Thermoelectric Nanoheterojunction-Mediated\nMultiple\nEnergy Conversion for Enhanced Cancer Therapy

Electron–hole recombination and exogenous local\nhypoxia\nboth impede the effectiveness of thermoelectric tumor catalytic therapy.\nHere, a thermoelectric heterojunction (Pt-TiO<sub>2–<i>x</i></sub>/Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>-PEG) was developed to enhance charge carrier separation and\nalleviate tumor hypoxia. By incorporating titanium oxide with oxygen\nvacancies and platinum single atoms onto Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene, we not only improve the charge\nseparation efficiency but also prevent the recombination of positive\nand negative charges generated by the thermoelectric effect, leading\nto an increased production of reactive oxygen species (ROS). Furthermore,\nthe Pt SAs exhibited excellent catalase-mimicking (CAT-mimicking)\nactivity, catalyzing hydrogen peroxide to generate oxygen and alleviating\nthe hypoxic tumor microenvironment. Titanium oxide with oxygen vacancies\nalso serves as a sonosensitizer for sonodynamic therapy (SDT), enhancing\nROS generation in collaboration with thermoelectric catalytic therapy.\nMoreover, the photothermal conversion efficiency of Pt-TiO<sub>2–<i>x</i></sub>/Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>-PEG is augmented by Pt SAs with a surface plasmon resonance\neffect, further boosting CAT-mimicking activity and thermoelectric\ncatalytic therapy efficacy. This tumor-specific thermoelectric heterojunction\nintegrates thermoelectric therapy, SDT, and photothermal therapy,\ndemonstrating excellent tumor suppression efficacy both in vitro and\nin vivo. Therefore, this study offers highly valuable and promising\ninsights into utilizing photothermoelectric/ultrasound-mediated methods\nfor cancer treatment.