RGD peptide-modified fluorescent gold nanoclusters as highly efficient tumor-targeted radiotherapy sensitizers.

Radiotherapy is a leading treatment approach of cancer therapy. While it is effective in killing tumor cells, it can also cause serious damage to surrounding normal tissue. Targeted radiotherapy with gold nanoparticle-based radiosensitizers is actively being investigated, and considered as a promising means to enhance the efficacy of radiotherapy against tumors under a relatively low and safe radiation dose. In this work, we report a green and one-step strategy to synthesize fluorescent gold nanoclusters by using a commercialized cyclic arginine-glycine-aspartic acid (c(RGDyC)) peptide as the template. The nanoclusters inherit special properties of both the Au core (red/NIR fluorescence emission and strong radiosensitizing effect) and c(RGDyC) shell (active cancer cell-targeting ability and good biocompatibility), and can be applied as fluorescent probes to stain αvβ3 integrin-positive cancer cells, as well as radiosensitizing agents to boost the killing efficacy of radiotherapy. Our data suggest that the as-designed gold nanoclusters have excellent biocompatibility, bright red/NIR fluorescence, active tumor targeting property, and strong radiosensitizing effect, making them highly promising towards potential clinical translation.