Patterned hydrogels with tunable properties

Abstract

Hydrogel components, scaffolds, and platforms are described herein. In some embodiments, a scaffold described herein is configured to be used in an organ-on-a-chip, and the scaffold comprises a solid exterior; a latticed interior volume disposed within the solid exterior; and a vasculature structure disposed within the latticed interior volume. The vasculature structure includes a vasculature inlet and a vasculature outlet. In another aspect, a perfused intra-lattice scaffold (PILS) platform may be used for performing assays, assessing equilibration time of a compound, and studying metabolic rates.

Description

Atty. Docket No.: PCT.1312PATTERNED HYDROGELS WITH TUNABLE PROPERTIESCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority pursuant to 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 63 / 706,418, filed October 11, 2024, which is hereby incorporated by reference in its entirety.BACKGROUND

[0002] Hydrogels are polymeric materials composed of three-dimensional networks that can absorb or include a large amount of water (e.g., such that water constitutes most or all of the fluid phase of the biphasic gel). Hydrogels have a broad range of applications, such as in biological scaffolding or organ-on-a-chip devices. Some previous hydrogels can undergo swelling or other dimensional change, such as in response to mechanical forces. In some cases, dimensional instability or other instability of a hydrogel can be disadvantageous for some applications.SUMMARY

[0003] In applications where mechanical and dimensional stability of hydrogels are important, approaches to compensate for swelling and other changes in hydrogels are beneficial. Improved mixing within the fluid phase of a hydrogel (such as caused by diffusion or convection) is also desired in some cases. The present disclosure, in some embodiments, includes forming hydrogels into 2D and / or 3D lattice structures so that dimensional expansion of the hydrogel due to swelling, as well as mechanical stresses from external sources, can be accommodated (e.g., without substantially changing the overall size of a structure formed from the hydrogel). The present disclosure may be beneficial to organ, tissue, and / or cell scaffolds in a variety of operating environments and may lead to advances in manufacturing for improving human health. The present hydrogel embodiments may also be beneficial to other applications of hydrogels in medical, biological, and mechanical fields.

[0004] In one aspect, the present disclosure is directed to a component comprising, consisting of, consisting essentially of, composed of, or formed from a hydrogel material, theAtty. Docket No.: PCT.1312 component comprising: at least one bulk hydrogel portion; and at least one lattice portion; wherein the at least one bulk hydrogel portion is integral with the at least one lattice portion.

[0005] In some embodiments, the at least one lattice portion comprises a repeating pattern formed of the hydrogel material, wherein the repeating pattern comprises a repeating pattern of solid hydrogel material and a repeating pattern of voids.

[0006] In some embodiments, the at least one bulk hydrogel portion and the at least one lattice portion are formed during the same continuous build process (e.g., by an additive manufacturing process).

[0007] In some embodiments, the at least one bulk hydrogel portion is continuous with the at least one lattice portion.

[0008] In some embodiments, the at least one lattice portion comprises a negative Poisson's ratio.

[0009] In some embodiments, the at least one lattice portion comprises a positive Poisson's ratio.

[0010] In some embodiments, the at least one lattice portion comprises a Poisson's ratio substantially equal to zero.

[0011] In some embodiments, the at least one bulk hydrogel portion comprises a higher density than the at least one lattice portion.

[0012] In some embodiments, the hydrogel material comprises a co-polymer and / or a hydrogel composite material.

[0013] In some embodiments, the hydrogel material comprises at least one of polyacrylamide (PAAm), polyethylene glycol (PEG), polyethylene glycol diacrylate (PEGDA), poly(N-isopropyl acrylamide) (PNIPAM), poly(acrylic acid) (PAA), alginate, gelatin methacrylate (GelMA), Collagen, Chitosan, and hyaluronic acid (HA). Other hydrogel materials (e.g., other acrylate or methacrylate based materials) may also be used.

[0014] In some embodiments, the repeating pattern comprises at least one of an interpenetrating network and a double network.Atty. Docket No.: PCT.1312

[0015] In some embodiments, the at least one lattice portion comprises a cubic lattice, a body-centered grid, a hexagonal grid, a re-entrant honeycomb structure, a chiral structure, a rotating rigid structure, or a combination of two or more of the foregoing.

[0016] In some embodiments, the repeating pattern comprises unit cell dimensions in a range from about 20 microns (pm) to about 500 pm.

[0017] In some embodiments, the unit cell dimensions vary throughout the component.

[0018] In some embodiments, the component comprises a stent (or micro-stent), wherein the at least one bulk hydrogel portion comprises a substantially cylindrical shape, thereby forming a body of the stent, and wherein the at least one lattice portion comprises a layer disposed at least partially around the at least one bulk hydrogel portion.

[0019] In some embodiments, the stent is expandable, and at least one lattice portion comprises a positive Poisson's ratio.

[0020] In another aspect, the present disclosure is directed to a scaffold configured to be used in an organ-on-a-chip, comprising: a solid exterior; a latticed interior volume disposed within the solid exterior; and a vasculature structure disposed within the latticed interior volume, wherein the vasculature structure comprises a vasculature inlet and a vasculature outlet.

[0021] In some embodiments, the scaffold is formed by an additive manufacturing process (e.g., 3D printing, digital light processing (DLP) for both single photon and two photon processing, extrusion-based processes, stereolithography (SLA), etc.). In some embodiments, the scaffold is formed by digital light processing (DLP).

[0022] In some embodiments, the scaffold comprises a hydrogel comprising one or more of polyacrylamide (PAAm), polyethylene glycol (PEG), polyethylene glycol diacrylate (PEGDA), poly(N-isopropyl acrylamide) (PNIPAM), poly(acrylic acid) (PAA), alginate, gelatin methacrylate (GelMA), collagen, chitosan, or hyaluronic acid (HA). Other hydrogel materials may also be used.

[0023] In some embodiments, the vasculature structure comprises a network of conduits fluidly connecting the vasculature inlet to the vasculature outlet.

[0024] In some embodiments, the vasculature inlet and the vasculature outlet are disposed on an outer surface of the solid exterior.Atty. Docket No.: PCT.1312

[0025] In some embodiments, the solid exterior comprises one or more gaps, indentations, or cutouts.

[0026] In some embodiments, the latticed interior volume comprises one or more volumes comprising repeating lattice structures.

[0027] In some embodiments, the repeating lattice structures comprise a cubic lattice, a body-centered grid, a hexagonal grid, a re-entrant honeycomb structure, a chiral structure, a rotating rigid structure, or a combination thereof.

[0028] In some embodiments, the scaffold further comprises an interstitial infill volume surrounding the vasculature.

[0029] In some embodiments, the interstitial infill volume comprises a repeating structure configured for supporting one or more living cells.

[0030] In some embodiments, cell seeding includes an adhesion layer disposed on the repeating structure and / or bioconjugation of the one or more living cells with the repeating structure and / or a layer disposed thereon.

[0031] In some embodiments, the scaffold further comprises a second vasculature structure comprising a second network of conduits fluidly connecting a second vasculature inlet to a second vasculature outlet, wherein the network of conduits is interlinked with the second network of conduits.

[0032] In some embodiments, the latticed interior volume comprises: a first portion comprising a lattice structure that includes a negative Poisson's ratio, and a second portion comprising a lattice structure that includes a positive Poisson's ratio.

[0033] In another aspect, the present disclosure is directed to a lattice structure comprising a six-sided (e.g., hexagonal) repeating pattern that repeats within a 2- dimensional plane, the six-sided repeating pattern comprising: two lateral sides (which may also be referred to herein as "struts") aligned substantially in a lateral direction; the two lateral sides comprising a first lateral side and a second lateral side; two pairs of sides, each pair of sides comprising a first side connected on one side to the first lateral side (i.e., the first strut) and a second side connected on one side to the second lateral side (i.e., second strut), wherein the first side and the second side are connected to each other on the side that is not connected to the respective first lateral side or second lateral side.Atty. Docket No.: PCT.1312

[0034] In some embodiments, the lattice structure is configured to expand from an initial unexpanded state to an expanded state.

[0035] In some embodiments, the lattice structure comprises a negative Poisson's ratio.

[0036] In some embodiments, in an unexpanded state, the connections between each of the first lateral side and second lateral side with each side of the first and second pairs of sides occurs at an acute angle from the perspective of or at a point in an interior of the six-sided pattern, and wherein, in an unexpanded state, the connections between each side of the first and second pairs with another side of the first and second pairs of sides occurs at an obtuse angle from the perspective of or at a point in an interior of the six-sided pattern.

[0037] In some embodiments, the obtuse angle is greater than 180 degrees.

[0038] In some embodiments, in an expanded state, each acute angle in the unexpanded state approaches or reaches 90 degrees and each obtuse angle in the unexpanded state approaches or reaches 180 degrees.

[0039] In another aspect, the present embodiments are directed to a platform for assessing drug metabolism, the platform comprising: an outer boundary (502) comprising a plurality of outer side walls and at least one outer bottom surface, the outer boundary defining an exterior geometry of the platform; an inner boundary comprising a plurality of inner side walls (514) and at least one inner bottom surface (523), the inner boundary defining a main compartment (512), a volume (i.e., a second volume) of which is disposed within a volume (i.e., a first volume) defined by the exterior geometry of the platform; a repeating lattice structure (504) disposed within a volume between the outer boundary and the inner boundary (i.e., a third volume); and at least one vasculature passageway (510) extending through the lattice structure from an inlet end (525) to an outlet end (527), wherein the outlet end of the at least one vasculature passage is open to, and in fluid communication with, the volume between the outer boundary and the inner boundary (i.e., the third volume).

[0040] In some embodiments, the platform further comprises at least one window or opening (516) (e.g., 2 round windows) disposed within at least one wall of the plurality of inner side walls, thereby fluidly connecting the volume between the outer boundary and theAtty. Docket No.: PCT.1312 inner boundary (i.e., the third volume) to the main compartment (i.e., the second volume). It is to be understood that, in some embodiments, such a window or opening is not merely a pore or micropore, but is instead a window or opening having a relatively large size, or a size that is similar to (e.g., within 10% or within 15% of) the size of the inlet or outlet of the platform.

[0041] In some embodiments, the second volume, when added to the third volume, is approximately equal to the first volume.

[0042] In some embodiments, the outer boundary, the inner boundary, the lattice structure, and the at least one vasculature passageway are composed of or formed from the same material. In some such cases, this "same material" comprises at least one of a hydrogel, a polymer, a 3D-printed material, and a bio-printed material. Other materials may also be used in some instances.

[0043] In some embodiments, the bulk / structural portions described herein (both patterned and un-patterned) may also be formed via injection molding, where the underlying geometries and topologies allow.

[0044] In some embodiments, the outer boundary, the inner boundary, the lattice structure, and the at least one vasculature passageway are formed via a single, continuous build process (e.g., a single additive manufacturing process).

[0045] In some embodiments, the platform includes a fluid inlet (e.g., a vertically oriented, single fluid inlet) for receiving fluid, the fluid inlet disposed within the lattice structure and fluidly coupled upstream of the at least one vasculature passageway.

[0046] In some embodiments, at least one vasculature passageway comprises multiple, substantially parallel vasculature passageways oriented along a length direction of the platform.

[0047] In some embodiments, the multiple, substantially parallel vasculature passageways are disposed at a vertical position higher than the outer bottom surface of the platform and lower than the inner bottom surface of the platform.

[0048] In some embodiments, at least one vasculature passageway further comprises one or more vasculature passageways disposed at a vertical position higher than the inner bottom surface of the platform.Atty. Docket No.: PCT.1312

[0049] In some embodiments, the outer boundary, the inner boundary, the lattice structure, and the at least one vasculature passageway comprise a thickness in a range from about 20 .m to about 500 |im.

[0050] In some embodiments, each vascular passageway of the multiple, substantially parallel vasculature passageways: (1) is disposed at a lateral spacing of from about 200 pm to about 1000 pm from at least one adjacent passageway, and (2) comprises an internal diameter in a range from about 20 pm to about 500 pm.

[0051] In some embodiments, the lattice structure within the third volume is fluidly coupled downstream of the at least one vasculature passageway and upstream of the main compartment, thereby enabling the lattice structure within the third volume to act as a conduit between the at least one vasculature passageway and the main compartment.

[0052] In another aspect, the present disclosure is directed to a system comprising a platform described herein, wherein the system further comprises: a pump fluidly coupled upstream of the fluid inlet; and a fluid reservoir fluidly coupled downstream of the third volume.

[0053] In some embodiments, the system includes at least one filter disposed fluidly downstream of the fluid reservoir, wherein the at least one filter is fluidly coupled in a fluid conduit upstream of the fluid inlet, the fluid conduit thereby forming a fluid circuit with other components of the system.

[0054] In some embodiments, the system includes at least one fluid (e.g., a therapeutic fluid, blood, dialysate, buffer, etc.) disposed within at least one of the first volume, the second volume, and the third volume; and at least one live cell seeded within interstitial infill disposed within the main compartment (i.e., the second volume).

[0055] In some embodiments, the system includes at least one sensor configured to measure a metabolic rate of at least one compound from the at least one fluid into the at least one live cell.

[0056] In another aspect, the present disclosure is directed to a method of determining a metabolic rate for a live cell to metabolize a compound within a platform, the platform comprising: at least one passageway through which a fluid initially containing the compound flows; a lattice structure (e.g., a repeating lattice structure) disposed downstream of, and in fluid communication with, the at least one passageway, a compartment disposedAtty. Docket No.: PCT.1312 downstream of the lattice structure, the compartment comprising an interstitial infill, at least one sensor disposed in operable communication with at least one flow passage of the platform, the at least one sensor configured to measure at least one property of the fluid. In some such embodiments, the method comprises: seeding the interstitial infill with the live cell; flowing fluid through the platform; measuring, via the at least one sensor, the at least one property of the fluid; and determining the metabolic rate based on, at least partially, the measured at least one property of the fluid.

[0057] In some embodiments, the lattice structure comprises a repeating lattice structure that comprises at least one of a thick triply periodic minimal surface configuration, a reentrant honeycomb pattern, and an octet-like lattice pattern.

[0058] In some embodiments, the platform further comprises a fluid inlet disposed fluidly upstream of the at least one passageway.

[0059] In some embodiments, the at least one sensor comprises: a first sensor operably coupled to, and configured to measure the fluid property within, at least one of the fluid inlet and the at least one passageway; and a second sensor operably coupled to, and configured to measure the fluid property within, the main compartment, wherein determining the metabolic rate based on, at least partially, the measured at least one property of the fluid comprises comparing the at least one property of the fluid measured by the first sensor to the at least one property of the fluid measured by the second sensor.

[0060] In another aspect, the present disclosure is directed to a method of performing an assay within a platform, the platform comprising: (1) at least one passageway through which a fluid flows; (2) a lattice structure disposed downstream of, and in fluid communication with, the at least one passageway; and (3) a main compartment (or reservoir) disposed downstream of, and in fluid communication with, the repeating lattice structure, the method comprising: establishing a baseline concentration of at least one compound within the fluid at a portion of the at least one passageway; sampling the fluid at the main compartment; determining a downstream concentration of the at least one compound within the fluid based on the sampling at the main compartment; determining a baseline equilibration time of the platform based on the amount of time it takes the downstream concentration to reach a predetermined percentage of the baseline concentration; and performing an assay within the platform, wherein performing the assayAtty. Docket No.: PCT.1312 comprises adjusting a second equilibration time determined from parameters measured during the assay, wherein the second equilibration time is adjusted, at least partially, using the baseline equilibration time.

[0061] In another aspect, the present disclosure is directed to a method of determining a metabolic rate comprising: determining a baseline equilibration time for a platform, the baseline equilibration time representative of an amount of time it takes for a compound within a fluid circulating through the platform to reach a steady-state concentration; subsequently seeding a portion of the platform with live cells; reestablishing flow of fluid through the platform; changing a concentration of the compound within the fluid from an initial concentration to a target concentration; sampling the fluid at a downstream location; determining a downstream concentration of the at least one compound within the fluid based on the sampling at the downstream location; determining a target equilibration time based on a time duration for the downstream concentration to reach a predetermined percentage of the target concentration; and determining a metabolic rate of the compound into the drug based at least partially on a difference between target equilibration time and the baseline equilibration time.

