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[Display omitted] • A multifunctional nanoplatform (g-CPFD) based on g-C 3 N 4 quantum dots is synthesized. • The g-CPFD achieves chemo-photodynamic combination therapy in one system. • The g-CPFD exhibits folate receptor-mediated targeting ability. • The g-CPFD is traceable and exhibits pH-responsive release property. Graphitic carbon nitride quantum dots (g-CNQDs) have shown great potential in imaging, drug delivery and photodynamic therapy (PDT). However, relevant research on g-CNQDs for PDT or drug delivery has been conducted separately. Herein, we develop a g-CNQDs-based nanoplatform (g-CPFD) to achieve simultaneously imaging and chemo-photodynamic combination therapy in one system. A g-CNQDs-based nanocarrier (g-CPF) is first prepared by successively introducing carboxyamino-terminated oligomeric polyethylene glycol and folic acid onto the surface of g-CNQDs via two-step amidation. The resultant g-CPF possesses good physiological stability, strong blue fluorescence, desirable biocompatibility, and visible light-stimulated reactive oxygen species generating ability. Further non-covalently loaded doxorubicin enables the system with chemotherapy function. Compared with free doxorubicin, g-CPFD expresses more efficient chemotherapy to HeLa cells due to improved folate receptor-mediated cellular uptake and intracellular pH-triggered drug release. Furthermore, g-CPFD under visible light irradiation shows enhanced inhibition on the growth of cancer cells compared to sole chemotherapy or PDT. Thus, g-CPFD exhibits exceptional anti-tumor efficiency due to folate receptor-mediated targeting ability, intracellular pH-triggered drug release and a combined treatment effect arising from PDT and chemotherapy. Moreover, this nanoplatform benefits imaging-guided drug delivery because of inherent fluorescent properties of doxorubicin and g-CPF, hence achieving the goal of imaging-guided chemo-photodynamic combination treatments. [ABSTRACT FROM AUTHOR]

• A drug delivery system based on fluorescent MoS 2 QDs is synthesized. • PEGylated MoS 2 QDs has good physiological stability and is suitable for carrier. • The drug delivery system is traceable and exhibits pH-responsive release property. Since low pH value is widely observed in most of solid tumors, pH-responsive drug delivery system (DDS) can provide a general strategy for tumor-targeting therapy. In this work, a traceable and pH-responsive DDS (MoS 2 -PEG-DOX) based on MoS 2 quantum dots (MoS 2 QDs) is successfully developed by covalently grafting MoS 2 QDs with diamine-terminated oligomeric polyethylene glycol (PEG) and then loading with a fluorescent antineoplastic anthracycline drug, doxorubicin (DOX). The functionalization of MoS 2 QDs with PEG imparts the nanocomposite with strong blue photoluminescence, low cytotoxicity, and excellent physiological stability. The MoS 2 -PEG-DOX nano-assembly can be effectively taken up by U251 cells, and an accelerated DOX release is then triggered by intracellular acid condition, which in turn diminishing unwanted side effects derived by the incorporation of DOX into healthy cells. Meanwhile, the cellular uptake of the MoS 2 -PEG-DOX nano-assembly, consequent DOX release and the localization of nanocarrier can be real-time monitored due to the inherent stable fluorescence of MoS 2 -PEG and DOX. These findings demonstrate that MoS 2 -PEG-DOX will be promising for high treatment efficacy with minimal side effects in future therapy. [ABSTRACT FROM AUTHOR]