performed, with a constant PAPBA concentration of 2 mg / mL and 0.2 mg / mL dasiglucagon, while varying glucose concentrations (FIG.25B). The profile indicates no increase in turbidity without glucose; however, both turbidity and the kinetics of LLPS increase with higher glucose concentrations (FIG. 25B). Time-dependent turbidity measurements of the PAPBA LLPS process were also performed at different pH conditions (FIG. 25C). To generate the data shown in FIG. 25C, concentrations of the components were maintained at 2 mg / mL PAPBA, 0.2 mg / mL dasiglucagon, and 100 mg / dL glucose. The results show that turbidity increases over time at pH levels of 7, 9, and 11, whereas no turbidity increase is observed at a pH of less than 7, indicating no LLPS (FIG. 25C). FIG.25D shows a plot of turbidity as a function of pH indicating that droplet formation at pH levels below 7 are unfavorable for LLPS, while LLPS is specifically favored in the pH range above 7, aligning with the pKa of phenylboronic acid, which is ~ pH 7. FIG. 25E shows the microscopic images associated with FIG.25D. To identify the factors responsible for LLPS, turbidity curves were prepared for PAPBA in response to different stimuli (urea, 1,6-hexanediol, and NaCl) (FIG.25F). As shown in FIG.25F, urea disrupts hydrogen bonding, hexanediol interferes with hydrophobic interactions, and NaCl affects ionic interactions. Moreover, FIG.25F shows that, after LLPS formation, the addition of hexanediol and urea disrupts LLPS, while NaCl promotes LLPS by inducing charge screening. Stimuli were also introduced in situ during mixing and droplet formation (FIG.25G). The results shown in FIG.25G inhibited formation correlates with the data for droplet disruption shown in FIG. 25F. FIG. 25H shows the turbidity results from addition of varying concentrations of each individual stimulus in the mixture. The results shown in FIG.25H indicate that both hexanediol and urea significantly disrupt LLPS assembly, while NaCl promote it, confirming that the LLPS system is majorly driven by hydrogen bonding and hydrophobic interactions. FIG. 25I shows microscopy images before and after the addition of stimuli. Dasiglucagon-Responsive Phase Regime of PAPBA LLPS and Dynamics of PAPBA LLPS Fluorescence microscopy was performed to illustrate the phase behavior of PAPBA liquid- liquid phase separation (LLPS) at a fixed glucose concentration of 100 mg / dL, with varying concentrations of dasiglucagon and PAPBA (FIG. 26A). As shown in FIG. 26A, the critical concentration required to observe LLPS was determined to be 1 mg / mL of PAPBA combined with 0.4 mg / mL of dasiglucagon at the same glucose level. The right side of FIG. 26A features a schematic representation of the phase regime, highlighting the concentration range conducive to LLPS. It also illustrates a trend showing an increase in droplet size as the concentration of dasiglucagon rises. FIG.26B shows a droplet size distribution profile indicating that the PAPBA LLPS droplets formed without dasiglucagon have smaller diameters compared to those formed in the presence of dasiglucagon, which resulted in larger droplet diameters. Inset microscopy images are included in FIG.26B for visual reference. FIG.26C demonstrates the possibility to form smaller droplets from PAPBA and glucose without the addition of dasiglucagon. FIG.26D shows zeta potential measurements of the LLPS components indicating that PAPBA exhibits a high zeta potential of ~ +15 mV, which decreases to ~ +11 mV upon the addition of net-negative dasiglucagon. This charge further shifts toward a less positive equilibrium when glucose is introduced, as the negative charge from boronic acid reduces the overall charge of the LLPS system. Zeta potential analysis was performed at pH 7, based on three independent measurements. FIG. 26E shows time-dependent dynamic light scattering (DLS) analysis demonstrating that as time progresses, the droplet diameter increases, supporting the droplet coalescence event associated with the LLPS mechanism. Initial measurements indicate that droplet micelles are approximately 1 µm, which grow to about 3–5 µm after approximately 9 minutes. FIG. 26F shows temperature-dependent DLS studies revealing that LLPS droplets are disrupted after a 3-minute incubation at 40 °C. However, maintaining the temperature around 25 °C allows the LLPS droplets to reform. This behavior indicates that the PAPBA LLPS system is dynamic and exhibits temperature reversibility. Driving an Upper Critical Solution Temperature (UCST) The kinetics of liquid-liquid phase separation (LLPS) were measured using a turbidity assay at 600 nm at 5 °C, followed by a thermal ramp from 5 °C to 40 °C (FIG.27A). The results indicate that an initial increase in temperature promotes LLPS (5–10°C). As the temperature rises further to around 25 °C, stable droplets are observed, but disruption occurs at temperatures above 25 °C. This trend suggests a behavior similar to that of UCST (Upper Critical Solution Temperature), attributed to the enthalpy-driven self-assembly of the LLPS system. The inset microscopy images illustrate the before and after states of thermal melting. The kinetics of PAPBA LLPS were also measured at varying temperatures (FIG. 27B). The kinetics of PAPBA LLPS at varying temperatures indicate that as the temperature increases, the droplets become disrupted, further supporting the UCST-like behavior (FIG.27B). LLPS kinetics were examined at different concentrations of PAPBA, followed by thermal ramp from 5 °C to 40 °C. The results are shown in FIG.27C. FIG.27D shows that as concentration of PAPBA increases, turbidity levels rise. Initially, increasing the temperature promotes LLPS (5–10 °C) before showing a transition melting temperature (Tm) at various temperatures. The transition melting observed in this profile was plotted as a function of PAPBA concentration, illustrated in panel (FIG.27E). FIG. 27F shows microscopic images taken after 5 minutes of thermal melting at 40 °C from experiments with different PAPBA concentrations show a trend: as the concentration of PAPBA increases, the size of the droplets recovered after thermal melting also increases. The size distribution of droplets is plotted in the right side of FIG.27F. Hydrophobicity and Charge in PAPBA LLPS. FIG.28A shows that the net-positive PAPBA, consisting of the modified sequence C10alkyl- G4R3Dap-PBA (SEQ ID NO: 3), interacts with the net-negative dasiglucagon in the presence of 100 mg / dL glucose, leading to the formation of liquid-liquid phase separation (LLPS). FIG.28B illustrates the phase regime with varying concentrations of PA. This panel shows that the critical concentration required for the modified C10alkyl-G4R3Dap-PBA to achieve LLPS is 2 mg / mL, accompanied by 0.2 mg / mL dasiglucagon and 100 mg / dL glucose. FIG. 28C illustrates the kinetics of droplet formation were assessed using a turbidity measurement at 600 nm. The results indicate slower kinetics for C10alkyl-G4R3Dap-PBA compared to C10alkyl-V2A2R3Dap-PBA. The corresponding microscopy images are shown in the inset, providing a visual reference for the findings. This suggests that hydrophobic valine and alanine play a crucial role in promoting LLPS. A mutated dasiglucagon that was designed to be net-positive was synthesized by replacing negatively charged amino acid residues with lysine and arginine (SEQ ID NO: 4) (FIG. 28D). The modified residues are highlighted in boxes in FIG. 28D. As further depicted in the microscopy images of FIG.28D, when mixed with the positively charged dasiglucagon, PAPBA did not self-assemble to form LLPS after glucose triggering, even with varying concentrations of the positively charged dasiglucagon. This highlights the importance of charge screening induced by the negatively charged dasiglucagon in facilitating LLPS.

