Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria.
Center for Chemistry and Biomedicine, Department of Pharmaceutical Chemistry, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria.
Eur J Pharm Biopharm. 2019 Jun;139:161-167. doi: 10.1016/j.ejpb.2019.02.017. Epub 2019 Mar 19.
The aim of the study was to establish a novel type of covalently mucus-binding polymers by targeting selectively amino groups within mucus glycoproteins.
N-Hydroxysuccinimide (NHS) was attached to carboxylic groups of polyacrylic acid (PAA). The reaction was mediated by the coupling reagent N,N'-dicyclohexylcarbodiimide (DCC) achieving polymeric NHS esters being able to form amide bonds with free amino groups. The chemical structure of the obtained conjugates was characterized via FTIR- and UV spectroscopy. Reactivity towards mucosal amino groups was evaluated UV spectrometrically upon addition of L-glycine. Furthermore, tensile force evaluations on intestinal mucosa as well as rheological experiments with mucus were performed in order to prove mucoadhesive potential.
Depending on the amount of NHS added to the synthesis, coupling rates of 876 to 1820 µmol NHS per gram polymer were obtained. Kinetic studies of amide bond formation showed a substrate dependent reaction velocity. Rheological synergism of PAA-NHS was proven by a 7.9-fold increased mucus viscosity compared to the control polymer. In further mucoadhesion studies PAA-NHS showed a 5.5-fold improved adhesion time compared to unmodified PAA. Tensile force evaluation confirmed these results with a 1.7-fold higher maximum detachment force (MDF) and 2.7-fold increased total work adhesion (TWA) for PAA-NHS compared to the unmodified control polymer.
The results of the present study provide strong evidence that coupling NHS to polymers could be a promising tool for the development of novel mucoadhesive excipients.
本研究旨在通过靶向黏蛋白糖蛋白中的氨基来建立一种新型的共价黏附聚合物。
N-羟基琥珀酰亚胺（NHS）与聚丙烯酸（PAA）的羧基相连。反应由偶联试剂 N，N'-二环己基碳二亚胺（DCC）介导，使聚合 NHS 酯能够与游离氨基形成酰胺键。通过傅里叶变换红外光谱（FTIR）和紫外光谱（UV）对所得缀合物的化学结构进行了表征。通过加入 L-甘氨酸的紫外光谱法评估了对黏膜氨基的反应性。此外，还进行了肠黏膜的拉伸力评估以及与黏液的流变学实验，以证明其黏膜黏附潜力。
根据合成中添加的 NHS 量，得到了 876 至 1820µmol NHS/克聚合物的偶联率。酰胺键形成的动力学研究表明反应速度取决于底物。与对照聚合物相比，PAA-NHS 的流变协同作用使黏液黏度增加了 7.9 倍。在进一步的黏膜黏附研究中，与未修饰的 PAA 相比，PAA-NHS 显示出 5.5 倍改善的黏附时间。拉伸力评估结果表明，与未修饰的对照聚合物相比，PAA-NHS 的最大分离力（MDF）提高了 1.7 倍，总黏附功（TWA）提高了 2.7 倍。
本研究结果为 NHS 与聚合物偶联可能成为开发新型黏膜黏附赋形剂的有前途的工具提供了有力证据。
