University of Innsbruck, Institute of Pharmacy/Pharmaceutical Technology, CCB-Centrum of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck, Austria.
Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand.
Carbohydr Polym. 2015 Mar 6;117:577-584. doi: 10.1016/j.carbpol.2014.09.078. Epub 2014 Oct 7.
It was the aim of this study to investigate the effect of unmodified as well as thiolated anionic poly(acrylic acid) (PAA) and cationic chitosan (CS) utilized in free-soluble form and as nanoparticulate system on the absorption of the hydrophilic compound FD4 across intestinal epithelial cell layer with and without a mucus layer. Modifications of these polymers were achieved by conjugation with cysteine to PAA (PAA-Cys) and thioglycolic acid to CS (CS-TGA). Particles were prepared via ionic gelation and characterized based on their amount of thiol groups, particle size and zeta potential. Effects on the cell layer concerning absorption enhancement, transepithelial electrical resistance (TEER) and cytotoxicity were investigated. Permeation enhancement was evaluated with respect to in vitro transport of FD4 across Caco-2 cells, while mucoadhesion was indirectly examined in terms of adsorption behaviour when cells were covered with a mucus layer. Lyophilized particles displayed around 1000 μmol/g of free thiol groups, particle sizes of less than 300 nm and a zeta potential of 18 mV (CS-TGA) and -14 mV (PAA-Cys). Cytotoxicity studies confirmed that all polymer samples were used at nontoxic concentrations (0.5% m/v). Permeation studies revealed that all thiolated formulations had pronounced effects on the paracellular permeability of mucus-free Caco-2 layers and enhanced the permeation of FD4 3.0- to 5.3-fold. Moreover, polymers administered as particles showed a higher permeation enhancement than their corresponding solutions. However, the absorption-enhancing effect of each thiolated formulation was significantly (p<0.05) reduced when cells were covered with mucus layer. In addition, all formulations were able to decrease the TEER of the cell layer significantly (p<0.05). Therefore, both thiolated polymers as nanoparticulate delivery systems represent a promising tool for the oral administration of hydrophilic macromolecules.
本研究旨在探讨未经修饰和巯基化的阴离子型聚丙烯酸（PAA）以及阳离子壳聚糖（CS）在游离形式和纳米颗粒系统中对亲水性化合物 FD4 在有或无黏液层的情况下穿过肠上皮细胞层的吸收的影响。这些聚合物的修饰是通过与半胱氨酸接枝到 PAA（PAA-Cys）和 CS（CS-TGA）上的巯基乙酸来实现的。通过离子凝胶化制备颗粒，并根据其巯基含量、粒径和zeta 电位进行表征。研究了对细胞层的吸收增强、跨上皮电阻（TEER）和细胞毒性的影响。通过 Caco-2 细胞体外 FD4 的渗透实验评估了渗透增强作用，而通过细胞被黏液层覆盖时的吸附行为间接考察了黏膜黏附作用。冻干颗粒的游离巯基含量约为 1000 μmol/g，粒径小于 300nm，zeta 电位为 18 mV（CS-TGA）和-14 mV（PAA-Cys）。细胞毒性研究证实所有聚合物样品均以无毒浓度（0.5%m/v）使用。渗透研究表明，所有巯基化制剂对无黏液的 Caco-2 层的细胞旁通透性均有显著影响，并将 FD4 的渗透增强 3.0-5.3 倍。此外，与相应的溶液相比，聚合物作为颗粒给药时显示出更高的渗透增强作用。然而，当细胞被黏液层覆盖时，每种巯基化制剂的吸收增强效果显著降低（p<0.05）。此外，所有制剂均能显著降低细胞层的 TEER（p<0.05）。因此，作为纳米颗粒给药系统的两种巯基化聚合物均代表了一种有前途的用于亲水性大分子口服给药的工具。
