pH-Responsive Nanoparticles Loaded with Graphene Quantum Dots and Doxorubicin for Intracellular Imaging, Drug Delivery and Efficient Cancer Therapy

Multifunctional core-shell structural nanoparticles (NPs) integrating of therapeutic and imaging modalities have presented superior prospects as drug delivery systems in the treatment of cancer. In this work, graphene quantum dots (GQDs) and doxorubicin (DOX) were encapsulated into the cores of PLGA (Poly (D, L-lactide-co-glycolide)) nanoparticles coated with bovine serum albumin via a double emulsion-solvent evaporation method to construct pH-responsive nanoparticles (DOX/PB and GQDs@DOX/PB NPs) with spherical core-shell structures. Subsequently, the cellular uptake, cytotoxicity and biocompatibility of the NPs were studied via in vitro experiments. The results demonstrated that DOX/PB NPs and GQDs@DOX/PB NPs exhibit high drug-loading efficiency and promote the release of DOX in a mild acidic microenvironment, which was expected to result in intelligent intracellular drug carriers. In vitro cytotoxicity measurements showed that all the NPs exhibit dose- and time-dependent cytotoxicity to the HeLa cells and PLGA NPs loaded with GQDs contribute to reducing cancer cell viability. Moreover, no significant difference in ROS level was determined during the endocytosis. In addition, all the NPs displayed excellent blood compatibility by hemolysis assay. These results demonstrate that pH-responsive NPs may be excellent candidates for efficient cancer therapy and in vivo biological imaging probes.