Functional Nanorealgar Quantum Dots with Aggregation-Induced Emission Enhancement for Tumor Neovascular-Targeted Theranostics

Realgar, a traditional Chinese medicine, has notable antitumor activity and can be used in various hematologic tumor and solid tumor therapies in a wide range of clinical applications. Nanosized realgar possesses higher surface activity and enhanced therapeutic effects on cancer cells compared with those of bulk realgar. In this study, we reported the design of high-performance nanorealgar quantum dots (NR QDs) with aggregation-induced emission enhancement of crystal units (CUs) with the addition of hydrochloric acid. The enhanced fluorescence characteristics of NR QDs are associated with an optimized crystal structure obtained by accelerating the growth process of NR CUs in which the smaller NR CUs facilitate a self-assembling arrangement and a complete structural optimization process, ultimately forming regular crystallization with a size quantization effect. To improve the theranostic efficiency of NR QDs, we synthesized NR QDs coupled with a tripeptide of arginine-glycine-aspartic acid (RGD) with tumor neovascular targeting. We intravenously injected NR@RGD QDs into BALB/c mice bearing a subcutaneously transplanted breast tumor (4T1). Our results indicate that functional NR@RGD QDs are effective chemotherapeutic drugs that can anchor into the tumor endothelial cells through an active targeting effect, inhibit the angiogenesis in the tumor, and eventually "cut-off" the nutrient-rich blood supply to the tumor. This promising antiangiogenesis therapeutic strategy induces NR@RGD QDs to penetrate tumor-fenestrated vascular networks and has potential clinical value.