WO2006059984A1 - Matériaux poreux modifiés et procédé de formation de ces matériaux - Google Patents

Matériaux poreux modifiés et procédé de formation de ces matériaux Download PDF

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WO2006059984A1
WO2006059984A1 PCT/US2004/040011 US2004040011W WO2006059984A1 WO 2006059984 A1 WO2006059984 A1 WO 2006059984A1 US 2004040011 W US2004040011 W US 2004040011W WO 2006059984 A1 WO2006059984 A1 WO 2006059984A1
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materials
acid
poly
coating
porous materials
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PCT/US2004/040011
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English (en)
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Peter X. Ma
Xiaohua Liu
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The Regents Of The University Of Michigan
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/26—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2201/00—Foams characterised by the foaming process
    • C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
    • C08J2201/046—Elimination of a polymeric phase
    • C08J2201/0462—Elimination of a polymeric phase using organic solvents
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2389/00—Characterised by the use of proteins; Derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers

Definitions

  • the present disclosure relates generally to porous materials, and more particularly to modified porous materials and method(s) of forming the same.
  • Porous materials are widely used in biomedical, industrial, and household applications.
  • porous materials In the biomedical field, porous materials have been used as scaffolds (templates) for tissue engineering/regeneration, wound dressings, drug release matrices, membranes for separations and filtration, sterile filters, artificial kidneys, absorbents, hemostatic devices, and the like.
  • porous materials In various industrial and household applications, porous materials have been used as insulating materials, packaging materials, impact absorbers, liquid or gas absorbents, membranes, filters and so forth.
  • porous materials may be useful in only certain limited environments.
  • porous polymer materials may be used as scaffolds for cell incorporation, proliferation and tissue regeneration in aqueous environments (such as in a tissue culture medium, in a bioreactor, or implanted inside a human or animal body).
  • a porous material made of a water-soluble polymer, natural macromolecule, or inorganic compound may work well in air, an organic solvent, or certain solutions; yet, it may not maintain its structure and function in an aqueous environment because it dissolves or seriously deforms in water or aqueous solutions.
  • Many porous metallic materials may also UMJ-171-A (UM-2930) 2 PATENT
  • Modifying porous materials having interconnected, complexly shaped three-dimensional surfaces.
  • the modification is accomplished by crosslinking the three-dimensional surfaces and/or by coating the three-dimensional surfaces with a layer of a predetermined material.
  • the porous materials are macro structures including at least one of nano-features, micro-features, and combinations thereof.
  • the modifying accomplishes changing surface properties of the porous materials, changing the three- dimensional surfaces, and/or rendering the porous materials substantially stable in a predetermined environment.
  • FIG. 1 is a SEM micrograph of a porous material formed from a 2% gelatin solution in water, dissolved at 5O 0 C and gelled at -76 0 C;
  • FIG. 2 is a SEM micrograph of a porous material formed from a 5% gelatin in 20/80 (v/v) acetone/water solvent mixture, dissolved at 5O 0 C and gelled at -76 0 C;
  • FIG. 3 is a SEM micrograph of a porous material formed from a 5% gelatin in 20/80 (v/v) dioxane/water solvent mixture, dissolved at 5O 0 C and gelled at -76 0 C;
  • FIG. 4 is a SEM micrograph of a porous material formed from a 2.5% gelatin in
  • FIG. 5 is a SEM micrograph of a porous material formed from a 5% gelatin in 20/80 (v/v) methanol/water solvent mixture, dissolved at 5O 0 C and gelled at -76 0 C; UMJ-171-A (UM-2930) 3 PATENT
  • FIG. 6A is a SEM micrograph of macro-porous and nano-fibrous gelatin scaffolds prepared from a 50/50 ethanol/water solvent mixture and paraffin spheres at 50X magnification;
  • FIG. 6B is a SEM micrograph of macro-porous and nano-fibrous gelatin scaffolds prepared from a 50/50 ethanol/water solvent mixture and paraffin spheres at IOOOX magnification;
  • FIG. 6C is a SEM micrograph of macro-porous and nano-fibrous gelatin scaffolds prepared from a 50/50 ethanol/water solvent mixture and paraffin spheres at IOOOX magnification
  • FIG. 6D is a SEM micrograph of macro-porous and nano-fibrous gelatin scaffolds prepared from a 50/50 ethanol/water solvent mixture and paraffin spheres at 20,00OX magnification;
  • FIG. 9 is a chart showing compressive modulus of solid-walled and nano-fibrous gelatin foams prepared with different gelatin concentrations; UMJ-171-A (UM-2930) 4 PATENT
  • FIG. 10 is a chart showing compressive modulus of macro-porous solid- walled and nano-fibrous gelatin scaffolds prepared with different gelatin concentrations
  • FIG. 1 IA is a SEM micrograph showing the surface morphology of nano-fibrous gelatin scaffolds
  • FIG. 1 IB is a SEM micrograph showing the surface morphology of the nano- fibrous gelatin scaffolds of Fig. 1 IA after crosslinking and immersion in water for 24 hours;
  • FIG. 12 is a schematic illustration of the pore structure.
