Metalloprotease-Mediated Hydrothermal Synthesis of Silver Nanoparticles with Enhanced Therapeutic Properties

Abstract: Silver nanoparticles (AgNPs) exhibit unique physicochemical properties, making them suitable for diverse applications. This study reports an efficient, one-step biosynthesis of AgNPs using a metallo-serine protease as bio-reducing agent via the hydrothermal method. The optimal conditions for biosynthesis were a combination of 600 U/mL enzyme concentration and 1.25% (5 mM) AgNO ₃, with steam sterilization at 121°C for 2 min. The SEM and EDS revealed spherical morphology of AgNPs with characteristic silver peaks at 3.00–3.5 keV and ~50–350 counts. The X-ray Diffraction confirmed a crystalline structure with an average of 30.07 nm. Furthermore, the FT-IR spectroscopy identified carboxylic acids, amine salts, and alkyl aryl ethers in the bio-capping of the particles. The AgNPs exhibited significant antimicrobial activity against several pathogens at 100 μg/mL and a radical scavenging activity of 68.15% at 500 μg/mL. These findings highlight the efficiency of enzyme-assisted synthesis of metal nanoparticles with enhanced therapeutic properties.