Ageing of pulsed-laser-deposited bioactive glass films

Bioactive glasses are osteoinductive biomaterials of great interest for medical applications as filler material in bone defects and as coating of implants. Bioactive glass thin films have been deposited on silicon plates by ArF laser ablation of silica-based glass targets (53% SiO2, 23% Na2O, 20% CaO, 4% P2O5). Ablation experiments have been carried out in vacuum (10(-4) mbar) and in a reactive atmosphere of nitrous oxide. Due to the high reactivity of some bioactive materials, a study of the ageing and degradation of the film properties has been performed. The evolution of the film chemical composition and bonding configuration has been followed by energy dispersive X-ray (EDS) and Fourier transform infrared (FTIR) spectroscopies. The study of samples exposed to the atmospheric humidity revealed important changes and the structural rearrangement of the local environment of the Si-O groups. A gradual shifting of the Si-O stretching vibration to higher wavenumbers, saturation of the Si-O non-bridging bonds and relief of the strain in the network have been observed. It has been demonstrated that the bioactive glass properties are preserved stable and unaltered when the films are maintained in alcohol. (C) 2002 Elsevier Science Ltd. All rights reserved.