Dendritic macroporous hydrogels prepared by crystal templating

Information

  • Patent Grant
  • 12031008
  • Patent Number
    12,031,008
  • Date Filed
    Monday, July 31, 2023
    a year ago
  • Date Issued
    Tuesday, July 9, 2024
    4 months ago
Abstract
The present invention includes a hydrogel and a method of making a porous hydrogel by preparing an aqueous mixture of an uncrosslinked polymer and a crystallizable molecule; casting the mixture into a vessel; allowing the cast mixture to dry to form an amorphous hydrogel film; seeding the cast mixture with a seed crystal of the crystallizable molecule; growing the crystallizable molecule into a crystal structure within the uncrosslinked polymer; crosslinking the polymer around the crystal structure under conditions in which the crystal structure within the crosslinked polymer is maintained; and dissolving the crystals within the crosslinked polymer to form the porous hydrogel.
Description
TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of hydrogels, and more particularly, to dendritic macroporous hydrogels prepared by crystal templating.


BACKGROUND

Without limiting the scope of the invention, its background is described in connection with hydrogels. Hydrogels are generally polymer chain networks that are water-insoluble, but that absorb water. Often described as being “superabsorbent,” hydrogels are able to retain up to 99% water and can be made from natural or synthetic polymers. Often, hydrogels will have a high degree of flexibility due to their high water content. Common uses for hydrogels include: sustained drug release, as scaffolds (e.g., in tissue engineering), as a thickening agent, as a biocompatible polymer, in biosensors and electrodes and for tissue replacement applications. Natural hydrogels may be made from agarose, methylcellulose, hyaluronic acid (HA), and other naturally-derived polymers.


One method for making hydrogels is a taught by U.S. Pat. No. 7,307,132, issued to Nestler, et al., for a method of producing low-odor hydrogel-forming polymers. Briefly, a low-odor hydrogel-forming acrylic acid polymer is prepared by preparing a polymeric hydrogel by free-radically polymerizing a monomer composition comprising at least 50% by weight of acrylic acid in an aqueous polymerization medium and converting said hydrogel into a particulate hydrogel or into hydrogel-forming powder; and optionally treating the particulate hydrogel or said hydrogel-forming powder with a crosslinking substance which, actually or latently, contain at least two functional groups capable of reacting with the carboxyl groups on the addition polymer; characterized by the acrylic acid used in step (a) containing less than 400 ppm of acetic acid and propionic acid.


Another method is taught by U.S. Pat. No. 6,943,206, issued to Haraguchi for an organic/inorganic hybrid hydrogel and method for manufacturing. Briefly, an organic/inorganic hybrid hydrogel is said to have superior homogeneity, transparency, mechanical properties, and swelling and shrinking properties. A dry body of the organic/inorganic hybrid hydrogel is obtained by removing water from said hydrogel. The organic/inorganic hybrid hydrogel comprises a water soluble polymer (A), a water swelling clay mineral (B) which can be homogeneously dispersed in water, and water (C), and water (C) is included in a three-dimensional network formed by (A) and (B).


DISCLOSURE OF THE INVENTION

More particularly, the present invention includes a method of making a porous hydrogel by preparing an aqueous mixture of an uncrosslinked polymer and a crystallizable molecule; casting the mixture into a vessel; drying the cast mixture to form an amorphous hydrogel film; growing the crystallizable molecule into a crystal structure within the uncrosslinked polymer; crosslinking the polymer around the crystal structure under conditions in which the crystal structure within the crosslinked polymer is maintained; and dissolving the crystals within the crosslinked polymer to form the porous hydrogel. In one aspect, the method further includes seeding the cast mixture with a seed crystal, e.g., of the crystallizable molecule.


In one aspect, the polymer is nucleic acids, amino acids, saccharides, lipids and combinations thereof, in monomeric, dimeric, trimeric, oligomeric or polymeric forms. In another aspect, the polymer used in the method is selected from the group consisting of collagen, chitosan, gelatin, pectins, alginate, hyaluronic acid, heparin and mixtures thereof. In certain embodiments, the polymer is a biopolymer, which may be, e.g., natural, synthetic or even synthetic and natural. In one aspect, the polymer may be gelled by a chemical crosslink, a physical crosslink, or a combination. The crosslink is induced by UV, temperature, pH, an ion, or ion-radical based methods or combinations thereof. Non-limiting examples of crystallizable molecules include: a small organic molecule selected from urea, beta cyclodextrin, glycine and guanidine or a salt such as potassium dihydrogen phosphate. In one aspect, the method may further comprise adding a cross-linking agent to the mixture, the crosslinking agent selected from group consisting of p-Azidobenzoyl hydrazide, N-5-Azido-2-nitrobenzoyloxsuccinimide, disuccinimidyl glutamate, dimethyl pimelimidate-(2)HCl, dimethyl suberimidate-2 HCl, disuccinimidyl suberate, bis [sulfo succ inimidyl suberate], 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide-HCl, isocyanate, aldehyde, glutaraldehyde, paraformaldehyde and derivatives thereof. In certain aspects, the crystal structure forms a lattice structure and supports the polymer during the crosslinking step. In another aspect, the step of growing the crystal structure is by seeding the mixture with a crystal. In another aspect, the step of growing occurs by spontaneous crystal formation, e.g., during the step of drying the cast mixture.


In another embodiment, the present invention includes a porous hydrogel made by a method that includes preparing an aqueous mixture of an uncrosslinked polymer and a crystallizable molecule; casting the mixture into a vessel; drying the cast mixture to form an amorphous hydrogel film; seeding the cast mixture with a seed crystal of the crystallizable molecule; growing the crystallizable molecule into a crystal structure within the uncrosslinked polymer; crosslinking the polymer around the crystal with a crosslinking agent under conditions in which the crystal structure within the crosslinked polymer is maintained; and dissolving the crystals within the crosslinked polymer to form the porous hydrogel. In one aspect, the polymer is nucleic acids, amino acids, saccharides, lipids and combinations thereof, in monomeric, dimeric, trimeric, oligomeric or polymeric form. In another aspect, the polymer is selected from the group consisting of collagen, chitosan, gelatin, pectins, alginate, hyaluronic acid, heparin and mixtures thereof. In certain embodiments, the polymer is a biopolymer, which may be, e.g., natural, synthetic or even synthetic and natural. In one aspect, the polymer may be gelled by a chemical crosslink, a physical crosslink, or a combination. The crosslink is induced by UV, temperature, pH, an ion, or ion-radical based methods or combinations thereof. Non-limiting examples of crystallizable molecules include: a small organic molecule selected from urea, beta cyclodextrin, glycine and guanidine or a salt such as potassium dihydrogen phosphate. In one aspect, the method may further comprise adding a cross-linking agent to the mixture, the crosslinking agent selected from group consisting of p-Azidobenzoyl hydrazide, N-5-Azido-2-nitrobenzoyloxsuccinimide, disuccinimidyl glutamate, dimethyl pimelimidate-(2)HCl, dimethyl suberimidate-2 HCl, disuccinimidyl suberate, bis[sulfosuccinimidyl suberate], 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide-HCl, isocyanate, aldehyde, glutaraldehyde, paraformaldehyde and derivatives thereof. In certain aspects, the crystal structure forms a lattice structure and supports the polymer during the crosslinking step. In another aspect, the step of growing the crystal structure is by seeding the mixture with a crystal.


Another embodiment of the present invention is a hydrogel that includes molecular pores, the hydrogel having one or more crosslinked polymers formed about a plurality of pre-formed molecular crystals, wherein the crystals are formed while the polymer is in uncrosslinked form and the molecular crystals form a porous structure within the polymers during crosslinking of the polymers.





BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures and in which:



FIG. 1 shows the chemical structures of biopolymers used in these hydrogels and a schematic of the crystal-templating technique;



FIGS. 2A to 2F are polarized light (FIGS. 2A and 2D) and phase contrast (FIGS. 2B, 2C, 2E, and 2F) microscopy images of crystal templated HA hydrogel; FIG. 2A) polarized light microscopy image of uncrosslinked HA hydrogel-urea crystal composite; (FIG. 2B) phase contrast microscopy image of uncrosslinked HA hydrogel-urea crystal composite; (FIG. 2C) phase contrast microscopy image of crosslinked HA hydrogel after removal of the urea crystals; (FIG. 2D) polarized light microscopy image of uncrosslinked HA hydrogel-urea crystal composite; (FIG. 2E) phase contrast microscopy image of uncrosslinked HA hydrogel-urea crystal composite; and (FIG. 2F) phase contrast microscopy image of crosslinked HA hydrogel after removal of the urea crystals;



FIGS. 3A to 3C are high magnification images of urea crystals and templated HA hydrogels; (FIG. 3A) time lapse series of the urea crystal front captures with video Brightfield microscopy; (FIG. 3B) atomic force microscopy (AFM) image of the surface of a rinsed urea-templated HA hydrogel in air; and (FIG. 3C) profile of the AFM image perpendicular to the orientation of the ridges;



FIGS. 4A to 4C show the urea seed crystal technique used to control the morphology of crystals and pores within HA hydrogels; (FIG. 4A) three separate nucleation points producing a hydrogel with three radial patterns; (FIG. 4B) line nucleation points producing a hydrogel with linear alignment of crystals; and (FIG. 4C) magnified view of FIG. 4B. Scale bars are 1000 μm (FIGS. 4A and 4B) and 100 μm (FIG. 4C);



FIGS. 5A to 5F shows the process of urea-templating scaled up from droplets to thick films; (FIG. 5A) photograph of scaled-up free standing films of plain and urea-templated HA and alginate; (FIG. 5B) top down view of the scanning electron microscopy images (SEM) of crystal templated HA after cross-linking and rinsing; (FIG. 5C) portion of the film curled back to expose crevices in the hydrogel created by urea crystals; (FIG. 5D) cross-section of the hydrogel perpendicular to the pore orientation; (FIG. 5E) parallel cross-section depicting the fibrillar morphology; and (FIG. 5F) magnified view of image of FIG. 5E; and



FIGS. 6A to 6F depict dendritic crystal growth within polymer solutions demonstrating many possible combinations of crystallizable molecules and polymers. The crystals were imaged by polarized light (FIGS. 6A to 6E) and phase contrast microscopy (FIG. 6F): (FIG. 6A) urea crystal and alginate; (FIG. 6B) urea crystal and 4-arm-PEG acrylate; (FIG. 6C) urea crystal and chitosan; (FIG. 6D) potassium phosphate crystal and hyaluronic acid; (FIG. 6E) b-cyclodextrin crystal and alginate; and (FIG. 6F) magnified image of b-cyclodextrin crystals and alginate. Scale bars are 1000 μm (FIGS. 6A to 6E) and 100 μm (FIG. 6F).





DETAILED DESCRIPTION

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.


To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as “a”, “an” and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as outlined in the claims.


The creation of macroporosity within tissue engineering scaffolds is important because it influences cellular infiltration, scaffold remodeling, nutrient diffusion, vascular in-growth and functional integration with native tissues. The present inventors have developed a novel crystal-templating technique to fabricate hydrogels with continuous dendritic porous networks. No other current method is capable of creating such scaffolds. Additional advantages of this technique are that it is compatible with natural biomaterials, it is fast, can be scaled up, and does not require any expensive equipment or reagents. Crystal-templating works by growing a dendritic crystal template within a solution of uncrosslinked biopolymer, crosslinking the biopolymer around the template, and removing the crystals by washing with water. The result is a macroporous hydrogel with a network of pores matching the shape of the crystal template. We have used urea crystal templates to pattern photocrosslinked HA and calcium-crosslinked alginate hydrogels. The crystal-templating technique and the materials created by it address the challenge of fabricating materials with intricate dendritic micro-architecture that is observed in native tissues.


The goal of tissue engineering is to create materials that can replace or repair injured tissue. To that end it is desirable to have tissue engineered constructs that mimic the microarchitecture of native tissues. An important structural feature of many tissues is highly branched networks of vessels and ducts. Examples are the bronchioles, the microvasculature, lymphatic vessels, the ductal networks of salivary gland, mammary gland, and kidney, and the dendritic trees produced by neurons [1-4]. Such networks exhibit branching, multiple length scales, a directional orientation, and three-dimensionality. A tissue may contain multiple entwined networks; for example, bronchioles, arterial vessels, and venous vessels within the lungs. Although many techniques are available for creating porosity within tissue engineered constructs they fall short of reproducing even one such network [5].


Briefly, current techniques available for creating porosity are gas-foaming, lyophilization, thermally-induced phase separation and porogen leaching of salts and uncrosslinked polymer microspheres [6-8]. Soft replica molding can transfer patterns from etched silicon to polymers such as poly(lactide-co-glycolide), however this is a two-dimensional technique and the stacked layers are a poor approximation of three-dimensional porosity [9-10]. The advantages of these methods are that they are easy to implement and scale-up. The disadvantage is that they provide little control over pore morphology and limited compatibility with natural materials. Rapid prototyping techniques permit precise control over pore morphology through the use of computer-aided design systems [11-13]. Rapid prototyping is suitable for creation of square and hexagonal lattices but not for the complex three-dimensional dendritic patterns observed in native tissues. Although rapid prototyping techniques are compatible with synthetic polymers they are not as suitable for natural materials which are water soluble and viscous. A further limitation is that the resolution of such techniques is larger than the length scale of individual cells and neuronal processes. Scaffolds depicted in the literature typically have features hundreds of microns in length which are too large to precisely guide cellular infiltration. Fabrication of three-dimensional multilayer constructs can be impractical because each scaffold must be built layer by layer with costly equipment.


Hydrogel scaffolds are uniquely suited for tissue engineering applications because they more closely resemble natural tissues with respect to mechanical properties, porosity, and water content than do other materials [14]. In particular, polysaccharides, such as hyaluronic acid (HA) and sodium alginate (SA) are attractive materials because they are composed of the same chemical constituents as native extracellular matrix components. They also exhibit excellent biocompatibility and non-immunogenicity. HA has found use as a dermal filler, adhesion barrier, intra-articular viscosupplement, vitreal substitute, drug delivery matrix and tissue engineering scaffold for cartilage, skin, adipose and vocal cord [15-21]. Alginate has been used extensively for cell encapsulation, drug delivery and tissue engineering of adipose and cartilage [22-24].


In comparison to synthetic materials, these polysaccharides are considerably more difficult to work with because they have high molecular weights, are polydisperse, organic insoluble, pH and temperature sensitive, and produce viscous solutions even at dilute concentrations. Thus, it is a challenge to create tissue engineered scaffolds with biomimetic porous networks in HA and SA hydrogels. To address this problem the present invention describes a crystal-templating technique that uses in situ crystallization to carve out pores within biopolymer hydrogels. Salts and small organic molecules can precipitate as crystalline branching networks under certain conditions. The similarity between such networks and the dendritic patterns of microvasculature and neuronal dendritic trees prompted us to use in situ crystallization to template biopolymer hydrogels with macroporous networks. SA and HA are both linear, unbranched, anionic, high molecular weight polysaccharides (their chemical structures are depicted in FIG. 1), however they are distinguished by their mode of crosslinking HA can be crosslinked by derivatization with methacrylate side chains and exposure to UV light and a photoinitiator [25]. Alginate can be crosslinked by addition of divalent cations which crosslink adjacent guluronic acid blocks [24]. Both modes of crosslinking are compatible with the crystal-templating technique of the present invention. Urea was chosen as the crystallite because of its high water solubility and propensity for extensive hydrogen bonding to permit interaction with biopolymer chains in solution.


