Preparation and Spectral Characterization of Some Bio-PhosphateGlasses for Bio-Medical Applications

Abstract

Three glass systems; CaO-Na2O-P2O5-B2O3, CaO-Na2O-P2O5-ZnO and Cao-Na2O-P2O5-CuO have been prepared by the melt-quenching method. In the chemical composition of these glasses, the B2O3, ZnO and CuO contents were systematically increased from 5 to 30, from 5 to 10 and from 0.01 to 5 mol%, respectively, at the expense of P2O5.Density, Vickers microhardness and fracturetoughness of the prepared glasses were measured. In vitro bioactivity of the glasses was assessed by soaking in the simulated body fluid (SBF) at 37 ±0.5 °C for 3, 7, 14 and 30 days. The glasses were tested in the form of glass grains as well as bulk slabs. The structure and composition of the solid reaction products were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR),transmission electron microscopy (TEM)and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The kinetics of degradation of the glass particles were monitored by measuring the weight loss of the particles and the ionic concentration of Ca, P, B, Zn and Cu in the SBF solution using inductive coupled plasma-atomic emission spectroscopy (ICP-AES).The obtained results revealed the formation of a bioactive hydroxyapatite (HA) layer, composed of nano-crystallites, on the surface of glass grains after the in vitro assays.The results have been used to understand the formation of HA as a function of glass composition and soaking time in the SBF. It can be pointed out that increasing B2O3 content in glass composition enhances the bioactivity of glasses. The nanometric particle size of the formed HA and in vitro bioactivity of the studied glasses make them possible candidates for tissue engineering application.On the other hand, results revealed that as Zn or Cu contents increased, the HA-like surface layer formation was significantly slowed down. The obtained results refer to that Zn or Cu-containing glasses are not effective for the apatite phase development however, they can be used in dental and load-bearing sites applications due to their high mechanical properties. Antibacterial behavior of two representative borophosphate samples, B5 and B30, Zn and Cu-containing glass samples against S. aureus and E. coli as Gram+ and Gram-, respectively were tested using disk-diffusion assays. The degree of susceptibility of the used micro-organisms to the tested antibacterial glasses was in the order of S. aureus > E. coli. Generally, Cu-containing glasses afford antibacterial behavior better than that exhibited by Zn-containing glasses. However, the two representative borophosphate did not show any antibacterial activity against the tested bacteria.The addition of antimicrobial agent to the prepared bioglass sample, when used as an implant, contribute to preventing bacteria from invading the surgical site of the implant and avoid severe complications that may arise due to the invading bacteria.