  • porous materials having interconnected, complexly shaped three-dimensional surfaces may be advantageously modified so as to stabilize the porous materials in a predetermined environment, to modify the surfaces thereof, to change the surface (physical) properties, and/or to change the biological properties.
  • the complexly shaped surfaces may be any suitable shape, as long as the pores are interconnected.
  • Some suitable non-limitative examples of 3-D pores forming the surfaces include spherical, cubical, square, channels (any shape, such as cylindrical channels, for example), and any other suitable geometries, including regular and/or non-regular.
  • the porous materials may be modified/stabilized by crosslinking the three- dimensional surfaces and/or by coating the three-dimensional surfaces with a layer of a predetermined material. Further, if a coating is used, the coating may optionally be crosslinked, if desired for a particular end use. It is to be understood that the crosslinking may be achieved via covalent bond formation and/or ionic bond formation.
  • the porous materials are macro structures including nano- features, micro-features, and/or combinations thereof. It is to be understood that, as defined herein, nano-features are intended to include features ranging in size between about 10 "10 meters and about 10 "6 meters; and micro-features are intended to include features ranging in size between about 10 "6 meters and about 10 "3 meters. UMJ-171-A (UM-2930) 5 PATENT
  • the modifying/stabilizing may be accomplished by crosslinking. Further, it is to be understood that the crosslinking density may be varied in a manner sufficient to achieve predetermined physical and/or biological properties.
  • Some non-limitative examples of physical properties include, but are not limited to mechanical properties, swelling properties, and/or surface properties (e.g. hydrophilicity/hydrophobicity).
  • a non-limitative example of a biological property is cell interaction with the porous materials.
  • each individual coating layer may range in thickness between about 10 ⁇ 10 meters and about 10 ⁇ 3 meters. In an embodiment, each coating layer may range in thickness between about 10 "9 meters and about 10 ⁇ 6 meters.
  • the porous materials in any of the embodiments disclosed herein may be formed from at least one of synthetic macromolecules; natural macromolecules; substantially non-macromolecular materials; natural macromolecule-containing materials; synthetic macromolecule-containing materials; oligomeric materials; fragments of macromolecules; macromolecule-containing composites; and mixtures thereof.
  • macromolecule is intended to include large molecules without repeating units, polymeric materials (i.e. large molecules with repeating units), co-polymers, and combinations thereof.
  • various non-limitative examples of some specific macromolecules, polymers, and monomers useful for forming polymers are given hereinbelow.
  • the natural macromolecules are proteins, carbohydrates, lipids, derivatives thereof, denatured forms thereof, modified forms thereof, fragments thereof, and/or mixtures thereof.
  • Some non-limitative examples of derivatives, modified forms and/or denatured forms include gelatin (a denatured protein that is a derivative of collagen).
  • suitable cell interactive materials which may be used as the porous materials and/or as coating materials include, but are not limited to f ⁇ bronectin; vitronectin, other members of the pexin family, laminin, hyaluronate, chitosan, alginates, polypeptides, peptides (for example, RGD peptides), and/or the like.
  • macromolecule-containing composites have macromolecules as a major component thereof.
  • Other components may include ceramic materials, metal materials, small molecules, inert additives, active additives, and/or mixtures thereof.
  • additives include pigments, surfactants, adhesion enhancers, predetermined ingredient-releasing enhancers, bioactive agents (for example, growth factors and hormones).
  • the substantially non-macromolecular materials may be ceramic materials, metallic materials, and/or mixtures thereof. It is to be understood that the ceramic materials in the composites and/or in the non-macromolecular materials may be any suitable ceramic materials. Some non-limitative examples of suitable ceramic materials include alpha- or beta- TCP (tri calcium phosphate), hydroxyapatite (HAP); carbonated HAP; bioglasses; oxides, and/or combinations thereof.
  • suitable ceramic materials include alpha- or beta- TCP (tri calcium phosphate), hydroxyapatite (HAP); carbonated HAP; bioglasses; oxides, and/or combinations thereof.
  • metal materials in the composites and/or in the non-macromolecular materials may be any suitable metal materials.
