Enhancement of Osseointegration via Endogenous Electric Field by Regulating the Charge Microenvironments around Implants

This study provides a Ta- and Ag-ion implant for constructing an EEF with a negatively charged cell membrane to study the effect of the EEF on osseointegration. This study demonstrates that the EEF regulates bone integration by regulating the opening and closing of Ca²⁺ ion channels, controlling the flow of calcium ions, and promoting bone integration at the bone-implant interface. Therefore, regulating bioelectric balance in the implant microenvironment may be a useful strategy.

Abstract

The regulation of the charged microenvironment around implants is an effective way to promote osseointegration. Although homeostasis of the charged microenvironment plays an integral role in tissues, current research is externally invasive and unsuitable for clinical applications. In this study, functional materials with different surface potential differences are prepared by changing the spatial layout of Ta and Ag on the surface of a Ti-6Al-4V alloy (TC4). This naturally formed an endogenous electric field (EEF) with a negatively charged cell membrane after in vivo implantation and promoted osseointegration at the interface between the bone and implant through the upregulation of Ca²⁺ concentration and activation of subsequent pathways. Interestingly, the promotion of stem cell differentiation, regulation of the direction of immune cell polarization, and antibacterial efficacy are determined by the free charge contained in the implant, rather than by the magnitude of the surface potential difference. This functional implant represents a unique strategy for regulating the charged microenvironment around the implant and enhancing osseointegration, thereby providing ideas and technical approaches for the clinical development of novel implant materials.