科研之友
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摘要
A novel drug delivery system based on arginine-glycine-aspartic acid (RGD)-conjugated graphene quantum dots (GQDs) was synthesized and utilized to load the antitumor drug doxorubicin (DOX) for targeted cancer fluorescence imaging as well as tracking and monitoring drug delivery without the need for external dyes. The inherent stable fluorescence of GQDs enables real-time monitoring of the cellular uptake of the DOX-GQDs-RGD nano-assembly and the consequent release of DOX. The release of DOX demonstrated strong pH dependence and implies hydrogen-bonding interaction between GQDs and DOX, an observation that suggests the possibility for GQDs serving as pH-sensitive drug carriers. As a nanocarrier, GQDs unlinked with DOX were nontoxic to U251 human glioma cells. Compared to free DOX, DOX-GQDs-RGD conjugates demonstrated substantial cytotoxicity to U251 glioma cells within a broad range of DOX concentrations. After applying the GQDs as drug carriers, the drug efficacy of DOX improved without concomitant DOX dosage increases. Cellular uptake results of DOX-GQDs-RGD conjugates indicate that not only DOX but also some GQDs penetrated into cell nuclei after 16 h of incubation. This enhancement combined with efficient nuclear delivery improved the cytotoxicity of DOX dramatically. This type of drug delivery system based on GQDs may find widespread applications in biomedicine.