[0062] In another aspect, the present disclosure is directed to a perfused intra-lattice scaffold (PILS) platform comprising: a bulk hydrogel shell (502) defining a main compartment (512); a lattice structure disposed within the bulk hydrogel shell (504); an open-ended vasculature (506) disposed through the lattice structure; and an interstitial infill portion (501) disposed at a bottom of the main compartment wherein the lattice structure comprises a first repeating pattern, wherein the interstitial infill portion comprises a second repeating pattern, and wherein the first repeating pattern is different from the second repeating pattern, such as in at least one attribute relevant to perfusion (e.g., bulk density, pattern geometry, average spacing between elements, etc.).

[0063] In some embodiments, the vasculature structure comprises at least one pore and / or at least one micro-pore.

[0064] In some embodiments, the at least one vasculature passageway comprises at least one pore and / or at least one micro-pore

[0065] In some embodiments, the platform further includes a structural hydrogel portion in contact with the repeating lattice structure (as described herein) and / or the bulkAtty. Docket No.: PCT.1312 hydrogel shell (as described herein), the structural hydrogel portion comprising a patterned portion configured for providing swelling invariance and / or shock absorption.

[0066] In some embodiments, the structural hydrogel portion is in fluid communication with the lattice structure (504), and is configured to be perfused.

[0067] In some embodiments, the structural hydrogel portion is not in fluid communication with the lattice structure (504).

[0068] In some embodiments, the structural hydrogel portion is not configured to be perfused.

[0069] In some embodiments, the patterned portion of the structural hydrogel portion comprises a different pattern geometry than the lattice structure (504).

[0070] These and other embodiments are further described in the detailed description which follows.BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The present teachings described herein will be more fully understood from the following description of various illustrative embodiments, when read together with the accompanying drawings. It should be understood that the description of the drawings below is for illustration purposes only and is not intended to limit the scope of the present teachings in any way.

[0072] FIG. 1 ill ustrates a side view of a platform for modeling organ-on-a-chip and other biological models, according to aspects of some embodiments of the present disclosure.

[0073] FIG. 2 ill ustrates an exploded view of a platform and platform assembly, according to aspects of some embodiments of the present disclosure.

[0074] FIG. 3 illustrates a view of a platform assembly, according to aspects of some embodiments.

[0075] FIG. 4A illustrates a top view of a platform assembly, according to aspects of some embodiments of the present disclosure.

[0076] FIG. 4B illustrates a perspective view of a platform assembly, according to aspects of some embodiments of the present disclosure.Atty. Docket No.: PCT.1312

[0077] FIG. 5 ill ustrates a perspective view of an organ chip, according to aspects of some embodiments of the present disclosure.

[0078] FIG. 6 ill ustrates a perspective view of another organ chip, according to aspects of some embodiments of the present disclosure.

[0079] FIG. 7 illustrates a perspective, cut-away or sectional view of another organ chip, according to aspects of some embodiments of the present disclosure.

[0080] FIG. 8 illustrates a view of organ chips within a platform assembly, according to aspects of some embodiments of the present disclosure.

[0081] FIG. 9A illustrates a view of a vasculature configuration, according to aspects of some embodiments of the present disclosure.

[0082] FIG. 9B illustrates a view of a vasculature configuration, according to aspects of some embodiments of the present disclosure.

[0083] FIG. 9C illustrates a view of a vasculature configuration, according to aspects of some embodiments of the present disclosure.

[0084] FIG. 10A illustrates a view of a vasculature configuration, according to aspects of some embodiments of the present disclosure.

[0085] FIG. 10B illustrates a view of a vasculature configuration, according to aspects of some embodiments of the present disclosure.

[0086] FIG. 11 illustrates a cut-away or sectional view of a vasculature configuration, according to some embodiments of the present disclosure.

[0087] FIG. 12A illustrates a view of a vasculature configuration, according to aspects of some embodiments of the present disclosure.

[0088] FIG. 12B illustrates a view of a vasculature configuration, according to aspects of some embodiments of the present disclosure.

[0089] FIG. 13 illustrates a cut-away or sectional view of a vasculature configuration, according to some embodiments of the present disclosure.

[0090] FIG. 14A illustrates a view of a scaffold for an organ chip, according to aspects of one embodiment of the present disclosure.

[0091] FIG. 14B is a table of exposure energy during digital light processing (DLP) printing and corresponding outer dimensions of the scaffold for the organ chip in FIG. 14A.Atty. Docket No.: PCT.1312

[0092] FIG. 15A illustrates a view of another scaffold for an organ chip, according to aspects of one embodiment of the present disclosure.

[0093] FIG. 15B is a table of exposure energy during DLP printing and corresponding outer dimensions of the scaffold for the organ chip in FIG. 15A.

[0094] FIG. 16 is a plot of dimensions of a DLP-printed PEGDA hydrogel when exposed to different cell media and temperatures, according to aspects of the present embodiments.

[0095] FIG. 17A illustrates a view of a scaffold for an organ chip with portions of lattice patterned hydrogel, according to aspects of the present embodiments.

[0096] FIG. 17B is a microscope image of a printed scaffold for an organ chip similar to the one shown in FIG. 17 A, according to aspects of the present embodiments.

[0097] FIG. 17C is a photograph of an assembled organ chip with a printed scaffold similar to the one shown in FIG. 17 A, according to aspects of the present embodiments.

[0098] FIG. 17D is a table of dimensions of an exemplary printed part, as designed and as printed, for a scaffold for an organ chip similar to the one shown in FIG. 17A, according to aspects of the present embodiments.

[0099] FIG. 18A illustrates a view of another scaffold for an organ chip with larger portions of lattice structured hydrogel, according to aspects of the present embodiments.

[0100] FIG. 18B is a microscope image of a printed scaffold for an organ chip similar to the one shown in FIG. 18A, according to aspects of the present embodiments.

[0101] FIG. 18C is a photograph of a printed scaffold for an organ chip similar to the one shown in FIG. 18A, according to aspects of the present embodiments.

[0102] FIG. 18D is a table of dimensions of an exemplary printed part, as designed and as printed, for a scaffold for an organ chip similar to the one shown in FIG. 18A, according to aspects of the present embodiments.

[0103] FIG. 19A illustrates a 3D rendering view of a scaffold for an organ chip with almost entirely lattice structured hydrogel, according to aspects of the present embodiments.

[0104] FIG. 19B illustrates another view of a 3D rendering view of a scaffold for an organ chip that is similar to the rendering in FIG. 19A, according to aspects of the present embodiments.Atty. Docket No.: PCT.1312

[0105] FIG. 19C is a microscope image of a printed scaffold for an organ chip per the design shown in FIG. 19A, according to aspects of the present embodiments.

[0106] FIG. 19D is a photograph of a printed scaffold for an organ chip per the design shown in FIG. 19A, according to aspects of the present embodiments.

[0107] FIG. 19E is a table of dimensions of an exemplary printed part, as designed and as printed, for a scaffold for an organ chip similar to the one shown in FIG. 19A, according to aspects of the present embodiments.

[0108] FIG. 20A shows an illustration of a material with positive Poisson's ratio.

[0109] FIG. 20B shows an illustration of a material with zero Poisson's ratio.

[0110] FIG. 20C shows an illustration of a material with negative Poisson's ratio.

[0111] FIG. 20D shows an illustration of a two-dimensional re-entrant honeycomb lattice.

[0112] FIG. 20E shows an illustration of a two-dimensional re-entrant honeycomb lattice with feature diameters indicated in millimeters, according to aspects of the present embodiments.

[0113] FIG. 20F shows an illustration of a re-entrant honeycomb before and after tension in the horizontal direction.

[0114] FIG. 21 shows illustrations and photographs of negative Poisson's ratio lattice materials under compression, according to aspects of some embodiments of the present disclosure.

[0115] FIG. 22A shows an illustration of a printed scaffold for an organ chip with a regular lattice interior, according to aspects of the present embodiments.

[0116] FIG. 22B shows a microscope image of a printed scaffold for an organ chip similar to the one shown in FIG. 22A, according to aspects of the present embodiments.

[0117] FIG. 22C shows a photograph of a printed scaffold for an organ chip similar to the one shown in FIG. 22A, with vasculature filled with fluid, according to aspects of the present embodiments.

[0118] FIG. 22D is a table of dimensions of an exemplary printed part, as designed and as printed, for a scaffold for an organ chip similar to the one shown in FIG. 22A, according to aspects of the present embodiments.Atty. Docket No.: PCT.1312

[0119] FIG. 23A shows a 3D rendering of a designed scaffold for an organ chip with a re-entrant honeycomb lattice in the scaffold, according to aspects of the present embodiments.

[0120] FIG. 23B shows a 3D rendering of a cross-sectional view of the designed scaffold shown in FIG. 23A, according to aspects of the present embodiments.

[0121] FIG. 23C shows a microscope image of a printed scaffold for an organ chip similar to the design shown in FIG. 23A, according to aspects of the present embodiments.

[0122] FIG. 23D shows a photograph of a printed scaffold for an organ chip similar to the one design shown in FIG. 23A, with vasculature filled with fluid, according to aspects of the present embodiments.

[0123] FIG. 23E shows an illustration of another cross-sectional view of the designed scaffold shown in FIG. 23A, according to aspects of the present embodiments.

[0124] FIG. 23F shows an illustration of a cross-sectional view of the printed scaffold corresponding to the view in FIG. 23E, according to aspects of the present embodiments.

[0125] FIG. 24A shows a 3D rendering of a designed scaffold for an organ chip with a re-entrant honeycomb lattice in the scaffold, according to aspects of the present embodiments.

[0126] FIG. 24B shows a 3D rendering of a cross-sectional view of the designed scaffold shown in FIG. 24A, according to aspects of the present embodiments.

[0127] FIG. 25A shows an illustration of a PILS scaffold for an organ chip, according to aspects of the present embodiments.

[0128] FIG. 25B shows an exemplary exploded view of the components of a PILS scaffold for an organ chip, according to aspects of the present embodiments.

[0129] FIG. 26A shows an illustration of a cross-sectional view of a PILS scaffold, according to aspects of the present embodiments.

[0130] FIG. 26B shows an illustration of a cross-sectional view of the PILS scaffold, according to aspects of the present embodiments.

[0131] FIG. 26C shows an illustration of a side view of a PILS scaffold, according to aspects of the present embodiments.

[0132] FIG. 26D shows an illustration of a top view of a PILS scaffold, according to aspects of the present embodiments.Atty. Docket No.: PCT.1312

[0133] FIG. 27 illustrates an example of a setup for a recirculatory flow through a cartridge including a PILS scaffold, according to aspects of the present embodiments.

[0134] FIG. 28A shows an exemplary flow simulation within a PILS scaffold, according to aspects of the present disclosure.

[0135] FIG. 28B is a graph of simulated equilibrium time in different scaffolds, according to an illustrative embodiment.

[0136] FIG. 29 illustrates a flow chart of a method for determining a metabolic rate, according to aspects of the present disclosure.

[0137] FIG. 30 illustrates a flow chart of a method for determining a metabolic rate, according to aspects of the present disclosure.DEFINITIONS AND DESCRIPTIONS OF TERMS

[0138] About, Approximately: As used herein, the terms "about" and "approximately" as used in reference to a value, refers to a value that is similar, in context to the referenced value. In general, those skilled in the art, familiar with the context, will appreciate the relevant degree of variance encompassed by "about" and "approximately" in that context. For example, in some embodiments, the terms "about" and "approximately" may encompass a range of values that within 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less of the referred value.

[0139] Ranges: All ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of "1.0 to 10.0" should be considered to include any and all subranges beginning with a minimum value of 1.0 or more and ending with a maximum value of 10.0 or less, e.g., 1.0 to 5.3, or 4.7 to 10.0, or 3.6 to 7.9. All ranges disclosed herein are also to be considered to include the end points of the range, unless expressly stated otherwise. For example, a range of "between 5 and 10" should generally be considered to include the end points 5 and 10. Further, when the phrase "up to" is used in connection with an amount or quantity, it is to be understood that the amount is at least a detectable amount or quantity. For example, a material present in an amount "up to" a specified amount can be present from a detectable amount and up to and including the specified amount.Atty. Docket No.: PCT.1312

[0140] "A" and "an": It is also to be understood that the article "a" or "an" refers to"at least one," unless the context of a particular use requires otherwise.

[0141] Associated with: As used herein, the term, "associated with" refers to two events or entities when presence, level and / or form of one is correlated with that of the other. For example, a particular entity (e.g., polypeptide, genetic signature, metabolite, microbe, etc.) is considered to be associated with a particular disease, disorder, or condition, if its presence, level and / or form correlates with incidence of and / or susceptibility to a disease, disorder, or condition (e.g., across a relevant population). In some embodiments, two or more entities are physically "associated" with one another if they interact, directly or indirectly, so that they are and / or remain in physical proximity with one another. In some embodiments, two or more entities (molecules or compounds) that are physically associated with one another are covalently linked to one another; in some embodiments, two or more entities that are physically associated with one another are not covalently linked to one another but are non-covalently associated, for example by means of hydrogen bonds, van der Waals interaction, hydrophobic interactions, magnetism, and combinations thereof.

[0142] Integral with: As used herein, the term "integral with" refers to two entities or components that are seamlessly joined to one another, without use of an attachment mechanism or means such as an adhesive or mechanical fastener. Such "integral" entities or components, for example, may be formed by producing both entities in the same additive manufacturing "print job" or other continuous, single process. That is, in some cases, a component, structure, or portion that is "integral with" another component, structure, or portion may be formed from the same material as the other component, structure, or portion (including as may occur if both are formed from the same build material in the same additive manufacturing print job or process).

[0143] Continuous: A "continuous" process (such as a continuous build process or manufacturing process) refers to a single process that proceeds in a single manner or mode (e.g., additive manufacturing carried out by DLP, in a layer-by-layer manner), as opposed to a "batch" process or "discontinuous" or "multi-stage" process in which the manner or mode changes. For instance, an exemplary non-continuous process would be injection molding to form one structure, followed by surface treatment of the structure. These two steps together would not constitute a "continuous" process as used herein. Similarly, anotherAtty. Docket No.: PCT.1312 example of a non-continuous process is a process that first forms a structure using additive manufacturing, and then forms a different structure using a different additive manufacturing process or "print job," and then joins the two structures together in a separate step (e.g., using an adhesive or mechanical fastener). The term "continuous with," when used in reference to a structure, is synonymous with "integral with" as described above.

[0144] Scaffold: As used herein, the term, "scaffold" refers to a structural framework or matrix, sometimes used within physical models of living tissues (e.g., synthetic tissues), that may also be used for drug discovery and for assessing the effectiveness of various therapies. A scaffold supports internal passages that approximate the geometries of human vasculatures, tissues, and other structures, and may be operatively coupled to cells seeded in an interstitial space within the scaffold. A scaffold enables delivery of biologically active materials to the cells and / or tissue(s) via fluid(s) flowing through the vasculature, and transport through vasculature walls.

[0145] Hydrogel: As used herein, the term, "hydrogel" refers to a three-dimensional network composed of or formed from polymers (in some cases, hydrophilic polymers), such as may be synthesized by crosslinking water-soluble polymers. Hydrogels can retain a large quantity of water within their network (e.g., such that water constitutes most or all of the fluid phase of the biphasic gel), including without destroying the original structure (e.g., of the non-fluid phase). Hydrogels can have flexibility and swelling or non-swelling properties.

[0146] Structural hydrogel: As used herein, a "structural" hydrogel component or feature provides a distinct mechanical property (e.g., rigidity, flexibility, negative Poisson ratio behavior, support, etc.) for an overall device or structure, particularly in comparison to one or more other hydrogel components or features within the overall device or structure. For example, a "structural" hydrogel component or feature, in some cases, encapsulates or surrounds (and optionally supports) another distinct hydrogel component or feature; and the "structural" hydrogel component may have a different Poisson ratio (e.g., negative, instead of positive), an increased flexibility, a higher stiffness, a higher or lower density, and / or a higher or lower thickness, as compared to the other distinct hydrogel component or feature.

[0147] Bulk hydrogel: As used herein, a "bulk" hydrogel (e.g., as compared to a "patterned" hydrogel) refers to a hydrogel structure that is formed from a hydrogel networkAtty. Docket No.: PCT.1312 that has not been patterned as described herein and does not include a lattice or lattice structure as described. A "bulk hydrogel shell," as used herein refers to an outer layer or portion of bulk hydrogel. In some cases, a bulk hydrogel shell is relatively thin (in terms of the 'wall thickness' of the structure), as compared to the overall size or volume. For instance, in some instances, a bulk hydrogel shell has an average thickness that is less than 15%, less 10%, or less than 5% of the corresponding dimension of the volume that is 'enclosed by' the shell.

