Multifunctional carbon dots with near-infrared absorption and emission for targeted delivery of anticancer drugs, tumor tissue imaging and chemo/photothermal synergistic therapy

Cancer therapy faces considerable challenges related to improving treatment efficiency and overcoming damage to healthy cells. To address these concerns, a strategy for tumor microenvironment-induced cancer imaging/drug release and synergistic chemo–photothermal therapy (chemo/PTT) is proposed in this study. Carbon dots with near-infrared (NIR) absorption and emission, referred to as RCDs, were first prepared and covalently coupled with a Pt(iv) prodrug to form a complex, referred to as RCD–Pt(iv). The surface of the prepared complex was then coated with the polyethylene glycol–chitosan–2,3-dimethylmaleic anhydride polymer (PEG–CS–DA) to obtain a tumor-targeted multifunctional nanoprobe (RCD–Pt(iv)/PEG–CS–DA). When the nanoprobe RCD–Pt(iv)/PEG–CS–DA entered the tumor cells, the acidic environment of the tumor cells allowed rapid PEG–CS–DA hydrolysis and RCD–Pt(iv) release. High levels of glutathione (GSH) in cancer cells reduced Pt(iv) to Pt(ii) and released the RCDs, resulting in cancer tissue imaging and targeted Pt(ii) release. Meanwhile, Pt(ii) collected in the tumor tissues could realize targeted chemotherapy, and the RCDs in the tumor tissues absorbed light energy under NIR light irradiation to produce a large amount of heat to quickly eliminate cancer cells. Thus, cancer tissue imaging/targeted drug release and synergistic chemo/PTT were achieved simultaneously.