Factors governing the sinterability, In vitro dissolution, apatite formation and antibacterial properties in B2O3 incorporated S53P4 based glass powders

In this report, we have systematically evaluated the role of boron in regulating the degradation, apatite formation and antibacterial properties of bioactive glasses by substituting SiO2 with B2O3 in S53P4 based glass composition. The structural analysis of the glasses has been carried out using neutron diffraction and Raman spectroscopic techniques. The structural analysis of S53P4 base glass has revealed the presence of silicate and phosphate units in the form of Q2Si, Q3Si and isolated Q0P units. With the increasing replacement of SiO2 with B2O3, Raman spectroscopy revealed the formation of non-ring metaborate units and borate rings consisting of both BO3 and BO4 units at the expense of Q2Si and Q3Si units. Furthermore, DSC, HSM and dilatometry results confirmed that the sinterability parameter (Sc) and fragility index (m) values of borosilicate bioactive glasses help in achieving superior sintering and thermal processing without devitrification. Additionally, in vitro SBF immersion studies revealed an accelerated release of Si4+ and Ca2+ ions from the borosilicate glasses. In vitro antibacterial assays against E.coli bacterial inoculum illustrate the critical role of B2O3 in the bioactive glass composition.