[0148] Paterned Hydrogel: As used herein, the term, "patterned hydrogel" refers to a hydrogel structure with at least one repeating pattern disposed therein, the repeating pattern at least partially defined by one or more voids and repeating multiple times and defined by a fixed spacing. It is to be understood that such a repeating pattern does not merely consist of the trivial repetition of atoms (e.g., carbon atoms within a polymer strand of the hydrogel). Instead, as understood by one of ordinary skill in the art (including in view of the present disclosure), a repeating pattern is generally a geometric pattern formed from the arrangement of hydrogel material at a more "macro" level, such that the repeating features (or average distance between corresponding repeating units) have a size on the order of microns (e.g., ones or tens of microns), as opposed to a size on the order of Angstroms or nanometers (e.g., below 10 nm).

[0149] Latice or Latice Structure: As used herein, the term, "lattice" or "lattice structure" refers to a repeating two-dimensional or three-dimensional pattern of structural members formed of 3D-printed hydrogels. The pattern may occur on a nanoscale (10 nm or greater), microscale (e.g., ones of microns or tens of microns), millimeter scale, and / or macroscale (i.e., as distinguished from crystal lattice structures, which may be formed and / or repeating on atomic or molecular level, on the order of ones to tens of Angstroms).

[0150] Interstitial space or infill: As used herein the term "interstitial space" refers to a space or volume in between other structures described herein. An "interstitial infill" refers to a structure disposed within an interstitial space.

[0151] Swelling invariance: As used herein, the term "swelling invariance" refers to the property of a hydrogel structure corresponding to zero or minimal change in overall size or volume of the hydrogel structure upon the intake or release of fluid by the hydrogel structure. For example, a hydrogel structure exhibiting "swelling invariance" may exhibit aAtty. Docket No.: PCT.1312 change in overall volume of less than 12%, less than 10%, less than 8%, less than 5%, less than 3%, or less than 1% upon the absorption or release of water, where the denominator is based on the original volume of the hydrogel structure immediately prior to the absorption or release event. Moreover, the absorption or release event can refer particularly to the absorption or release of an amount of water or aqueous fluid having a volume that is greater than 12% or greater than 10% of the original volume of the hydrogel structure immediately prior to the event. That is, the amount of water or aqueous fluid absorbed or released is large enough such that a significant change in volume of the hydrogel structure would ordinarily be expected in a traditional hydrogel structure; yet such a change in volume does not occur in the case of a hydrogel structure having "swelling invariance." In some instances, for example, the overall volume of such a "swelling invariant" hydrogel changes by an amount between 0% and 20%, between 0% and 15%, between 0% and 10%, between 0% and 8%, between 0% and 5%, between 0% and 3%, between 0% and 1%, between 1% and 20%, between 1% and 15%, between 1% and 10%, between 1% and 8%, between 1% and 5%, or between 1% and 3%, between 5% and 20%, between 5% and 15%, or between 5% and 10% of the total volume of water or aqueous fluid absorbed or released. The foregoing percentages (e.g., 5-10%) may also refer to a swelling amount of a hydrogel component described herein when equilibrated in deionized water, as compared to the volume of the as-designed or as-printed hydrogel component (as described below with reference to Figure 17, for instance).

[0152] Vasculature and vascular structure: As understood by a person of ordinary skill in the art, the term "vasculature" refers to a perfusable 2D or 3D interconnected tubular transport system. More particularly, a "vasculature" or "vascular structure" can convey biological fluids, nutrients, drugs, biologies, and / or gases or other substances to a cell, cellular aggregate, or tissue, including to maintain viability of the cell / tissue. "Vasculature" or a "vasculature structure" may also convey waste away from a cell, cellular aggregate, or tissue. In some cases, "vasculature" or a "vascular structure" described herein interpenetrates or is embedded within another network or within a tissue or a tissue mimic or substitute or extracellular matrix, such as a hydrogel structure described herein. For instance, in some instances, a vasculature or vascular structure described herein comprises one or more channels layered with, partially or completely overlapping, surrounding,Atty. Docket No.: PCT.1312 embedded within, and / or interwoven with one or more channels of a tissue or other network, or embedded within a hydrogel structure. Further, in some embodiments, the "vasculature" or "vascular structure" of a device, system, or method described herein does not consist of or comprise regular cylinders or other regular geometric shapes (e.g., such regular geometric shapes joined together to form a network), but instead has an irregular geometric structure, shape, or cross-section. Additionally, in some cases, the "vasculature" or "vascular structure" of a device, system, or method described herein has a perfusable architecture or structure mimicking a mammalian (e.g., human) vascular system that includes an artery, arteriole, capillary bed, venule, vein, or a combination of two or more of the foregoing.

[0153] Upstream and downstream: As understood by one of ordinary skill in the art, the terms "upstream" and "downstream" are relative to the direction of fluid flow within a structure.

[0154] Directions or orientations: As one example, it is to be understood that a "vertical" orientation or a "vertical" direction is an "up and down" orientation or direction (e.g., based on the orientation of the 'long axis' of the relevant structure, as compared to the 'short axis' of the relevant structure). Moreover, such an "up and down" or "vertical" orientation or direction can be relative to the force of gravity exerted by the earth, such that "down" is toward the ground, and "up" is toward the sky, when the relevant platform, component, device, or system is used as intended and as described herein. However, it is further to be understood that terms such as "vertical" and "horizontal" as used herein are to be understood as terms relative to one another to indicate different directions or orientations, analogous to the standard use of terms such as "x-direction" and "y-direction" and "z-direction" in a Cartesian coordinate system, or "length" and "width" and "height" in geometry. Thus, for instance, unless the context clearly indicates otherwise, a "vertical" direction or orientation described herein is orthogonal or perpendicular to a "horizontal" direction or orientation described herein. These terms may also be replaced, in general, with Cartesian directions or orientations, such as "z" (e.g., for "height" or the "vertical" direction or orientation) and "x" or "y" (e.g., for "length" or "width" or the "horizontal" direction or orientation).Atty. Docket No.: PCT.1312

[0155] Digital light processing (DLP): As used herein and as understood by a person of ordinary skill in the art, the term, "digital light processing" (DLP) refers to a 3D printing technology used to rapidly produce photopolymer parts using a projected light source to cure an entire layer at once. In some cases, DLP uses a range of wavelengths from 360 nm to 405 nm, typically as the light source in connection with a photocurable polymer resin.

[0156] Additive manufacturing: The terms "additive manufacturing," "three- dimensional printing system," "three-dimensional printer," "printing," and the like generally describe various solid freeform fabrication techniques for making three-dimensional articles or objects by selective laser sintering (SLS), stereolithography (SLA), dynamic light projection (DLP), selective deposition, jetting, fused deposition modeling (FDM), multijet modeling (MJM), and other additive manufacturing techniques now known in the art or that may be known in the future that use a build material or ink to fabricate three-dimensional objects.DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0157] It is contemplated that methods, systems, compositions, and processes described herein encompass variations and adaptations developed using information from the embodiments described herein. Adaptation and / or modification of the methods, systems, compositions, and processes described herein may be performed, as contemplated by this description.

[0158] Throughout the description, where methods, systems, compositions, and / or processes are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are embodiments of the systems and / or compositions that consist essentially of, or consist of, the recited components, and that there are embodiments of the processes and methods that consist essentially of, or consist of, the recited steps.

[0159] It should be understood that the order of steps or order for performing certain action is immaterial so long as the method and / or processes remain operable. Moreover, two or more steps or actions may be conducted simultaneously.Atty. Docket No.: PCT.1312

[0160] The mention herein of any publication, for example, in the Background section, is not an admission that the publication serves as prior art with respect to any of the claims presented herein. The Background section is presented for purposes of clarity and is not meant as a description of prior art with respect to any claim.

[0161] Documents are incorporated herein by reference as noted. Where there is any discrepancy in the meaning of a particular term, the meaning provided in the Definitions and Description of Terms section above is controlling.

[0162] Headers are provided for the convenience of the reader; the presence and / or placement of a header is not intended to limit the scope of the subject matter described herein.

[0163] Provided herein are improved technologies for manufacture (e.g., printing) of hydrogel (e.g., polymer) structures with internal lattice structures that exhibit improved mechanical properties under compression and swelling. These improved hydrogel structures may be used as scaffolds in organ chips, among other applications.1. Platform for Biological Models

[0164] The present disclosures relate to systems and platforms for modeling organ- on-a-chip (also called organ chips) and other biological models, according to aspects of the present embodiments. The system may include physical platforms with other components such as inlet ports, outlet ports, sensors, conduits, filters, and fluid warmers, that can hold one or more scaffolds that support internal vasculatures. These systems may be used, for example, to perfuse organs and / or to study the functioning of organs in a simulated and active (i.e., including live cells) environment.

[0165] In some aspects, the present disclosure provides methods to generate a system, including a polymer (e.g., a hydrogel), that includes control of environmental factors used for assaying synthetic tissue and / or organ models, real-time and / or continuous tracking of biomarkers via sensors, an ability to rapidly image tissues and / or cells, processing of assay data, machine learning tools for diagnosing results, and updating of scaffold print files such that updated models can be reprinted, assays may be rerun, and the results may be reanalyzed.Atty. Docket No.: PCT.1312Platform Components and Designs

[0166] FIG. 1 illustrates a side view of a platform for modeling organ-on-a-chip and other biological models, according to aspects of the present embodiments. FIG. 2 illustrates a platform assembly, according to aspects of the present embodiments. The platform 30 may include a base 42, a glass base 38 configured to be seated in the base 42 and to support one or more chips 40A, 40B, O-rings 36 for sealing the chips 40A, 40B to a glass cover 26, a clip 34 laterally slidable across a case 32, and a cover retainer 28 for holding the glass cover 26 in place. The fluid inlet 14 and fluid outlet 16 are visible in FIG. 2. With the exception of the chips 40A, 40B, the glass base 42, the glass cover 26, and the O-rings 36, each of the other components of the platform assembly 30 (e.g., the base 42, the clip 34, the case 32, and the cover 28) may be formed via additive manufacturing (e.g., 3D printing) and may be composed of a polymer material (e.g., a hydrogel).

[0167] Referring again to FIG. 1, the platform 30 (specifically the base 42) may include a base clip 46 that is shaped to be engaged with a corresponding case clip 44 (e.g., integrally formed with the case 32) for holding the base 42 to the case 32. In some embodiments, the platform 30 comprises or is formed from a biocompatible, rigid resin. In some embodiments, the platform may include a base and case clips 46, 44 on each end. Each of the chips 40A, 40B may be disposed within the case 32 via corresponding recesses 54 disposed within the case 32. Each chip 40A, 40B may include an internal 3D printed scaffold 70 with an internal vasculature 60 disposed therein. The scaffold 70 may be formed of hydrogel material. The vasculature 60 may include a vasculature inlet 48 and a vasculature outlet 52, both being fluidly coupled (via microchannels disposed within the case 32 (not shown)) to the respective fluid inlet 14 and fluid outlet 16 disposed in the case 32. The vasculature 60 may include a network of flow passages fluidly connecting the vasculature inlet 48 and vasculature outlet 52, and geometrically defining the boundaries of an interstitial space defined therewithin. The platform 30 and chips 40A, 40B, may further comprise an interstitial infill 58 that includes an internal structure (for example, a 3D-printed repeating structure) enabling active cells to be seed thereto. Cells may be added into the interstitial space via an access port 56 disposed within the scaffold 70.

[0168] FIG. 3 ill ustrates a view of a platform assembly 50, according to aspects of the present embodiments. The platform assembly 50 includes a 4x4 grid of recesses enabling 16Atty. Docket No.: PCT.1312 chips to be disposed therein. In some embodiments, the platform 30 includes an internal micro-fluid framework that acts as a manifold such that fluids can be routed to and from each of the (in this case) 16 cells 40, via only a single fluid inlet 14 and a single fluid outlet 16.

[0169] FIGS. 4A and 4B illustrate views of a platform assembly, according to aspects of the present embodiments.

[0170] FIG. 5 illustrates a view of an organ chip 40, according to aspects of the present embodiments. As sown in FIG. 5, the vasculature 60 disposed within the hydrogel scaffold 70 of the chip 40 may have a larger diameter at each of the inlet and outlets, and may include a plurality or network of smaller vasculature passages 60A connecting therebetween. In some embodiments, the internal diameter of the vasculature decreases from the vasculature inlet to a center of the chip 40, and then increases from the center of the cell to the vasculature outlet. In some embodiments, the main volume of the organ chip 40 includes a bulk hydrogel 41.

[0171] FIG. 6 ill ustrates a view of another organ chip 40, according to aspects of the present embodiments. FIG. 7 illustrates a view of another organ chip 40, according to aspects of the present embodiments.

[0172] FIG. 8 illustrates a view of organ chips 40A, 40B within a platform assembly 30, according to aspects of the present embodiments. The platform 30 may include a first chip 40A that includes a scaffold including a vasculature that is representative of a tumor, and a second chip 40B that includes a scaffold including a vasculature that is representative of a liver. The platform 30 may include one or more sensors 64 disposed within the vasculature, within the interstitial space, as well as in other potential locations such as in the inlet and outlet lines. The one or more sensors 64 may include sensors for measuring luminescence, colorimetry, electrochemical activity, fluorescence, and / or metabolic activity.

[0173] FIGS. 9A, 9B, and 9C illustrate views of different vasculature configurations denoted as 70 in each figure. In the configuration shown in FIG. 9A, the vasculature 70 includes a single passageway or channel 60 through the interstitial infill 58. The channel 60 may take a serpentine path making several turns (for example 90, 180, 270, and / or other number of degree turns) through the interstitial infill 58. In the configuration shown in FIG. 9B, the vascular configuration 70 may include multiple vasculature (each denoted as 60),Atty. Docket No.: PCT.1312 wherein each vasculature 60 includes an internal network of connections or passageways disposed within the interstitial infill 58 between a vasculature inlet and a vasculature outlet. In the configuration shown in FIG. 9B, the multiple vasculatures 60 may not connect to each other. In the configuration shown in FIG. 9C, the vasculature configuration 70 may include an open vasculature 60 where passageways connect to adjacent passageways within the interstitial infill 58 forming a two dimensional and / or three-dimensional interconnected network.

[0174] FIGS. 10A and 10B illustrate views of vasculature configurations 60, according to aspects of the present embodiments. FIG. 11 illustrates a view of a vasculature configuration 60, according to aspects of the present embodiments. In the embodiments illustrated in FIGS. 10A, 10B, and 11, the interstitial infill 58 includes a repeating lattice structure or framework. The scaffolds can include bulk hydrogel 70 and interstitial infill 58.

[0175] FIGS. 12A and 12B illustrate views of vasculature configurations 60, according to aspects of the present embodiments. FIG. 13 illustrates a view of a vasculature configuration 60, according to aspects of the present embodiments. In the embodiments illustrated in FIGS. 12A, 12B, and 13, the interstitial infill 58 includes a plurality of packed and interconnected microspheres.Materials, Compositions, Coatings, and Cells

[0176] The present embodiments include structures for the scaffolds, vasculatures, and organ chips that may include, but are not limited to, the following hydrogels: polyacrylamide (PAAm), polyethylene glycol (PEG), polyethylene glycol diacrylate (PEGDA), poly(N-isopropyl acrylamide) (PNIPAM), poly(acrylic acid) (PAA), alginate, gelatin methacrylate (GelMA), collagen, chitosan, hyaluronic acid (HA) as well as different types of co-polymers, interpenetrating networks, double network, hydrogel composites, and combinations of any of the above materials.

[0177] In some embodiments, the present disclosure provides and / or utilizes conjugates (and / or materials, such as hydrogels, generated from them, and / or systems that include them) which comprise one or more polymer and coating moieties (e.g., a polypeptide), optionally associated with one another via a linker(s). In some embodiments, the coating moiety is selected from a group consisting of a polypeptide, a small molecule, aAtty. Docket No.: PCT.1312 peptidomimetic, a lipid, a lipid nanoparticle, a nucleic acid, a (poly)saccharide, or a combination thereof.

