Green synthesis of silver nanoparticles using Keratinase from Pseudomonas aeruginosa-C1M, characterization and applications as novel multifunctional biocatalyst.

Introduction: This study explores the biogenic synthesis of silver nanoparticles (AgNPs) using keratinase from Pseudomonas aeruginosa-C1M as a reducing and stabilizing agent. The synthesis of AgNPs was characterized by a color change from transparent to dark brown and a UV-Vis absorption peak at 450 nm, confirming nanoparticle formation. The study further investigates the structural, morphological, and functional properties of these AgNPs, particularly their antibacterial activity and their potential role in azo dye decontamination.

Methods and results: The FTIR confirmed that AgNPs nanoparticles formation with keratinase. X-ray diffraction analysis showed that the prepared AgNPs were crystalline in nature and had face-centered cubic lattice planes. When observed under the transmission electron microscope and scanning electron microscope the nanoparticles were monodispersed spheres of different sizes. The diameter of the AgNPs was ~ 119 nm according to dynamic light scattering. High dispersion, long-term stability and excellent colloidal properties were supported by a high negative zeta potential value. The silver nanoparticles were found to have an antibacterial activity with zone of inhibition 25 mm and 33 mm against pathogenic strains of Staphylococcus aureus and Escherichia coli respectively. The synthesized zero-valent silver nanoparticles assisted in the decontamination of azo dyes (methyl red, methyl orange, safranin O and methyl violet) through the incorporation of sodium borohydride and light-catalyzed processes.

Conclusion: This study demonstrates, for the first time, that keratinase from Pseudomonas aeruginosa-C1M can be used for AgNPs synthesis. The biogenic AgNPs exhibited potent antibacterial activity and played a crucial role in detoxifying hazardous azo dyes. These findings highlight the dual-functional potential of AgNPs for applications in antimicrobial treatments and environmental remediation. Future studies should explore their mechanism of action, scalability, and industrial applications.