Synthesis and Characterization of Keratin–Mesoporous Silica Nanocomposite Using Keratin Extracted from Quail Feathers, and Evaluation of Its Antibacterial Activity and Biocompatibility

Nanoproteins and mesoporous silica nanoparticles (MSNPs) have attracted considerable attention due to their unique biological and physicochemical properties; however, studies combining these biomacromolecules and inorganic carriers remain limited, particularly when employing natural keratin derived from avian feathers. In the present study, keratin was extracted for the first time from quail feathers and converted into nanokeratin (nK) through an ultrasonic process, followed by its loading onto MSNPs. UV–visible spectroscopy confirmed the presence of peptide bonds and aromatic amino acids in both nK and the nanocomposite (nK-MSNPs). Fourier-transform infrared spectra revealed characteristic keratin functional groups, including amide I, amide II, and cysteine (S-S), alongside Si-O-Si bands at 1100 and 800 cm⁻¹, indicative of MSNPs within the nanocomposite. X-ray diffraction confirmed an amorphous structure. The average particle sizes of nK and nK-MSNPs were 245.4 and 211.4 nm, respectively, with polydispersity indices of 0.594 and 0.148. Zeta potential values (-9.6 and -16.9 mV) demonstrated electrostatic stability, while electron microscopy images revealed reduced aggregation in the nanocomposite compared to nK alone. The nanocomposite also retained chemical stability over 90 days. Cytotoxicity evaluation using the MTT assay on human fibroblast cells (hFF) showed that nK-MSNPs were non-toxic even at relatively high concentrations. Moreover, antibacterial assays revealed significant inhibition zones of 22.8 ± 0.5 mm against Staphylococcus aureus and 20.2 ± 0.4 mm against Escherichia coli (P<0.05), comparable to a reference antibiotic. Collectively, these findings suggest that nK-MSNPs, owing to their porous structure, long-term stability, biocompatibility, and antibacterial activity, hold strong potential for biomedical applications.