[0178] In some embodiments, a polypeptide as described herein may, for example, be selected from the group consisting of a collagen, a fibrin, an integrin, a selectin, a cadherin, a member of the immunoglobulin superfamily (IgSF) (e.g., a nectin, a mucin), a laminin, Matrigel, an extracellular matrix (ECM) protein, an antibody, an antibody fragment, etc. In some embodiments, a polypeptide is a collagen. In some embodiments, a polypeptide is a fibrin. In some embodiments, a polypeptide is an integrin. In some embodiments, a polypeptide is a selectin. In some embodiments, a polypeptide is a cadherin. In some embodiments, a polypeptide is an IgSF. In some embodiments, a polypeptide is a nectin. In some embodiments, a polypeptide is a fibronectin. In some embodiments, a polypeptide is a mucin. In some embodiments, a polypeptide is a laminin. In some embodiments, a polypeptide is a Matrigel. In some embodiments, a polypeptide is an ECM protein. In some embodiments, a polypeptide is an antibody. In some embodiments, a polypeptide is an antibody fragment.

[0179] The present disclosure teaches that, in some embodiments, a bioprinted entity provided and / or utilized in accordance with the present disclosure includes a polymer portion, such as a hydrogel portion (e.g., PEGDA), a coating moiety (e.g., a polypeptide), covalently linked to one another, optionally via a linker (e.g., acrylated PEG SVA), wherein the coating moiety facilitates the association of a cell.

[0180] In some embodiments, a cell associated with the bioprinted entity may be selected from a naturally occurring cell and / or an engineered cell. In some embodiments, a cell associated with the bioprinted entity may be a naturally occurring cell. In some embodiments a cell associated with the bioprinted entity may be an engineered cell. In some embodiments, one or more cells associated with the bioprinted entity may be a combination of a naturally occurring and an engineered cell.

[0181] In some embodiments, a cell associated with the bioprinted entity and / or seeded therein is selected from a group consisting of an endothelial cell, a biliary endothelial cell, a cholangiocyte, a liver parenchymal cell, a hepatocyte (HC), a primary human hepatocyte (PHH), a heptic stellate cell (HSCs), a Kupffer cell (KC), a liver sinusoidal endothelial cell (LSEC), a mucous cell, a parietal cell, a chief cell, an endocrine cell (e.g., a GAtty. Docket No.: PCT.1312 cell, a D cell, a enterochromaffin cell, a EC-like cell, a X / A cell), a columnar epithelial cell, a cardiac fibroblast (CF), a cardiomyocyte, a smooth muscle cell, an enterocyte, a goblet cell, a Paneth cell, a stem cell, a neuron, a glia, a keratinocyte, a melanocyte, a Merkel cell, a Langerhan cell, a germ cell, a stromal cell, a seminiferous tubule, a Leydig cell, a tubule epithelial cell, a macula densa cell, a glomerular endothelial cell, a podocyte, a mesangial cell, a parietal epithelial cell, an immortalized cell (e.g., a 3T3 cell, a A549 cell, a HeLa cell, a HEK 293 cell, a HEK 293T cell, a Huh7 cell, a Jurkat cell, a OK cell, a Ptk2 cell, a Vero cell), a patient-derived cell (e.g., a tumor cell), a T cell, a peripheral blood mononuclear cell (PBMC), and / or an induced pluripotent stem cell (iPSC).2. Hydrogel Swelling and Variability

[0182] P rinted hydrogel structures such as the printed scaffolds of the present embodiments may suffer large variations in dimensions due to swelling in various environments, which may result in problems with fitting of components in organ chips and platforms for biological modes. The swelling of printed structures may be affected by a variety of factors such as variations in lots of monomers, exposure energy during DLP printing, orientation of the printed scaffold on the build platform during printing, intensity distribution of the light in DLP across the build, and printer-to-printer variations. When printed hydrogel structures are exposed to different environmental factors such as temperature, humidity, surrounding liquid, etc., there is an osmotic pressure effect on the structures.Printing Variability

[0183] Examples of variability due to the printing process are illustrated in FIGS. 14 and 15, which show scaffolds for organ chips and their resulting dimensions depending on exposure energy during printing DLP printing. FIG. 14A illustrates a view of a scaffold 100 for an organ chip, according to aspects of the present embodiments, with a design that has a solid bulk hydrogel 102 surrounding an inner vasculature region 106 with inlet and outlet 104, and interstitial fill region 107. FIG. 14B is a table of exposure energy during DLP printing and corresponding outer dimensions of the scaffold for an organ chip in FIG. 14A, according to aspects of the present embodiments. The dimensions were measured using imageAtty. Docket No.: PCT.1312 processing software (for example, Java-based software and / or open-source software and / or Imaged software) to obtain measurements from images taken by microscope (e.g., a fluorescent microscope, e.g., a 3-color fluorescent microscope, e.g., an EVOS microscope). These results show differences in the major and minor outer diameters of the scaffold depending on exposure energy during printing. In some embodiments, scaffolds similar to the scaffold 100 in FIG. 14A may be used in conjunction with a platform 30 and take the place of organ chips 40A, 40B.

[0184] FIG. 15A illustrates a view of another scaffold 110 for an organ chip, according to aspects of the present embodiments, with a design that has a solid bulk hydrogel 112 surrounding an inner vasculature region 116 with inlet and outlet 114 and interstitial fill region 117. The region of bulk hydrogel 112 is smaller in this design (i.e., relative to the vasculature region) than in the one shown in FIG. 15A. FIG. 15B is a table of exposure energy during DLP printing and corresponding outer dimensions of the scaffold for an organ chip in FIG. 15A, according to aspects of the present embodiments. The dimensions here were also measured using imaging software (e.g., ImageJ) to obtain measurements from images taken by microscope (e.g., a fluorescent microscope, e.g., a 3-color fluorescent microscope, e.g., an EVOS microscope). The results here also show that there is variation in measured dimensions with exposure energy during printing. The error values are the standard deviation of 3 samples and 3 replications of measurement for each sample.

[0185] For typical hydrogel printing, the overall dimensions of a printed hydrogel object will have some have some level of deviation based on resolution and repeatability of the printer. Swelling will increase the level of deviation depending on the swelling ratios. Thus, it is difficult to standardize the production of hydrogel structures and make the sizes of hydrogel scaffolds uniform. There are also batch-to-batch variations in monomers in terms of the degree of functionalization, and other variations in materials and precursors used in printing. Thus, there is lack of uniformity for printed or bioprinted structures, and lack of uniformity upon swelling.Swelling-Induced Dimensional Changes

[0186] Hydrogels tend to swell when exposed to fluids (e.g., water). For a neutral hydrogel network, the interaction between water and hydrophilic segments on the polymerAtty. Docket No.: PCT.1312 chains of the hydrogel will facilitate the penetration of water into the hydrogel network, weakening the intermolecular interactions between polymer chains. With water filling up the porous space between the polymer chains inside the network, the overall dimension of the hydrogel thus expands. The hydrogel does not disintegrate during swelling, unlike the dissolution of a polymer in its favorable agent. The stretching and reformation of the chain configuration leads to swelling and competes with the water-polymer interaction force to reach equilibrium (e.g., with new dimensions).

[0187] FIG. 16 is a plot of dimensions of a DLP-printed PEGDA hydrogel at different temperatures and in different cell media, according to aspects of the present embodiments. The plot shows the swelling of DLP-printed PEGDA hydrogel is temperature dependent. With decreasing temperature, the dimensions of the PEGDA hydrogel gradually increase. The plot shows that under different media conditions (e.g., phosphate buffered saline (PBS) or Dulbecco's Modified Eagle Medium (DMEM)), the dimension of the hydrogel also varies. The acceptable dimensions, or the working window acceptable for bulk hydrogel scaffolds in organ chips, in some embodiments, is indicated between the two dashed lines. For applications in cell chips and platforms of the current embodiments, a close fit between a printed hydrogel scaffold and other components in platforms is needed. Due to the swelling and variation in hydrogel dimensions with environmental conditions, precise control of working temperature and cell media is needed in order to have a suitable fit. Previous efforts to accommodate dimensional changes upon swelling include characterizing and adjusting swelling parameters for every raw material batch to match target dimensions, which is inefficient and unscalable. Changing material formulations is also problematic if specific functions of materials are required. Thus, a different approach to solve the issue of dimensional changes of printed hydrogels upon swelling is needed.3. Lattice Structured Hydrogel as Swelling-Invariant and Shock-Absorbing Material

[0188] For conventionally designed hydrogels, swelling is ubiquitous, but can be unfavorable in many biomedical applications, including tissue engineering, internal wound closure, biosensors, electronics, actuators, organ-on-a-chip devices, organs, and many others. The swelling behavior leads to the expansion of the prepared hydrogels creating downstream issues such as weakened dimensional instability that causes damage to theAtty. Docket No.: PCT.1312 surrounding tissues, mechanical property integrity, poor perfusion due to subpar mechanical interfacing with the chip (and / or other flow channels), and interconnectivity with other components in microphysiological systems (MPS). The use of hydrogels in microphysiological systems (MPS), tissue engineering, and other applications are constrained by requirements on hydrogel performance such as size, dimensional stability, and mechanical integrity. The dimensions of prepared hydrogels are in a nonequilibrium state, which can attain equilibrium through introduction into a native functioning environment with adequate equilibration time. The networks of hydrogels are stable during swelling, but the applications are restricted with volume expansion and deterioration of mechanical performance, in particular applications such as scaffolds for tissue regeneration, organs and organ on-a-chip models where the dimensional changes compromise the hydrogel properties and can potentially damage surrounding organs, tissues or connections for MPSs.

[0189] In connection with the present disclosed embodiments, hydrogels are printed into 2D or 3D lattice structures, e.g., with a regular pattern of struts and openings rather than a solid bulk hydrogel, such that the dimensional expansion of the hydrogel can be compensated. The resulting lattice structured hydrogel remains of a consistent overall dimension under different swelling conditions (e.g., temperature, surrounding media, etc.), and able to withstand more mechanical stresses than a bulk hydrogel. The resulting lattice structured hydrogel is thus much better suited to applications in organ chips and other mechanical and biomedical applications. The 2D or 3D lattice structured hydrogels act as a mechanical buffer layer to maintain consistent dimensions for organ-on-a-chip applications. In some embodiments, the lattice structured hydrogel acts as a cushion to protect and maintain the shape of the vasculature and interstitial tissue architecture. In some embodiments, the lattice structured hydrogel acts as a protective lattice structure.

[0190] In some embodiments, lattice structures can also be applied to composite structures and / or composite materials. In some embodiments, multiple regions or layers of lattice structures may be integrated into one object to achieve anisotropic behavior, different ratios of deformation under compression or tension, which may be useful for applications such as drug release or drug loading or other mechanical applications.

[0191] In some embodiments, exposure energy during digital light processing (DLP) controls the extent of polymerization and affects the mechanical performance, degree ofAtty. Docket No.: PCT.1312 polymerization, crosslinking density of the polymer chains thus yielding different swelling values to the extent of dimension variations. The lattice structures' stiffness can be controlled by varying the exposure energy. In some embodiments, DLP is used to print acrylate-based polymers. According to aspects of the present disclosure, DLP may include varied energy exposure modalities, in connection with both single photon and two photon processing.

[0192] Previous efforts in the literature at combating the swelling of hydrogels include anti-swelling hydrogels such as Zhan, Yiwei, et al. "Advances in versatile anti-swelling polymer hydrogels," Materials Science and Engineering: C 127 (2021): 112208, and Lucast, Donald H., Donald R. Battles, and Steven S. Kantner, "Moldable medical adhesive," U.S.Patent No. 4,871,812 (issued October 3, 1989), both of which are incorporated herein by reference in their entireties.

[0193] In the present disclosures, hydrogels are printed using a 3D printing method (e.g., digital light processing (DLP)), to have lattice structures in their interior volumes rather than a solid bulk interior. In some embodiments, the printing method may include other additive manufacturing or 3D printing techniques. In the following sections, different designs of lattices in printed scaffolds are disclosed. In some embodiments, scaffolds are designed to be larger after swelling to their equilibrium states.

[0194] In some embodiments, lattices are a three-dimensional (3D) or two- dimensional (2D) pattern or array of repeating structures (e.g., components such as struts connected at joints and leaving voids or openings or gaps in a repeating pattern). In some embodiments, lattices may include simple cubic 3D lattices, Kelvin cell 3D lattices, bodycentered 3D lattices, body-centered cubic 3D lattices, and / or hexagonal lattices. In some embodiments, lattices may have uniform unit cell dimensions throughout the volume of a printed object. In some embodiments, lattices may have variable unit cell dimensions in different parts of a volume of a printed object in accordance with the needs of the printed object. In some embodiments, different types of lattice patterns, different lattice scales, and different lattice geometries may be used in a single printed object.

[0195] For a scaffold design with bulk hydrogel and interstitial space around the vasculature, the scaffold may swell under typical operating conditions (e.g., temperature, fluid environment for cell growth, etc.) and thus may crack upon insertion of the scaffoldAtty. Docket No.: PCT.1312 into a perfusion system. In some embodiments, a "shock-absorbing" lattice in place of the bulk hydrogel may dissipate the energy that results from compression fitting of a potentially over-swollen scaffold. In some embodiments, the lattice structure may save the scaffold from cracking, which may otherwise result in fit and perfusion failures. As described herein, the addition of a lattice structure may help to avoid or minimize the challenges associated with swelling, thereby enabling the structure to maintain its as-designed print geometry and performance.

[0196] In some embodiments, a hydrogel scaffold with a lattice structure may be swollen to a specific percentage. Owing to the shock-absorption property as described herein, the scaffold may be able to fit in a pre-formed slot in a perfusion system without breakages and may continue to perfuse if the scaffold dehydrates during the period of perfusion. In some embodiments, the "shock-absorber" lattice absorbs the external stress and protects the interior volume of the scaffold, and helps to mitigate the variation in dimensions across multiple scaffolds made from different monomers, using different printers, etc. With the incorporation of a well-organized lattice, hydrogels can absorb mechanical energy by deforming and redistributing stress. The interconnected network of polymer chains allows for efficient energy dissipation. The lattice helps to accommodate dimensional changes due to swelling.Design 1: Scaffold with Lattice Regions

[0197] FIG. 17A illustrates a 3D rendering of a scaffold 120 for an organ chip with portions of lattice structured hydrogel 124, according to aspects of the present embodiments. FIG. 17A shows a perspective view of the top surface and sides of the scaffold 120. This design is similar to the scaffolds used in organ chips as shown in some previous figures herein, but rather than a solid bulk hydrogel as the main body of the scaffold, there are portions 124 that have a 3D lattice structure with an array of struts and openings. The scaffold 120 also features cutouts 128 and indentations 130 for use when incorporated into a platform for biological modeling. The scaffold 120 may also include inlet and outlet ports 126 for access to an internal vasculature region 134, and an access opening 132 to allow different fluid environments to be provided to the vasculature region 134.Atty. Docket No.: PCT.1312

[0198] FIG. 17B is a microscope image of a printed scaffold 120 for an organ chip similar to the one shown in FIG. 17 A, according to aspects of the present embodiments. This scaffold was printed by DLP printing and has all the major features of FIG. 17A visible. FIG. 17C is a photograph of an assembled organ chip with a printed scaffold 120 similar to the one shown in FIG. 17A, according to aspects of the present embodiments. In this example, there is fluid filling the vasculature 134 and inlet and outlet 126.

[0199] FIG. 17D is a table of dimensions of an exemplary printed part, as designed and as printed, for a scaffold for an organ chip similar to the one shown in FIG. 17A, according to aspects of the present embodiments. The results show that the dimensions as printed differ from the dimensions in the intended designs by over-swelling ratios of between 3.8% and 5.8%. These results were obtained for a scaffold reaching equilibrium in DI water (deionized water). In some embodiments, the over swelling ratio is calculated based on the swollen dimensions of a scaffold after reaching equilibrium in a lx PBS medium compared to the designed value. In some embodiments, swelling is observed after equilibrium in DI water, PBS, or cell culture media, with different swelling ratios under different solvent conditions and temperatures (see FIG. 16).

