Samarium doped carbon dots for near-infrared photo-therapy

Photo-assisted tumor therapy, encompassing photodynamic therapy (PDT) and photothermal therapy (PTT), has garnered considerable attention as a promising approach for tumor treatment owing to its stimuli-responsive nature and noninvasive characteristics. Carbon dots (CDs) have recently emerged as a novel type of nanomaterial with great potential in the field of anticancer therapy. However, the development of multifunctional CDs nano-platforms that integrate multiple therapeutic performance remains a challenge, especially in near-infrared (NIR) window. In this study, we synthesized samarium-doped carbon dots (Sm/CDs) via a one-step hydrothermal process for fluorescence imaging guided PTT/PDT in NIR-II window. Sm/CDs demonstrated remarkable absorption and emission properties in the NIR region, enabling efficient generation of heat energy, superoxide (•O₂^–) and hydroxyl radicals (•OH) under NIR irradiation. The photothermal conversion efficiencies of Sm/CDs reached up to 34.12 % and 24.38 % when exposed to 808 nm and 1060 nm wavelengths, respectively. Moreover, long-term toxicity experiments conducted in vivo as well as fluorescence experiments confirmed the potential of such functional CDs for fluorescence imaging and excellent biocompatibility. It is noteworthy that the tumor is nearly eradicated when exposed to either 808 nm or 1060 nm, demonstrating significant efficacy in both scenarios. This study provides a multifunctional CDs nano-platform that offers a promising bimodal phototherapeutic strategy to enhance the synergistic treatment of tumors through PDT and PTT.