(Invited) Green Composites from Cellulose, Wool, Hair and Chicken Feather. Synthesis, Structure and Antimicrobial Property

Abstract

Novel composites between cellulose (CEL) and keratin (KER) from three different sources (wool, hair and chicken feather) were successfully synthesized in a simpleone-step process in which butylmethylimidazolium chloride (BMIm+Cl-), an ionic liquid, was used as the sole solvent. The method is green and recyclable because [BMIm+Cl-] used was recovered for reuse. Spectroscopy (FTIR, XRD) and imaging (SEM) results confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. KER retains some of its secondary structure in the composites. Interestingly, the minor differences in the structure of KER in wool, hair and feather produced pronounced differences in the conformation of their corresponding composites with wool has the highest α-helix content and feather has the lowest content. These results correlate well with mechanical and antimicrobial properties of the composites. Specifically, adding CEL into KER substantially improves mechanical strength of all three composites ([CEL+wool], [CEL+hair] and [CEL+feather]. The fact that feather has the lowest content of α-helix (and wool has the highest) enables the [CEL+ feather] composite to have strongest mechanical strength (and [CEL+wool] composite has the weakest strength). All three composites exhibit antibacterial activity against MRSA. The antibacterial property is due not to CEL but to the protein and strongly depends on the type of the keratin, namely, the bactericidal effect is strongest for feather and weakest for wool.