[0200] In some embodiments, introducing the lattice structure 124 into the scaffold 120 increases the overall dimensional tolerance of the scaffold 120. In some embodiments, a dimensional tolerance is the distance to which a printed scaffold may exceed the target dimensions and still fit into a rigid container (e.g., a cell in a perfusion system or platform made of resin). In some embodiments, the dimensional tolerance is about 200 pm for a printed scaffold with bulk hydrogel. In some embodiments, the dimensional tolerance is about 1000 pm for a printed scaffold with a lattice structured hydrogel. Thus, in some cases, the dimensional tolerance of a printed scaffold formed from a lattice structured hydrogel of the present disclosure is at least 2 times, at least 3 times, or at least 5 times the dimensional tolerance of an otherwise identified printed scaffold formed from a bulk hydrogel of the same composition, rather than from a lattice structured hydrogel. In some instances, the dimensional tolerance of a printed scaffold formed from a lattice structured hydrogel of the present disclosure is 2-10, 2-8, 2-5, 3-10, 3-8, or 3-5 times the dimensional tolerance of an otherwise identified printed scaffold formed from a bulk hydrogel of the same composition, rather than from a lattice structured hydrogel. In some embodiments, a higher tolerance isAtty. Docket No.: PCT.1312 better because a structure is able to achieve a good fit into a rigid container despite swelling. In some embodiments, a lattice structured hydrogel can 'absorb' deformation from swelling.Design 2: Scaffold with Lattice Regions

[0201] FIG. 18A illustrates a 3D rendering of another scaffold 150 for an organ chip with larger portions of lattice structured hydrogel 154 in addition to bulk hydrogel 152 around the perimeter of the scaffold 150, according to aspects of the present embodiments. FIG. 18A shows a perspective view of the top surface and sides of the scaffold 150. In some embodiments of this scaffold design 150, the latticed portions 154 take up a larger volume in this scaffold 150 than the latticed portions 124 in scaffold 120 (shown in FIGS. 17A-17C). In some embodiments, this scaffold 150 includes inlets and outlets 156 leading to vasculature 163 in the center bottom of the scaffold 150, indentations 160 and cutouts 158 to accommodate the scaffold 150 in a platform for biological modeling, and an access opening 162 to provide fluid environments to the vasculature 163. In some embodiments, the scaffold 150 includes solid bulk hydrogel 152 surrounding what is shown in FIG. 18A.

[0202] FIG. 18B is a microscope image of a printed scaffold for an organ chip similar to the one shown in FIG. 18A, according to aspects of the present embodiments. The main components of the scaffold 150, including the latticed portions 154, the inlets and outlets 156, the bulk hydrogel 152, the access opening 162, and the vasculature 163, are visible in this image. FIG. 18C is a photograph of a printed scaffold 150 for an organ chip similar to the one shown in FIG. 18A, according to aspects of the present embodiments.

[0203] FIG. 18D is a table of dimensions of an exemplary printed part, as designed and as printed, for a scaffold 150 for an organ chip similar to the one shown in FIG. 18A, according to aspects of the present embodiments. The results show that the dimensions as printed differ from the dimensions in the intended designs by over-swelling ratios of between 3.8% and 6.3%. These results were obtained for a scaffold reaching equilibrium in DI water (deionized water).Design 3: Scaffold with Lattice Regions

[0204] FIG. 19A illustrates a view 3D rendering of another printed scaffold 200 for an organ chip with almost entirely lattice structured hydrogel 204, according to aspects of theAtty. Docket No.: PCT.1312 present embodiments. FIG. 19A shows a perspective view of the top surface and sides of the scaffold 200. Some regions of solid hydrogel 202 are around the perimeter of the scaffold 200. In some embodiments, the scaffold 200 may include latticed structure 204 surrounding a vasculature 212, inside an access opening 210. In some embodiments, scaffold 200 may include an inlet and outlet 206 in fluid communication with the vasculature 212. In some embodiments, the vasculature 212 may be surrounded by a lattice structured (interstitial) infill 214 region. Accordingly, in some embodiments, both the vasculature 212 and the interstitial infill region 214 (neither of which are shown in Fig. 19A) may be intertwined and may occupy the volume defined by the access opening 210.

[0205] FIG. 19B illustrates another 3D rendering of a printed scaffold 250 for an organ chip that is very similar to the scaffold 200 in FIG. 19A, according to aspects of the present embodiments. FIG. 19B shows a perspective view of the bottom surface and sides of scaffold 250. In some embodiments, scaffold 250 may include a lattice structured body 254, a vasculature 262 surrounded by lattice structured (interstitial) infill 264.

[0206] FIG. 19C is a microscope image of a printed scaffold 200 for an organ chip similar to the one shown in FIG. 19A, according to aspects of the present embodiments. The main features of the scaffold 200 are visible in the image of FIG. 19C. FIG. 19D is a photograph of a printed scaffold 200 for an organ chip (i.e., to fit inside the organ chip) similar to the one shown in FIG. 19A, according to aspects of the present embodiments. As shown in FIG. 19D, the vasculature region remains protected from breakage despite the overswollen nature of the scaffold.

[0207] FIG. 19E is a table of dimensions of an exemplary printed part, as designed and as printed, for a scaffold 200 for an organ chip similar to the one shown in FIG. 19A, according to aspects of the present embodiments. These results show that the dimensions as printed differ from the dimensions in the intended designs by over-swelling ratios of between 2.6% and 6.0%. These results were obtained for a scaffold reaching equilibrium in DI water (deionized water).Poisson's Ratio

[0208] In solid materials, Poisson's ratio is a quantity that is the negative of the ratio of transverse strain to axial strain and is due to the tendency for a material to expand inAtty. Docket No.: PCT.1312 directions perpendicular to a direction of compression or, conversely, to contract in directions perpendicular to a direction of stretching. In the present embodiments, designing lattice structures with zero or negative values of Poisson's ratio may result in structures that may better withstand mechanical forces and have invariant overall physical dimensions under swelling conditions (e.g., at different temperatures, in contact with different fluids, etc.).

[0209] FIGS. 20A-20C show illustrations of materials with positive, zero, and negative Poisson's ratios, where the shapes change differently upon stretching in the vertical direction. FIG. 20A shows an illustration of a material with positive Poisson's ratio. The original shape 300 is stretched in the vertical direction (as indicated by the up and down arrows in FIG. 20A), resulting in a deformed shape 302 that is narrower in the horizontal direction. This behavior is typical for most materials, which have positive Poisson's ratios. FIG. 20B shows an illustration of a material with zero Poisson's ratio. The original shape 304 has some interior voids that help accommodate deformation upon stretching in the vertical direction, such that there is no deformation in the horizontal direction at all, resulting in a Poisson's ratio of zero.

[0210] FIG. 20C shows an illustration of a material with negative Poisson's ratio. The original shape 308 includes a lattice structure of struts connected at joints. When the material 308 is stretched in the vertical direction, the joints allow the struts to bend, so that the material expands in the horizontal direction (i.e., the horizontal direction being perpendicular to the vertical direction indicated by the up and down arrows in FIG. 20C), resulting in a negative Poisson's ratio. In some embodiments, negative Poisson's ratio (NPR) structures may include a re-entrant lattice, a re-entrant honeycomb lattice, re-entrant structures, chiral structures, rotating rigid structures, or an auxetic material, or combinations of the above structures.

[0211] FIG. 20D shows an illustration of a two-dimensional re-entrant honeycomb lattice 500, which has a negative Poisson's ratio. The dotted line rectangle indicates one unit cell; the double-ended arrows indicate the lengths of two struts; and the two small arrows indicate the thickness of a strut. In some embodiments, the unit cell dimensions may be between about 20 pm and about 500 pm (for example, from about 100 pm to about 500 pm). FIG. 20E shows an illustration of a two-dimensional re-entrant honeycomb lattice 500Atty. Docket No.: PCT.1312 with feature diameters indicated in millimeters, according to aspects of the present embodiments. In some embodiments, a re-entrant honeycomb lattice 500 may have strut thicknesses of about 0.2 mm to 0.25 mm. In some embodiments, a re-entrant honeycomb lattice 500 may have vertical struts about 0.85 mm long (e.g., between about 0.5 mm and 1 mm long), and diagonal struts about 0.5 mm long (e.g., between about 0.3 mm and 0.8 mm long).

[0212] FIG. 20F shows an illustration of a re-entrant honeycomb before and after tension in the horizontal direction (left and right of the large arrow, respectively). For illustration purposes, one of the unit cells is shown in hatching. See also X. C. Teng et al., "A simple 3D re-entrant auxetic metamaterial with enhanced energy absorption", Int. J. Meeh. Sci. 229 (107524) (2022), which is incorporated herein, by reference.

[0213] In some embodiments, the present disclosure includes lattice structures that have a positive Poisson's ratio, and lattice structures that have zero or negative Poisson's ratio. In some embodiments, the lattice structures are incorporated into the interior volume of shapes produced by additive manufacturing (e.g., 3D printing, digital light processing (DLP)). In some embodiments, a printed object may include a lattice region having a positive Poisson's ratio, another lattice region having a negative Poisson's ratio, and / or another region that may include a bulk solid rather than a lattice.

[0214] FIG. 21 shows illustrations and photographs of negative Poisson's ratio lattice materials under compression, according to aspects of the present embodiments. A block 320 of material with an NPR re-entrant honeycomb lattice is shown as a printed block and compressed in different ways by hand in the center row of photos (i.e., Example 1 or "Ex.1"). A block 330 with a central circular opening 332 surrounded by an NPR re-entrant honeycomb lattice is shown and compressed in different ways by hand in the bottom row of photos (i.e., Example 2 or "Ex. 2"). The compression for block 330 is largely accommodated by the NPR lattice, so that the central opening 332 remains circular with minimal distortion. As a result, flow of fluid through the interior vasculature will be less affected compared to a regular lattice, because the re-entrant honeycomb can withstand higher compressive stress. The deformation (expansion or contraction) of a material in directions perpendicular to the specific direction of loading is the decisive factor for a swelling-invariant hydrogel with theAtty. Docket No.: PCT.1312 introduction of a lattice structure. The top row of images shows diagrams of an NPR lattice being compressed at different levels of strain e.Design 4: Scaffold with Regular Lattice

[0215] FIG. 22A shows an illustration of a 3D rendering scaffold 350 for an organ chip with a regular lattice interior 354, according to aspects of the present embodiments. FIG. 22A shows a perspective view of the bottom surface and sides of the scaffold 350. In some embodiments, the scaffold 350 includes latticed structure 354 taking up nearly the entire interior volume of the scaffold 350, surrounded by solid outer surfaces 352. The scaffold 350 may also include input and output ports 358 that connect to vasculature 356. The scaffold 350 may also include a solid boundary 362 (e.g., a solid inner wall 362) defining an interface between the volume occupied by the vasculature 356 and the latticed structure 354.

[0216] FIG. 22B shows a microscope image of a printed scaffold 350 for an organ chip similar to the one shown in FIG. 22A, according to aspects of the present embodiments. The main features of scaffold 350 are visible in FIG. 22B, which also shows a lattice infill 360 surrounding the vasculature 356. In some embodiments, there may be a solid boundary 362 surrounding the vasculature 356 and forming / defining an access point. The printed scaffold 350 may also include the latticed structure 354 surrounded by the solid outer surface 352.

[0217] FIG. 22C shows a photograph of a scaffold 350 (e.g., a printed scaffold) in a chip, (i.e., a scaffold fitted into a chip) that may be used in connection with an organ chip similar to the one shown in FIG. 22A, with vasculature 356 filled with fluid, according to aspects of the present embodiments. The fluid is visible filling the conduits of the vasculature 356 between the inlet 358 and outlet 358. The lattice infill 360 surrounding the vasculature 356, as well as the latticed structure 354 are also visible in the photograph of FIG. 22C.

[0218] FIG. 22D is a table of dimensions of an exemplary printed part, as designed and as printed, for a scaffold for an organ chip similar to the one shown in FIG. 22C, according to aspects of the present embodiments. These results show that the dimensions as printed differ from the dimensions in the intended designs by over-swelling ratios of between 0% and 4.6%. These results were obtained for a scaffold reaching equilibrium in DI water (deionized water).Atty. Docket No.: PCT.1312

[0219] In some embodiments, regular lattice patterns include grid, honeycomb, rectilinear, etc., which have a positive Poisson's ratio, so that the entire scaffold structure will become thinner when stretched. In contrast, a hydrogel with a negative Poisson's ratio lattice will enable the entire scaffold to expand or compress simultaneously in all directions.Design 5: Scaffold with Re-Entrant Honeycomb Lattice

[0220] FIG. 23A shows an illustration of a 3D rendering 400 for an organ chip with a re-entrant honeycomb lattice 404 in the scaffold, according to aspects of the present embodiments. FIG. 23A shows a perspective view of the bottom surface and sides of the scaffold 400. The re-entrant honeycomb lattice 404 takes up nearly the entire interior volume of the scaffold aside from the vasculature 406. Inputs and outputs 408 are connected to the vasculature 406, which is surrounded by a latticed infill 414. A solid boundary 416 surrounds the vasculature 406 and infill 414 and forms an access opening 412 (shown in FIG. 23B). The printed scaffold 400 also includes a solid outer wall 402.

[0221] FIG. 23B shows a 3D rendering of a cross-sectional view of the printed scaffold 400 shown in FIG. 23A, according to aspects of the present embodiments. The cross-sectional view shows the internal re-entrant lattice 404 sandwiched between the outer surface 402 and inner surface 416. The vasculature 406 is visible as a series of conduits. The infill 410 lattice is disposed around and above the vasculature 406.

[0222] FIG. 23C shows a microscope image of a printed scaffold 400 for an organ chip similar to the one shown in FIG. 23A, according to aspects of the present embodiments. The lattice of the infill 410 is visible as a regular lattice, while the lattice 404 in the surrounding material is a re-entrant honeycomb lattice.

[0223] FIG. 23D shows a photograph of a printed scaffold 400 fitted in a chip for an organ chip similar to the one shown in FIG. 23A, with vasculature filled with fluid, according to aspects of the present embodiments. The fluid filling the vasculature is India ink, and visibly fills the conduits of the vasculature 406 between the input and output 408. In some embodiments, other suitable dyes and / or inks may be used for visualization of flow through the vasculature. The solid outer wall 402, in let / outlet 408, and infill 410 are also visible in the photograph shown in FIG. 23D.Atty. Docket No.: PCT.1312

[0224] FIG. 23E shows a 3D rendering of another cross-sectional view of the printed scaffold 400 shown in FIG. 23A, according to aspects of the present embodiments. The view in FIG. 23E is formed by cutting through the scaffold 400 closer to one of the inlet or outlet 408 so that more of the re-entrant honeycomb lattice 404 is visible. One conduit of the vasculature 406 is visible, and connects to the inlet or outlet 408.

[0225] FIG. 23F shows an illustration of a cross-sectional view of the printed scaffold 400 corresponding to the view in FIG. 23E, according to aspects of the present embodiments. Additional markings on FIG. 23F indicate some notable dimensions for the reentrant honeycomb lattice. In some embodiments, the width of a unit cell may be about 1.0 mm (e.g., 1.03 mm), the height of a unit cell may be about 1.1 mm (e.g., 1.09 mm, 1.11 mm) in the bottom layers of the lattice 404, but the height may be about 0.8 mm (e.g., 0.77 mm, 0.75 mm, 0.72 mm) in the top layer of the lattice 404. The thickness of the struts in the lattice may be about 0.15 mm (e.g., 0.17 mm, 0.1 mm) to 0.4 mm (0.17 mm, 0.34 mm). In some embodiments, the interior dimensions of the struts in the re-entrant lattice may vary from these values and may vary through the interior of the scaffold 400 according to needs and conditions. The solid outer wall 402 is also visible in the views of both FIG. 23E and FIG.23F.Design 6: Scaffold with Re-Entrant Honeycomb Lattice

[0226] FIG. 24A shows a 3D rendering of a printed scaffold 450 for an organ chip with a re-entrant honeycomb lattice 454 in the scaffold, according to aspects of the present embodiments. FIG. 24A shows a perspective view of the top surface and sides of the scaffold 500. Similar to other printed scaffolds in the present disclosures, the lattice 454 takes up a significant portion of the interior volume of the scaffold 450. The lattice 454 is surrounded by solid sides 452. An opening 458 or access point 458 provides access to vasculature 456 at the bottom of the opening 458. Inlet 460 and outlet 460 are at the top surface of the scaffold 450, which connect to vasculature 456.

