Auger electrons (AEs) are very low-energy electrons emitted by radionuclides such as I-125 (125I). This energy is deposited across a small distance (<0.5 μm), resulting in high linear energy transfer that is potent for causing lethal damage to cancer cells. Thus, AE-emitting radiotherapeutic agents have great potential for cancer treatment. In this study, thermosensitive liposomes (TSLs) encapsulating 125I-labeled doxorubicin (DOX) derivatives were developed for Auger electron therapy, targeting the DNA of cancer cells. A radioiodinated DOX derivative [125I]5 highly accumulated in the nuclei of cancer cells and showed potent cytotoxicity against Colon 26 cancer cells by AEs. Subsequently, [125I]5 was loaded into the TSLs with high encapsulation efficiency. Potent release of [125I]5 from TSLs was achieved with heating, whereas a decreased release was observed without heating. Furthermore, TSLs encapsulating [125I]5 showed a high uptake in the nuclei at 42 °C for 1 h. We supposed that [125I]5 was released by heating at 42 °C and accumulated in the nuclei in the cells. These results suggest that the combination of TSLs encapsulating [125I]5 and hyperthermia is an effective cancer therapy.
奥杰电子(AEs)是 I-125(125I)等放射性核素发射的能量极低的电子。这种能量在很小的距离(0.5 微米)内沉积,产生高线性能量转移,可对癌细胞造成致命损伤。因此,发射 AE 的放射治疗剂在癌症治疗中具有巨大的潜力。在这项研究中,研究人员开发了包裹125I标记的多柔比星(DOX)衍生物的热敏脂质体(TSLs),用于奥杰电子治疗,靶向癌细胞的DNA。放射性碘化 DOX 衍生物[125I]5 在癌细胞核内高度聚集,并通过 AEs 显示出对结肠 26 癌细胞的强大细胞毒性。随后,[125I]5 以极高的封装效率被载入 TSL。在加热的情况下,[125I]5 能从 TSLs 中有效释放,而在不加热的情况下,释放量则有所减少。此外,封装了[125I]5 的 TSL 在 42 °C、持续 1 小时后在细胞核中显示出较高的吸收率。这些结果表明,封装了[125I]5的TSL与热疗相结合是一种有效的癌症疗法。