Surface modifications of plasma-sprayed bioglasses upon interaction with phosphate buffer and albumin solutions: a photoelectron spectroscopy study

X-ray photoelectron spectroscopy (XPS) was used to define the chemical composition of the outermost surface layer and the surface modification of a plasma-coated phospho-silicate glass (identified as BVA) when immersed in potassium phosphate buffer or in phosphate-buffered human albumin solution. Its behaviour was compared with that of a soda-lime-based glass (identified as BVH) treated in the same way. The surface percentage composition of plasma-sprayed glass was consistent with the bulk composition. After incubation with buffer, a Ca-P-rich layer developed only on the surface of BVA glass. Human serum albumin was bound reversibly to both glasses; however, the protein completely covered the BVA glass surface within 24 h, with the formation of a mixed albumin-Ca-P layer, whereas 4 days of incubation were necessary for complete coverage of the BVH glass surface. The thickness of the organic/inorganic overlayer has also been estimated.