(Invited) Cellulose-Chitosan-Keratin Composite Materials: Synthesis, Immunological and Antibacterial Properties

We have developed a simple and recyclable method to synthesize novel biocompatible composites from cellulose (CEL), chitosan (CS) and keratin (KER).  Butylmethylimidazolium chloride [BMIm⁺Cl^-], an ionic liquid (IL), was used as a sole solvent for dissolution and preparation of the composites.  Since majority of [BMIm⁺Cl^-] used (>88%) was recovered for reuse, the method is recyclable.  Various spectroscopic and imaging techniques including powder X-ray diffraction (XRD), FT-IR, near-IR, ¹³C CP MAS –NMR, and scanning electron microscope were used to monitor the dissolution process, to characterize the composites and to confirm that CEL, CS and KER were successfully regenerated by the method.  The [CEL-CS+KER] composites obtained retain properties of their components, namely superior mechanical strength (from CEL), excellent antimicrobial activity (from CS), superior adsorption capability for organic pollutants (from CS) and ability to controlled delivery of drug (from KER).  For example, the composites can effectively adsorb various endocrine disruptors including polychlorophenols and bisphenol A, and toxin such as microcystins.  The composites were found to substantially reduce growth of Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 25923), methicillin resistant S. aureus (ATCC 33591) and vancomycin resistant Enterococcus faecalis (ATCC 51299).  The composites are non-toxic to fibroblasts; i.e., fibroblasts were found to grow and proliferate in the presence of the composites.  Antibiotic such as ciproprofloxacin can be encapsulated into the composite and kinetic its release can be controlled by judiciously adjusting composition of the composites.