Honeycomb sandwich-structured P(VDF-TrFE) membrane enhances bone regeneration through an ultrasonic resonance effect

A biomimetic electrical microenvironment is known to facilitate bone defect repair. Nevertheless, precise and non-invasive modulation of the in situ electrical microenvironment poses a formidable challenge. This study develops a poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) membrane with a precisely controlled porous structure. Ultrasonic stimulation is applied to induce Acoustic-Mechanic-Electric (AcME) conversion and regulate the membrane’s surface potential to modulate the in situ electrical microenvironment. When the ultrasound frequency aligns with the membrane’s inherent frequency, maximal electrical energy conversion occurs via the resonance effect, which generates the highest possible surface potential. The maximal AcME conversion is achieved by a 12 μm pore-sized P(VDF-TrFE) membrane with a resonance frequency of 40 kHz, resulting in the highest surface potential of -65.56 mV. Finite element modeling indicates that the deformation and stress of porous membranes are higher than that of non-porous membranes under the stimulation of ultrasound, yielding the highest surface potential. In vitro experiments and sequencing analysis show that the honeycomb sandwich-structured P(VDF-TrFE) membrane under the stimulation of the resonance ultrasound promoted osteogenic differentiation of rBMSCs through the PI3K-Akt signaling pathway. When the porous membranes are implanted to cover cranial defects, the bone defect repair is significantly enhanced under the stimulation of ultrasound compared with the non-porous membranes. This study establishes a new strategy for efficient AcME conversion on piezoelectric membranes and offers new insights into the applications of ultrasound-responsive piezoelectric materials for bone defect repair.