Can polymers influence antifungal activity of silver nanospheres? A study on Candida albicans

Introduction: Silver nanoparticles are well known for their antibacterial, antiviral, and antifungal properties. Although the exact mechanism is not fully understood, it is believed to be strongly related to the release of Ag+ ions, which contribute to cell death. Polymers can interact with the cell surface, potentially enhancing ion release and increasing the antimicrobial effect. In this study, we used biocompatible polymers in a seed-mediated growth method to produce silver nanospheres and evaluate their activity against Candida albicans. Methodology: Candida albicans was cultured on Sabouraud Agar and standardized to 10⁶ CFU/mL. Silver nanospheres were synthesized using Carbopol® 940 (CBP), Alginate (Alg), and Sodium Poly-4-Styrene-Sulfonate (PSS), then purified by centrifugation prior to use in the experiments. The nanospheres were incubated with fungal cells for 24 hours. After incubation, each test sample was serially diluted from 10⁻¹ to 10⁻⁴, and 10 µL of each dilution was plated on Sabouraud Agar. Results and discussion: Our findings showed that AgNP-PSS resulted in the greatest reduction in fungal activity, with a 4 Log₁₀ reduction, compared to AgNP-CBP (2.7 Log₁₀) and AgNP-Alg (1.7 Log₁₀). We believe this enhanced effect may be related to the presence of sulfur groups in the PSS molecules. Conclusion: AgNPs exhibited the expected antifungal activity against Candida albicans in vitro, and the results with PSS suggest that polymer interactions play a key role in mediating their mechanism of action.