Preparation and characterization of three-dimensional porous bioelectrets and study on bone repair in osteoporosis

Bone tissue possesses inherent electroactivity that is physiologically associated with osseous repair processes. Electret materials, which are capable of maintaining stable surface charges without external power, offer novel opportunities for in situ electrical stimulation therapies. This study fabricated a three-dimensional porous microcarrier bioelectret that combines polarized electret effects with naringin (NG) delivery to enhance bone regeneration in osteoporotic zebrafish. The microcarrier was prepared through in situ dopamine polymerization on nano-hydroxyapatite (nHAP@PDA), followed by integration with chitosan (CS) matrix, and was finalized with charge implantation via high-voltage polarization. The optimized 1 mg nHAP@PDA/CS (1nHAP@PDA/CS) formulation exhibited interconnected pores with high porosity. The surface charge density reached 105.2 nC/m² post-polarization and retained 12.4 nC/m² after 14 days. In rat bone mesenchymal stem cells (rBMSCs) culture, NG-loaded electrets (NG/nHAP@PDA/CS) increased ALP expression compared to nHAP@PDA/CS microcarriers. In the osteoporotic zebrafish model, NG/nHAP@PDA/CS electrets demonstrated therapeutic effects: The spinal calcein staining area showed enhancement at 8 days post-treatment, and skull mineralization, as quantified by alizarin red S staining, expanded. Treated zebrafish exhibited improved locomotion capacity, with increased swimming velocity and extended travel distance. These findings demonstrate the potential of NG/nHAP@PDA/CS electrets for bone regeneration applications.