Surface functionalization of phosphate-based bioactive glasses with 3-aminopropyltriethoxysilane (APTS)

Abstract

The effect of SrO substitution for CaO, in the 50P2O5-10Na2O-(40-x)CaO-xSrO glass system, on the ability to graft 3-aminopropyltriethoxysilane (APTS) at the glass surface has been investigated and is partially compared to changes occurring further from the surface. The step used for the APTS grafting led to Na leaching and successively to Ca and/or Sr leaching. This gave rise to a P2O5- rich glass surface, especially on sample containing both Ca and Sr ions. The hydration of the phosphate chainswas found to be the most pronounced for the glasses containing large quantity of SrO as evidenced by contact angle and X-ray photoelectron spectroscopy (XPS). The increase in phosphate chain hydration was attributed to the expansion of the glass network when Sr ions are introduced. Finally, based on the N1s XPS peak, N species were found at the surface of the glasses in two configurations: NH2 and – NH2-OH as proof of APTS grafting. APTS grafting on phosphate glass is of importance for the grafting of proteins.