Sustainably synthesized biogenic silver nanoparticles for environmental and biological applications

Herein we report the potential applications of green synthesized silver nanoparticles (Ag NPs) as an efficient photocatalyst, an antibacterial agent and a larvicidal agent. The nanoparticles were synthesized via green approach using Pergularia daemia leaf extract as a natural reducing and capping agent. The presence of phytochemicals responsible for larvicidal and antibacterial activity, as well as their role in nanoparticle formation, was analyzed using GC-MS. The biosynthesized Ag NPs were further characterized through XRD, UV-Vis spectroscopy, FTIR, and SEM analysis. The synthesized Ag NPs exhibited potent larvicidal activity against Aedes aegypti and Culex quinquefasciatus, with LC₅₀ values of 4.17 ppm and 4.52 ppm, respectively. Histopathological analysis revealed severe tissue damage in treated larvae, particularly affecting the midgut, hindgut, muscles, and nerve ganglia. In antibacterial studies, the nanoparticles demonstrated strong activity against Pseudomonas aeruginosa and Escherichia coli, with an inhibition zone of 17 mm at a concentration of 150 ppm which is higher than the commercial material. Additionally, the Ag NPs exhibited high efficiency of 94% in degrading methylene blue dye, emphasizing their potential for environmental remediation. These findings suggest that biosynthesized silver nanoparticles with multifunctional biological properties operate efficiently on exposure to visible light, making them a promising candidate to act as a photocatalyst.