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

Apatite-based bone graft materials are widely used for bone repair; however, their limited bioactivity and slow remodeling often hinder replacement by newly formed bone. Electrical surface polarization has emerged as a promising strategy for modifying the surface properties of apatite-based biomaterials without altering their chemical composition. This study investigated whether different degrees of electrical polarization produce distinct biological responses in apatite-based materials. Synthesized carbonate apatite (CA) was used for mechanistic in vitro evaluation, whereas a clinically relevant xenograft material was employed for in vivo validation. Material characterization confirmed the formation of B-type CA with a 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 with nonpolarized controls, with the strongest effects observed under higher polarization conditions. Increased resorption pit depth and volume further indicated enhanced osteoclast functionality. In vivo implantation of polarized xenograft materials into rat femoral defects resulted in significantly greater early bone formation and increased bone-material affinity than nonpolarized materials. Histological evaluation and affinity index analysis demonstrated more favorable early tissue responses under higher polarization conditions. These findings indicate that electrical surface polarization modulates osteoclast-material interactions and influences early bone healing responses in a polarization-dependent manner. Electrical polarization may therefore represent a useful surface functionalization strategy for apatite-based bone graft materials.