Neem-Mediated Silver Nanoparticles: Characterization and Biological Applications against Mosquito Larvae and Pathogenic Bacteria

Abstract

Introduction: Nanotechnology offers sustainable solutions for healthcare and environmental management. Silver nanoparticles (AgNPs) were green-synthesized using Azadirachta indica (Neem) leaf extract, a plant renowned for its broad pharmacological activities. Aim: To biosynthesize neem-mediated AgNPs, characterize them physicochemically, and evaluate their larvicidal and antibacterial potency. Materials and Methods: Aqueous neem leaf extract was mixed with AgNO₃; formation was tracked by colour change and UV–Vis spectroscopy (458–459 nm). FTIR identified functional groups, SEM measured morphology/size, and standard bioassays determined larvicidal activity against Culex quinquefasciatus larvae and antibacterial activity against selected pathogens. Results: UV–Vis confirmed AgNP formation; FTIR showed hydroxyl, carbonyl and amine groups acting as reducing/stabilizing agents. SEM revealed 20–50 nm predominantly spherical particles. Probit analysis gave 24-h LC₅₀ values of 0.0279 mg L⁻¹ (AgNPs) versus 0.1985 mg L⁻¹ (neem extract). Agar-well diffusion assays showed larger inhibition zones for AgNPs than for extract, strongest against Staphylococcus aureus. Conclusion: Neem-mediated AgNPs were successfully synthesized and characterized, showing strong larvicidal and antibacterial activities. These results highlight their potential as eco-friendly agents for vector control and antimicrobial use. Further in vivo and environmental safety studies are needed to confirm their applicability.