Preparation of Keratin-Metal Complexes Derived from Different Treatments of Chicken Feather Waste

The work presented in this paper focuses on the extraction of keratin from chicken feather waste by the following two methods: (1) alkaline hydrolysis or (2) the reduction by L-cysteine reducing agent; resulting in the extracted yields of 35% and 55%, respectively. The keratin samples produced from the two extraction methods possessed different physical and chemical properties including molecular weight, crystallinity index, thermal behavior, metal binding ability (iron, copper, silver and zinc), antimicrobial activity, and cytotoxicity. The alkaline hydrolysis method yielded keratin of a lower molecular weight, crystallinity index and thermal degradation than the reduction method by L-cysteine. However, their chemical identity was determined to be qualitatively similar as characterized by infrared spectroscopy. The keratin produced by alkaline hydrolysis give rise to a higher metal content adsorbability and thus subsequently led to greater antimicrobial activity with an acceptable value of cytotoxicity. Overall, the work presented a biomaterial from chicken waste with outstanding properties particularly using the alkaline hydrolysis extraction method, which can be applied in a variety of biomedical industries.