  • suitable metal materials include stainless steel, titanium, base alloys such as chromium alloys, cobalt alloys, titanium alloys, gold, noble alloys, and/or the like, and/or mixtures thereof.
  • the coating may be accomplished by any suitable means, including but not limited to mechanical application, thermal application, adhering, self-assembling, molecular entrapment, chemical bonding, and/or combinations thereof. Non-limitative methods of coating are discussed further hereinbelow. Further, it is to be understood that when a coating is used, the coating may be formed from the same, a similar, or different material from that of the porous materials.
  • porous materials may be made of synthetic polymers, natural macromolecules, inorganic compounds, ceramic or metallic materials. These porous materials can be made using many different fabrication technologies, including sintering, stretching, extrusion, self-assembly, phase inversion, phase separation, porogen-leaching, gas-foaming, etching, casting, and solid free form fabrication techniques (computer-assisted design and computer-assisted manufacture, i.e., CAD- CAM. See, for example, the inventor's recent publications in this regard: Ma, P. X. (2004), “Scaffolds for tissue fabrication," Materials Today 7, 30-40; and Ma, P. X. (2004), “Tissue Engineering,” In Encyclopedia of Polymer Science and Technology, Kroschwitz, J.I., ed. (Hoboken, NJ, John Wiley & Sons, Inc.)
  • the porous materials may also be formed from biodegradable materials suitable for tissue regeneration.
  • biodegradable materials include poly(L-lactic acid) (PLLA), polyglycolic acid (PGA), poly ⁇ actide-co-glycolide) (PLGA), and/or mixtures thereof. It is to be understood that the coating may be formed of any suitable material
  • the coating is formed from gelatin, vitronectin, fibronectin, laminin, peptides, polypeptides, chitosan, hyaluronate, alginates, and/or mixtures thereof.
  • the present disclosure concerns fabrication and methods of stabilizing/modifying nano- (size scale 10 '9 -10 "6 m) and/or micro- (size scale 10 "6 -10 "3 m) structures, as well as the macro-structures (>10 "3 m) of porous materials.
  • interconnected complex shaped 3D surfaces of the porous materials are crosslinked via chemical (either covalent or ionic) bond formation, or are coated with a very thin layer(s) of a material(s) that is stable in the service environment to maintain the nano-/micro-features as well as the macro-structure.
  • the crosslinking density may also be tailored to achieve desired mechanical, swelling and/or other physical properties. At least two different embodiments are disclosed to achieve the stabilization/modification of such complex 3D surfaces.
  • One embodiment is to "directly" crosslink the surfaces of a porous material, for example, if it is made of a synthetic polymer (including polymers of multiple types of monomers), a mixture of polymers, a polymer-containing composite, i.e., at least one of the components of the porous material is a polymer; a natural macromolecule (such as proteins, carbohydrates, lipids, their derivatives including denatured forms, modified forms, fragments, and any combinations of them), a mixture of macromolecules, and/or a macromolecule-containing composite, i.e., at least one of the components of the porous material is a naturally derived macromolecule.
  • a second embodiment is to coat the 3D complex-shaped surfaces of the interconnected porous materials with a composition containing at least one polymer or macromolecule if the coating itself is substantially stable under the service environment. If the coating itself is not substantially stable under the service environment, the coating composition may then be crosslinked (termed "indirect” crosslinking).
  • the initial porous materials may be polymer/macromolecule-free (such as a ceramic or metallic structures), polymer/macromolecule-containing, substantially polymeric/macromolecular, or entirely polymeric/macromolecular materials.
  • the polymer/macromolecule may actually be a smaller molecule than a normal polymer or macromolecule, such as an oligomer or a fragment of a natural macromolecule.
  • the polymer can actually be synthesized in situ using monomers and other chemicals such as initiators and/or solvents, etc.
  • coatings When coatings are used, they may be mechanically or thermally applied, physically adhered (via van der Waals, hydrogen-bond, and electrostatic interactions; mechanically entangled or restricted), self-assembled, molecularly entrapped (interpenetrated), and/or chemically bonded to the complex-shaped 3D surfaces of the porous materials.
  • the coating formulation generally does not substantially dissolve or seriously deform the porous materials in an undesired way.
  • porous gelatin materials having nano-fibrous structure, or nano-fibrous structure with micro- to UMJ-171-A (UM-2930) 9 PATENT
  • PLLA nano-fibrous materials with or without designed micro- or/and macro-pores were used. These porous PLLA materials are coated with a composition (e.g., gelatin) different from the porous material (PLLA). If the coating itself is not stable under the service environment, the coating material is then crosslinked.
  • a composition e.g., gelatin
  • coated materials can protect the base materials from destruction or deformation under certain environments (e.g., in an organic solvent for PLLA).
