Structural characterization, antifungal activity and optical properties of gold nanoparticles prepared by reverse micelles

Gold nanoparticles have been prepared successfully through reverse micellar route using Tergitol NP-9 as a surfactant. The effect of the gold salt concentration has been studied on the morphology, grain size, surface area and optical properties of nano-sized gold particles. TEM studies show that the gold nanoparticles prepared at 0.05 M concentration are anisotropic having nearly hexagonal morphologies with an average grain size of 20 nm. However, gold nanoparticles synthesized at the molar concentrations of 0.04 M and 0.03 M are spherical with an average size of 25 nm and 15 nm respectively. UV-Visible spectroscopy shows a main surface plasmon resonance peaks at 540 nm and 580 nm along with the peaks at shorter wavelengths which may be due to the higher order plasmon resonance of the gold nanoparticles. The surface area of the gold nanoparticles varies in accordance with change in the TEM particle sizes. The antifungal activity of the nanocrystalline gold alone and in combination with fluconazole was studied against Candida. The activity was found to increase with decrease in the particle size of the gold nanoparticles. The fluconazole in combination with gold nanoparticles show maximum inhibition which was evident by the increase in the fold area of inhibition.