Surface Functionalization Modulates the Antifungal Performance of Silver Nanoparticles

The development of alternative antifungal materials requires nanosystems with controlled stability, reactivity, and biological performance. In this study, silver nanoparticles with different surface coatings were synthesized by wet reduction in water solution and subsequently characterized. The investigated nanosystems included citrate/glutathione-functionalized AgNPs (AgNPs-cit-GSH), citrate/L-cysteine-functionalized AgNPs (AgNPs-cit-L-Cys), and starch-coated AgNPs (AgNPs-S). Uv-Vis and FT-IR spectroscopies, DLS and Z Potential measurements confirmed the nanosize, surface functionalizations and colloidal stability. The selected capping agents were designed to modulate nanoparticle colloidal behaviour, aggregation, silver ion release, and interactions with fungal surfaces. Their antifungal activity was investigated against fungal species of clinical and environmental relevance belonging to the genera Candida and Aspergillus. The activity of the investigated nanosystems against fungal growth and biofilm formation varied according to both surface coating and fungal species. These findings indicate that surface chemistry plays a key role in determining the antifungal performance of AgNPs. Elucidating the relationship between surface functionalization, the mechanisms of action, and antifungal activity will allow for the optimization or combination of these nanosystems, thereby maximizing their efficacy against target fungi.