TiCT-enhanced photo-thermoelectric performance of BiTe in scaffold for improved osteogenic potential.

Photo-thermoelectric bismuth telluride (BiTe) generated electrical stimulation through photothermal-driven thermoelectric effect, offering promising potential for bone repair. Nevertheless, photo-thermoelectric conversion performance of BiTe was limited by low carrier mobility, high thermal conductivity, and rapid electron-hole pair recombination. To address this, BiTe@titanium carbide MXene (TiCT) heterojunction was constructed via electrostatic self-assembly, and subsequently incorporated heterojunction into poly-L-lactic acid scaffold fabricated by laser additive manufacturing. On one hand, TiCT possessed a high metal-like conductivity provided extra carrier transport channels, which effectively enhanced the carrier mobility. On the other hand, TiCT and BiTe formed the heterojunction induced phonon scattering effect, which significantly enhanced the interfacial thermal resistance and thus contributed to the decrease in thermal conductivity. Further, the built-in electric field of heterojunction facilitated electron-hole pair separation. Compared to BiTe, BiTe@TiCT exhibited a 45.25 % increase in carrier mobility and a 34.15 % reduction in thermal conductivity. Meanwhile, BiTe@TiCT exhibited superior electron-hole pair separation efficiency, and its current density even achieved a 96.23 % enhancement. The enhanced electrical stimulation effectively promoted cell proliferation rate, differentiation ability, bone morphogenetic protein, and osteogenic gene expression intensity by up-regulating the intracellular calcium ion concentration. Overall, this study proposed a new perspective for repairing bone defects using photo-thermoelectric scaffolds.