  • these coating materials themselves or incorporated additives could have certain other functions (such as physical or biological functions, including improving cellular interactions and releasing drugs or biological factors).
  • the polymers and macromolecules that may be used as the porous materials and/or coating materials in accordance with the present disclosure are numerous.
  • Some exemplary, non-limitative water insoluble (hydrophobic) polymers/rnacromolecules that are suitable for the porous materials and/or for coating on hydrophilic porous materials include at least one of polytetrafluoroethylene (PTFE), polyvinylchloride (PVC), polyethylenes (PE), polypropylenes (PP), polystyrenes, polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), polyvinylacetate (PVAc), polyphenylene oxide, polypropylene oxide (PPO), polyvinylidene fluoride (PVDF), polybutylene, polyamides (PA, Nylons), polyesters, polycarbonates, polyurefhanes, polysiloxanes, polyimides, polyetheretherketone (PEEK), polysulfones, polyethersulphone, cellulose and its derivatives, and mixtures thereof.
  • PTFE polytetrafluoroethylene
  • PVC polyvinylchloride
  • PE
  • some exemplary suitable hydrophobic unsaturated monomers include, but are not limited to the following: at least one of acrylates, methacrylates (eg. methyl methacrylate), ethylene, propylene, tetra- UMJ-171-A (UM-2930) 10 PATENT
  • Monomers of condensation polymers can also be used to form porous materials and/or coatings in situ.
  • Some non-limitative monomer types in this category are diacids and diols (pairs), ⁇ -hydroxy carboxylic acids, lactones, diacids and diamines (pairs), amino acids, lactams, diisocyanates and diols (pairs), and mixtures thereof.
  • biodegradable polymers and macromolecules may also be used as the porous materials and/or coatings, for example, when controlled release properties are desired.
  • Some exemplary, non-limitative biodegradable polymers include at least one of poly(lactide-co-glycolide) (PLGA), poly(L-lactic acid) (PLLA), poly(D,L-lactic acid) (PDLLA), polyglycolic acid (PGA), polyanhydrides, poly(ortho ethers), poly( ⁇ - caprolactone) (PCL), poly(hydroxy butyrate) (PHB) , poly(propylene fumarate) (PPF), polyphosphoesters (PPE), polyphosphazenes, and mixtures thereof.
  • Further suitable non-limitative examples include degradable natural macromolecules (typically enzymatically degradable) such as collagen, gelatin, and many other proteins, carbohydrates, and their derivatives.
  • Some exemplary, non-limitative water-soluble (hydrophilic) polymers/macromolecules that are suitable for the porous materials and/or for coating on hydrophobic porous materials include polyvinyl alcohol, polyethylene oxide UMJ-171-A (UM-2930) 11 PATENT
  • polyethylene glycol polymethacrylic acid (PMAA), polyvinyl pyrolidone, polyacrylic acid, poly(lysine), poly(allylamine), poly(ethylenimine), poly(acrylamide), poly(acrylamide-co-arylic acid), poly(acrylamide-co-diallyldimethylammonium chloride), poly(vinyl alcohol), poly(ethylene glycol), polyethylene-block-poly(ethylene glycol), poly(propylene glycol), poly(2-hydroxypropyl methacrylate), poly(2- hydroxyethyl methyacrylate), poly(4-hydroxystrene), polyethylene monoalcohol, poly(vinyl alcohol-co-ethylene), poly(styrene-co-allyl alcohol), hydroxyethylcellulose, alginate, pectin, chitin, chitosan, dextran, hyaluronic acid, collagen, gelatin, and mixtures thereof.
  • PMAA polymethacrylic acid
  • suitable acid- containing hydrophilic monomers include at least one of monomers containing carboxylic acid: acrylic acid, methacrylic acid, 4-vinylbenzoic acid, crotonic acid, oleic acid, elaidic acid, itaconic acid, maleic acid, fumaric acid, acetylenedicarboxylic acid, tricarbollylic acid, sorbic acid, linoleic acid, linolenic acid, eicosapentenoic acid, other unsaturated carboxylic acids, anhydrides, their derivatives, and/or mixtures thereof; and/or other organic acids such as sulfonic acid, and/or phosphonic acid replacement of the carboxyl group of the above listed unsaturated carboxylic acids, their derivatives, and/or mixtures thereof.
  • suitable amine-containing hydrophilic monomers include at least one of allylmine, 4-vinylaniline, L-lysine, D-lysine, DL-lysine, acrylamide, derivatives thereof, and mixtures thereof.