The method described in the present invention includes five steps: film casting, solvent evaporation, crystal growth, crosslinking, and rinsing. These steps are depicted in FIG. 1. Small droplets (˜2 μL) of biopolymer and urea were cast onto microscope slides. The droplets were evaporated at ˜50% relative humidity to produce thin hydrated films of about 5 mm in diameter on microscope slides. Solvent evaporation is required to achieve the super-saturation conditions necessary for crystallization. Evaporation also greatly increases the biopolymer concentration and solution viscosity. The combination of high viscosity and hydrogen bonding suppresses spontaneous urea crystallization and facilitates super-saturation. Urea seed crystals were deposited on the tips of a fine pair of tweezers and applied to the centers of each HA/urea and SA/urea film. Crystal growth began immediately and produced long dendritic branches that extended from the center to the edge of the film. Within seconds the entire volume of the hydrogel films were filled with urea crystals. These crystals comprised the urea crystal template.



FIG. 1 shows the chemical structures of biopolymers used in these hydrogels and schematic of the crystal-templating technique. Crystal templated hydrogels were created by casting solution of biopolymer and urea, e.g., hyaluronic acid and alginate. The solvent was evaporated to achieve supersaturation conditions concentrations of urea. As seen in 1 the biopolymer-urea droplet is added to the glass slide, followed by drying 2. Resulting in the application of a seed crystal to the center of the film nucleated crystallization as seen in 3. Following crystallization the biopolymer is crosslinked by either UV or calcium 4. A water rinse 5 removes the urea crystals leaving behind a macroporous hydrogel templated 6 with the pattern of the urea crystals.


After the completion of the crystallization the films were crosslinked by either UV exposure or calcium as appropriate. Both methods of crosslinking are rapid and accurately preserve the configuration of the crystal template. After crosslinking the crystals were easily removed with water. The end products were hydrogels with dendritic macroporous networks. Crystal-templated HA hydrogels are shown in FIG. 2. These thin films are easily observable by transmission light microscopy. Droplets containing both biopolymer and urea crystals (i.e., biopolymer-urea “composites”) were highly birefringent when observed through crossed polarizers. These composite films exhibited a characteristic maltese cross pattern indicative of radial alignment. The colors of the composites in polarized light appeared to correspond to film thickness; the films were thickest at the center and thinned out toward the edges. After crosslinking and rinsing, the hydrogels lost most of their birefringence and exhibited only a faint white color when viewed through crossed polarizers. The hydrogel morphology consisted of aligned straight “fibrils” that were the inverse shape of the crystal template.



FIGS. 2A to 2F are polarized light (FIGS. 2A and 2D) and phase contrast (FIGS. 2B, 2C, 2E, and 2F) microscopy images of crystal templated HA hydrogel. FIGS. 2A to 2D are images of the uncrosslinked hydrogel-crystal composite. FIGS. 2E and 2F images of the hydrogels after crosslinking and removal of the urea crystals. Crystal growth was nucleated at the center of each hydrogel and grew radially outward toward the edge of the hydrogel. The hydrogel-crystal composites in the first column exhibit a maltese cross characteristic of alignment. The crystal template pattern was retained by the hydrogel after crosslinking and rinsing. Scale bars are 1000 μm in FIGS. 2A to 2C and 100 μm in FIGS. 2D to 2F.


Images of urea crystal growth were captured using video microscopy. FIG. 3A depicts high magnification images of a growing urea crystal front. FIGS. 3A to 3C are high magnification images of urea crystals and templated hyaluronic acid hydrogels. FIG. 3A is a time lapse series of the urea crystal front captured with video Brightfield microscopy. Images are five seconds apart. Scale bar=10 μm. FIG. 3B is an AFM image of the surface of a rinsed urea-templated HA hydrogel in air. The ridges correspond to the HA hydrogel. The grooves between the ridges had contained urea crystals that were washed out. This image demonstrates that HA hydrogel was templated by the crystallization of urea. FIG. 3C shows a profile of the AFM image perpendicular to the orientation of the ridges.


It was found that the crystals were thin tightly packed needles that sprouted a high density of branches. As the urea branches approached neighboring crystals the local concentration of urea became depleted and branch growth was terminated; therefore, the longest continuous branches were those that grew in the most radial direction away from the point of nucleation. Direct observation of crystal growth confirmed that the crystals grew continuously; therefore, we conclude that the porous network within the crystal-templated hydrogels is also continuous.


Branches were not observed when urea crystals were grown in the absence of biopolymer which indicates the importance of viscosity to induction of dendritic growth. Such an effect has been observed by others that have examined crystal growth in the presence of polymers [26, 27]. We found that the growth rate was highly dependent on the ratio of urea to HA concentrations. This ratio was adjusted by fixing the HA concentration at 10 mg/mL and varying the urea concentration from 2.5 to 180 mg/mL. Crystal growth could not be nucleated for a ratio of 0.25. For increasing ratios, the growth rate also increased and reached a rate of 1000 μm/sec for a ratio of 6. For ratios of 8 and greater a viscous liquid was expelled from the crystals shortly after crystallization. This liquid was easily visible under polarized light as dark liquid on the surface of the birefringent urea crystals. The liquid was likely rich in HA and photoinitiator which are impurities with respect to urea crystals. At higher ratios the urea crystals became increasingly more tightly packed and less branched. Bulk polyhedral urea crystals were observed on the surface of the needle crystals when the ratio was 18. We concluded that ratios of 6 and under were most effective at templating the biopolymer because this ensured that the hydrogel was templated by the crystals rather than excluded from the template.


The micro-topography of a rinsed urea-templated HA hydrogel was observed by contact mode AFM in air (FIG. 3B). The surface of the hydrogel consisted of alternating parallel valleys and ridges. The valleys were carved out by the growth of urea crystals. During crystallization, the crystal front expels the biopolymer as an impurity. Thus, the biopolymer was compressed into the interstices between urea crystals and formed the radially aligned thin ridges. A profile of the hydrogel perpendicular to the length of the ridges is shown in FIG. 3C. The dimensions of these ridges, less than 1 μm in height and spaced between 1 and 2 μm apart, are consistent with our observations under the light microscope in FIG. 3A.


Urea crystal growth can be nucleated two ways. Spontaneous nucleation occurs when the concentration of urea exceeds a critical super-saturation. Typically, spontaneous nucleation occurred on the edges of the hydrogels. Hydrogels never had more than one spontaneous nucleation event because crystal growth was very rapid.



FIGS. 4A to 4C show that the urea seed crystal technique can be used to control the morphology of crystals and pores within HA hydrogels. FIG. 4A shows three separate nucleation points produced a hydrogel with three radial patterns. FIG. 4B shows a line of nucleation points produced a hydrogel with linear alignment of crystals. FIG. 4C shows a magnified image of FIG. 4B. Scale bars are 1000 μm (FIG. 4A and FIG. 4B) and 100 μm (FIG. 4C).


Applying a seed crystal to initiate urea crystal growth was a simple method for controlling the macro-morphology structure of the crystal template. This was done in conditions that suppressed spontaneous nucleation by partially drying the hydrogel droplets under humid conditions. At equilibrium under humid conditions the hydrated films have a concentration of urea great enough to sustain crystal growth but too low for spontaneous nucleation. Un-nucleated hydrogel films could be maintained for days until the introduction of a seed crystal. This permits selection of both the time and location of the nucleation. Films produced by the application of one seed in the center of the film are depicted in FIG. 2. Application of three seeds produced the three domain template in FIG. 4A. Individual seeds produced radial crystal growth, whereas a line of seeds produced parallel alignment throughout the hydrogel film (FIG. 4B). Thus, seed nucleation is a simple method for engineering template morphology.


