Influence of L-Histidine Surface Capping Agent on Antifungal Activity of Silver Nanoparticles Against Candida albicans

Candida albicans is one of the most successful opportunistic pathogens in human history. Under conditions of a weakened immune system C. albicans can cause recurrent mucosal infections and life-threating contagious infections with high mortality rates. Silver nanoparticles are known for their antifungal properties against C. albicans, largely through apoptotic mechanisms. The antifungal properties of silver nanoparticles depend on their size, shape, and surface capping agent. Amino acids are a desirable nanoparticle surface capping agent because the amino acid can increase water solubility and biocompatibility. However, amino acid caps may also reduce the antifungal activity of silver nanoparticles. Currently, there is no information about the interaction between silver nanoparticles capped with an amino acid and Candida albicans. The purpose of this experiment is to determine whether L-histidine-capped silver nanoparticles will cause apoptosis in C. albicans. Spherical L-histidine-capped silver nanoparticles were synthesized by a hydrothermal method. We will characterize the nanoparticles using Transmission Electron Microscopy (TEM), X-ray diffraction, X-ray spectroscopy, and Ultraviolet-visible spectroscopy. We will then culture C. albicans with variable concentrations of L-histidine-capped silver nanoparticles to determine the half maximal inhibitory concentration (IC₅₀). The C. albicans cells will be preserved and analyzed under low-voltage TEM to observe whether apoptosis occurs. The results of this experiment will indicate the effectiveness of L-histidine-capped silver nanoparticles, which may lead to the development of novel therapies, against Candida albicans. Research supported by NIGMS MBRS-RISE GM 60655.