Synthesis of Silver Nanoparticles Using Phytochemicals of Azadirachta indica as Reducing and Stabilizing Agents: Characterization and Antibacterial, Antifungal, Antiparasitic Applications and Biocompatibility Assessment

Abstract

The present study reports the green synthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of Azadirachta indica (Neem) as a natural reducing and stabilizing agent. The phytochemical-rich extract facilitated the conversion of Ag⁺ ions from silver nitrate (AgNO₃) into stable AgNPs under mild conditions, confirmed by a visible color change from pale yellow to dark brown and further validated through UV–Visible spectroscopy showing a characteristic surface plasmon resonance band around 440 nm. The synthesized nanoparticles were systematically characterized using FTIR, XRD, and SEM analyses, which confirmed the involvement of phytochemicals in reduction and capping, the crystalline nature, and the predominantly spherical morphology of

AgNPs. Biological evaluation demonstrated strong, concentration-dependent antibacterial activity against both Gram-positive and Gram-negative bacteria, with notable efficacy against Pseudomonas aeruginosa and Staphylococcus aureus. Significant antifungal activity was observed against Candida albicans, Aspergillus niger, and related fungal strains. In addition, the AgNPs exhibited promising antiparasitic activity against selected protozoan parasites, showing increased inhibition with rising nanoparticle concentration. Biocompatibility assessment revealed acceptable cytotoxicity levels and low hemolysis at lower concentrations, indicating a favorable safety profile for biomedical applications. Overall, the study highlights that Azadirachta indica-mediated AgNPs possess multifunctional biological activities along with good biocompatibility, making them potential candidates for future antimicrobial and therapeutic applications.