In Vitro Mineralization Property of Borosilicate Bioactive Glass under DC Electric Field

Abstract

Borosilicate bioactive glass has excellent bioactivity and bone conductivity, but most bioactive glasses exhibit nonlinear degradation and mineralization behavior, with mineralization property declining over time. The DC electric field, as an outfield-assisted approach to regulation, can interfere in the ion exchange and diffusion of the glass to modify its property. In this study, a DC electric field is used to intervene in vitro mineralization of borosilicate bioactive glass to accelerate the bioactivity in the slower degradation phase. Borosilicate bioactive glass with the composition of 18SiO2-6Na2O-8K2O-8MgO-22CaO-2P2O5-36B2O3, prepared by the melting method, was immersed in simulated body fluid (SBF). A current in range of 0-90 mA was applied to study the effect of DC electric field on the degradation and in vitro mineralization property of borosilicate bioactive glass. The results show that the application of electric field increases the degradation rate and ion release of borosilicate bioactive glass. Compared to the control group (without electric field), the weight loss rate increased by 3%-5% and the dissolution of B and Ca ions increased by 2.3-2.9 times and 1.9-2.3 times, respectively. Meanwhile, the electric field assists glass network hydrolysis and surface hydroxylation, accelerating the generation of hydroxyapatite (HA). Analyzing the surface structure of the borosilicate bioactive glass particles, we found that an apatite layer was formed on the surface of the sample exposed to the electric field. Hence, the application of a DC electric field can improve the degradation and in vitro mineralization property of bioactive glass, providing a new idea for bone repair effect enhancement.

Effect of pH on the In Vitro Degradation of Borosilicate Bioactive Glass and Its Modulation by Direct Current Electric Field

“…The DC stimulation of osteogenesis may be related to electrochemical reactions occurring at the electrodes, such as changes in oxygen partial pressure and pH [ 33 ]. In the previous study, we found that applying a DC electric field can improve the degradation and mineralization of a borosilicate bioactive glass [ 34 ]. However, the mechanism by which the DC electric field affects the degradation of the glass is unclear.…”