Green Synthesis of Silver Nanoparticles Using Spermacoce alata Leaf Extract With Enhanced Antibacterial, Antioxidant, and Catalytic Performance

This study reports, for the first time, the use of Spermacoce alata (SA) leaf extract as an efficient bioresource for the green synthesis of multifunctional silver nanoparticles (SA‐AgNPs). Comprehensive characterization by ultraviolet–visible (UV–Vis), Fourier transform infrared (FTIR), field‐emission scanning electron microscopy (FE‐SEM), high‐resolution transmission electron microscopy (HR‐TEM), EDAX, dynamic light scattering (DLS), X‐ray diffraction (XRD), and zeta potential analyses confirmed the formation of predominantly spherical, crystalline, and well‐dispersed nanoparticles with an average size of ∼18 nm and good colloidal stability (−22.8 mV). The SA‐AgNPs exhibited strong antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa , with minimum inhibitory concentrations of 128 and 64 µg mL ⁻¹ , respectively. The DCFH‐DA assay revealed significant intracellular ROS generation (173% in S. aureus and 79% in P. aeruginosa ), indicating an oxidative stress‐mediated antibacterial mechanism. Additionally, SA‐AgNPs showed concentration‐dependent antibiofilm activity against both pathogens, which was further supported by FE‐SEM analysis. The nanoparticles demonstrated excellent biocompatibility and enhanced antioxidant activity (70.88%), surpassing butylated hydroxytoluene (55.04%). Moreover, SA‐AgNPs displayed efficient catalytic performance in NaBH ₄ ‐mediated degradation of organic dyes and rapid conversion of toxic p‐nitrophenol. Overall, this work establishes SA‐AgNPs as promising biogenic nanomaterials for antimicrobial and environmental remediation applications.