The droplets deposited on microscope slides formed thin films a few microns thick as estimated by electron microscopy. Crosslinked films could be released from the surfaces of the microscope slides by agitation and transferred to solution for storage if desired. These films remained intact and did not fall apart, but could be enzymmatically degraded by hyaluronidase and dissolved by treatment with a calcium chelator, EDTA. Scale-up of the urea-templating procedure was accomplished for both HA and SA using a procedure similar to that used for the droplets. The scaled-up films were prepared by casting 2.6 mL of solution into 12-well plates with diameters of 2.2 cm per well. Three to four days were required to evaporate solvent. Crystal growth could be nucleated both spontaneously and by seed crystal.



FIGS. 5A to 5F shows the process of urea-templating was scaled up from droplets to thick films. FIG. 5A is a photograph of scaled-up freestanding films of plain and urea-templated HA and alginate. FIGS. 5B to 5E are SEM images of crystal templated HA after crosslinking and rinsing. FIG. 5B is a top down view. HA hydrogel was sculpted into a “fibrous” morphology. In FIG. 5C, this portion of the film was curled back to expose the crevices in the hydrogel that had been created by urea crystals. FIG. 5D shows a cross-section of the hydrogel perpendicular to the pore orientation depicting that the pores are present throughout the thickness of the hydrogel. FIG. 5E is a parallel cross-section depicting the fibrillar morphology. FIG. 5F is a magnified view of FIG. 5E.


Crystal-templated films were opaque white and had a fibrillar morphology observable even by eye (FIG. 5A). In contrast, non-templated films of HA were transparent and featureless. Non-templated SA films were a light milky white and had a fine granular morphology when viewed under phase contrast microscopy. All templated and non-templated HA and SA films were durable, pliable and easy to handle in both dry and swollen conditions.


Scaled-up templated films were too thick for their features to be observed by optical microscopy; therefore, the morphology of these films was investigated by SEM. Dehydration of swollen hydrogel specimens can easily create artifacts in the hydrogel structure and particularly on the surface. To minimize such artifacts the SEM specimens were extensively soaked and rinsed with methanol rather than water to remove urea. Urea is highly soluble in methanol (˜160 mg/mL) and the templated hydrogel swelled minimally. The urea crystals had been so tightly packed that the templated HA hydrogel had a fibrillar appearance. When observed from the top-down a repeating “arrowhead” fibrillar morphology of the film was clearly revealed (FIG. 5B). A curled portion of the film viewed at an angle revealed the interior crevices among the fibers that had contained the crystal template (FIG. 5C). Cross-sections of the film perpendicular and parallel to the fiber orientation are depicted in FIGS. 5D and 5E, respectively. These cross-sections demonstrate that the pore and fiber morphology was present throughout the thickness of the film and not confined to the surfaces; thus, confirming that the templates are three-dimensional.


The crystal-templating technique is different from existing technology because the crystals are grown within the hydrogel. That is, crystallization begins at a point of nucleation and then radiates outwards filling the entire three dimensional volume. This process of growth ensures that the resulting pores are interconnected and oriented. Importantly, the crystals are suspended within the viscous biopolymer solution permitting crystal growth in three dimensions. Scale-up can be achieved because crystallization occurs rapidly over large distances. Crystallization of urea within HA and SA hydrogels was both easily reproducible and highly robust with respect to the concentrations of urea and biopolymer. This robustness to concentration permitted the hydrogels to be scaled from droplets to large films. The formation of the crystal templates was, however, sensitive to ambient humidity which affected the rate of solvent evaporation and the final water content of the evaporated, equilibrated hydrogel films. This sensitivity was circumvented through the use of controlled humidity conditions. Although crystal-templating lacks precise control over the final pore morphology this can be alleviated through temporal and spatial control of the nucleation event through the use of seed nucleation.


In addition to hyaluronic acid and alginate poly(ethylene glycol) acrylate hydrogels are also patternable by urea crystallization. Exploration of other crystallites and crystal growth conditions will yield a range of template morphologies. For example, engineered potassium phosphate templates were determined that possess dendritic structures that are much larger and thicker than the urea templates. Crystal engineering is a set of techniques that tailors the supramolecular assembly of crystalline materials by manipulating crystal growth conditions. Important parameters are the concentrations and ratios of biopolymer and urea, solution viscosity, pH, and temperature. Additives such as surfactants and chiral molecules can selectively adhere to crystal faces and thereby control the branching, size and chirality of the resulting crystal structures [28]. Such techniques may be able to refine the crystal structures and to produce a wide selection of crystal templates.


The applications of crystal-templated hydrogels extend beyond tissue engineering because these hydrogels present a unique platform for the creation of composite materials. For example, infusion of the pores with cell adhesive proteins would be ideal for tissue engineering scaffolds. Polymerization reactions and biomineralization within the pores can yield novel composites in which one component is distributed throughout the other component in oriented dendritic micron-sized pores.


Sodium hyaluronate from Streptococcus equi of molecular weight 1.6×106 Da as indicated by supplier and low viscosity alginic acid from brown algae were obtained from Sigma-Aldrich (St. Louis, Missouri). Tetra-functional poly(ethylene glycol) acrylate (PEG4A, MW=10 kDa) was obtained from SunBio. Photoinitiator, Irgacure 2959, was obtained from Ciba Specialty Chemicals (Basel, Switzerland). Photopolymerizations were initiated by a longwave UV lamp filtered around 365 nm and with an intensity of 22 mW/cm2 (Blak-Ray B-100A, UVP, Upland, CA).


Photocrosslinkable HA was prepared by our standard procedure of derivatization of HA with glycidyl methacrylate to yield GMHA [25]. Urea-templated GMHA films were prepared as depicted in FIG. 1A. An aqueous solution was prepared of 10 mg/mL GMHA with 40 mg/mL urea and 0.5 mg/mL photoinitiator (Irgacure 2959) in distilled deionized water. Droplets of 2 μL were dispensed onto a glass microscope slide. The solvent was partially evaporated overnight at ambient conditions or in sealed containers with ˜50% relative humidity maintained by saturated solutions of calcium nitrate. GMHA is very hygroscopic and retained residual moisture in equilibrium with the humid atmosphere. Thus, evaporation yielded viscous hydrogel films that were super-saturated with urea. After drying, urea seed crystals were deposited onto the tips of a fine pair of tweezers by scraping the tweezers against solid urea. Then the tweezers were carefully touched to the center of each droplet to nucleate crystallization. Similarly, a razor-blade scraped against urea was used to nucleate straight lines. GMHA was crosslinked by 1 minute of exposure to UV. The hydrogels were rinsed in water to remove urea.


Templated alginate hydrogels were prepared as shown in FIG. 1B. Aqueous solutions of 10 mg/mL alginate with 40 mg/mL urea were dispensed onto microscope slides and air-dried. After crystallization the hydrogels were crosslinked by covering the droplet 200 mg/mL calcium chloride solution for one minute. Rinsing with water removed excess calcium chloride and urea.


Templated PEG4A hydrogels were prepared from aqueous solutions of 60 mg/mL PEG4A, 40 mg/mL urea and 0.5 mg/mL Irgacure 2959. Potassium phosphate templated GMHA was prepared from a solution of 20 mg/mL GMHA, 10 mg/mL potassium dihydrogen phosphate and 0.5 mg/mL Irgacure 2959. These droplets were incubated in humid chambers equilibrated with saturated sodium chloride solutions until crystal growth was complete.


Scale-up of Crystal Templated Hydrogels. Thick crystal-templated hydrogels were prepared under sterile conditions to prevent contamination during solvent evaporation. Aqueous solutions were prepared as described above, filter sterilized (0.22 μm PVDF, Millipore), and dispensed into sterile, non-tissue culture treated 12-well plates. Each well was 2.2 cm in diameter and a volume of 2.6 mL of sterile solution was dispensed per well. The solvent was evaporated in a sterile horizontal flow hood in the dark for four days. During this time urea crystallization either nucleated spontaneously or was nucleated by the seed crystal technique. Once nucleated, crystallization is rapid and therefore spontaneously nucleated films had only one nucleation point. GMHA films were crosslinked by 1 minute of UV exposure, and rinsed extensively with exchanges of water over several days to remove urea. Alginate films were crosslinked by immersion in 200 mg/mL calcium chloride for twenty minutes and then rinsed extensively with water.


