Zwitterions consist of equal molar cationic and anionic moieties and thus exhibit overall electroneutrality. Zwitterionic materials include phosphorylcholine, sulfobetaine, carboxybetaine, zwitterionic amino acids/peptides, and other mix-charged zwitterions that could form dense and stable hydration shells through the strong ion-dipole interaction among water molecules and zwitterions. As a result of their remarkable hydration capability and low interfacial energy, zwitterionic materials have become ideal choices for designing therapeutic vectors to prevent undesired biosorption especially nonspecific biomacromolecules during circulation, which was termed antifouling capability. And along with their great biocompatibility, low cytotoxicity, negligible immunogenicity, systematic stability and long circulation time, zwitterionic materials have been widely utilized for the delivery of drugs and therapeutic genes. In this review, we first summarized the possible antifouling mechanism of zwitterions briefly, and separately introduced the features and advantages of each type of zwitterionic materials. Then we highlighted their applications in stimuli-responsive “intelligent” drug delivery systems as well as tumor-targeting carriers and stressed the multifunctional role they played in therapeutic gene delivery.

两性离子由等摩尔的阳离子和阴离子部分组成，因此表现出整体电中性。两性离子材料包括磷酸胆碱、磺基甜菜碱、羧基甜菜碱、两性离子氨基酸/肽以及其他混合电荷的两性离子，它们可以通过水分子和两性离子之间的强离子偶极相互作用形成致密且稳定的水合壳。由于其卓越的水合能力和低界面能，两性离子材料已成为设计治疗载体的理想选择，以防止循环过程中不需要的生物吸附，特别是非特异性生物大分子，这被称为防污能力。两性离子材料具有良好的生物相容性、低细胞毒性、可忽略的免疫原性、系统稳定性和较长的循环时间，已被广泛用于药物和治疗基因的递送。在这篇综述中，我们首先简要总结了两性离子可能的防污机理，并分别介绍了各类两性离子材料的特点和优点。然后我们强调了它们在刺激响应“智能”药物递送系统以及肿瘤靶向载体中的应用，并强调了它们在治疗基因递送中发挥的多功能作用。