  • suitable hydroxyl-containing hydrophilic monomers include, but are not limited to 2-hydroxypropyl methacrylate, 2- hydroxyethyl methyacrylate, 4-hydroxystrene, ethylene glycol, propylene glycol, derivatives thereof, and/or mixtures thereof.
  • Poly(ethylene glycol) acrylate, poly(ethylene glycol) methacrylate, and/or mixtures thereof may also be used to form porous materials and/or coatings.
  • Non-limitative examples of these materials include those containing acid, amine, hydroxyl, or/and other hydrophilic groups in some and/or all of their structural units. Many of them may be copolymers in some way, containing both hydrophilic and hydrophobic moieties.
  • crosslinking agent(s) include, but are not limited to ethyl-3-(3-dimethylaminopropyl) carbodiimide HCl (EDC), dialdehydes (e.g.
  • glutaraldehyde ethylene glycol dimethacrylate, N,N-niethylenebisacrylamide, 1,6- hexamethylenediisocyanate, divinylsulfone, 1,6-hexanedibromide, PEG diacrylate, PEG dimethacrylate, dextramethacrylate, and/or mixtures thereof.
  • Gelatin was dissolved in ethanol/water (or water, methanol/water, dioxane/water, acetone/water) solvent mixtures to form gelatin solutions of different concentrations (from 2% (m/v) to 20% (m/v)).
  • the stock gelatin solution was stored in a water bath to maintain at a desired temperature (4O 0 C to 8O 0 C).
  • 2 mL gelatin solution was added to a Teflon vial (cylindrical in shape with a diameter of 18 mm) and capped.
  • the Teflon vial with gelatin solution was quickly transferred to a freezer at -76 0 C, -18 0 C, 4 0 C, or left at room temperature.
  • the gelatin solution was maintained at the desired temperature (gel formation) for at least 4 hours.
  • the gelatin gels were soaked in 50 mL cold ethanol UMJ-171-A (UM-2930) 13 PATENT
  • Macro/micro-porous and nano-fibrous gelatin materials were fabricated by combining particulate-leaching and phase-separation techniques. Paraffin spheres were prepared as reported at Ma, P.X. and Choi J. "Biodegradable polymer scaffolds with well-defined interconnected spherical pore network,” Tissue Engineering 7(1): 23-33 (2001), the disclosure of which is incorporated herein by reference in its entirety.
  • paraffin spheres of selected size were added to Teflon molds (cylindrical vials with a diameter of 18 mm), and the top surface was leveled. The molds were then preheated at 37 0 C for 20, 40, 80, or 200 minutes to ensure that paraffin spheres were substantially adhered to each other.
  • the gelatin/paraffin composite was then soaked in 50 mL cold ethanol (-18 0 C) for 24 h.
  • the composite was then transferred into 50 mL 1,4-dioxane for solvent exchange for 24 h with fresh 1,4-dioxane replaced every 8 h.
  • the composite was then kept in a freezer at -18 0 C for 12 h to be completely frozen.
  • the frozen composite was freeze-dried in an ice/salt bath for 4 days followed by vacuum drying at room temperature for 3 days.
  • the gelatin/paraffin composite was cut into discs with 2.0 mm thickness. The composite was soaked in 50 mL hexane to leach out paraffin spheres. Hexane was UMJ-171-A (UM-2930) 14 PATENT
  • the process of dissolving paraffin may be carried out in an oven at 37 0 C.
  • Cyclohexane was used for solvent exchange.
  • the gelatin scaffold was frozen at -18 0 C for 12 hours and freeze-dried at between -1O 0 C and -5 0 C in an ice/salt bath for 4 days followed by vacuum drying at room temperature for 3 days.
  • Solid- walled gelatin scaffolds were also prepared by using a similar procedure except that the gelatin/paraffin composite was air-dried and no solvent extraction was applied.
  • Example 3 Chemical crosslinking of 3D nano-fibrous and macroporous gelatin matrices
  • Chemical crosslinking of 3D gelatin scaffold using l-ethyl-3-(3- dimethylaminopropyl) carbodiimide HCl (EDC) and N-hydroxy-succinirnide (NHS) was carried out in ⁇ 2-[N-mo ⁇ holino]ethanesulfonic acid ⁇ hydrate (MES) buffer (pH 5.3, 0.05 M) at 4oC for 24 h.
  • MES N-mo ⁇ holino]ethanesulfonic acid ⁇ hydrate
  • the scaffolds were then washed with distilled water at 37 0 C three times and were frozen at— 18 0 C for at least 12 h.
  • the chemically crosslmked scaffolds were freeze-dried for 4 days and vacuum dried at room temperature for 3 days.
  • the dried gelatin foam was then stored in a desiccator for later use.