Plain GMHA films required an additional humidifying step after air-drying and before photocrosslinking This step was required because the photocrosslinking reaction was moisture sensitive. It is likely necessary for water to be retained within the film to permit diffusion of photoinitiator and movement of GMHA chains during photoexposure. Therefore, air-dried films were placed in a sealed container at ˜85% relative humidity which was achieved by equilibration with saturated potassium chloride solution. GMHA films were incubated under these conditions for four days and then photocrosslinked by 1 minute of exposure to UV.


It is contemplated that any embodiment discussed in this specification can be implemented with respect to any method, kit, reagent, or composition of the invention, and vice versa. Furthermore, compositions of the invention can be used to achieve methods of the invention.


It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.


All publications and patent applications mentioned in the specification are indicative of the level of skill of those skilled in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.


The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or” Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects.


As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.


The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, MB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.


All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.


While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.

Claims
  • 1. A system comprising: a hydrogel composition; anda protein coupled to the hydrogel composition;wherein the hydrogel composition includes: (a) uncrosslinked hyaluronic acid; and (b) uncrosslinked alginate located around the uncrosslinked hyaluronic acid;wherein the uncrosslinked alginate is configured to crosslink around the uncrosslinked hyaluronic acid with an ion when the uncrosslinked alginate is exposed to the ion;wherein the uncrosslinked hyaluronic acid is not configured to crosslink with the ion when the uncrosslinked hyaluronic acid is exposed to the ion.
  • 2. The system of claim 1, wherein the uncrosslinked alginate includes sodium alginate.
  • 3. The system of claim 2, wherein: the uncrosslinked alginate includes guluronic acid;based on the uncrosslinked alginate including the guluronic acid, the uncrosslinked alginate is configured to crosslink around the uncrosslinked hyaluronic acid with the ion when the uncrosslinked alginate is exposed to the ion.
  • 4. The system of claim 3, wherein the hydrogel composition includes at least one crystal.
  • 5. The system of claim 3, wherein the hydrogel composition consists essentially of the uncrosslinked hyaluronic acid, the uncrosslinked alginate, the protein, and water.
  • 6. The system of claim 2, wherein the ion is a cation.
  • 7. The system of claim 2, wherein the ion is calcium.
  • 8. The system of claim 7, wherein the hydrogel composition includes sodium hyaluronate.
  • 9. The system of claim 7, wherein: the uncrosslinked alginate includes guluronic acid;based on the uncrosslinked alginate including the guluronic acid, the uncrosslinked alginate is configured to crosslink around the uncrosslinked hyaluronic acid with the ion when the uncrosslinked alginate is exposed to the ion.
  • 10. A system comprising: a substrate;a hydrogel composition on the substrate;wherein the hydrogel composition includes: (a) uncrosslinked hyaluronic acid; and (b) uncrosslinked alginate located around the uncrosslinked hyaluronic acid;wherein the uncrosslinked alginate is configured to crosslink around the uncrosslinked hyaluronic acid with an ion when the uncrosslinked alginate is exposed to the ion;wherein the uncrosslinked hyaluronic acid is not configured to crosslink with the ion when the uncrosslinked hyaluronic acid is exposed to the ion.
  • 11. The system of claim 10, wherein the uncrosslinked alginate includes sodium alginate.
  • 12. The system of claim 11, wherein: the uncrosslinked alginate includes guluronic acid;based on the uncrosslinked alginate including the guluronic acid, the uncrosslinked alginate is configured to crosslink around the uncrosslinked hyaluronic acid with the ion when the uncrosslinked alginate is exposed to the ion.
  • 13. The system of claim 12, wherein the hydrogel composition includes at least one crystal.
  • 14. The system of claim 12, wherein the hydrogel composition consists essentially of the uncrosslinked hyaluronic acid, the uncrosslinked alginate, and water.
  • 15. The system of claim 11, wherein the substrate includes a protein.
  • 16. The system of claim 11, wherein the ion is a cation.
  • 17. The system of claim 11, wherein the ion is calcium.
  • 18. The system of claim 17, wherein the hydrogel composition includes sodium hyaluronate.
  • 19. The system of claim 17, wherein: the uncrosslinked alginate includes guluronic acid;based on the uncrosslinked alginate including the guluronic acid, the uncrosslinked alginate is configured to crosslink around the uncrosslinked hyaluronic acid with the ion when the uncrosslinked alginate is exposed to the ion.
Parent Case Info

This application is a continuation of U.S. patent application Ser. No. 17/231,653, filed Apr. 15, 2021, which is a continuation of U.S. patent application Ser. No. 16/597,106, filed Oct. 9, 2019, now U.S. Pat. No. 10,982,068, issued Apr. 20, 2021, which is a continuation of U.S. patent application Ser. No. 15/890,719, filed Feb. 7, 2018, now U.S. Pat. No. 10,442,911, issued Oct. 15, 2019, which is a continuation of U.S. patent application Ser. No. 15/135,978, filed Apr. 22, 2016, now U.S. Pat. No. 9,896,561, issued Feb. 20, 2018, which is a continuation of U.S. patent application Ser. No. 14/277,170, filed May 14, 2014, now U.S. Pat. No. 9,320,827, issued Apr. 26, 2016, which is a continuation of U.S. patent application Ser. No. 13/909,707, filed Jun. 4, 2013, now U.S. Pat. No. 8,728,499, issued May 20, 2014, which is a continuation of U.S. patent application Ser. No. 12/919,667, filed Aug. 26, 2010, now U.S. Pat. No. 8,668,863, issued Mar. 11, 2014, which claims priority to Patent Cooperation Treaty Application Serial No. PCT/US2009/035257, filed Feb. 26, 2009, which claims priority to U.S. Provisional Patent Application Ser. No. 61/031,651, filed Feb. 26, 2008 and entitled “Dendritic Macroporous Hydrogels Prepared By Crystal Templating.” The content of each of the above applications is hereby incorporated by reference.

STATEMENT OF FEDERALLY FUNDED RESEARCH

This invention was made with government support under Grant no. BES0201744 and BES0500969 awarded by the National Science Foundation. The government has certain rights in this invention.

