Carbon dot/WS2 heterojunctions for NIR-II enhanced photothermal therapy of osteosarcoma and bone regeneration

Abstract

Osteosarcoma as an aggressive malignant neoplasm is commonly treated by surgical resection, chemotherapy, and radiotherapy, but surgery induces bone defects and chemo/radiotherapy causes severe systemic toxicity. We have designed a novel low-toxic bifunctional 0D/2D heterojunction (HJ) that can be used to generate effective photothermal effects in the second NIR window (NIR-II, 1000–1350 nm) for simultaneous osteosarcoma treatment and bone regeneration. To construct this 0D/2D nanostructure, biocompatible, positively charged NIR-II-responsive carbon dots (CDs) were synthesized by an ultrafast microwave-assisted hydrothermal method, followed by electrostatically driven assembly on both sides of negatively charged WS2 nanosheets. We found that the HJs exhibited enhanced NIR-II absorption and photothermal conversion efficiency. Due to the deep-tissue penetration ability of 1064 nm laser, complete osteosarcoma ablation was realized at a low power density even when being covered by a 10-mm-thick additional tissue. Furthermore, osteogenic differentiation was remarkably enhanced by mild photothermal effects of CD/WS2 HJs, which significantly up-regulated bone-related gene expressions, particularly, heat shock protein expression. Designed CD/WS2 HJs can be used in osteosarcoma treatment and bone-tissue engineering.