Development of a gel permeation chromatography method for the determination of molecular weight of bacterial cellulose and cellulose nanocrystals

从植物中提取的纤维素是最丰富的天然生物聚合物之一，在我们日常生活中的许多产品中都有应用。作为一种聚合物，其应用很大程度上取决于其分子量。凝胶渗透色谱法是测定分子量的标准方法之一，该方法要求聚合物溶解形成溶液。然而，强氢键阻碍纤维素在大多数溶剂体系中的溶解度，使其分子量测定困难。有几种溶剂体系是合适的。细菌纤维素，由细菌产生，以纳米纤维的形式，基本上是纯净的。由于其结晶度高，寻找合适的溶剂体系尤其具有挑战性。类似的问题也存在于纤维素纳米晶体中，它们也是高度结晶且难以溶解的。因此，尽管包括替代硬脑膜和闭塞性伤口敷料在内的医疗设备已经商业化，并且正在寻求许多潜在的生物医学和医疗设备应用，但细菌纤维素的确切分子量尚未确定。本项目将研究有效溶解细菌纤维素的溶剂体系，并开发一种测定细菌纤维素分子量的新方法。一系列溶剂系统结合GPC柱和GPC操作条件将进行研究。项目完成后，将制定使用GPC测定细菌纤维素和纤维素纳米晶体分子量的标准操作程序。该方法也可以应用于常规提取的植物纤维素。

Cellulose derived from plant sources is one of the most abundant natural biopolymer and finds applications in many products in our daily life. As a polymer, application is strongly dependent on its molecular weight. Gel permeation chromatography is one of the standard methods for molecular weight determination which requires the dissolution of the polymer to form a solution. However strong hydrogen bonding which hinders cellulose solubility in most solvent systems makes its molecular weight determination difficult. There a few solventsystems that are found to be suitable. Bacterial cellulose, produced by bacteria, is in the form of nanofiber that is substantially pure. Due to its high degree of crystallinity, it is especially challenging to find a suitable solvent system. Similar problem exists for cellulose nanocrystals which are also highly crystalline and difficult to dissolve. As a result, no definitive molecular weight has been determined for bacterial cellulose even though medical devices including replacement dura mater and occlusive wound dressing are already commercialized and many potential biomedical and medical device applications are being pursued. This project will investigate solvent systems for effective bacterial cellulose dissolution and develop a new procedure for molecular weight determination of bacterial cellulose. A range of solvent systems in combination with GPC columns and GPC operating conditions will be investigated. Upon completion of the project, a standard operating procedure using GPC for molecular weight determination of bacterial cellulose and cellulose nanocyrstals will be developed. This procedure can also be applied to conventionally derived plant cellulose.