Claims

CLAIMS What is claimed:

1. A peptide amphiphile comprising: an alkyl moiety of attached to the N-terminus of a sequence of 5–12 amino acidthe sequence comprising: a hydrophobic subsequence of 2–8 hydrophobic amino acid residues, wherein the N- terminus of the hydrophobic subsequence is attached to the alkyl moiety; a positively charged subsequence of 2–5 positively charged amino residues, wherein the N-terminus of the positively charged subsequence is attached to the C-terminus of the hydrophobic subsequence; and a terminal amino acid residue comprising an amine-containing side chain, wherein the N-terminus of the terminal amino acid residue is attached to the C-terminus of the positively charged subsequence; the C-terminus of the terminal amino acid residue or ; and the amine-based side chain of the terminalis attached to a boronic acid moiety, wherein the boronic acid moiety is a moiety of formula: ,n is 0–4; RX, at each occurrence, is independently halo, –C1-4haloalkyl, –CN, –NO2, –C(O)H, –CO2H, –CO2C1-4alkyl, or –SO2C1-4alkyl; and X−is an anion having a net charge of −1.

2. The peptide amphiphile of claim 1, wherein each hydrophobic amino acid residue is a non- aromatic amino acid residue.

3. The peptide amphiphile of claim 1, wherein the peptide amphiphile is a peptide amphiphile of formula (I): Y1AA8AA7AA6AA5AA4AA3AA2AA1B1,wherein: Y1is the alkylis the sequence of amino acid residues, wherein: AA1is the terminal amino acid residue; B1is the boronic acid moiety; is the positively charged subsequence; and4. The peptide amphiphile of claim 3, wherein AA1is a non-native amino acid residue.