US Referenced Citations (181)
Number Name Date Kind
4141973 Balazs Feb 1979 A
4196070 Chao et al. Apr 1980 A
4818542 DeLuca et al. Apr 1989 A
4937270 Hamilton et al. Jun 1990 A
5017229 Burns et al. May 1991 A
5266326 Barry et al. Nov 1993 A
5395383 Adams et al. Mar 1995 A
5415631 Churinetz May 1995 A
5531716 Luzio et al. Jul 1996 A
5531735 Thompson Jul 1996 A
5532221 Huang et al. Jul 1996 A
5563186 Thompson Oct 1996 A
5622707 Dorigatti et al. Apr 1997 A
5688775 Renn et al. Nov 1997 A
5714166 Tomalia Feb 1998 A
5750585 Park et al. May 1998 A
5760200 Miller et al. Jun 1998 A
5795584 Totakura Aug 1998 A
5863551 Woerly Jan 1999 A
5866554 Shalaby et al. Feb 1999 A
5874100 Mahoney et al. Feb 1999 A
5919442 Yin et al. Jul 1999 A
5925009 Mahoney et al. Jul 1999 A
5939323 Valentini et al. Aug 1999 A
5981821 Barikosky Nov 1999 A
5981825 Brekke Nov 1999 A
5984948 Hassan Nov 1999 A
5993661 Ruckenstein et al. Nov 1999 A
6007833 Chudzik Dec 1999 A
6030958 Burns et al. Feb 2000 A
6060534 Ronan et al. May 2000 A
6083930 Roufa et al. Jul 2000 A
6096018 Luzio et al. Aug 2000 A
6124273 Drohan et al. Sep 2000 A
6133325 Schwartz et al. Oct 2000 A
6150581 Jiang et al. Nov 2000 A
6156572 Bellamkonda Dec 2000 A
6165201 Sawhney et al. Dec 2000 A
6174999 Miller et al. Jan 2001 B1
6184266 Ronan et al. Feb 2001 B1
6235726 Burns et al. May 2001 B1
6271278 Park et al. Aug 2001 B1
6281341 Mares-Guia et al. Aug 2001 B1
6294202 Burns et al. Sep 2001 B1
6334968 Shapiro et al. Jan 2002 B1
6368356 Zhong et al. Apr 2002 B1
6372244 Antanavich Apr 2002 B1
6387978 Ronan et al. May 2002 B2
6410044 Chudzik Jun 2002 B1
6425918 Shapiro et al. Jul 2002 B1
6500777 Wiseman et al. Dec 2002 B1
6511650 Eiselt Jan 2003 B1
6521223 Calias et al. Feb 2003 B1
6548081 Sadozai et al. Apr 2003 B2
6566345 Miller et al. May 2003 B2
6599526 Dimitrijevich Jul 2003 B2
6600011 McDonnell et al. Jul 2003 B2
6608117 Gvozdic Aug 2003 B1
6610669 Calias et al. Aug 2003 B1
6630167 Zhang Oct 2003 B2
6630457 Aeschlimann et al. Oct 2003 B1
6638917 Li et al. Oct 2003 B1
6642363 Mooney et al. Nov 2003 B1
6653240 Crawford Nov 2003 B2
6653420 Domschke Nov 2003 B2
6656974 Renn et al. Dec 2003 B1
6693089 Li et al. Feb 2004 B1
6703041 Burns et al. Mar 2004 B2
6723709 Pressato et al. Apr 2004 B1
6750262 Hahnle Jun 2004 B1
6767928 Murphy et al. Jul 2004 B1
6793675 Shapiro Sep 2004 B2
6818018 Sawhney Nov 2004 B1
6841153 Chegini et al. Jan 2005 B1
6869938 Schwartz et al. Mar 2005 B1
6897271 Domschke May 2005 B1
6913765 Li et al. Jul 2005 B2
6924370 Chudzik Aug 2005 B2
6943154 Miller et al. Sep 2005 B2
6960617 Omidian Nov 2005 B2
6977231 Matsuda Dec 2005 B1
6991652 Burg Jan 2006 B2
7022313 O'Connor Apr 2006 B2
7060287 Hubbard et al. Jun 2006 B1
7083697 Dao et al. Aug 2006 B2
7201917 Malaviya Apr 2007 B2
7235295 Laurencin et al. Jun 2007 B2
7252832 Stone et al. Aug 2007 B1
7265098 Miller et al. Sep 2007 B2
7347850 Sawhney Mar 2008 B2
7347988 Hu et al. Mar 2008 B2
7459021 Bukshpan Dec 2008 B2
7504286 Cho Mar 2009 B2
7553903 Riegel Jun 2009 B2
7572894 Jin et al. Aug 2009 B2
7592418 Pathak et al. Sep 2009 B2
7629388 Mikos et al. Dec 2009 B2
7682540 Boyan et al. Mar 2010 B2
7741476 Lebreton Jun 2010 B2
7758654 Hoganson Jul 2010 B2
7833284 Lieberman Nov 2010 B2
7919542 Hudgins Apr 2011 B2
7968110 Hubbard Jun 2011 B2
7988992 Omidian Aug 2011 B2
7989505 Hu et al. Aug 2011 B2
7998204 Stone et al. Aug 2011 B2
7998380 Turng Aug 2011 B2
8025901 Kao et al. Sep 2011 B2
8075908 Delaney Dec 2011 B2
8097273 Fukuhira et al. Jan 2012 B2
8110242 Hawkins Feb 2012 B2
8133840 Mika et al. Mar 2012 B2
8277831 Young et al. Oct 2012 B2
8323675 Greenawalt Dec 2012 B2
8324184 Prestwich et al. Dec 2012 B2
8455001 Ito et al. Jun 2013 B2
8460695 Greenawalt Jun 2013 B2
8551136 Lu Oct 2013 B2
8802115 Altschuler et al. Aug 2014 B2
8809301 Athanasiadis et al. Aug 2014 B2
8927521 Jackson Jan 2015 B2
9034357 Stopek May 2015 B2
9421221 McKay et al. Aug 2016 B2
9770539 Parakka et al. Sep 2017 B2
9987130 Weber Jun 2018 B2
10786595 Zimnitsky et al. Sep 2020 B2
10940229 Saito et al. Mar 2021 B2
11541075 Gooding et al. Jan 2023 B2
20020131933 Delmotte Sep 2002 A1
20030134132 Winterton Jul 2003 A1
20040018160 Hu et al. Jan 2004 A1
20040091605 Bayer et al. May 2004 A1
20040138329 Hubbell et al. Jul 2004 A1
20040241436 Hsieh et al. Dec 2004 A1
20050107868 Nakayama May 2005 A1
20050196426 Cruise et al. Sep 2005 A1
20050282148 Warren et al. Dec 2005 A1
20060173394 Stroock et al. Aug 2006 A1
20070015136 Sanchez-Schmitz et al. Jan 2007 A1
20070026038 Bayer et al. Feb 2007 A1
20070031498 Zhong et al. Feb 2007 A1
20070051630 Larsson et al. Mar 2007 A1
20070202084 Sadozai et al. Aug 2007 A1
20080069857 Yeo Mar 2008 A1
20080182012 Fisher et al. Jul 2008 A1
20080254091 Lee et al. Oct 2008 A1
20080264793 Vigh et al. Oct 2008 A1
20080292664 Giammona et al. Nov 2008 A1
20090062233 Ji et al. Mar 2009 A1
20090081265 Pappas Mar 2009 A1
20090170973 Mattiasson et al. Jul 2009 A1
20090181074 Makower et al. Jul 2009 A1
20090294049 Udipi et al. Dec 2009 A1
20100055158 Vitaris et al. Mar 2010 A1
20100062232 Schauer et al. Mar 2010 A1
20100114313 Lack May 2010 A1
20100121261 Kablik et al. May 2010 A1
20100217403 Champion et al. Aug 2010 A1
20100273667 Kotov Oct 2010 A1
20110008442 Zawko et al. Jan 2011 A1
20110029003 Lavigne et al. Feb 2011 A1
20120039959 Tessmar et al. Feb 2012 A1
20120088832 Mayes et al. Apr 2012 A1
20120239063 Lee Sep 2012 A1
20120244107 Heckroth et al. Sep 2012 A1
20120282302 McCanless Nov 2012 A1
20130034592 Yamamoto et al. Feb 2013 A1
20130052236 Tessmar et al. Feb 2013 A1
20130095143 Font et al. Apr 2013 A1
20130195789 Lu Aug 2013 A1
20130211320 Alkhamesi et al. Aug 2013 A1
20130252921 Lee et al. Sep 2013 A1
20130316007 Ma et al. Nov 2013 A1
20140256831 Ito et al. Sep 2014 A1
20140322351 Gawande et al. Oct 2014 A1
20150010490 Kim et al. Jan 2015 A1
20150010636 Delaney Jan 2015 A1
20210269638 Kim et al. Sep 2021 A1
20220168334 Dowling Jun 2022 A1
20230095832 Ng Mar 2023 A1
20230101687 Traverso et al. Mar 2023 A1
Foreign Referenced Citations (38)
Number Date Country
108969392 Dec 2018 CN
109294002 May 2021 CN
113813448 Dec 2022 CN
116019973 Apr 2023 CN
114984300 Aug 2023 CN
1806367 Sep 1997 EP
1105094 Aug 1999 EP
1778144 Aug 2005 EP
11806367 Nov 2007 EP
202011004849 Aug 2021 IN
04235124 Aug 1992 JP
06100468 Apr 1994 JP
20000027821 Feb 2000 JP
