Mucus is a highly hydrated viscoelastic gel present on various moist surfaces in our body including the eyes, nasal cavity, mouth, gastrointestinal, respiratory and reproductive tracts. It serves as a very efficient barrier that prevents harmful particles, viruses and bacteria from entering the human body. However, the protective function of the mucus also hampers the diffusion of drugs and nanomedicines, which dramatically reduces their efficiency. Functionalisation of nanoparticles with low molecular weight poly(ethylene glycol) (PEGylation) is one of the strategies to enhance their penetration through mucus. Recently a number of other polymers were explored as alternatives to PEGylation. These alternatives include poly(2-alkyl-2-oxazolines), polysarcosine, poly(vinyl alcohol), other hydroxyl-containing non-ionic water-soluble polymers, zwitterionic polymers (polybetaines) and mucolytic enzymes. This review discusses the studies reporting the use of these polymers or potential application to facilitate mucus permeation of nanoparticles.

粘液是一种高度水合的粘弹性凝胶，存在于我们身体的各种潮湿表面上，包括眼睛，鼻腔，口腔，胃肠道，呼吸道和生殖道。它是防止有害颗粒，病毒和细菌进入人体的非常有效的屏障。然而，粘液的保护功能也阻碍了药物和纳米药物的扩散，从而大大降低了它们的效率。具有低分子量聚乙二醇（PEGylation）的纳米颗粒的功能化是增强其通过粘液渗透的策略之一。最近，探索了许多其他聚合物作为聚乙二醇化的替代方法。这些替代品包括聚（2-烷基-2-恶唑啉），聚肌氨酸，聚（乙烯醇），其他含羟基的非离子水溶性聚合物，两性离子聚合物（聚甜菜碱）和粘液溶解酶。这篇综述讨论了研究报告，这些研究报告了使用这些聚合物或潜在的应用来促进粘液渗透纳米颗粒。