  • Example 4 Surface coating of nano-fibrous PLLA scaffolds using a self-assembly process
  • PLLA scaffolds were first wetted in ethanol solution for 2 h and rinsed to remove possible surface contaminants. A series of water/ethanol solvent mixtures (30/70, 50/50, 70/30, 80/20, 90/10, and 100/0) were used for solvent exchange.
  • PLLA scaffolds were then soaked in Milli-Q water ( ⁇ > 18.2 M ⁇ -cm) for 2 days before self-assembly process began.
  • PDAC poly(diallyldimethylammonium chloride)
  • the PDAC/gelatin was fixed by crosslinking gelatin with EDC and NHS in MES buffer at 4 0 C for 24 h. After being rinsed with water at 37 0 C for 60 min, the scaffold surfaces were blotted with filtered paper and then transferred into a freezer set to -18 0 C and kept for 4 h. The surface-modified scaffolds were then freeze-dried for 5 days.
  • Example 5 Surface coating of nano-fibrous PLLA scaffolds using an entrapment process PLLA scaffolds were first soaked in ethanol for 2 h, and then washed with double distilled water. Gelatin was dissolved in dioxane/water solvent mixture at 45 0 C.
  • the pretreated PLLA scaffolds were immersed in the solution and soaked for a designated time, and then moved out and quickly put into 200 mL ice-water mixture for 10 min.
  • Chemical crosslinking of gelatin with EDC and NHS was carried out in MES buffer at 4 0 C for 24 h.
  • the scaffolds were then washed with distilled water at 4 0 C for 3 times, followed by rinsing in water at 4O 0 C for 12 h (water was changed every 3 h) to ensure the removal of un-entrapped gelatins.
  • the surface-modified scaffolds were freeze-dried for 3 days, and then vacuum dried at room temperature for 2 more days.
  • the morphology of the scaffolds was observed using SEM (Philips XL30 FEG).
  • the scaffolds were coated with gold using a sputter coater (DeskII, Denton vacuum Inc). During the process of gold coating, the gas pressure was kept at 50 mtorr, and the current was 40 mA. The coating time was 200 s. Samples were analyzed at 10 kV. Example 7. Mechanical Testing
  • the compressive moduli of PLLA scaffolds were measured using an MTS Synergie 200 mechanical tester (MTS Systems Corporation, Eden Prairie, MN). For compressive testing, the specimens were circular discs about 17mm in diameter and 3.0mm in thickness. The crosshead speed was 0.5 mm/min and the compressive modulus was defined as the initial linear modulus. Six specimens were tested for each sample. The averages and standard deviations were graphed. To compare mechanical properties, a two-tailed Student's t-test (assuming equal variances) was performed to determine the statistical significance (p ⁇ 0.05).
  • Example 8 Surface area measurement
  • the surface area of nano-fibrous gelatin scaffold was measured using a BELSORP-mini gas adsorption instrument (BEL Japan, Inc.). At least 0.1 g sample was used for each measurement, and BET method was used for calculation.
  • Dp is the overall density of gelatin foam
  • DQ is the density of gelatin. Dp was determined by:
  • ⁇ W/Wo
  • W was the actual weight of gelatin foam in solution
  • Wo was the original dry weight.
  • the surface of samples was blotted with filter paper when the samples were taken out from solution.
  • ⁇ e the scaffold samples were soaked in the solution for 2 h before measurement. All data were presented as means + standard deviation (SD). To test the significance of observed differences between the study groups, an unpaired Student's t-test was applied. A value of p ⁇ 0.05 was considered to be statistically significant.
  • Gelatin was dissolved in double distilled water to form different concentrations of gelatin solutions (e.g. 2% or 5% (g/mL)).
  • the gelatin solution temperature was balanced at 5O 0 C in a water bath.
  • 2 niL gelatin solution was added to a Teflon vial and capped.
  • the Teflon vial with gelatin solution was quickly transferred to a freezer at - 76 0 C (or -18 0 C).
  • the gelation of gelatin solution occurred and the gel was kept at the temperature for at least 2 hours.
  • the frozen gelatin gel was freezing-dried at ice-salt bath at -5 0 C to -10 0 C for one week.
  • Porous gelatin foam was created with a pore size ranging from 50 ⁇ m to 500 ⁇ m. Decreasing gelation temperature led to the decrease of average pore size. Most of pores were irregular closed pores. The surface of pore wall was smooth with no specific microstructure observed ( Figure 1). UMJ-171-A (UM-2930) 18 PATENT
  • the procedure was similar to that for preparing gelatin foams with water except that acetone/water solvent mixture was utilized instead of water.
  • the acetone/water mixture composition ranges from 5/95 to 30/70 (v/v).
