Application of Raman microspectroscopy to the characterisation of bioactive materials

Bioactive materials offer a more stable and stronger bond between the living tissue and the implant than bioinert materials due to reactions occurring at the material surface when implanted. These reactions lead to formation of a biologically active hydroxycarbonate apatite (HCA) layer to which the living tissue can strongly adhere. It is therefore of primary importance to be able to characterise in vitro the formation of such HCA layers. We report on the use of Raman microspectroscopy to characterise the surface reactions occurring in two types of bioactive materials after immersion in simulated body fluid (SBF) or phosphate buffer saline (PBS). The materials investigated were (1) sol–gel derived bioactive 58S glass foams and (2) bioresorbable polylactic (PDLLA) and poly(lactic-coglycolic) acid (PLGA) foams containing bioactive glass particles (45S5 Bioglass). The results show that Raman microspectroscopy is a very sensitive technique for qualitative and quantitative detection of HCA formation on the materials under different in vitro conditions.