a School of Pharmacy and Life Sciences , Robert Gordon University , Garthdee Road , Aberdeen , UK.
Drug Dev Ind Pharm. 2019 Jan;45(1):67-75. doi: 10.1080/03639045.2018.1517776. Epub 2018 Sep 25.
A significant barrier to oral insulin delivery is its enzymatic degradation in the gut. Nano-sized polymer-insulin polyelectrolyte complexes (PECS) have been developed to protect insulin against enzymatic degradation. Poly(allylamine) (Paa) was trimethylated to yield QPaa. Thiolation of Paa and QPaa was achieved by attaching either N-acetylcysteine (NAC) or thiobutylamidine (TBA) ligands (Paa-NAC/QPaa-NAC and Paa-TBA/QPaa-TBA thiomers). PEC formulations were prepared in Tris buffer (pH 7.4) at various polymer: insulin mass ratios (0.2:1-2:1). PECS were characterized by %transmittance of light and photon correlation spectroscopy. Insulin complexation efficiency and enzyme-protective effect of these complexes were determined by HPLC. Complexation with insulin was found to be optimal at mass ratios of 0.4-1:1 for all polymers. PECS in this mass range were positively-charged (20-40 mV), nanoparticles (50-200 nm), with high insulin complexation efficiency (>90%). Complexation with TBA polymers appeared to result in disulfide bridge formation between the polymers and insulin. In vitro enzymatic degradation assays of QPaa, Paa-NAC, and QPaa-NAC PECS showed that they all offered some protection against insulin degradation by trypsin and α-chymotrypsin, but not from pepsin. QPaa-NAC complexes with insulin are the most promising formulation for future work, given their ability to offer protection against intestinal enzymes. This work highlights the importance of optimizing polymer structure in the delivery of proteins.
口服胰岛素传递的一个主要障碍是其在肠道中的酶降解。已经开发出纳米级聚合物-胰岛素聚电解质复合物（PECS）来保护胰岛素免受酶的降解。聚（烯丙胺）（Paa）被三甲胺化以得到 QPaa。通过连接 N-乙酰半胱氨酸（NAC）或硫代丁基脒（TBA）配体（Paa-NAC/QPaa-NAC 和 Paa-TBA/QPaa-TBA 硫醚）来实现 Paa 和 QPaa 的硫代化。在 Tris 缓冲液（pH 7.4）中以各种聚合物：胰岛素质量比（0.2:1-2:1）制备 PEC 配方。通过透光率和光相关光谱法对 PECS 进行表征。通过 HPLC 测定这些复合物的胰岛素络合效率和酶保护作用。发现所有聚合物的最佳胰岛素络合比例为 0.4-1:1。在该质量范围内的 PECS 带正电荷（20-40 mV），纳米颗粒（50-200nm），胰岛素络合效率高（>90%）。与 TBA 聚合物的络合似乎导致聚合物和胰岛素之间形成二硫键。QPaa、Paa-NAC 和 QPaa-NAC PEC 的体外酶降解试验表明，它们都能提供一些保护，防止胰蛋白酶和α-糜蛋白酶对胰岛素的降解，但不能防止胃蛋白酶的降解。QPaa-NAC 与胰岛素的复合物是未来工作最有前途的制剂，因为它们能够提供针对肠道酶的保护。这项工作强调了优化蛋白质传递中聚合物结构的重要性。
