Comparative analysis of gold nanoparticles coated with various surface-coatings on radiosensitization of melanoma

This study investigated the radiosensitizing effects of gold nanoparticles (AuNPs) with various surface-coatings under X-ray irradiation through in vitro and in vivo condition to optimize surface-coating selection for enhanced radiosensitization. Citrate-coated AuNPs (cAuNPs), glutathione-coated AuNPs (gAuNPs).11-mercapto-undecanoic acid-coated AuNPs (mAuNPs), thiopronin-coated AuNPs (tAuNPs), 1-thio-b-D-Glucose tetraacetic acidcoated AuNPs (tgAuNPs) and polyethylene glycol-coated AuNPs (pAuNPs) with the same 15-nm gold core, were synthesized. In vitro experimental data on detection of hydroxyl radicals in aqueous solution and cellular uptake excluded tAuNPs, tgAuNPs, and pAuNPs from further cellular experiments. At a fixed cellular uptake of cAuNPs, gAuNPs, and mAuNPs of approximately two pg/cell in melanoma cells, gAuNPs showed the most obvious radiosensitization with a sensitizer sensitization ratio of 1.30 based on the clonogenic survival assay. In vivo experiments demonstrated that these three AuNPs significantly inhibited tumor growth and extended the survival of tumor-bearing mice. Further investigations revealed that AuNPs significantly elevated apoptosis in mouse tumor tissues, overexpressed BAX, and Caspase-3, and down-regulated Bcl2 proteins. The findings indicate that AuNPs enhanced tumor cell apoptosis through the mitochondrial apoptotic pathway when combined with radiation, highlighting their significant role in radiosensitization. Therefore, the type of AuNP surfacecoating affected its radiosensitizing ability and these AuNPs are beneficial for the radiotherapy of melanoma.