2001212224 Aug 2001 JP
20010259212 Aug 2001 JP
2003062057 Mar 2003 JP
3805654 May 2006 JP
3796165 Jul 2006 JP
20020027747 Apr 2002 KR
20020032351 May 2002 KR
20030055102 Jul 2003 KR
101507301 Apr 2015 KR
101985368 Sep 2019 KR
102078334 Feb 2020 KR
1997039737 Oct 1997 WO
2002064192 Aug 2002 WO
2002092678 Nov 2002 WO
2005020849 Mar 2005 WO
2009108760 Mar 2009 WO
2013174661 Nov 2013 WO
2014093489 Jun 2014 WO
2018056937 Mar 2018 WO
2020051920 Mar 2020 WO
2022025229 Feb 2022 WO
2022038213 Feb 2022 WO
2022265367 Dec 2022 WO
2022265368 Dec 2022 WO
2023019143 Feb 2023 WO
Non-Patent Literature Citations (71)
Entry
Cho et al., “Alginate Film as a Novel Post-Surgical Tissue Adhesion Barrier,” Journal of Biomaterials Science-Polymer Edition, 2010, 21(6-7), 14 pages total.
Chang et al., “Electrospun anti-adhesion barrier made of chitosan alginate for reducing peritoneal adhesions,” Carbohydrate Polymers, 2012, 9 pages total.
Hirasaki et al., “Development of a Novel Antiadhesive Material, Alginate Flakes, Ex Vivo and In Vivo,” Surgery Today, 2011, 8 pages total.
Xu et al., “Preparation and characterization of alginate hydrogel membranes crosslinked using a water-soluble carbodiimide,” Journal of Applied Polymer Science, 2003, 7 pages total.
Oerther et al., “Hyaluronate-alginate gel as a novel biomaterial: Mechanical properties and formation mechanism,” 1999, Biotechnology Bioeng, pp. 206-215.
Oerther et al., “High interaction alginate-hyaluronate associations by hyaluronate deacetylation for the preparation of efficient biomaterials,” 2000, Biopolymers, pp. 273-281.
Nezhat et al., “Adhesion Prevention and Management,” Prevention & Management of Laparoendoscopic Surgical Complications, 3rd edition, Society of Laparoendoscopic Surgeons, 2011, 11 total pages.
Zhang et al., “Thermosensitive methyl cellulose-based injectable hydrogels for post-operation anti-adhesion,” Jan. 30, 2014, Carbohydr Polym., 101:171-8, 8 total pages.
Wiseman et al., “Metaanalysis of the safety and efficacy of an adhesion barrier (Interceed TC7) in laparotomy,” Apr. 1999, J Reprod Med., 44(4):325-31, 3 total pages.
Al-Jaroudi et al., “Adhesion prevention in gynecologic surgery,” Obstet Gynecol Surv., May 2004; 59(5):360-7, 9 total pages.
Ten Broek et al., “Efficacy of polyethylene glycol adhesion barrier after gynecological laparoscopic surgery: results of a randomized controlled pilot study,” Gynecol Surg., Feb. 2012, 9(1):29-35.
Ten Broek et al., “Benefits and harms of adhesion barriers for abdominal surgery: a systematic review and meta-analysis,” The Lancet, Jan. 4, 2014, 383(9911):48-59, 12 pages total.
Yang et al., “Prevention of abdominal adhesion formation by thermosensitive PECE-hydrogel in a rat uterine horn model,” J Biomed Mater Res B Appl Biomater., Jan. 2011, 96(1):57-66, 10 pages total.
Mettler et al., “A safety and efficacy study of a resorbable hydrogel for reduction of post-operative adhesions following myomectomy,” Hum Reprod., May 2008, 23(5):1093-100, 8 pages total.
Lauder et al., “Use of a modified chitosan-dextran gel to prevent peritoneal adhesions in a porcine hemicolectomy model,” J Surg Res., Aug. 2012,176(2):448-54, 7 pages total.
Johns et al., “Initial feasibility study of a sprayable hydrogel adhesion barrier system in patients undergoing laparoscopic ovarian surgery,” J Am Assoc Gynecol Laparosc., Aug. 2003, 10(3):334-8, 5 pages total.
Tjandra et al., “A sprayable hydrogel adhesion barrier facilitates closure of defunctioning loop ileostomy: a randomized trial,” Dis Colon Rectum., Jun. 2008, 51(6):956-60, 5 pages total.
Diamond, “Reduction of adhesions after uterine myomectomy by Seprafilm membrane (HAL-F): a blinded, prospective, randomized, multicenter clinical study; Seprafilm Adhesion Study Group,” Fertil Steril., Dec. 1996, 66(6):904-10, 7 pages total.
Falabella et al., “Novel Macromolecular Crosslinking Hydrogel to Reduce Intra-Abdominal Adhesions,” Journal of Surgical Research, vol. 159, Issue 2, Apr. 2010, pp. 772-778, 7 total pages.
Hill-West et al., “Efficacy of adhesion barriers. Resorbable hydrogel, oxidized regenerated cellulose and hyaluronic acid,” Mar. 1996, 5 total pages.
Becker et al., “Prevention of postoperative abdominal adhesions by a sodium hyaluronate-based bioresorbable membrane: a prospective, randomized, double-blind multicenter study,” Oct. 1996, 2 total pages.
Li et al., “The value of an absorbable adhesion barrier, Interceed, in the prevention of adhesion reformation following microsurgical adhesiolysis,” Apr. 1994, 5 total pages.
Luo et al., “Cross-linked hyaluronic acid hydrogel films: new biomaterials for drug delivery,” Journal of Controlled Release, Oct. 3, 2000, 16 total pages.
Shu et al., “In situ crosslinkable hyaluronan hydrogels for tissue engineering,” Biomaterials, Mar.-Apr. 2004, 10 total pages.
Vrijland et al., “Fewer intraperitoneal adhesions with use of hyaluronic acid-carboxymethylcellulose membrane: a randomized clinical trial,” Feb. 2002, 7 total pages.
Bennett et al., “Next-Generation HydroGel Films as Tissue Sealants and Adhesion Barriers,” Nov./Dec. 2003, 7 total pages.
European Patent Office, Examination Report mailed Jul. 29, 2020 in European patent application No. 19 156 162.0, 9 pages total.
Shen et al., “A Study on The Fabrication of Porous Chitosan/Gelatin Network Scaffoldfor Tissue Engineering,” Polymer International, vol. 49, Issue 12, Nov. 21, 2000, pp. 1596-1599.
Lindenhayn et al., “Retention of Hyaluronic Acid in Alginate Beads: Aspects for In Vitro Cartilage Engineering,” J. Biomed. Mater. Res., 1999, vol. 44, pp. 149-155.
U.S. Patent and Trademark Office, Office Action mailed Mar. 27, 2013, in U.S. Appl. No. 12/919,667 (“Zawko”).
Applicant's Reply to Office Action Mailed Mar. 27, 2013, filed via EFS on Jul. 18, 2013, in U.S. Appl. No. 12/919,667 (“Zawko”).
U.S. Patent and Trademark Office, Notice of Allowance mailed Nov. 7, 2013, in U.S. Appl. No. 12/919,667 (“Zawko”).
Specogna, Erika, et al., “Dehydration, Dissolution, and Melting of Cyclodextrin Crystals,” J. Phys. Chem. B 2015, 119, pp. 1433-1442.
Zhang, Lifeng, et al., “Ultrafine Cellulose Acetate Fibers with Nanoscale Structural Features,” J. Nanosci. Nanotechnol. 2008, vol. 8, No. 9, pp. 4461-4469.
Nie, Huarong, et al., “Effects of Chain Conformation and Entanglement on the Electrospinning of Pure Alginate,” Biomacromolecules 2008, 9, pp. 1362-1365.