[0227] FIG. 24B shows a 3D rendering of a cross-sectional view of the printed scaffold 450 shown in FIG. 24A, according to aspects of the present embodiments. The vasculature 456 is visible as a series of connected conduits. The re-entrant honeycomb lattice 454 is visible between the outer surface 452 and inner surface 462. (The inner surfaceAtty. Docket No.: PCT.1312462 is also visible in the view shown in FIG. 24A.) In some embodiments, scaffold 450 does not have an infill lattice surrounding the vasculature 456. There is a gap 464 at the bottom of the scaffold 450 to accommodate the vasculature 456.4. Applications of Lattice Structured Hydrogels

[0228] The present embodiments describe hydrogels with lattice structures used as scaffolds for organ chips. In some embodiments, hydrogels with lattice structures may also be used in other structures and applications in areas such as biomedical devices, organ scaffolds, tissue scaffolds, strain sensors, mechanical applications, nanoparticles, stents, among others.

[0229] In some embodiments, lattice structured hydrogels may be printed by additive manufacturing (e.g., 3D printing, bioprinting) methods, and used to support growth of organs. In some embodiments, organ scaffolds may be used in tissue engineering and regenerative medicine to create functional replacement organs. Incorporating lattice structures within organ scaffolds helps to resemble and replicate intricate 3D frameworks, providing support while allowing nutrient diffusion and waste removal.

[0230] In some embodiments, lattice structured hydrogels may be used in tissue scaffolds. In a tissue scaffold, lattice designs may be employed to shield intricate structures that are prone to damaging due to repeated handling. Additionally, adding lattice to replace bulk hydrogels could benefit applications including drug testing wherein loss of drugs due to non-specific binding or absorption is a major concern. With the incorporation of lattice structure in hydrogel, it can mimic the extracellular matrix (ECM) and may further support cell adhesion which is crucial for bone tissue engineering. For cell seeding, the lattice provides a 3D environment that may be used for seeding osteogenic cells, which may promote bone regeneration. In some embodiments, lattice structured hydrogels may be used to grow microbes for producing chemicals.

[0231] In some embodiments, lattice structured hydrogels may be used in a strain sensor. Mechanical displacements of the lattice as a result of deformations caused by an external force can be transformed into resistance. In some embodiments, the strain sensor may include conductive elements such as carbon, graphite powder, and / or sodium chloride.Atty. Docket No.: PCT.1312

[0232] In some embodiments, lattice structured hydrogels may be used in an organ on a chip (OOAC) (i.e., an organ chip) platform, including, in some embodiments, a planar neurovascular unit. In some embodiments, lattice structured hydrogels can be used in the vicinity of larger vasculature passages to absorb shocks and vibrations associated with the circulation of blood. In some embodiments, lattice structures in an OOAC platform can help to replace the bulky regions that lead to high sorption or waste of expensive fabrication materials.

[0233] In some embodiments, lattice structured hydrogels may be used for control of mechanical properties and prevention of crack propagation, for example, via crack tip softening (CTS) to improve the toughness and fatigue threshold, for example in polyacrylamide hydrogels. In some embodiments, a lattice structure in a hydrogel may be used to enhance toughness, making hydrogels more resistant to crack propagation, thereby improving fracture resistance. In some embodiments, lattice structured hydrogels may be used for targeted release of drugs from polymeric nanoparticles.

[0234] In some embodiments, lattice structured hydrogels may be used for drug loading in an interconnected porous hydrogel, for example, using post-loading and in situ loading. In some embodiments, the porosity of a hydrogel determines its drug loading capability. Lattice structures can introduce more voids in the hydrogel to increase the drug loading capacity. This enables the sustained release over time. In some environments (e.g., pH, temperature), changing the lattice structure can facilitate the tuning of drug release kinetics.

[0235] In some embodiments, lattice structured hydrogels may be used in connection with nanoparticles with internal lattice structure, where an internal pore structure and an external surface area can be used for various applications. In some embodiments, a nanoparticle may be composed of a hydrogel with a lattice structure according to the present disclosure. In some embodiments, introducing a lattice structure to a nanoparticle interior may tune its shape and stretchability. In some embodiments, nanoparticles of up to about 300 nm diameter may have lattice structures with pore sizes in the range from a few nanometers to tens of nanometers.

[0236] In some embodiments, lattice structures according to the present embodiments, may be used in connection with stents. In some embodiments, the Poisson'sAtty. Docket No.: PCT.1312 ratio of the lattice structure would be adjusted to approximately match that of the stent. For example, in some embodiments, if the stent has a position Poisson's ratio, the lattice structure would also include a positive Poisson's ratio.

[0237] In some embodiments, hydrogels with additional properties (e.g., thermal, pH, light, and / or chemical responsiveness) may be formed into lattice structures of the present disclosures. In some embodiments, hydrogels with surface functionalization may be formed into the lattice structures of the present disclosures. In some embodiments, such hydrogels with lattice structures may be useful for applications such as drug delivery, where the release rate of a loaded drug can be tuned by changing the lattice structure in combination with pH responsiveness, for example.5. Perfused Intra-Lattice Scaffold (PILS) for Fast Equilibration Applications

[0238] Pharmaceutical developments, including drug discovery and clearance, involve evaluating efficacy, safety and toxicity of drugs via various healthy and diseased tissue types. Drugs may be classified by the rate at which they are metabolized in the body, which is the focus of pharmacokinetics. Drugs that are metabolized quickly are known as high clearance drugs, whereas drug that are metabolized relatively slowly are known as low clearance drugs. Accordingly, the time duration of a drug within a system is an important characteristic to control. Specifically, high clearance drugs may have a half-life (i.e., time duration for concentration of a drug to decrease to half of the initial value) of about a few minutes.

[0239] P rinted hydrogel-based scaffolds and other types of platforms, which may be used to facilitate drug discovery and development, may face certain challenges due to their inherent property to act as fluid reservoirs. Equilibrium time refers to the amount of time taken by a hydrogel-based scaffold to reach a pre-determined concentration of a drug before dosing can be performed, and potential cell / drug interactions can be captured.Measurement of drug metabolism in a hydrogel-based scaffold may be challenging if mass transport in the system is not significantly faster than the rate of drug metabolism. Concentration gradients within a hydrogel-based scaffold may make it difficult to determine the effective drug concentration that is available to the cells. The accumulation of metabolites may also interfere with drug metabolism and / or other cell processes.Atty. Docket No.: PCT.1312Additionally, the hydrogel itself may function as a reservoir of drug, absorbing more drug per volume than the cell media around it (partitioning). The resulting limitation to accurately applying pharmacokinetic and pharmacodynamic models (PK / PD models) to hydrogel-based scaffolds may decrease the applicability and replicability of hydrogel-based scaffolds to in- vitro systems. Substrates composed of polydimethylsiloxane (PDMS) based materials (and / or other hydrophobic materials) may be prone to adsorption while other types of substrates may be prone to absorption. Both adsorption and absorption may act to impede drug development. An aspect of the present disclosure is directed to a design-based solution to achieve faster equilibration times, e.g., in order to enhance the capacity of hydrogel-based scaffolds for drug development. Achieving fast equilibrium times may ensure that any changes in a drug concentration after reaching steady state are primarily due to cellular metabolism.

[0240] In some embodiments, a hydrogel-based scaffold includes a Perfused IntraLattice Scaffold (PILS). A PILS scaffold may include a perfused latticed design in the bulk region of the hydrogel, allowing a larger portion of the scaffold to act as a vessel for convective mixing. In some cases, perfusion of the bulk region of hydrogel results in reduced transport time and length scales compared to those of a diffusive transport. Accordingly, a PILS may reach equilibrium more quickly under perfusion, while offering a lower total volume of hydrogel, and reducing the required drug volume for testing. A PILS scaffold may lead to a minimal impact of a bulk hydrogel on drug kinetics of the rest of a system, a challenge that is pronounced with a solid bulk hydrogel. Additionally, perfusion of the bulk region of hydrogel may result in an increase in the surface area that comes into contact with the media. In some embodiments, the design of a PILS scaffold may include maximization of the surface area based on the intra-lattice parameters.

[0241] A PILS scaffold may be compatible with various lattice structures or patterns. In some embodiments, a PILS scaffold may include a lattice pattern that promotes significant interaction with a fluid under laminar flow (e.g., a static mixer). In some embodiments, a PILS may include a rectangular lattice pattern. In some embodiments, a PILS scaffold may include thick triply periodic minimal surfaces. In some embodiments, a PILS scaffold may include an octet-like lattice pattern, may significantly reduce the equilibration time compared to a solid structure.Atty. Docket No.: PCT.1312

[0242] A PILS scaffold is versatile and can be adapted for various applications where rapid equilibrium is important, such as studying small-molecule drugs. A PILS scaffold may be used with a wide range of cell types. In some embodiments, a PILS scaffold may be used with hepatic cells for liver models. In some embodiments, a PILS scaffold may be used with cardiomyocytes for heart models. In some embodiments, a PILS scaffold may be used with neuronal cells for brain models. In some embodiments, a PILS scaffold may be used with renal cells for kidney models. In some embodiments, a PILS scaffold may be used with stem cells for regenerative medicine. In some embodiments, a PILS scaffold may be used with cancer cells for oncology research. In some embodiments, a PILS scaffold may be particularly suited for studying pharmacokinetics and pharmacodynamics of small-molecule drugs, including anticancer drugs, cardiovascular drugs, neuroactive drugs, antibiotics, antivirals, and compounds used in regenerative medicine.

[0243] Several parameters may be evaluated to gain a comprehensive understanding of a hydrogel's performance as a drug delivery system, and to further select its design for specific applications. In some embodiments, performance of a PILS scaffold may be evaluated by measuring equilibrium time of a drug. In some embodiments, measurement of equilibrium time may involve adding a known amount of a drug to a system and initiating perfusion. As the drug is absorbed into the PILS scaffold, concentration of the liquid portion within the system decreases. The amount of time that is taken for the drug concentration to reach equilibrium may be used to assess the transport of the drug into the PILS scaffold. In some embodiments, drug absorption rate is measured during an assay. Drug absorption rate refers to the rate at which a drug is absorbed into a hydrogel, which can provide insights into the efficiency of a hydrogel as a drug delivery system. In some embodiments, the drug release profile is measured during an assay. In some embodiments, drug concentration is measured by fluorescence or mass spectroscopy, and the rate of absorption may accordingly be calculated therefrom. Drug release profile refers to monitoring how a drug is released from a hydrogel over time, which can be crucial for understanding the controlled release capabilities of a scaffold. In some embodiments, a diffusion coefficient is measured during an assay. Diffusion coefficient is defined as diffusivity of a drug within a hydrogel, which may help modeling and predicting drug transport behavior. In some embodiments, concentration gradient is measured during an assay. The concentration gradient of a drug within a hydrogelAtty. Docket No.: PCT.1312 indicates how uniformly a drug is distributed. In some embodiments, structural integrity is assessed during an assay. The ability of a hydrogel scaffold to maintain its structural integrity throughout an assay can be helpful for a consistent performance. In some embodiments, fluid dynamics simulations (i.e., simulation of flow characteristics within a system) is used to ensure there are no dead spots and / or areas with insufficient perfusion.

[0244] According to aspects of the present disclosure, PILS scaffolds may be applied to any 3D-printed, perfused hydrogel scaffold format, regardless of shape or size. That is, the PILS framework may be applied to a multitude of geometries in order to accommodate various use cases. This method is not exclusive to DLP-printed scaffolds and can be applied to any method for producing 3D printed hydrogels. This method reduces the system pressure requirements while maintaining an open architecture that can enable integration with standard measurement techniques. Furthermore, the disclosed embodiments enable the addition of one or more drugs into the system.

[0245] FIG. 25A shows a 3D rendering of a PILS scaffold 500 for an organ chip, according to aspects of the present embodiments. The bulk hydrogel 502 (shown transparent) may include a lattice 504 that is enclosed within a thin wall 514. The PILS scaffold 500 may incorporate an open-ended vasculature 506 including an inlet 508 and individual channels 510 that guide the media from the inlet 506 into the latticed hydrogel 502. The media perfuses the latticed hydrogel 502 which serves as a conduit for transferring the media into well 512, via two circular windows 516 disposed within wall 514. The open- ended vasculature may further comprise one or more main branches 511 connected downstream of the inlet 508, each main branch connected to one or more stem lines 513, each stem line 513 connecting to one or more (for example, two in some embodiments) individual channels 510. In some embodiments, each stem line 513 is associated with two individual channels 510 in a "tuning fork" arrangement, with the stem line 513 corresponding to the handle of the tuning fork and each of the two individual channels 510 corresponding to the elongated vibrating members of the tuning fork. In some embodiment, the stem line 513 is arranged at an angle from the plane defined by the two individual channels 510 (i.e., such that the stem line 513 is not contained within the plane defined by each pair of two individual channels 510). In some embodiments, pairs of individual channels 510 are arranged in a vertical configuration 515 (as shown in FIG. 26A). In someAtty. Docket No.: PCT.1312 embodiments, pairs of individual channels 510 are arranged in a horizontal or lateral configuration 517 (also as shown in FIG. 26A). In some embodiments, each individual channel 510 includes a smaller internal diameter than each stem line 513, and each stem line includes a smaller internal diameter than each main branch. In some embodiments, the inlet 508 includes a bell-shaped or funnel-shaped outer profile 521.

[0246] FIG. 25B shows an exemplary exploded view of the components of a PILS scaffold 500 for an organ chip, according to aspects of the present embodiments. The exploded view may include a bulk hydrogel 502, a lattice 504, an open-ended vasculature 506 and an infill lattice 501. In this example, the lattice 504 has an octet-like pattern. Infill 501 is disposed around and above the vasculature 506. This exemplary exploded view illustrates separate components of a PILS scaffold 500 that are printed as a single object.

[0247] The minimum bulk density of a scaffold may be determined by structural requirements of the scaffold. The maximum solid density of a scaffold may be influenced by a minimum distance from a flow path to the center of a non-perfused area and a minimum viable channel diameter. In some embodiments, the minimum distance from a flow path to the center of a non-perfused area is 200 pm. In some embodiments, the minimum viable channel diameter is 150 pm. In some embodiments, a solid infill ranges from about 20% to about 60% (e.g., 15% to 65%). As an example, a scaffold may have a total volume of 126.39 mm3, including 31.42 mm3of solid infill, and 94.97 mm3of void, resulting in a solid infill of 24.8%.

[0248] FIG. 26A shows a 3D rendering of a cross-sectional view of a PILS scaffold 500, according to aspects of the present embodiments. The cross-sectional view shows the structure of lattice 504 that is enclosed within thin wall 514. The hollow spaces 518 within the lattice 504 enable the media guided by the individual channels 510 to perfuse PILS scaffold 500 and flow into well 512 through circular windows 516. Along a top surface 523, the lattice 504 forms a solid, continuous surface disposed around and above individual channels 510, thereby forming the bottom of well 512 (and preventing fluid from flowing out of the well 512). In some embodiments, the PILS scaffold 500 may include two circular windows 516 that are laterally spaced from each other, each being disposed in a top portion (e.g., top 50%) of the thin wall 514. In some embodiments, the PILS scaffold 500 may include one or more cylindrical casings 519 formed within the continuous hydrogelAtty. Docket No.: PCT.1312 structure, each cylindrical casing 519 concentrically disposed about an individual channel. In some embodiments, one or more cylindrical casings 519 at least partially protrude into the interior of the well 512. In some embodiments, one or more cylindrical casings 519 are integral with the thin wall 514 such that a longitudinally extending line along the outer surface of the one or more cylindrical casings 519 abuts and / or is in contact with the thin wall 514.

[0249] The thickness of the wall 503 of the bulk hydrogel 502 wall may be influenced by several factors, including: diameter, thickness, and spacing (e.g., vertical 515 and lateral 517) of the individual channels 510, the diameter of the circular windows 516, overall dimensions of the bulk hydrogel 502, and the overall dimensions of an organ chip system.

[0250] In some embodiments, the maximum distance x within a system can be defined by x = / 7.Dt where D is the diffusivity of the drug in the hydrogel and t is the desired equilibration time of the system. For example, to achieve an equilibrium time of 5 minutes, for a drug that has a diffusivity of 200 pm2 / s (e.g., a small molecule drug), the maximum thickness of a solid portion within the system is about 350 pm (e.g., about 346 pm). In another example, changing the desired equilibration time to 2.5 minutes, but keeping everything else the same results in a maximum thickness of about 250 pm (e.g., about 245 pm).

