Green Synthesis of Silver Nanoparticles Using Maltose and Cysteine and Their Effect on Cell Wall Envelope Shapes and Microbial Growth of Candida spp.

In this work, silver nanoparticles (AgNPs) were synthesized by a green methodology using maltose and cysteine. Fungistatic and fungicide activity were evaluated on Candida albicans ATCC 10231 and Candida parapsilosis ATCC 22019. AgNPs were characterized by UV-visible spectrophotometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering in dynamic mode (DLS). AgNPs were spherical shape with sizes between 10–20 nm and positive surface charge. Inhibitory effect was determining by both minimum inhibitory concentration that inhibit 50% of fungal growth (MIC₅₀) and minimum fungicide concentration (MFC) of AgNPs. MIC₅₀ values obtained were between 0.02 to 0.25 μg/ml AgNPs and MFC values between 0.25 to 0.5 μg/ml for the two strains of Candida. TEM images showed that AgNPs caused drastic alteration on cell wall (increased thickness) and disruption of cytoplasmic membrane. Finally, cytotoxic effect of AgNPs on murine fibroblast was evaluated and a cytotoxic effect on 50% of murine fibroblast cells (CC₅₀) were obtaining at a mean concentration of 10 μg/ml of AgNPs (up to 500 times higher than MIC₅₀). In conclusion, we can consider AgNPs as an alternative in the development of new anti-fungal agents with fungicide effect on Candida species at non-toxic concentrations for mammalian cells.