Fabrication and Characterization of Electrospun Poly(Vinyl Alcohol) Nanofibers Loaded with a Bioactive Hydrolysate Obtained from Microbial Bioconversion of Feathers

Abstract

The adequate disposal of agro-industrial wastes is an extremely challenging topic from the environmental standpoint. Particularly, chicken feathers are largely available as a keratin-rich material with under-exploited potential. In this work, bioactive keratin hydrolysates were produced from chicken feathers using Bacillus velezensis P45 to incorporate into poly(vinyl alcohol) (PVA) nanofibers. PVA polymeric solutions (10% and 15%, w/v) were prepared and mixed with the bioactive feather hydrolysate (BFH) at 1%, 2.5%, and 5% (w/w) before the electrospinning. Nanofibers with mean diameters of 257.8 ± 64.7 nm (10% PVA; 5% BFH) and 297.1 ± 80.5 nm (15% PVA; 5% BFH) were obtained. Thermogravimetric analysis showed three weight loss events, with 10% of the mass lost up to 300°C. Infrared spectroscopy showed typical peaks of PVA and amide bands corresponding to keratin peptides. The biological activity of the hydrolysates was preserved after electrospinning, and the hemolytic activity was below 1% as expected for biocompatible materials. The scavenging activity of 2,2-diphenyl-1-picrylhydrazyl radical was observed for the nanofibers, reaching 38.8% (850.7 µM Trolox equivalent antioxidant capacity [TEAC]). In addition, the antioxidant capacity released from the nanofibers, referring to the 2,2′-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid radical scavenging, was 48.9% (1075.33 µM TEAC) and 49.2% (1080.89 µM) for the incorporation of 5% BHF into 15% and 10% PVA, respectively. In this study, polymeric nanofibers containing an antioxidant hydrolysate obtained from microbial bioconversion of feathers were produced for the first time. This interesting biocompatible material may have possible applications in protection against oxidative damage.