Aptamer functionalised small gold nanorod-based nanoprobes: targeting EpCAM over-expressed cancer cells for photothermal therapy

Small gold nanorods (SGNRs) are beneficial for photothermal therapy owing to their exceptional properties such as high binding and internalization rate into cells, as well as efficient heat generation. We have functionalized small gold nanorods with SYL3C aptamer to target EpCAM-expressed cancer cells. A higher binding rate was observed in cancer cells with over-expressed EpCAM (PC3, FLO-1 and MCF-7) than the non-tumour cells (HEK293), indicating specific binding of the nanoprobes. Z-stack fluorescence microscopy analysis revealed that the nanoprobes bind to the cell membrane of FLO-1 and MCF-7 cancer cells. It was found that SYL3C nanoprobes of different sizes introduced more death in FLO-1 cells than in HEK293 cells and the death rate of FLO-1 treated with small gold nanorod-based SYL3C nanoprobe was significantly higher than that treated with large gold nanorod-based nanoprobes. These findings demonstrate an enhanced efficacy of aptamer functionalized small gold nanorods in photothermal therapy resulting from an increased affinity to EpCAM expressed cancer cells and the enhanced photothermal effect of the small gold nanorods, thus providing insight into the development of gold nanoprobes for efficient photothermal therapy of cancer.