  • Gelatin foams were created with pore size ranging from 10 ⁇ m to 50 ⁇ m. Thick pore walls (10 ⁇ m to 50 ⁇ m) and uneven pore distribution were observed. Most of pores were round close pores. The surface of pore wall was smooth with no special microstructures ( Figure 2).
  • Example 13 Gelatin in Dioxane/Water Mixture The procedure was similar to that of preparing gelatin foams with water except that dioxane/water solvent mixture was utilized instead of water.
  • the dioxane/water mixture composition ranges from 5/95 to 40/60 (v/v).
  • Gelatin foams were created with pore size ranging from 50 ⁇ m to 500 ⁇ m.
  • Gelatin was dissolved in ethanol/water solvent mixture to form different concentrations of gelatin solutions (from 2% (m/v) to 20% (m/v)).
  • the gelatin solution temperature was balanced in a water bath (temperature ranges from 4O 0 C to 8O 0 C).
  • 2 mL gelatin solution was added to a Teflon vial and capped.
  • the Teflon vial with gelatin solution was quickly transferred to a freezer at -76 0 C, -18 0 C, 4 0 C, or left at room temperature.
  • the gelatin solution was maintained at the desired temperature (gel formation) for at least 4 hours.
  • the gelatin gels were soaked in 50 mL cold ethanol (- 18 0 C) for 24h. The gels were then transferred into 50 mL dioxane for solvent exchange.
  • Dioxane on the surface of the gelatin gel was wiped with blotting paper and the gel was frozen at -18 0 C for at least 12 h.
  • the gel was freeze-dried in an ice/salt bath at -5 0 C to
  • Nano-f ⁇ brous gelatin microstructure was created with fiber diameters ranging from 50 nm to 500 nm. No macropores (>10 um) were observed inside the gelatin foam (Figure 4).
  • Example 15 Gelatin in Methanol/Water Mixture The procedure was similar to that for preparing gelatin foams with ethanol/water except that methanol was utilized instead of ethanol.
  • the methanol/water mixture composition ranges from 20/80 to 50/50 (v/v).
  • Nano-f ⁇ brous microstructure was obtained with the methanol/water solvent mixture composition ranging from 20/80 (v/v) to 50/50 (v/v).
  • Lower gelation temperature leads to more typical nano-fibrous structure, while only agglomerates were observed in foams prepared at room temperature.
  • the increase of gelatin solution concentration led to increase of network density of the gel.
  • No macropores (>10 um) were observed inside the gelatin foam (Figure 5).
  • Example 17 Macroporous and nano-fibrous gelatin materials Nano-fibrous gelatin scaffolds with designed macropores were fabricated by combining particulate-leaching technique and phase-separation techniques (see Example 2).
  • the matrices have very high porosity (Table 1). The porosity decreased with increasing gelatin concentration.
  • Porosity as high as 98% was obtained when gelatin concentration was 5%.
  • the fiber diameter ranged from 50 nm to 500 nm. The average fiber diameter did not statistically change with gelatin concentration. It is also worth noticing that the fiber diameter of the scaffolds became more uniform as the gelatin solution increased.
  • Example 18 Varying macropore size and inter-pore connectivity of nano-fibrous gelatin materials Using different paraffin sphere size, one can obtain gelatin scaffolds with different macropore sizes (Figure 7). The interconnectivity between the pores of the gelatin scaffold was controlled by varying the heat treatment time of paraffin spheres ( Figure 8). The longer time of heat treatment, the larger bonding areas between the spheres, and therefore higher interconnectivities between the macropores.
  • Macro-porous and nano-fibrous gelatin scaffolds (7.5%, 250-420 ⁇ m paraffin spheres) had a surface area of 32.02 (m 2 /g) as measured using method described earlier (Example 8).
  • V D 3 — ⁇ D 3 (2)
  • nano-fibrous scaffold was more than 3 orders of magnitude higher than that of solid-walled scaffold.
  • Example 20 Mechanic properties of Relatin foams
  • the compression modulus of solid- walled gelatin foam was higher than that of nano-fibrous gelatin foam at the concentration of 5.0%.
  • the modulus of nano- fibrous gelatin foam increased much faster than that of solid- walled gelatin foam as gelatin concentration increased, and the compression modulus of nano-fibrous gelatin foam was significantly higher than that of solid- walled gel foam as the concentration increased to 10.0% or above ( Figure 9).
  • the PLLA scaffolds dissolve in CH 2 Cl 2 , CHCl 3 and Dioxane before their surfaces were coated with gelatin. After the surface was coated with gelatin, the PLLA scaffold could maintain its original size in the above solvents (Table 3).
