BIOLOGICAL SYNTHESIS, CHARACTERIZATION AND ANTIFUNGAL POTENTIAL OF SILVER NANOPARTICLES AND THEIR FORMULATION

Abstract

The biological synthesis of silver nanoparticles (AgNPs) has gained increasing attention as an eco-friendly and sustainable alternative to conventional chemical and physical methods. In this study, AgNPs were synthesized using aqueous extracts of Azadirachta indica (Neem) leaves, which served as natural reducing and stabilizing agents. The successful formation of nanoparticles was confirmed by a visible color change from pale yellow to brown, corresponding to the excitation of surface plasmon resonance. The synthesized AgNPs were comprehensively characterized using UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and electron microscopy (SEM/TEM), along with dynamic light scattering (DLS) and zeta potential analysis to determine size distribution and stability. The results indicated well-dispersed, crystalline nanoparticles with an average size of 20–30 nm and good colloidal stability.

The antifungal potential of the synthesized AgNPs was evaluated against Candida albicans, Aspergillus niger, and Fusarium oxysporum using agar well diffusion, broth dilution, and MIC/MFC assays. The nanoparticles exhibited strong dose-dependent antifungal activity, with significant zones of inhibition compared to the standard drug fluconazole. Mechanistic studies suggested that AgNPs exerted their antifungal effect through disruption of the fungal cell membrane, induction of reactive oxygen species (ROS), and interaction with key proteins and enzymes.

For practical applications, AgNPs were incorporated into a carbopol-based gel formulation, which demonstrated excellent stability (pH, viscosity, and homogeneity) and enhanced antifungal efficacy compared to pure nanoparticles. These findings highlight the potential of biologically synthesized AgNPs and their formulations as sustainable and effective antifungal agents for applications in medicine, agriculture, and textiles.