金纳米粒子对黑色素瘤细胞的重离子辐射增敏效应研究

采用配体交换法合成了粒径15 nm左右的11-巯基十一烷酸包被的金纳米粒子（mAuNPs），使用透射电镜和纳米粒度电位仪对合成后的金纳米粒子进行了表征，然后用MTT法检测了mAuNPs对体外培养小鼠黑色素瘤B16-F10细胞的毒性。在传能线密度（LET）为50 keV/μm的碳离子束照射下，利用香豆素-3-羧酸（3CCA）作为荧光探针检测mAuNPs对水溶液中羟自由基的增强效应、二氯荧光素双醋酸盐（DCFHDA）检测mAuNPs对细胞内活性氧（ROS）的增强效应、克隆形成法检测mAuNPs对B16-F10细胞的辐射增敏效应。实验结果表明:mAuNPs对小鼠黑色素瘤B16-F10细胞基本无毒；mAuNPs对水溶液中的羟自由基产额增强为1.08~2.95倍；在共培养浓度为5 μg/mL情况下mAuNPs增加了胞内活性氧水平，mAuNPs在10%细胞存活水平下的辐射增敏比（SER）为1.15。因此，mAuNPs在黑色素瘤细胞中展现出对重离子的辐射增敏效应。

Radiosensitizing Effect of Gold Nanoparticles on Melanoma Cells Under Heavy Ion Irradiation

Gold nanoparticles coated with 11-mercaptoundecanoic acid (mAuNPs) in diameter of 15 mm were synthesized using the ligand exchange method. The synthesized gold nanoparticles mAuNPs were characterized by transmission electron microscopy and Zetasizer. Then, the MTT assay was used to evaluate the toxicity of mAuNPs to mouse melanoma B16-f10 cells. All subsequent irradiation experiments were performed under a carbon ion beam with a linear energy transfer (LET) value of 50 keV/μm. First, coumarin-3-carboxylic acid (3-CCA) was used as a fluorescent probe to detect the radiation enhancement effect of mAuNPs on hydroxyl radicals in aqueous solution. Second, dichlorofluorescein diacetate (DCFH-DA) was used to evaluate the radiation enhancement effect of mAuNPs on intracellular reactive oxygen species (ROS). More importantly, the radiosensitizing effect of mAuNPs on B16-F10 cells under irradiation with carbon ions was assessed with the clonogenic survival assay. Our experimental results showed that mAuNPs had nearly no toxicity to mouse melanoma B16-F10 cells. The yield of hydroxide radicals in ultra-pure water in the presence of mAuNPs after exposure to carbon ions increased by a factor of 1.08~2.95. At a co-culture concentration of 5 μg/mL, mAuNPs increased the level of intracellular ROS and the sensitizer enhancement ratio (SER) of mAuNPs in B16-F10 cells at 10% survival level was 1.15. Thus, our study indicates that mAuNPs have radiation enhancement effect on melanoma cells under heavy ion irradiation.