  • Nano-fibrous gelatin without crosslinking swelled enormously (Table 2) and lost the nano-fibrous feature upon immersion in water, while crosslinked nano-fibrous microstructure maintained its size and nano-fibrous structure (Table 2 and Figure 11).
  • VfVo Volume ratio

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Abstract

La présente invention décrit des matériaux poreux modifiés ayant des surfaces tridimensionnelles interconnectées mises en forme de façon complexe. La transformation est réalisée par réticulation des surfaces tridimensionnelles et/ou par enrobage des surfaces tridimensionnelles avec une couche d’une substance prédéterminée. Les matériaux poreux sont des macro-structures incluant au moins une caractéristique parmi les nano-caractéristiques, les micro-caractéristiques, et les combinaisons de celles-ci. La transformation opère un changement des propriétés de surface des matériaux poreux, une modification des surfaces tridimensionnelles et/ou rend les matériaux poreux pratiquement stables dans un environnement prédéterminé.
PCT/US2004/040011 2004-11-30 2004-11-30 Matériaux poreux modifiés et procédé de formation de ces matériaux WO2006059984A1 (fr)

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007053955A1 (fr) * 2005-11-14 2007-05-18 Corporation De L'ecole Polytechnique De Montreal Reseaux de nanogaines poreux, procede de production et utilisations
DE102006033168A1 (de) * 2006-07-10 2008-01-17 Gelita Ag Verwendung von Gelatine und einem Vernetzungsmittel zur Herstellung einer vernetzenden therapeutischen Zusammensetzung
EP1885779A1 (fr) * 2005-05-27 2008-02-13 Fujifilm Corporation Procede de fabrication d'une construction auto-assemblee
US8197924B2 (en) 2010-10-05 2012-06-12 Ford Global Technologies, Llc Compostable interior panel for use in a vehicle and method of manufacture
CN105063092A (zh) * 2015-09-02 2015-11-18 常州市长宇实用气体有限公司 一种固定化酶制备紫草天然染料的方法
US9295751B2 (en) 2006-07-10 2016-03-29 Gelita Ag Use of gelatin and a cross-linking agent for producing cross-linking medical glues
JP2017006028A (ja) * 2015-06-18 2017-01-12 株式会社ジーシー 細胞工学用支持体、及び細胞工学用支持体の製造方法
CN110227178A (zh) * 2019-07-30 2019-09-13 广东工业大学 一种生物陶瓷支架及其应用

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JPH02182259A (ja) * 1989-01-06 1990-07-16 Ube Ind Ltd 止血用絆創膏

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Publication number Priority date Publication date Assignee Title
JPH02182259A (ja) * 1989-01-06 1990-07-16 Ube Ind Ltd 止血用絆創膏

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1885779A1 (fr) * 2005-05-27 2008-02-13 Fujifilm Corporation Procede de fabrication d'une construction auto-assemblee
EP1885779A4 (fr) * 2005-05-27 2009-05-06 Fujifilm Corp Procede de fabrication d'une construction auto-assemblee
WO2007053955A1 (fr) * 2005-11-14 2007-05-18 Corporation De L'ecole Polytechnique De Montreal Reseaux de nanogaines poreux, procede de production et utilisations
US8257624B2 (en) 2005-11-14 2012-09-04 Favis Basil D Porous nanosheath networks, method of making and uses thereof
DE102006033168A1 (de) * 2006-07-10 2008-01-17 Gelita Ag Verwendung von Gelatine und einem Vernetzungsmittel zur Herstellung einer vernetzenden therapeutischen Zusammensetzung
US8637081B2 (en) 2006-07-10 2014-01-28 Tetec Tissue Engineering Technologies Ag Use of gelatin and a cross-linking agent for producing a cross-linking therapeutic composition
US9295751B2 (en) 2006-07-10 2016-03-29 Gelita Ag Use of gelatin and a cross-linking agent for producing cross-linking medical glues
US9744218B2 (en) 2006-07-10 2017-08-29 Tetec Tissue Engineerging Technologies Ag Multi-chamber applicator for gelatin solution
US8197924B2 (en) 2010-10-05 2012-06-12 Ford Global Technologies, Llc Compostable interior panel for use in a vehicle and method of manufacture
JP2017006028A (ja) * 2015-06-18 2017-01-12 株式会社ジーシー 細胞工学用支持体、及び細胞工学用支持体の製造方法
CN105063092A (zh) * 2015-09-02 2015-11-18 常州市长宇实用气体有限公司 一种固定化酶制备紫草天然染料的方法
CN110227178A (zh) * 2019-07-30 2019-09-13 广东工业大学 一种生物陶瓷支架及其应用

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