Sulfur-containing polypeptides, capable of reactive oxygen species (ROS)-responsive structural change, are one of the most important building blocks for the construction of polypeptide-based drug delivery systems. However, the relatively low ROS sensitivity of side-chain thioethers limits the biomedical applications of these polypeptides because they usually require a high concentration of ROS beyond the pathological ROS level in the tumor microenvironment. Herein, we report the design and synthesis of a selenium-containing polypeptide, which undergoes random coil-to-extended helix and hydrophobic-to-hydrophilic transitions in the presence of 0.1% H2O2, a concentration that is much lower than the ROS requirement for thioether. ROS-responsive micelles were thus prepared from the amphiphilic copolymer consisting of the hydrophilic poly(ethylene glycol) (PEG) segment and hydrophobic selenopolypeptide segment and were used to encapsulate doxorubicin (DOX). The micelles could be sensitively dissociated inside tumor cells in consequence of ROS-triggered oxidation of side-chain selenoether and structural change of the micelles, thereby efficiently and selectively releasing the encapsulated DOX to kill cancer cells. This work provides an alternative design of ROS-responsive polypeptides with higher sensitivity than that of the existing sulfur-containing polypeptides, which may expand the biomedical applications of polypeptide materials.
含
硫多肽能够发生活性氧(ROS)响应的结构变化,是构建
多肽药物输送系统的最重要组成部分之一。然而,侧链
硫醚对ROS的敏感性相对较低,限制了这些
多肽在
生物医学领域的应用,因为它们通常需要高浓度的ROS,超过肿瘤微环境中的病理ROS
水平。在此,我们报告了一种含
硒多肽的设计和合成,该
多肽在0.1%
H2O2(远低于
硫醚对ROS的要求)的存在下发生随机卷曲到扩展螺旋和疏
水到亲
水的转变。因此,由亲
水性聚
乙二醇(P
EG)段和疏
水性
硒多肽段组成的两亲性共聚物制备了ROS响应性胶束,并用于包裹
阿霉素(DOX)。由于侧链
硒醚的氧化和胶束的结构变化,胶束可以在肿瘤细胞内敏感地解离,从而有效地选择性地释放包裹的DOX来杀死癌细胞。这项工作提供了ROS响应性
多肽的另一种设计,其敏感性高于现有的含
硫多肽,这可能会扩大
多肽材料的
生物医学应用。