Tilley, Richard, “Crystals and Crystal Structures,” John Wiley & Sons, Ltd, England, 2006, 29 pages.
Rowley, J.A. et al., “Alginate hydrogels as synthetic extracellular matrix materials,” Biomaterials, 1999, 20, 45-53.
International Search Report and Written Opinion for PCT/US2011/055461, dated Dec. 1, 2011, 10 pages.
Masters et al., “Designing scaffolds for valvular interstitial cells: Cell adhesion and function on naturally derived materials,” J. Biomed. Mater. Res., (2004), 71A: 172-180.
Miralles et al., “Sodium alginate sponges with or without sodium hyaluronate: In vitro engineering of cartilage,” J. Biomed. Mater. Res., (2001), vol. 57: 268-278.
Zawko, “Crystal templating dendritic pore networks and fibrillar microstructure into hydrogels,” Acta Biomaterialia, vol. 6, Issue 7, Jul. 2010, pp. 2415-2421.
Bekkers et al., “Targeted dendrotomy reveals active and passive contributions of the dendritic tree to synaptic integration and neuronal output,” Proc Natl Acad Sci USA, Jul. 3, 2007, vol. 104, No. 27, pp. 11447-11452.
Brisken et al., “Alveolar and lactogenic differentiation,” J Mammary Gland Biol Neoplasia, Oct. 2006; 11(3-4):239-48.
Chung et al., “Effects of auricular chondrocyte expansion on neocartilage formation in photocrosslinked hyaluronic acid networks,” Tissue Eng. Sep. 2006;12(9):2665-73.
Duffy et al, “Rapid Prototyping of Microfluidic Systems in Poly(dimethylsiloxane),” Anal. Chem. 1998, 70, 23, 4974-4984.
International Search Report and Written Opinion for PCT/US2009/035257, dated Oct. 12, 2009, 12 pages.
Khademhosseini et al, “Microscale technologies for tissue engineering and biology,” Proc Natl Acad Sci U S A., Feb. 21, 2006;vol. 103, No. 8, pp. 2480-2487.
King et al., “Biodegradable Microfluidics,” Advanced Materials, vol. 16, Issue 22, pp. 2007-2012.
Larina et al., “Ca2+ dynamics in salivary acinar cells: distinct morphology of the acinar lumen underlies near-synchronous global Ca2+ responses,” J Cell Sci., 2005, Sep. 2015;118(Pt 18):4131-9.
Baier Leach et al., “Photocrosslinked hyaluronic acid hydrogels: natural, biodegradable tissue engineering scaffolds,” Biotechnol Bioeng, Jun. 5, 2003; 82(5):578-89.
Ma et al. “Biodegradable Polymer Scaffolds with Well-Defined Interconnected Spherical Pore Network,” Tissue Engineering, vol. 7, No. 1, 2001, pp. 23-33.
Oaki et al., “Experimental Demonstration for the Morphological Evolution of Crystals Grown in Gel Media,” Crystal Growth & Design, 2003, vol. 3, No. 5, pp. 711-716.
Peppas et al. “Hydrogels in pharmaceutical formulations,” European Journal of Pharmaceutics and Biopharmaceutics, Jul. 2000; 50(1), pp. 27-46.
Shah et al., “Branching morphogenesis and kidney disease,” Development, Jul. 2004; 131(7), pp. 1449-1462.
Liu Tsang et al., “Fabrication of 3D hepatic tissues by additive photopatterning of cellular hydrogels,” FASEB Journal, Mar. 2007; 21(3), pp. 790-801.
Uludag et al., “Technology of mammalian cell encapsulation,” Advanced Drug Delivery Reviews, Aug. 20, 2000, 42(1-2), pp. 29-64.
Xu et al., “Biomimetric Mineralization,” Journal of Materials Chemistry, 2007, 17, pp. 415-449.
Yang et al., “The design of scaffolds for use in tissue engineering. Part II. Rapid prototyping techniques,” Tissue Engineering, Feb. 2002, vol. 8, No. 1, pp. 1-11.
Huang et al., “Artificial Vasculature: Rapid Fabrication of Bio-inspired 3D Microfluidic Vascular Networks,” Advanced Materials, Jul. 10, 2009, vol. 21, pp. 3567-3571.
Depierro et al., “Influence of Polymerization Conditions on Nanostructure and Properties of Polyacrylamide Hydrogels Templated from Lyotropic Liquid Crystals,” Chemical Materials, Oct. 18, 2006, vol. 18, No. 23, pp. 5609-5617.
Huang et al., “Rapid Fabrication and Characterization of 3-D Branched Microvascular Flow Networks,” Advanced Materials, Oct. 12-16, 2009, vol. 21, pp. 3567-3571.
Seidel et al, “Synthesis of polyHEMA hydrogels for using as biomaterials. Bulk and solution radical-initiated polymerization techniques,” Materials Research, 2000, vol. 3, No. 3, pp. 79-83.
U.S. Appl. No. 13/269,344, filed Oct. 7, 2011, entitled, “Anti-Adhesive Barrier Membrane Using Alginate and Hyaluronic Acid for Biomedical Applications,” by Sarah Mayes.
U.S. Appl. No. 13/269,366, filed Oct. 7, 2011, entitled “One-Step Processing of Hydrogels for Mechanically Robust and Chemically Desired Feature,” by Sarah Mayes.
Non-Final Office Action dated Jun. 25, 2013 from U.S. Appl. No. 13/269,344, filed Oct. 7, 2911, entitled “Anti-Adhesive Barrier Membrane Using Alginate and Hyaluronic Acid for Biomedical Applications,” by Sarah Mayes, (“Schmidt”)(pp. 7-8 describing how Schmidt includes a hydrogen having hyaluronic acid and cross-linked alginate).
“Halobarrier Gel by Anika”, Anika.com, downloaded Sep. 6, 2023, https://anika.com/medical/products/surgical-solutions/#:˜:text=Hyalobarrier%C2%AE%20Gel%20and%20Hyalobarrier,in%20the%20abdomino%2Dpelvic%20area.
“Supro Adhesion Barrier Gel”, ansermedical.com, downloaded Sep. 6, 2023, https://www.ansermedical.com/products/adhesion-barrier-supro-gel.
“An Absorbable Gel for Adhesion Prevention”, fziomed.com, downloaded Sep. 6, 2023, https://www.fziomed.com/products/peritoneal-surgery/.
Froelich et al. “Alginate-Based Materials Loaded with Nanoparticles in Wound Healing”, Pharmaceutics, April 223; 15 (4): 1142, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10143535/.
Bovone et al. “Engineering Hydrogel Adhesion for Biomedical Applications via Chemical Design of the Junction”, pubs.acs.org., ACS Biomater. Sci. Eng. 2021, 7, 9, 4048-4076, https://pubs.acs.org/doi/10.1021/acsbiomaterials.0c01677.
Andersen et al. “In Situ Gelation for Cell Immobilization and Culture in Alginate Foam Scaffolds”, ncbi.nlm.nih.gov., Tissue Eng Part A., Feb. 1, 2014; 20(3-4): 600-610, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3926177/.
Related Publications (1)
Number Date Country
20230383086 A1 Nov 2023 US
Provisional Applications (1)
Number Date Country
61031651 Feb 2008 US
Continuations (7)
Number Date Country
Parent 17231653 Apr 2021 US
Child 18361981 US
Parent 16597106 Oct 2019 US
Child 17231653 US
Parent 15890719 Feb 2018 US
Child 16597106 US
Parent 15135978 Apr 2016 US
Child 15890719 US
Parent 14277170 May 2014 US
Child 15135978 US
Parent 13909707 Jun 2013 US
Child 14277170 US
Parent 12919667 US
Child 13909707 US