Abstract
Biological application of nanoparticles (NPs) is a rapidly developing area of nanotechnology, providing new possibilities in the diagnosis and treatment of human diseases. Nowadays, NPs have shown abilities to be used as alternative treatment for difficult diseases. Therefore, it is important to understand NP chemistry, preparation, interaction and possible mechanisms involved in its interaction with cancer cells and bacterial membranes. This study reports comparison between Au, Ag and ZnO NPs, and discusses their toxicity and physicochemical properties. In addition, this work aims to review different strategies of surface modification and functionalization of colloidal nanoparticles.