Chitosan materials from carbonic acid solution
Inventors
McCarthy, Simon • McGrath, Barbara • KUHN, Sam • Kimball, Jess • Stolten, Michael • Bennett, Amanda
Assignees
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Publication Number
US-10632143-B2
Publication Date
2020-04-28
Expiration Date
Abstract
The present invention comprises chitosan materials and methods of using carbonic acid for aqueous solubilization of neutralized or pre-treated chitosan gels and provides, among other things, substantially acid salt free composition native final forms without requiring subsequent acid salt elution. The invention includes chitosan-based solid and semi-solid material forms, optionally reinforced with chitosan fibers, such as powders, fibers, films, matrices, sponges, implants, scaffolds, fillers, and hydrogels. Native final forms are produced from chitosan powder solubilized in an aqueous acidic solution, processed to form a high pH hydrated chitosan gel precipitate material that is then neutralized by water washing and re-solubilized substantially to chitosan solution using carbonic acid. Chitosan materials can be mixed in solution with one or more of other hydrophilic polymers to create compositional heterogeneity and pharmaceutical agents to achieve controlled release of the agent(s) from the final forms at the site of application.
Core Innovation
The invention relates to producing native solid or semi-solid chitosan final forms substantially free of acid salts. It addresses the need to avoid residual acid salts that would otherwise be present when chitosan is processed and then formed into solid or semi-solid materials.
The described approach uses aqueous solubilization and re-solubilization rather than acid-salt elution. A hydrated chitosan gel precipitate is neutralized and pre-conditioned, and then the washed gel precipitate is re-solubilized directly into a carbonic acid solution.
The resulting chitosan compositions are characterized as acid salt free and include defined solid or semi-solid final forms such as powder, fiber, matrix, sponge, implant, filler, and molded hydrogel. The document further states that dried or hydrated structures formed from the carbonic-acid route do not re-dissolve in the original carbonic-acid solvent.
Claims Coverage
The provided claim set includes two independent claims. Across these, there are about three central inventive content elements: a substantially acid salt-free chitosan solubilized gel material, exclusion of gelatin, and selection of specified solid/semi-solid native final forms.
Substantially acid salt free chitosan solubilized gel material
A solid or semi-solid native final form composition comprising a substantially acid salt free chitosan solubilized gel material.
Exclusion of gelatin
The solid or semi-solid composition does not include gelatin.
Specified native solid or semi-solid forms
The composition is selected from one of a powder, fiber, matrix, sponge, implant, filler, and molded hydrogel.
Water content range for the composition
The composition has water in an amount between about 70% (w/w) and about 10% (w/w).
Incapacity of repeated solubilization in carbonic acid over a pH range
The composition is incapable of repeated solubilization in a carbonic acid aqueous solution having a pH between about 3.4 to about 7.0.
Non-inclusion of gelatin with selected forms
A solid or semi-solid composition comprising a substantially acid salt free chitosan solubilized gel material, wherein the composition does not include gelatin and is selected from one of a powder, fiber, sponge, implant, and molded hydrogel.
The independent claims are directed to acid-salt-free chitosan solubilized gel compositions that exclude gelatin and are provided in specified native solid/semi-solid forms. The claim set further emphasizes composition definition through water content and, in dependent refinements, solubilization resistance in carbonic acid within a defined pH range.
Stated Advantages
Improved biocompatibility by avoiding residual acid salts.
Reduced adherence to wet tissue.
Ability to remain intact on wet surfaces for 4–7 days without significant change.
High water absorbency (about 1000% w/w; with stated ranges including about 1200–1600% w/w).
Easy removal intact.
Controlled release as supported by described examples and elution/conductivity studies.
Documented Applications
Wound treatment, including use of the compositions on wounds or wet tissue surfaces for four to seven days.
Regenerative medicine use as described in connection with the chitosan materials.
Drug delivery vehicles, including compositions configured for controlled release of pharmaceutical active agents.
Controlled release examples using poly(diallyl dimethyl ammonium chloride) and chitosan-arginine, including evaluation involving gamma irradiation in relation to elution/conductivity and shelf-life expectations.
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