Biogenic Silver Nanoparticles Exhibit Antifungal and Antibiofilm Activity Against Candida albicans via Intracellular ROS Production

Abstract

The emergence of antifungal resistance in Candida albicans necessitates the development of novel therapeutic strategies. This study evaluates the antifungal and antibiofilm activity of biogenic silver nanoparticles (bAgNPs) synthesized using Staphylococcus saprophyticus bacterial supernatant. UV–Visible spectroscopy confirmed the formation of bAgNPs, with a distinct absorbance peak at 418 nm. Minimum inhibitory concentration (MIC) testing determined that 50 μg/mL effectively inhibited fungal growth. bAgNPs significantly reduced biofilm biomass, with an 80 μg/mL concentration resulting in over a 70% reduction, as demonstrated by crystal violet staining and fluorescence microscopy. Mechanistic studies revealed that bAgNPs induced reactive oxygen species (ROS) production, with fluorescence intensity peaking at 80 μg/mL, leading to oxidative stress-mediated cell death. The yeast-to-hyphal transition, a key virulence mechanism, was inhibited, impeding the fungal invasiveness. Furthermore, the disruption of cell membrane integrity was confirmed by SYTO 9/propidium iodide staining, where over 60% of cells displayed compromised membranes at MIC. MTT assay results demonstrated that bAgNPs impaired mitochondrial function by reducing metabolic activity by 75% at MIC. These findings suggest that bAgNPs target multiple critical pathways, including ROS-mediated oxidative damage, membrane disruption, and metabolic impairment, thereby exerting a potent antifungal effect; thus, they present a promising approach for treating biofilm-associated C. albicans infections.