Nanostructure, dissolution and morphology characteristics of microcidal silver films deposited by magnetron sputtering

Novel microcidal silver films for burn dressings have been produced by magnetron sputtering. The nanostructure and dissolution characteristics of these films exhibiting antimicrobial behavior were studied as a function of the process conditions, namely, gas composition, gas pressure and input power, using transmission electron microscopy (TEM), high-resolution scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and resistivity. TEM revealed that bioactive films were nanocrystalline, with a grain size of the order of 15 nm and the presence of twins. Surface morphology studies before and after dissolution suggested that bioactive films released silver at therapeutic levels in the form of nanoparticles or grains. Chemical species identification with XPS showed that the biologically active films were metallic in nature. The importance of oxygen in the sputtering environment, the resultant nanostructure and presence of twins are discussed to explain the unique antimicrobial properties of these silver films.