Submitted to: Textile Research Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2012
Publication Date: 1/1/2013
Citation: Cardamone, J.M. 2013. Keratin sponge/hydrogel II, active agent delivery. Textile Research Journal. 83(9):917-927.
Interpretive Summary: Wool as a pure source of keratin was investigated for the potential to form new products for the pharmaceutical and biomedical industries. We discovered new market potential for fine- and coarse-grade wool by extracting keratin peptide and protein in the form of various sponge implantable materials. Sponges with different appearances and densities were examined as porous, interpenetrating networks capable of absorbing and releasing moisture and for the potential to deliver the drug, riboflavin, to the intestine. In vitro studies showed that keratin sponges were physiological-responsive in releasing riboflavin into simulated gastric fluid. We characterized the type of riboflavin delivery from keratin sponge materials as a two-stage, sustained delivery system with rapid delivery of 70% and 40% riboflavin up to 8 minutes, then subsequently, slow delivery of 100% and 50%, as the accumulated amounts delivered up to 60 minutes, from fine- and coarse- wool-keratin sponges, respectively. These novel keratin sponges can be tailored for physical and mechanical characteristics and behaviors to meet specific, implantable end-uses. Their unique ability to behave as a solid and a liquid makes them useful as supports for cell infiltration and tissue growth. The added benefit of using keratin above the synthetic materials is keratin’s ability to respond to pH changes because of the reactivity of numerous functional groups, its biocompatibility, and its potential to attach biologically active substance and/or co/factors for advanced biomedical and biotechnological applications.
Technical Abstract: Keratin sponge/hydrogels from oxidation and reduction hydrolysis of fine and coarse wool fibers were formed to behave as cationic hydrogels to swell and release active agents in the specific region of the gastro-intestinal (GI) tract. Their porous, interpenetrating networks (IPN) were effective for delivering riboflavin into simulated gastric fluid (SGF), pH 1.2, reaching saturated equilibrium within one hour with swelling ratios 3.7 to 5.7 greater than in 85% RH. Diffusion drug release according to the Korsmeyer-Peppas mathematical model involving fractional release at timed intervals suggested the mechanism of quasi-Fickian diffusion of the drug by transport through the IPN, not by solvent penetration. Within 60 minutes, 100% riboflavin was released from fine-wool-keratin at a rate of 0.595% to 0.917% per minute, whereas only 49% was released from coarse-wool-keratin at a rate of 0.281% to 0.550% per minute. Within 8 minutes 60% to 82% riboflavin was delivered at 3.7% per minute from fine-wool-keratin and 23% to 39% was released from coarse-wool-keratin at 1.39% to 1.66% per minute. Keratin sponge/hydrogels can function in controlled release systems requiring initial immediate-release followed by lower dosage-release over a prolonged period for site-specific delivery to the stomach. Swelling studies and the mobility of water favorably framed keratin sponge/hydrogels as microfluidic devices with implied applications as suitable scaffolds for enzyme immobilization and cell infiltration and growth. As microfluidic biomaterials they provide the reactivity of keratin’s numerous functional groups for opportunities to attach biologically active substances and/or cofactors for advanced biomedical and biotechnological applications.