Synthesis, characterisation and in vitro evaluation of sol-gel derived SiO2-P2O5-CaO-B2O3 bioactive system

Multicomponent xB(2)O(3)[100-x](61SiO(2)center dot 9P(2)O(5)center dot 30CaO] system with 0 <= x <= 30 mol% was prepared by sol gel method. The morphology of the 600 degrees C heat treated samples was characterised through Scanning Electron Microscopy (SEM). X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS) were used to characterise the local structure, the nature of the chemical bonding and the surface composition of these samples. Up to 10 mol% B2O3 the samples have a glass-ceramic character, a crystalline phase characteristic to hydroxyapatite being detected through XRD measurements. With further increasing x the samples present a vitreous character. PTIR spectroscopy revealed a complex silicate and phosphate network consisting mainly of meta- and pyro-type units. The development of hydroxyapatite, A and B-type of carbonate-substituted hydroxyapatite was followed based on FTIR and XPS spectra analysis. The bioactivity of the samples has been analysed in vitro in simulated body fluid (SBF). The evolution of apatite layers self-assembled on the samples surface after immersion in SBF was analysed and discussed as a function of both boron content and immersion time. The results indicate that after five days of immersion, the microstructure of the sample with 10 mol% B2O3 is quite close to that of dry human trabecular bone. (c) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.