[0251] FIG. 26B shows a 3D rendering cross-sectional view of the PILS scaffold 500, according to aspects of the present embodiments. The cross-sectional view may include the lattice 504 inside the bulk hydrogel 502, the circular windows 516 disposed in the thin wall 514, and individual channels 510. In some embodiments, the wall 503 of the bulk hydrogel 502 is 0.20 mm thick. In some embodiments, the circular windows 516 have a diameter of 1.00 mm. In some embodiments, the distance between the centers of the two circular windows 516 and the bottom of the bulk hydrogel 502 is 3.50 mm. In some embodiments, the individual channels 510 have a diameter of 0.2mm, and the casings 519 have a thickness of 0.2 mm. In some embodiments, the distance between the centers of individual channels 510 and the bottom of the bulk hydrogel 502 is 0.5 mm. In some embodiments, pairs of individual channels 510 include a vertical distance 515 of 1.20mm. In some embodiments, pairs of individual channels 510 include a lateral distance 517 of 1.20mm therebetween. InAtty. Docket No.: PCT.1312 some embodiments, the PILS scaffold 500 has an intra-lattice surface area of 546.82 mm2, resulting in a surface area per volume of 4.33 mm2 / mm3.

[0252] FIG. 26C shows an illustration of a side view of a PILS scaffold 500, according to aspects of the present embodiments. In some embodiments, the PILS scaffold 500 has a thickness 520 of 4.75 mm.

[0253] FIG. 26D shows an illustration of a top view of a PILS scaffold 500, according to aspects of the present embodiments. The top view of the PILS scaffold 500 may include vasculature inlet 508 and an access point 528. In some embodiments, the PILS scaffold 500 has a length 526 of 14.72 mm, and a width 522 of 9.20 mm. In some embodiments, the access point 528 has a length 532 of 7.50 mm, and a width 530 of 5.98 mm.

[0254] FIG. 27 illustrates an example of a setup 550 for a recirculatory flow through a cartridge 552 including a PILS scaffold 500, according to aspects of the present embodiments. The cartridge 552 may include two fluidly independent reservoirs 556A, 556B. The reservoir 556A may include (and / or contain) a PILS scaffold 500, and a well 570 located on top of the PILS scaffold 500. An internal channel 556 may receive the media from an outlet of a pump 554 and direct it to the PILS scaffold 500. The media is introduced 560 via the PILS scaffold 500 inlet, traverses the interstitial space 562 via individual channels, disperses 564 into latticed hydrogel, and returns 566 to the well within PILS scaffold 500, and finally via an at least partially vertically oriented conduit 568 to well 570. The internal channel 572 may direct the media from well 570 to an inlet of pump 554 which feeds it back into internal channel 558, thereby completing a perfusion cycle. The pump 554 generates a positive pressure through the PILS scaffold 500, which creates a pressure gradient that renders a backflow unlikely. In some embodiments, a one-way valve may be integrated to prevent a backflow.

[0255] In some embodiments, positioning of the circular windows 516 ensures proper circulation by creating a fluidic resistance to the flow. While some areas may experience weaker circulation due to print variability and / or bubble formation, the flow variation has minimal impact on the assay.

[0256] In some embodiments, the top of the PILS scaffold 500 is open to the atmosphere and may be seeded with cells from above. The cartridge 552 may be sealed with a lid 553 which includes pore filters. In some embodiments, the pores have a size of 0.22Atty. Docket No.: PCT.1312 pm. Such pore filters allow for gas exchange, while preventing contaminants from entering. Cell seeding is performed in a sterile environment before the lid 553 is placed.

[0257] FIG. 28A shows an exemplary flow simulation 580 within a PILS scaffold, according to aspects of the present disclosure. The flow simulation 580 may be performed using any suitable fluid dynamic software package. The flow simulation 580 may include a fluid media 582 flowing through latticed hydrogel 504. The media is introduced 560 via the PILS scaffold inlet 508, traverses 562 the interstitial space via individual channels, disperses 564, 565 into the lattice 504, and finally returns to the well through the circular windows 516 (shown in FIGS. 25B and 26A). Accordingly, molecules (for example, drug candidates) within the media permeate the entire scaffold 504, achieving a fast equilibration time, which is otherwise challenging with existing conventional geometries.

[0258] FIG. 28B is a graph 590 of simulated equilibrium time (concentration change as a function of time) in different scaffolds, according to an illustrative embodiment. Plots 592 and 594 show simulated equilibrium times for non-latticed large and small volume scaffolds respectively, whereas plot 596 shows the simulated equilibrium time for a PILS scaffold. The equilibration time achieved by a PILS scaffold 500 may be an order of magnitude faster than that of conventional scaffolds under similar circumstances (i.e., the volume of the PILS scaffold 500 is on par with that of the non-lattice large volume scaffold 592).

[0259] FIG. 29 illustrates a method 800 for determining a metabolic rate (for example, for a drug or compound in a fluid flowing through a platform described in the present disclosure to be metabolized within the platform), according to aspects of the present disclosure. At step 802, the method 800 includes providing a platform with open- ended flow channels coupled to lattice structure. At step 804, the method 800 includes seeding the lattice structure with live cells. At step 806, the method 800 includes flowing fluid (i.e., the fluid containing the drug or compound) through the platform. At step 808, the method 800 includes measuring at least one property of the fluid. At step 810, the method 800 includes optionally comparing measurements of the fluid property from multiple locations. At step 812, the method 800 includes determine the metabolic rate.

[0260] FIG. 30 illustrates a method 900 for determining a metabolic rate (for example, for a drug or compound in a fluid flowing through a platform described in theAtty. Docket No.: PCT.1312 present disclosure to be metabolized within the platform), according to aspects of the present disclosure. At step 902, the method 900 includes providing platform with open- ended flow channels coupled to a lattice structure (as described herein). At step 904, the method 900 includes establishing a baseline concentration. At step 906, the method 900 includes initiating a flow through the platform. At step 908, the method 900 includes assessing a baseline equilibration time. At step 910, the method 900 includes seeding the lattice structure / interstitial infill with live cells. At step 912, the method 900 includes establishing a target concentration at inlet. At step 914, the method 900 includes flowing fluid (containing compound) through the platform. At step 916, the method 900 includes measuring at least one property of the fluid (e.g., concentration) at a downstream location within the platform (or fluidly downstream of the platform). At step 918, the method 900 may include comparing measurements of the fluid property from multiple locations. At step 920, the method 900 includes recording a time for the downstream measurement to equilibrate with inlet target condition. At step 922, the method 900 includes determining a metabolic rate based at least on measured property and baseline equilibration time.

[0261] According to the present disclosure, in connection with embodiments in which drugs are introduced into the platforms and systems disclosed herein, equilibration time may need to be tuned. The swelling invariant patterned hydrogels and perfused intralattice scaffolds of the present disclosure may be patterned or designed in different ways in order to tune the mechanical properties, geometries, and / or other attributes of the systems, devices, and platforms described herein, thereby enabling tuning of the equilibration time as well. In some embodiments, the swelling invariant patterned hydrogels and perfused intralattice scaffolds (PILS) of the present disclosure may be selectively tuned to adjust the diffusion of different molecules or agents. In some embodiments, the swelling invariant patterned hydrogels and perfused intra-lattice scaffolds of the present disclosure may include pores (for example, micro-pores) disposed therein to allow for larger agents like cells to move through the hydrogel. In some embodiments, the swelling invariant patterned hydrogels and perfused intra-lattice scaffolds of the present disclosure may be used in connection with various applications including (but not limited to): cell culture scaffolds, organ-on-a-chip (i.e., organ chip) scaffolds, platforms or systems with the ability to tuneAtty. Docket No.: PCT.1312 equilibration of drugs, and / or platforms or systems with the ability to tune fitting of scaffolds with other microfluidic components and / or geometries.

[0262] Some additional non-limiting example embodiments are described below. It is to be understood that features of the various components, platforms, scaffolds, systems, and methods can be used with one another. For example, the "method" embodiments described below may use any of the "platform" or "scaffold" embodiments described below as the recited "platform" or "scaffold" of the method. For example, the methods of Embodiments 51-56 may use the platform of any of Embodiments 57 and following. Similarly, the "system" embodiments described below may use any of the "platform" or "scaffold" embodiments described below as the recited "platform" or "scaffold" of the system. For example, the system of Embodiment 47 may use the platform of any of Embodiments 57 and following (not only the platform of Embodiment 40). Other combinations are contemplated in the present disclosure, as will be appreciated by the person of ordinary skill in the art, in view of the teachings of the present disclosure.

[0263] E mbodiment 1. A component comprising, consisting of, consisting essentially of, or formed from a hydrogel material, the component comprising: at least one bulk hydrogel portion; and at least one lattice portion; wherein the at least one bulk hydrogel portion is integral with the at least one lattice portion.

[0264] Embodiment 2. The component of Embodiment 1, wherein the at least one lattice portion comprises a repeating pattern formed of the hydrogel material, wherein the repeating pattern comprises a repeating pattern of solid hydrogel material and a repeating pattern of voids.

[0265] E mbodiment 3. The component of Embodiment 1 or Embodiment 2, wherein the at least one bulk hydrogel portion and the at least one lattice portion are formed during the same continuous build process (e.g., by an additive manufacturing process).

[0266] E mbodiment 4. The component of any one of Embodiments 1-3, wherein the at least one bulk hydrogel portion is continuous with the at least one lattice portion.

[0267] E mbodiment 5. The component of any one of Embodiments 1-4, wherein the at least one lattice portion comprises a negative Poisson's ratio.Atty. Docket No.: PCT.1312

[0268] E mbodiment 6. The component of any one of Embodiments 1-4, wherein the at least one lattice portion comprises or has a positive Poisson's ratio.

[0269] E mbodiment 7. The component of any one of Embodiments 1-4, wherein the at least one lattice portion comprises or has a Poisson's ratio substantially equal to zero.

[0270] Embodiment 8. The component of any one of Embodiments 1-7, wherein the at least one bulk hydrogel portion comprises or has a higher density than the at least one lattice portion.

[0271] E mbodiment 9. The component of any one of Embodiments 1-8, wherein the hydrogel material comprises a co-polymer and / or a hydrogel composite material.

[0272] Embodiment 10. The component of any one of Embodiments 1-8, wherein the hydrogel material comprises at least one of polyacrylamide (PAAm), polyethylene glycol (PEG), polyethylene glycol diacrylate (PEGDA), poly(N-isopropylacrylamide) (PNIPAM), poly(acrylic acid) (PAA), alginate, gelatin methacrylate (GelMA), collagen, chitosan, and hyaluronic acid (HA).

[0273] E mbodiment 11. The component of Embodiment 2, wherein the repeating pattern comprises at least one of an interpenetrating network and a double network.

[0274] E mbodiment 12. The component of any one of Embodiments 1-11, wherein the at least one lattice portion comprises a cubic lattice, a body-centered grid, a hexagonal grid, a re-entrant honeycomb structure, a chiral structure, a rotating rigid structure, or a combination of two or more of the foregoing.

[0275] Embodiment 13. The component of Embodiment 2, wherein the repeating pattern comprises unit cell dimensions in a range from about 20 pm to about 500 pm.

[0276] E mbodiment 14. The component of Embodiment 13, wherein the unit cell dimensions vary throughout the component.

[0277] E mbodiment 15. The component of any one of Embodiments 1-14, wherein: the component comprises a stent, the at least one bulk hydrogel portion comprises a substantially cylindrical shape, thereby forming a body of the stent, and the at least one lattice portion comprises a layer disposed at least partially around the at least one bulk hydrogel portion.

[0278] E mbodiment 16. The component of any one of Embodiments 1-15, wherein:Atty. Docket No.: PCT.1312 the stent is expandable, and the at least one lattice portion comprises a positive Poisson's ratio.

[0279] E mbodiment 17. A scaffold configured to be used in an organ-on-a-chip, comprising: a solid exterior; a latticed interior volume disposed within the solid exterior; and a vasculature structure disposed within the latticed interior volume, the vasculature structure comprising a vasculature inlet and a vasculature outlet.

[0280] Embodiment 18. The scaffold of Embodiment 17, wherein the scaffold is formed by an additive manufacturing process (e.g., 3D printing, digital light processing (DLP) with single photon processing, digital light processing (DLP) with two-photon processing, or stereolithography (SLA)).

[0281] Embodiment 19. The scaffold of Embodiment 17 or Embodiment 18, wherein the scaffold comprises a hydrogel comprising one or more of polyacrylamide (PAAm), polyethylene glycol (PEG), polyethylene glycol diacrylate (PEGDA), poly(N-isopropyl acrylamide) (PNIPAM), poly(acry lie acid) (PAA), alginate, gelatin methacrylate (GelMA), collagen, chitosan, or hyaluronic acid (HA).

[0282] Embodiment 20. The scaffold of any one of Embodiments 17-19, wherein the vasculature structure comprises a network of conduits fluidly connecting the vasculature inlet to the vasculature outlet.

[0283] Embodiment 21. The scaffold of any one of Embodiments 17-20, wherein the vasculature inlet and the vasculature outlet are disposed on an outer surface of the solid exterior.

[0284] Embodiment 22. The scaffold of any one of Embodiments 17-21, wherein the solid exterior comprises one or more gaps, indentations, or cutouts.

[0285] E mbodiment 23. The scaffold of any one of Embodiments 17-22, wherein the latticed interior volume comprises one or more volumes comprising repeating lattice structures.

[0286] Embodiment 24. The scaffold of any one of Embodiments 17-23, wherein the repeating lattice structures comprise a cubic lattice, a body-centered grid, a hexagonal grid, aAtty. Docket No.: PCT.1312 re-entrant honeycomb structure, a chiral structure, a rotating rigid structure, or a combination of two or more of the foregoing.

[0287] E mbodiment 25. The scaffold of any one of Embodiments 17-24, wherein the scaffold further comprises an interstitial infill volume surrounding the vasculature structure.

[0288] Embodiment 26. The scaffold of Embodiment 25, wherein the interstitial infill volume comprises a repeating structure configured for supporting one or more living cells.

[0289] Embodiment 27. The scaffold of any one of Embodiments 17-26, wherein: the scaffold further comprises a second vasculature structure comprising a second network of conduits fluidly connecting a second vasculature inlet to a second vasculature outlet, and the network of conduits is interlinked with the second network of conduits.

[0290] E mbodiment 28. The scaffold of any one of Embodiments 17-27, wherein the latticed interior volume comprises: a first portion comprising a lattice structure that includes or has a negative Poisson's ratio, and a second portion comprising a lattice structure that includes or has a positive Poisson's ratio.

[0291] Embodiment 29. A lattice structure comprising a six-sided (e.g., hexagonal) repeating pattern that repeats within a 2-dimensional plane, the six-sided repeating pattern comprising: two lateral sides or struts aligned substantially in a lateral direction, the two lateral sides comprising a first lateral side (or first strut) and a second lateral side (or second strut); two pairs of sides, each pair of sides comprising a first side connected on one side to the first lateral side (i.e., the first strut) and a second side connected on one side to the second lateral side (i.e., the second strut), wherein the first side and the second side are connected to each other on the side that is not connected to the respective first lateral side or second lateral side.

[0292] Embodiment 30. The lattice structure of Embodiment 29, wherein the lattice structure is configured to expand from an initial unexpanded state to an expanded state.

[0293] Embodiment 31. The lattice structure of Embodiment 29 or Embodiment 30, wherein the lattice structure comprises or has a negative Poisson's ratio.Atty. Docket No.: PCT.1312

[0294] E mbodiment 32. The lattice structure of any one of Embodiments 29-31, wherein, in an unexpanded state, the connections between each of the first lateral side and second lateral side with each side of the first and second pairs of sides occurs at an acute angle from the perspective of or at a point in an interior of the six-sided pattern, and wherein, in an unexpanded state, the connections between each side of the first and second pairs with another side of the first and second pairs of sides occur at an obtuse angle from the perspective of or at a point in an interior of the six-sided pattern.

[0295] Embodiment 33. The lattice structure of Embodiment 32, wherein the obtuse angle is greater than 180 degrees.

[0296] Embodiment 34. The lattice structure of Embodiment 32 or Embodiment 33, wherein, in an expanded state, each acute angle in the unexpanded state approaches or reaches 90 degrees and each obtuse angle in the unexpanded state approaches or reaches 180 degrees.

