Effective photothermal chemotherapy with docetaxel-loaded gold nanospheres in advanced prostate cancer.

Background: Multifunctional gold nanospheres (MGNs)-loaded with docetaxel (MGN@DTX) were prepared and evaluated for therapeutic efficacy in nude mice bearing human prostate cancer xenografts. Methods: MGNs were prepared from PEGylated hollow gold nanospheres (HGNs) coated with folic acid and DTPTT chelate. Then, the effect of radiolabelled MGNs (Tc-99m-MGNs) on PC-3 cell apoptosis was assessed by flow cytometry, while their binding affinity to these cells was evaluated by cell binding assays. Next, biodistribution of Tc-99m-MGNs in xenograft bearing mice was measured by SPECT imaging. Also, DTX loading and release rates were estimated in MGN@DTX. Finally, in vitro stability in human serum and cytotoxicity of MGN@DTX were assessed, as well as their antitumor effect in xenograft bearing mice. Results: Tc-99m-MGNs (97.69% purity) showed good binding affinity to PC-3 cells, a specific recognition blocked by excess folic acid. Interestingly, MGN@DTX remained stable in human serum for 24 h, and exhibited higher mean cytotoxicity after NIR laser irradiation than free DTX. By day 28, tumor inhibition rates were higher in the MGN@DTX + NIR laser irradiation group compared with the DTX and MGNs + NIR laser irradiation groups. Conclusions: Loading chemotherapeutic drugs into MGNs can increase antitumor potency, reduce normal cell damage and decrease drug resistance, thus representing a promising approach for advanced prostate cancer treatment.