Abstract This work introduces a comparative study on the use of two layered clays, a natural Wyoming montmorillonite (commercialized as Cloisite®Na; Mt) and a synthetic hectorite (commercialized as Laponite® XLG; Lap), to encapsulate metformin (MF), which is the most widely used oral drug for the treatment of type II diabetes. The aim was the evaluation of the suitability of the synthetic Lap clay as substrate for the controlled release of MF in comparison to the montmorillonite clay previously studied, in view to dispose of a convenient and well-regulated clay-based component for pharmaceutical formulation production. The combination of molecular modeling and experimental characterization techniques, such as FTIR, XRD, CHN chemical analysis and EDX, allowed us to study the adsorption process and the final molecular arrangement of MF in the interlayer space of the two silicates. The intercalation of MF in both clays follows an ion-exchange mechanism that leads to a basal spacing increase of 0.36 nm and 0.40 nm for the Lap-MF and Mt-MF systems, respectively, and the intercalated amount of MF matches the cation exchange capacity of each clay. Calculations at molecular level showed thermodynamically favorable systems produced by cation exchange reaction, where the MF species form a monolayer in the interlayer of both clays. In view to the application of these materials as delivery systems of MF, the release of the drug from Lap-MF and Mt-MF intercalation compounds was evaluated in pH conditions that simulate those of the gastrointestinal tract. Interestingly, Lap-MF allows a complete release of the loaded drug, guaranteeing the possibility of reaching an efficient drug delivery system. However, the large MF release in acid medium in both systems makes necessary a further encapsulation of the intercalation compound in a protective polymer matrix to increase the delivery in the intestine. Promising results were obtained using pectin as encapsulating matrix, leading to a gradual release of MF in the simulated gastrointestinal tract conditions.

中文翻译：

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二甲双胍嵌入层状粘土矿物的理论与实验研究

摘要 本工作介绍了使用两层粘土，即天然怀俄明州蒙脱石（商品名为 Cloisite®Na；Mt）和合成锂蒙脱石（商品名为 Laponite® XLG；Lap）来封装二甲双胍 (MF) 的比较研究。是治疗II型糖尿病最广泛使用的口服药物。目的是与先前研究的蒙脱石粘土相比，评估合成 Lap 粘土作为 MF 受控释放底物的适用性，以便处理方便且规范良好的粘土基成分用于药物制剂生产。分子建模和实验表征技术的结合，如 FTIR、XRD、CHN 化学分析和 EDX，允许我们研究吸附过程和 MF 在两种硅酸盐的层间空间中的最终分子排列。MF 在两种粘土中的插入遵循离子交换机制，导致 Lap-MF 和 Mt-MF 系统的基础间距分别增加 0.36 nm 和 0.40 nm，并且 MF 的插入量与阳离子交换容量相匹配每个粘土。分子水平的计算表明由阳离子交换反应产生的热力学有利系统，其中 MF 物质在两种粘土的夹层中形成单层。鉴于这些材料作为 MF 递送系统的应用，在模拟胃肠道的 pH 条件下评估了药物从 Lap-MF 和 Mt-MF 嵌入化合物中的释放。有趣的是，Lap-MF 允许完全释放装载的药物，保证达到有效药物输送系统的可能性。然而，两种系统中酸性介质中的大量 MF 释放使得有必要将嵌入化合物进一步封装在保护性聚合物基质中，以增加肠道中的递送。使用果胶作为封装基质获得了有希望的结果，导致 MF 在模拟胃肠道条件下逐渐释放。