The Antifungal Effect of Surface Modified CuO Nanoparticles Against Candida Species

Candida infections have increased dramatically in spite of the vast arsenal of antifungal drugs. One non-conventional and promising therapeutic option for infections treatment can be implemented with inorganic materials, such as extremely small size copper oxides nanoparticles (CuO NPs, ~7 nm) that are readily soluble in water with high colloidal stability and are capable of interacting efficiently with the micro-organisms. However, stronger synergetic effect may potentially obtained with copper oxide nanoparticles modified with molecules of azole-type drug, thereby improving therapeutic efficiency toward candidiasis.

To address this aim, the synthesized CuO NPs were modified with biocompatible citrate ions. Consequently, the charge of nanoparticles surface altered from positive to negative (pH>5) and provided an accessible linker for interaction with conventional azole antifungals. The interactions were controlled by pH and the conjugation were confirmed by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential. In addition, the modified CuO NPs were tested against Candida albicans and non-albicans species by means of the broth dilution method following determination of the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). The results provide insights towards accessible surface for routine conjugation of azole-based drugs to nanoparticles.