Unraveling Nanoparticles Mechanism Against Candida albicans:Global Gene Expression Analysis

Objectives: Search for the mechanism of action of silver nanoparticles in the inhibition of Candida albicans by identifying genetic expression by RNA-seq.
Methods: AgNPs were synthesized using silver nitrate as precursor and characterized by Transmission Electron Microscopy (TEM) and UV-Vis Spectroscopy. Microdilution test was performed in Candida albicans at AgNPs serial dilutions (0.10 to1.62 mg/mL) and incubated aerobically at 37°C for 24h. Serial dilutions of AgNPs (0.002 to 1.62 mg/mL ) were tested on HGF(ATCC) using the MTT method and incubated at 37°C in 5%CO₂ for 24h for the evaluation of cytotoxic effect. Statistical analysis One-Way ANOVA (p<0.05) and Tukey test were performed. RNA extraction of Candida albicans treated with AgNPs was isolated with RiboPure^TM Yeast Kit (Invitrogen). RNA-seq was performed using Genome analyzer II (Illumina) and differential expression analyzed with Edge R.The assays were performed in triplicated.
Results: AgNPs were obtained with a particle size in 33.5±9.8 nm and UV-Vis absorbance peak in 420nm. Microdilution test showed a fungicidal concentration of 0.050 mg/mL for AgNPs. MTT assay demonstrated a non-cytotoxic effect on HGF. Differential gene expression (p<0.05) was observed with 3871 genes upregulated like YRF1, IFH1, PLD1 and 3862 genes downregulated such as STF2, ZCF8. Suggesting a role in these Candida albicans genes in response to AgNPs.
Conclusions: Synthesis method was effective in the obtention of spherical AgNPs. AgNPs showed effectiveness against Candida albicans and fulfilled the cell viability parameters. RNA-seq analysis indicated differential gene expression in several genes affected by AgNPs. Genetic expression used to elucidate its mechanism of AgNPs as antifungal has not been reported before, so, these results may lead to considerate them as an option for antimicrobial dental biomaterials application.