The role of Ag particles deposited on TiO2 or Al2O3 self-organized nanoporous layers in their behavior as SERS-active and biomedical substrates

In this paper, we present recent results of investigations of hybrid materials consisting of nanoporous oxides layers loaded with Ag nanoparticles: Ag/TiO2-n/Ti and Ag/Al2O3-n/Al (where "n-"stands for nanotubes), which could be used as active SERS substrates or as bioactive materials in medicine (implants). Simple electrochemical, chemical and physical methods appear suitable for fabricating such hybrid materials having different functional properties. Such materials may play a double role, as our investigations have shown: they are active and stable substrates in SERS investigations of adsorbate adsorbent interactions (Ti- or Al-based materials) as well as biocompatible and bactericidal substrates (Ti-based composites). In both applications -SERS and bio - Ag nanoparticles play a crucial role. The new hybrid materials were characterized by high-resolution SEM and surface analytical techniques: local AES, XPS, SERS (Surface-Enhanced Raman Spectroscopy). For the biomedical applications, the hybrid materials were tested with the use of S. epidermidis cells (antibacterial tests), as well as in U2OS cell culture (to study living cell adhesion and alkaline phosphatase activity, ALP). The tests have shown the highly beneficial role of Ag nanoparticles in enhancing the functional properties of the new hybrid materials. (C) 2012 Elsevier B.V. All rights reserved.