Constructing Bi2Te3-Ti3C2TX Schottky junction in PCL scaffold to amplify photo-thermal-electricity coupling effect for accelerating cell osteogenic differentiation

Bismuth telluride (Bi₂Te₃) exhibits great potential in thermoelectric therapy for bone defect repair due to its excellent thermoelectric conversion and electron-phonon decoupling properties. Nonetheless, its therapeutic efficacy is restricted by excessively low carrier mobility, insufficient body temperature gradient, and fast charge recombination. Herein, Bi₂Te₃ was bridged on the -O^- functional group of Mxene (Ti₃C₂T_x) using in-situ sedimentation to construct a Bi₂Te₃-Ti₃C₂T_X Schottky junction responsive to near-infrared (NIR) light. Then introduced into polycaprolactone (PCL) particles to prepare bone scaffold. Under NIR irradiation, Ti₃C₂T_X acts as a metalloid to generate coherent electron oscillations, converting light energy into lattice heat and providing sufficient temperature gradient for activating thermoelectric effects. Subsequently, Ti₃C₂T_X and Bi₂Te₃ form a Schottky junction to filter low-energy carriers, further increasing the average carrier energy to improve carrier mobility. Furthermore, the interface dipole field in heterojunctions can directionally drive electron-hole separation. Thermal imaging display scaffold possesses a temperature gradient of 30 °C. Results prove a significant optimization in carrier mobility and charge separation, resulting 45 % and 3.5-fold increase in Seebeck coefficient and current density respectively. The enhanced electrical signal can facilitate Ca²⁺ influx, synergizing photothermal sensitive HSP70 to promote actin cytoskeleton and cell proliferation. Moreover, current can upregulate the expression of BMP-2 and osteogenic related genes, increasing ALP and ARS by 2.5-fold to accelerate osteoblast differentiation.