The anchoring of fibrinogen to a bioactive glass investigated by FT-IR spectroscopy

The attachment of fibrinogen on the bioactive glass surface is investigated by means of Fourier transform infrared spectroscopy (FT-IR). The β-sheet/β-turn ratio estimated from the deconvolution of the amide I band of adsorbed fibrinogen indicates a good biocompatibility of the substrate. In vitro study shows the bioactive character of bioactive glass with attached fibrinogen, and at the same time severe conformational changes in secondary structures of the adsorbed fibrinogen molecules were identified. These changes were found to be determined by electrostatic interaction between the positive charged site of the protein and negative charges on bioactive glass surface, and, by interaction between protein carboxyls and, the phosphate and calcium ions from simulated body fluid (SBF). The most pronounced conformational modifications were observed in the first three days of immersion in SBF; after seven days of immersion these changes were attenuated. FT-IR imaging measurements were also performed to understand the role played by the attached fibrinogen on the hydroxyapatite (HA) layer formation on the glass surface. The HA layer was observed during the first days in relation to the sample without fibrinogen.