Significance of modified gold nanocages in photothermal therapy and radiosensitivity enhancement

Objective To investigate the significance of modified gold nanocages (GNCs) in photothermal therapy and radiosensitivity enhancement for murine mammary carcinoma 4T1 cells. Methods A molecule probe, CD44-PEG-GNCs, was constructed on the basis of GNCs. Inductively coupled plasma mass spectrometry (ICP-MS) and transmission electron microscopy (TEM) were used to analyze Au uptake by 4T1 cells. The cell counting kit-8(CCK-8) assay was used to determine the impact of the probe on the viability of 4T1 cells. The CCK-8 assay and the Hoechst/PI double staining were used to evaluate the photothermal killing effects of near infrared laser (NIR). The colony forming assay and the Hoechst/PI double staining were used to measure the viability of 4T1 cells after irradiation with 6 MV of X-ray. Results ICP-MS and TEM showed that 4T1 cells had an uptake of a large number of GNCs, in which the number of CD44-PEG-GNCs taken up by 4T1 was 3-4 times larger than that of PEG-GNCs. The cell toxicity assay revealed that in a certain range of concentration, GNCs showed little effect on the viability of 4T1 cells, which was reduced to 81.2% in 48 hours. The CCK-8 assay, the Hoechst/PI double staining, and the colony forming assay showed that after NIR irradiation and radiotherapy, large-scale apoptosis was induced in CD44-PEG-GNCs-contained tumor cells by photothermal therapy combined with radiotherapy, which had substantially better outcomes than other groups. Conclusions The GNC-based molecular probe actively targets 4T1 cells with little cytotoxicity, indicating that it enhances the sensitivity of tumor towards photothermal therapy and radiotherapy. Key words: Molecular probe; Photothermal therapy; Radiosensitivity; Breast neoplasms