Tuning of the ion release properties of silver nanoparticles buried under a hydrophobic polymer barrier

Tuning of Ag ion release from silver-polymer nanocomposites is very important for biomedical applications of nanocomposite materials to reduce the potential toxicity effects toward human cells. In this work a well defined model system consisting of nearly two dimensional silver nanoparticle arrangements which are either directly accessible or covered by polymer barrier was used. The Ag nanoparticles (AgNPs) with nominal thickness ranging from 1.3 to 8.3 nm and the polytetrafluoroethylene polymer layers were synthesized by physical vapor deposition techniques. Study of the Ag ion release was accompanied with a control of the composite morphology (Ag nanoparticle size, concentration, and distribution) to understand the mechanism and the kinetics of the interfacial ion transfer reactions of the AgNPs. The surface plasmon resonance of the AgNPs and the composite morphology variation as well as the time-dependent release of silver ions after immersion in water were examined by UV-visible spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry. A correlation between changes in the surface plasmon resonance, composite morphology, and the kinetics of Ag ion release was found. It is shown that the strong dependence of the silver ion release on the particles' size leads to significant redistribution of the composite morphology and suppression of the Ag ? release with time. It is also observed that a polymer barrier stabilizes the morphology of the composites and can be applied to control the Ag ion release rate.