Electrical Surface Polarization as a Functionalization Strategy to Improve Bone Regeneration of Apatite-Based Graft Materials

Apatite-based bone graft materials are widely used for bone regeneration; however, their limited bioactivity and slow remodeling often hinder complete replacement by newly formed bone. Electrical surface polarization has emerged as a promising non-chemical strategy to modify biomaterial surface properties without altering bulk characteristics. In this study, we investigated the effects of electrical surface polarization on apatite-based biomaterials using synthesized carbonate apatite (CA) for mechanistic in vitro evaluation and a clinically relevant xenograft material for in vivo validation. Material characterization confirmed the formation of B-type carbonate apatite with bone-like mineral composition. Thermally stimulated depolarization current measurements verified successful induction of surface charges, with polarization intensity dependent on treatment conditions. In vitro studies using human peripheral blood-derived osteoclast precursors demonstrated that electrically polarized CA surfaces significantly enhanced osteoclast differentiation and resorptive activity compared to non-polarized controls, with the strongest effects observed on positively polarized surfaces. Three-dimensional analysis revealed increased resorption pit depth and volume, indicating enhanced osteoclast functionality. In vivo implantation of polarized xenograft materials into rat femoral defects resulted in significantly increased new bone formation and improved implant-bone integration compared to non-polarized materials. Higher polarization conditions promoted more mature bone tissue formation and greater bone-material affinity. These results demonstrate that electrical surface polarization effectively modulates osteoclast-material interactions and enhances bone regeneration, highlighting its potential as a simple and translatable functionalization strategy for apatite-based bone graft materials.