Abstract：
As nanocarriers (NCs) can improve the solubility of drugs, prevent their degradation by gastrointestinal (GI) enzymes and promote their transport across the mucus gel layer and absorption membrane, the oral bioavailability of these drugs can be substantially enhanced. All these properties of NCs including self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), liposomes, polymeric nanoparticles, inorganic nanoparticles and polymeric micelles depend mainly on their surface chemistry. In particular, interaction with food, digestive enzymes, bile salts and electrolytes, diffusion behaviour across the mucus gel layer and fate on the absorption membrane are determined by their surface. Bioinert surfaces limiting interactions with gastrointestinal fluid and content as well as with mucus, adhesive surfaces providing an intimate contact with the GI mucosa and absorption enhancing surfaces can be designed. Furthermore, charge converting surfaces shifting their zeta potential from negative to positive directly at the absorption membrane and surfaces providing a targeted drug release are advantageous. In addition to these passive surfaces, even active surfaces cleaving mucus glycoproteins on their way through the mucus gel layer can be created. Within this review, we provide an overview on these different surfaces and discuss their impact on the performance of NCs in the GI tract.
摘要：
由于纳米载体（NCs）可以提高药物的溶解度，防止它们被胃肠道（GI）酶降解，并促进它们穿过粘液凝胶层和吸收膜的运输，这些药物的口服生物利用度可以显著提高。NCs的所有这些特性，包括自乳化给药系统（SEDDS），固体脂质纳米粒（SLN），纳米结构脂质载体（NLCs），脂质体，聚合物纳米颗粒，无机纳米粒子和聚合物胶束主要取决于它们的表面化学。特别是,与食物的互动，消化酶，胆汁盐和电解质，通过粘液凝胶层的扩散行为和吸收膜上的命运取决于它们的表面。生物惰性表面限制与胃肠液和内容物以及粘液的相互作用，可设计提供与GI粘膜紧密接触的粘合表面和吸收增强表面。此外，电荷转换表面直接在吸收膜和提供靶向药物释放的表面处将它们的ζ电位从负转变为正是有利的。除了这些被动表面，甚至在通过粘液凝胶层的途中切割粘液糖蛋白的活性表面也可以被创建。在这次审查中，我们对这些不同的表面进行了概述，并讨论了它们对胃肠道中NC性能的影响。