5. The peptide amphiphile of claim 3, wherein AA2, AA3, and AA4are each independently an arginine residue, a lysine residue, an ornithine residue, or a histidine residue.

6. The peptide amphiphile of claim 3, wherein AA5, AA6, AA7, and AA8are each independently a glycine residue, an alanine residue, a valine residue, an isoleucine residue, or a leucine residue.

7. The peptide amphiphile of claim 1, wherein the boronic acid moiety is a moiety of formula: .

8. The peptide amphiphile of claim 1, wherein n is 0 or 1.

9. The peptide amphiphile of claim 1, wherein RX, at each occurrence, is independently halo or –C1-4haloalkyl.

10. The peptide amphiphile of claim 9, wherein RX, at each occurrence, is independently –F or –C1-4fluoroalkyl.

11. The peptide amphiphile of claim 1, wherein the peptide amphiphile is a peptide amphiphile of formula (I-a): , orR5, R6, R7, and R8are each independently hydrogen, .

12. The peptide amphiphile of claim 11, wherein R2, R3, and R4are .

13. The peptide amphiphile of claim 11, wherein R5, R6, R7, and R8are each independently methyl or .

14. Theof claim 1, wherein the peptide amphiphile of formula (I) is: .

15. A droplet comprising: the peptide amphiphile of claim 1; glucose; and optionally, glucagon and / or a glucagon analogue.

16. The droplet of claim 15, wherein: the peptide amphiphile of claim 1 is present at about 0.05–4% by weight (wt%); and glucagon and / or a glucagon analogue is present at about 0.01–2 wt%.

17. The droplet of claim 15, wherein the glucose is present at about 1–20 mM.

18. The droplet of claim 15, wherein the glucagon analogue comprises dasiglucagon and / or a depsi-glucagon analogue.

19. The droplet of claim 15, wherein the droplet has a diameter of about 0.2–5 µm.

20. The droplet of claim 15, wherein the droplet is formed by liquid-liquid phase separation.

21. A hydrogel comprising:the peptide amphiphile of claim 1; glucose; and a diluent peptide amphiphile, the diluent peptide amphiphile comprising: the alkyl moiety of attached to the N-terminus of a sequence of 5–12 amino acidthe sequence comprising: a hydrophobic subsequence of 2–8 hydrophobic amino acid residues, wherein the N- terminus of the hydrophobic subsequence is attached to the alkyl moiety; and a positively charged subsequence of 2–5 positively charged amino residues, wherein the N-terminus of the positively charged subsequence is attached to the C-terminus of the hydrophobic subsequence; and the C-terminus of the positively charged subsequence .

22. The hydrogel of claim 21, wherein the diluent peptide amphiphile is a diluent peptide amphiphile of formula (II): (II), wherein:Y1is the alkyl moiety; andthe C- .

23. The hydrogel of claim 22, wherein the diluent peptide amphiphile of formula (II) is:.

24. The hydrogel of claim 21, wherein: the peptide amphiphile of claim 1 is present at about 0.1–2.0 wt%; and the diluent peptide amphiphile is present at about 0.1–4 wt%.

25. The hydrogel of claim 21, wherein the glucose is present at about 1–20 mM.

26. The hydrogel of claim 21, wherein glucagon and / or a glucagon analogue is encapsulated within the hydrogel.

27. The hydrogel of claim 26, wherein the glucagon analogue comprises dasiglucagon and / or a depsi-glucagon analogue.

28. The hydrogel of claim 26, wherein the glucagon and / or glucagon analogue is co- formulated with a cationic polymer within the hydrogel.

29. The hydrogel of claim 28, wherein the cationic polymer is protamine.

30. A pharmaceutical composition comprising: the droplet of claim 15 or the hydrogel of claim 21; and a pharmaceutically acceptable excipient.

31. A method of modulating glucose levels in a subject, the method comprising: administering a therapeutically effective amount of the droplet of claim 15, the hydrogel of claim 21, or the pharmaceutical composition of claim 30.

32. The method of claim 31, wherein the subject in need thereof is experiencing a hypoglycemic event or at risk of experiencing a hypoglycemic event.

33. The method of claim 31, wherein the subject in need thereof has diabetes.

34. A kit comprising the droplet of claim 15, the hydrogel of claim 21, or the pharmaceutical composition of claim 30; delivery or administration apparata or devices; and optionally, packaging, a label, or instructions for use.

35. Use of the droplet of claim 15, the hydrogel of claim 21, or the pharmaceutical composition of claim 30 to deliver glucagon and / or a glucagon analogue to a subject in need thereof.

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