Bacterial allantoin mediated optimally biosynthesized silver nanoparticles exhibit antioxidant, antibacterial, and seed germination promoting activities

Abstract

The biosynthesis of silver nanoparticles (AgNPs) presents a sustainable, cost-effective, and scalable alternative to conventional synthesis techniques. This study investigates microbial allantoin as a biogenic reducing agent for the synthesis of AgNPs, emphasizing their antioxidant, antibacterial, and seed germination enhancement properties. Optimally synthesized allantoin-mediated AgNPs exhibited a crystalline size of 3.66 nm with a band gap energy of 3.39 eV. Scanning Electron Microscopy (SEM) analysis showed spherical nanoparticles with an average particle size of 84 nm, while particle size analysis revealed a zeta potential of −26.7 mV and a hydrodynamic diameter of 137.1 nm. The AgNPs displayed significant free radical scavenging activity, achieving 58% and 70% inhibition in H₂O₂ and DPPH assays, respectively. Furthermore, these AgNPs demonstrated substantial antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. Additionally, allantoin-mediated AgNPs promoted germination in Cicer arietinum seeds within 48 h, indicating their potential as plant growth stimulants. This pioneering study on microbial allantoin-derived AgNPs suggests promising applications across pharmaceuticals, environmental science, and cosmetic fields.