The Development Of Chloride-Containing Silicate Bioactive Glasses With Different Network Connectivity Values

Background:Bioactive glasses are widely used in medical applications such as the repair of soft and hard tissues in the oral cavity due to their good osteogenic,angiogenic and antibacterial properties.Different defect sites require materials with different repair rates.Therefore,it is important to develop bioactive glasses with controlled degradation rates to suit different clinical needs.Previous studies have found that the addition of chlorine to glass can expand the network structure of glass and obtain chloride-containing bioactive glasses with good bioactivity and biosafety,but this series of glass has the characteristic of rapid degradation.This project proposes the scientific hypothesis that bioactive materials with controlled degradation rates can be obtained by modulating the network connectivity of the glass.Aim:This study aims to prepare chloride-containing bioactive glasses with different NC values and to investigate the effects of different NC values on the structure,degradation rate and apatite formation ability of chloride-containing bioactive glasses.Methods:In this study,chloride-containing silicate glasses with nominated NC values varying from 1.5 to 3.35 were synthesised via a melt quench route.The thermal properties of the glasses,such as glass transition temperature（T_g）,were investigated by DSC;The percentage of chloride retention of the glasses and their ability to release ions were examined by ISE and ICP-OES;the structure and apatite formation ability of the glasses were analysed by XRD and FTIR;and the biosafety of the glass was evaluated by EdU cell proliferation experiments.Results:The ISE results showed that the percentage of chloride retention of the glass was approximately 80%when the NC value was less than 2.07.With an increase in NC value from 2.07 to 3.35,the percentage of chloride retention decreased from 80%to 30%,while the T_gincreased gradually from 626 to 702℃.The glasses with NC value less than 2.57 partially crystallized to apatite-like phase,while the glasses with NC value higher than 3.18 partially crystallized to SiO₂,the rest of the glasses were largely amorphous.All the studied glasses are highly bioactive,which could form apatite-like phase within 6 h immersion in Tris buffer.Meanwhile,the first time to apatite formation for the studied chloride-containing silicate glasses prolonged with increasing in glass NC value.Furthermore,the proliferative effect of all the glasses on MC3T3-E1 cells was not significantly different compared to the control group.Conclusion:Chloride-containing silicate glasses with NC values above2.4 had high bioactivity and were able to generate apatite within 6 h.However,the degradation rate of the glasses decreased with increasing NC values.