A liposomal formulation of gold nanoparticles (GNPs) and carboplatin, named LipoGold, was produced with the staggered herringbone microfluidic method. The radiosensitizing potential of LipoGold and similar concentrations of non-liposomal GNPs, carboplatin and oxaliplatin was evaluated in vitro with the human colorectal cancer cell line HCT116 in a clonogenic assay. Progression of HCT116 tumor implanted subcutaneously in NU/NU mice was monitored after an irradiation of 10 Gy combined with either LipoGold, GNPs or carboplatin injected directly into the tumor by convection-enhanced delivery. Radiosensitization by GNPs alone or carboplatin alone was observed only at high concentrations of these compounds. Furthermore, low doses of carboplatin alone or a combination of carboplatin and GNPs did not engender radiosensitization. However, the same low doses of carboplatin and GNPs administered simultaneously by encapsulation in liposomal nanocarriers (LipoGold) led to radiosensitization and efficient control of cell proliferation. Our study shows that the radiosensitizing effect of a combination of carboplatin and GNPs is remarkably more efficient when both compounds are simultaneously delivered to the tumor cells using a liposomal carrier.
Keywords: cancer treatment; chemoradiotherapy; gold nanoparticles; liposomes; low energy electrons; platinum drugs; radioenhancement; radiosensitization.