[0297] E mbodiment 35. A platform for assessing drug metabolism, the platform comprising: an outer boundary (502) comprising a plurality of outer side walls and at least one outer bottom surface, the outer boundary defining an exterior geometry of the platform; an inner boundary comprising a plurality of inner side walls (514) and at least one inner bottom surface (523), the inner boundary defining a main compartment (512), a volume (i.e., a second volume) of which is disposed within a volume (i.e., a first volume) defined by the exterior geometry of the platform; a repeating lattice structure (504) disposed within a volume between the outer boundary and the inner boundary (i.e., a third volume); and at least one vasculature passageway (510) extending through the lattice structure from an inlet end (525) to an outlet end (527), wherein the outlet end of the at least one vasculature passage is open to, and in fluid communication with, the volume between the outer boundary and the inner boundary (i.e., the third volume).

[0298] Embodiment 36. The platform of Embodiment 35, further comprising at least one window (516) disposed within at least one wall of the plurality of inner side walls,Atty. Docket No.: PCT.1312 thereby fluidly connecting the volume between the outer boundary and the inner boundary (i.e., the third volume) to the main compartment (i.e., the second volume).

[0299] E mbodiment 37. The platform of Embodiment 35, wherein the second volume, when added to the third volume, is approximately equal to the first volume.

[0300] Embodiment 38. The platform of Embodiment 35, wherein the outer boundary, the inner boundary, the lattice structure, and the at least one vasculature passageway are composed of the same material, and wherein the same material comprises at least one of a hydrogel, a polymer, a 3D-printed material, and a bio-printed material.

[0301] E mbodiment 39. The platform of Embodiment 38, wherein the outer boundary, the inner boundary, the lattice structure, and the at least one vasculature passageway are formed via a single, continuous build process.

[0302] E mbodiment 40. The platform of Embodiment 35, further comprising a fluid inlet (e.g., a vertically oriented, single fluid inlet) for receiving fluid, the fluid inlet disposed within the lattice structure and fluidly coupled upstream of the at least one vasculature passageway.

[0303] Embodiment 41. The platform of Embodiment 35, wherein the at least one vasculature passageway comprises multiple, substantially parallel vasculature passageways oriented along a length direction of the platform.

[0304] E mbodiment 42. The platform of Embodiment 41, wherein the multiple, substantially parallel vasculature passageways are disposed at a vertical position higher than the outer bottom surface of the platform and lower than the inner bottom surface of the platform.

[0305] E mbodiment 43. The platform of Embodiment 35, wherein the at least one vasculature passageway further comprises one or more vasculature passageways disposed at a vertical position higher than the inner bottom surface of the platform.

[0306] E mbodiment 44. The platform of Embodiment 35, wherein the outer boundary, the inner boundary, the lattice structure, and the at least one vasculature passageway comprise a thickness in a range from about 0.1 mm to about 0.5 mm.

[0307] Embodiment 45. The platform of Embodiment 41, wherein each vascular passageway of the multiple, substantially parallel vasculature passageways:Atty. Docket No.: PCT.1312 is disposed at a lateral spacing of from about 0.6 mm to about 2 mm from at least one adjacent passageway, and comprises an internal diameter in a range from about 0.1 mm to about 0.5 mm.

[0308] E mbodiment 46. The platform of Embodiment 35, wherein the lattice structure within the third volume is fluidly coupled downstream of the at least one vasculature passageway and upstream of the main compartment, thereby enabling the lattice structure within the third volume to act as a conduit between the at least one vasculature passageway and the main compartment.

[0309] E mbodiment 47. A system comprising the platform of Embodiment 40, the system further comprising: a pump fluidly coupled upstream of the fluid inlet; and a fluid reservoir fluidly coupled downstream of the third volume.

[0310] Embodiment 48. The system of Embodiment 47, further comprising at least one filter disposed fluidly downstream of the fluid reservoir, wherein the at least one filter is fluidly coupled in a fluid conduit upstream of the fluid inlet, the fluid conduit thereby forming a fluid circuit with other components of the system.

[0311] E mbodiment 49. The system of Embodiment 47, further comprising: at least one fluid (e.g., a therapeutic fluid, blood, dialysate, etc.) disposed within at least one of the first volume, the second volume, and the third volume; and at least one live cell seeded within interstitial infill disposed within the main compartment (i.e., the second volume).

[0312] E mbodiment 50. The system of Embodiment 49, further comprising at least one sensor configured to measure a metabolic rate of at least one compound from the at least one fluid into the at least one live cell.

[0313] E mbodiment 51. A method of determining a metabolic rate for a live cell to metabolize a compound within a platform, the platform comprising: at least one passageway through which a fluid initially containing the compound flows; a lattice structure disposed downstream of, and in fluid communication with, the at least one passageway,Atty. Docket No.: PCT.1312 a compartment disposed downstream of the repeating lattice structure, the compartment comprising an interstitial infill, at least one sensor disposed in operable communication with at least one flow passage of the platform, the at least one sensor configured to measure at least one property of the fluid, the method comprising: seeding the interstitial infill with the live cell; flowing fluid through the platform; measuring, via the at least one sensor, the at least one property of the fluid; and determining the metabolic rate based on, at least partially, the measured at least one property of the fluid.

[0314] E mbodiment 52. The method of Embodiment 51, wherein the repeating lattice structure comprises at least one of a thick triply periodic minimal surface configuration, a reentrant honeycomb pattern, and an octet-like lattice pattern.

[0315] E mbodiment 53. The method of Embodiment 51, wherein the platform further comprises a fluid inlet disposed fluidly upstream of the at least one passageway.

[0316] Embodiment 54. The method of Embodiment 53, wherein the at least one sensor comprises: a first sensor operably coupled to, and configured to measure the fluid property within, at least one of the fluid inlets and the at least one passageway; and a second sensor operably coupled to, and configured to measure the fluid property within, the main compartment, wherein determining the metabolic rate based on, at least partially, the measured at least one property of the fluid comprises comparing the at least one property of the fluid measured by the first sensor to the at least one property of the fluid measured by the second sensor.

[0317] E mbodiment 55. A method of performing an assay within a platform, the platform comprising: (1) at least one passageway through which a fluid flows; (2) a lattice structure disposed downstream of, and in fluid communication with, the at least one passageway; and (3) a main compartment (or reservoir) disposed downstream of, and in fluid communication with, the lattice structure, the method comprising:Atty. Docket No.: PCT.1312 establishing a baseline concentration of at least one compound within the fluid at a portion of the at least one passageway; sampling the fluid at the main compartment; determining a downstream concentration of the at least one compound within the fluid based on the sampling at the main compartment; determining a baseline equilibration time of the platform based on the amount of time it takes the downstream concentration to reach a predetermined percentage of the baseline concentration; and performing an assay within the platform, wherein performing the assay comprises adjusting a second equilibration time determined from parameters measured during the assay, wherein the second equilibration time is adjusted, at least partially, using the baseline equilibration time.

[0318] E mbodiment 56. A method of determining a metabolic rate comprising: determining a baseline equilibration time for a platform, the baseline equilibration time representative of an amount of time it takes for a compound within a fluid circulating through the platform to reach a steady-state concentration; subsequently seeding a portion of the platform with live cells; reestablishing flow of fluid through the platform; changing a concentration of the compound within the fluid from an initial concentration to a target concentration; sampling the fluid at a downstream location; determining a downstream concentration of the at least one compound within the fluid based on the sampling at the downstream location; determining a target equilibration time based on a time duration for the downstream concentration to reach a predetermined percentage of the target concentration; and determining a metabolic rate of the compound based at least partially on a difference between target equilibration time and the baseline equilibration time.

[0319] Embodiment 57. A perfused intra-lattice scaffold (PILS) platform comprising: a bulk hydrogel shell (502) defining a main compartment (512); a lattice structure disposed within the bulk hydrogel shell (504);Atty. Docket No.: PCT.1312 an open-ended vasculature (506) disposed through the lattice structure; and an interstitial infill portion (501) disposed at a bottom of the main compartment, wherein the lattice structure comprises a first repeating pattern, wherein the interstitial infill portion comprises a second repeating pattern, and wherein the first repeating pattern is different from the second repeating pattern.

[0320] E mbodiment 58. The platform of Embodiment 57, wherein the first repeating pattern and the second repeating pattern differ in one or more of bulk density, pattern geometry, and average spacing between elements.

[0321] E mbodiment 59. The scaffold of any one of Embodiments 17-28, wherein the vasculature structure comprises at least one pore and / or at least one micro-pore.

[0322] E mbodiment 60. The platform of any one of Embodiments 35-46, wherein the at least one vasculature passageway comprises at least one pore and / or at least one micropore.

[0323] E mbodiment 61. The platform of Embodiment 35 or Embodiment 57, further comprising a structural hydrogel portion in contact with the repeating lattice structure (of Embodiment 35) and / or the bulk hydrogel shell (of Embodiment 57), the structural hydrogel portion comprising a patterned portion configured for providing swelling invariance and / or shock absorption.

[0324] E mbodiment 62. The platform of Embodiment 61, wherein the structural hydrogel portion is in fluid communication with the lattice structure (504), and is configured to be perfused.

[0325] E mbodiment 63. The platform of Embodiment 61, wherein the structural hydrogel portion is not in fluid communication with the lattice structure (504).

[0326] Embodiment 64. The platform of Embodiment 63, wherein the structural hydrogel portion is not configured to be perfused.

[0327] E mbodiment 65. The platform of Embodiment 61, wherein the patterned portion of the structural hydrogel portion comprises a different pattern geometry than the lattice structure.

[0328] Embodiment 66. The platform of Embodiment 57, further comprising: a structural hydrogel portion in contact with the bulk hydrogel shell.Atty. Docket No.: PCT.1312

[0329] E mbodiment 67. The platform of Embodiment 66, wherein the structural hydrogel portion comprises: at least one bulk hydrogel portion; and at least one lattice portion; wherein the at least one bulk hydrogel portion is integral with the at least one lattice portion.

[0330] Embodiment 68. The platform of Embodiment 67, wherein: the at least one lattice portion of the structural hydrogel portion comprises a third repeating pattern formed of a hydrogel material, and the third repeating pattern comprises a repeating pattern of solid hydrogel material and a repeating pattern of voids.

[0331] E mbodiment 69. The platform of Embodiment 68, wherein the at least one bulk hydrogel portion and the at least one lattice portion of the structural hydrogel portion are continuous with one another.

[0332] E mbodiment 70. The platform of Embodiment 67, wherein the at least one lattice portion of the structural hydrogel portion comprises a negative Poisson's ratio.

[0333] E mbodiment 71. The platform of Embodiment 67, wherein the at least one bulk hydrogel portion of the structural hydrogel portion has a higher density than the at least one lattice portion of the structural hydrogel portion.

[0334] E mbodiment 72. The platform of Embodiment 67, wherein the at least one lattice portion of the structural hydrogel portion comprises a cubic lattice, a body-centered grid, a hexagonal grid, a re-entrant honeycomb structure, a chiral structure, a rotating rigid structure, or a combination of two or more of the foregoing.

[0335] Embodiment 73. The platform of Embodiment 68, wherein the third repeating pattern comprises unit cell dimensions in a range from about 20 pm to about 500 pm

[0336] E mbodiment 74. The platform of Embodiment 68, wherein: the third repeating pattern comprises a six-sided repeating pattern that repeats within a 2- dimensional plane, the six-sided repeating pattern comprising: two lateral sides aligned substantially in a lateral direction, the two lateral sides comprising a first lateral side and a second lateral side;Atty. Docket No.: PCT.1312 two pairs of sides, each pair of sides comprising a first side connected on one side to the first lateral side and a second side connected on one side to the second lateral side, wherein the first side and the second side are connected to each other on the side that is not connected to the respective first lateral side or second lateral side.

[0337] Embodiment 75. The platform of Embodiment 74, wherein, in an unexpanded state, connections between each of the first lateral side and second lateral side with each side of the first and second pairs of sides occur at an acute angle from the perspective of or at a point in an interior of the six-sided pattern, and wherein, in an unexpanded state, connections between each side of the first and second pairs with another side of the first and second pairs of sides occur at an obtuse angle from the perspective of or at a point in an interior of the six-sided pattern.

[0338] E mbodiment 76. The platform of Embodiment 75, wherein the obtuse angle is greater than 180 degrees.

[0339] E mbodiment 77. The platform of Embodiment 75, wherein, in an expanded state, each acute angle in the unexpanded state approaches or reaches 90 degrees and each obtuse angle in the unexpanded state approaches or reaches 180 degrees.EQUIVALENTS

[0340] Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. The scope of the present invention is not intended to be limited to the above Description, but rather is as set forth in the following claims.

Claims

Atty. Docket No.: PCT.1312CLAIMS1. A perfused intra-lattice scaffold (PILS) platform comprising: a bulk hydrogel shell defining a main compartment; a lattice structure disposed within the bulk hydrogel shell; an open-ended vasculature disposed through the lattice structure; and an interstitial infill portion disposed at a bottom of the main compartment, wherein the lattice structure comprises a first repeating pattern, wherein the interstitial infill portion comprises a second repeating pattern, and wherein the first repeating pattern is different from the second repeating pattern.

2. The platform of claim 1, wherein the first repeating pattern and the second repeating pattern differ in one or more of bulk density, pattern geometry, and average spacing between elements.

3. The platform of claim 1, further comprising: a structural hydrogel portion in contact with the bulk hydrogel shell.

4. The platform of claim 3, wherein the structural hydrogel portion comprises a patterned portion configured for providing swelling invariance and / or shock absorption.

5. The platform of claim 3, wherein the structural hydrogel portion is in fluid communication with the lattice structure, and is configured to be perfused.Atty. Docket No.: PCT.13126. The platform of claim 3, wherein the structural hydrogel portion is not in fluid communication with the lattice structure.

7. The platform of claim 6, wherein the structural hydrogel portion is not configured to be perfused.

8. The platform of claim 4, wherein the patterned portion of the structural hydrogel portion comprises a different pattern geometry than the lattice structure.

9. The platform of claim 3, wherein the structural hydrogel portion comprises: at least one bulk hydrogel portion; and at least one lattice portion; wherein the at least one bulk hydrogel portion is integral with the at least one lattice portion.

10. The platform of claim 9, wherein: the at least one lattice portion of the structural hydrogel portion comprises a third repeating pattern formed of a hydrogel material, and the third repeating pattern comprises a repeating pattern of solid hydrogel material and a repeating pattern of voids.

11. The platform of claim 10, wherein the at least one bulk hydrogel portion and the at least one lattice portion of the structural hydrogel portion are continuous with one another.Atty. Docket No.: PCT.131212. The platform of claim 9, wherein the at least one lattice portion of the structural hydrogel portion comprises a negative Poisson's ratio.

13. The platform of claim 9, wherein the at least one bulk hydrogel portion of the structural hydrogel portion has a higher density than the at least one lattice portion of the structural hydrogel portion.

14. The platform of claim 9, wherein the at least one lattice portion of the structural hydrogel portion comprises a cubic lattice, a body-centered grid, a hexagonal grid, a reentrant honeycomb structure, a chiral structure, a rotating rigid structure, or a combination of two or more of the foregoing.

15. The platform of claim 10, wherein the third repeating pattern comprises unit cell dimensions in a range from about 20 pm to about 500 pm.

16. The platform of claim 10, wherein: the third repeating pattern comprises a six-sided repeating pattern that repeats within a 2-dimensional plane, the six-sided repeating pattern comprising: two lateral sides aligned substantially in a lateral direction, the two lateral sides comprising a first lateral side and a second lateral side; two pairs of sides, each pair of sides comprising a first side connected on one side to the first lateral side and a second side connected on one side to the second lateral side, wherein the first side and the second side are connected to each other on the side that is not connected to the respective first lateral side or second lateral side.Atty. Docket No.: PCT.131217. The platform of claim 16, wherein, in an unexpanded state, connections between each of the first lateral side and second lateral side with each side of the first and second pairs of sides occur at an acute angle from the perspective of or at a point in an interior of the six-sided pattern, and wherein, in an unexpanded state, connections between each side of the first and second pairs with another side of the first and second pairs of sides occur at an obtuse angle from the perspective of or at a point in an interior of the six-sided pattern.

18. The platform of claim 17, wherein the obtuse angle is greater than 180 degrees.

19. The platform of claim 17, wherein, in an expanded state, each acute angle in the unexpanded state approaches or reaches 90 degrees and each obtuse angle in the unexpanded state approaches or reaches 180 degrees.

Images