Piezo-metastructured arrays enhance osteoblast mitochondrial quality control to promote osseointegration under...

Titanium (Ti)-based implants often exhibit poor osseointegration in osteoporotic bone defects, primarily due to osteoporosis frequently accompanied by excessive reactive oxygen species (ROS), which induce mitochondrial oxidative stress within osteoblasts, leading to dysfunctional mitochondria. To address this challenge, a piezo-metastructured array composed of BaTiO₃ nanorods decorated with hydroxyapatite (HA) nanoparticles (termed as BTH array) was constructed on Ti, which can significantly enhance piezoelectric potential (PP) under low-intensity pulsed ultrasound (LIPUS) treatment. Based on the simulation results, the enhanced PP of BTH array under LIPUS arises from the effects of nanorod pattern induced acoustic impedance matching and the overlapping built-in electric field at BaTiO₃/HA interface. The elevated PP activates voltage-gated calcium channels in osteoblasts under osteoporosis mimicking conditions, allowing Ca²⁺ released from degraded HA to flux into cells and appropriately elevate mitochondrial calcium levels, thereby promoting ATP synthesis. The enhanced ATP synthesis supports cytoskeletal remodeling of cells, thereby triggering migrasome formation to eliminate damaged mitochondria and promote the fission of healthy ones. This process restores mitochondrial quality control, leading to the mitigation of mitochondrial oxidative stress and ultimately enhancing osseointegration of Ti-based implants in osteoporosis bone. Thus, piezo-metastructured array coating mediated ATP synthesis in osteoblasts under LIPUS represents a promising strategy to improve implant osseointegration under osteoporosis conditions.