基于酶促交联与阈渗机制的胶原蛋白-纳米纤维素互穿聚合物网络(IPN)构建及成膜机理研究

In order to resolve the common problems (inferior strength, heat and humidity-sensitive, etc.) occurred in collagen film/casing and other edible packaging，based on the edibility nature of this film, from the point of view of using the natural substances as raw materials and bio-manufacturing as processing method, we attempt to apply the interpenetrating polymer network (IPN) concept into preparation and enhancing of collagen film. First, glutamine transaminase (TGase) is used to cross-link collagen to form the first network, wherein the crosslinking sites and efficiency will be estimated at the levels of molecular, micro and macro, as well as the influences of the external factors (Hofmeister sequence effect, pH and ionic strength, etc.), and some foreign substrates are added into the reaction system for further synergy of crosslinking with both the homologous and heterologous manners, consequently contributing to clarifying the mechanism of enzymatic cross-linking collagen and expanding the theory of TGase crosslinking to hard insoluble protein. After that, nano cellulose is introduced into the collagen network to construct the second structure, wherein the size effect of nano cellulose, percolation threshold mechanism, and phase compatibility are illustrated to enrich and perfect the reinforcement theory of nanocellulose in the biological macromolecular matrix. In the presenting process of constructing the interpenetrating network, many related researches are conducted alternatively, including the Zeta potential, particle size, rheological properties of the film-forming solution, mechanical properties and thermal stability of resulting composite film, with the aim of providing applied fundamental theory and potential improvement technology available for fully enhancing performance of food materials including collagen film.

针对胶原蛋白肠衣以及其它可食膜的共性问题（如强度差，不耐湿热等），本课题从其可食本质特性出发，以天然选材与生物制造的角度，采用互穿聚合物网络（IPN）概念，首先利用谷氨酰胺转氨酶（TGase）交联胶原蛋白形成第一网络，从分子、微观、宏观等水平上研究TGase对胶原蛋白的交联位点与效果和外界因素（Hofmeister序列效应、pH、离子强度等）的影响规律，以及利用外源物对其进行同源/异源交联增效，以阐明胶原蛋白的酶促交联机制并拓展TGase对不溶性硬蛋白的交联理论；同时，引入纳米纤维素（NC）构架第二网络，研究NC强化的尺寸效应、阈渗机制以及相融合，以丰富与完善NC在生物大分子基质中的强化机制理论。在以上IPN构建中，穿插研究成膜液稳态（Zeta电势、粒径分布和流变学特性），复合膜性能（机械强度、热稳定性等），从而为全面提升胶原蛋白膜等可食膜性能提供应用基础理论与技术改良手段。

针对胶原蛋白肠衣以及其它可食膜的共性问题（如强度差，不耐湿热等），本课题从其可食本质特性出发，以天然选材与生物制造的角度，采用互穿聚合物网络（IPN）概念，首先利用谷氨酰胺转氨酶（TGase）交联胶原蛋白形成第一网络，从分子、微观、宏观等水平上研究了TGase对胶原蛋白的交联位点与效果和外界因素（Hofmeister序列效应、pH、离子强度等）的影响规律，以及利用外源物对其进行同源/异源交联增效，阐明了胶原蛋白的酶促交联机制并拓展了TGase对不溶性硬蛋白的交联理论；同时，本课题引入了纳米纤维素（NC）构架第二网络，研究了NC强化的尺寸效应、阈渗机制以及相融合，对NC在生物大分子基质中的强化机制理论进行了丰富与完善。在以上IPN构建中，完成了穿插研究成膜液稳态（Zeta电势、粒径分布和流变学特性），复合膜性能（机械强度、热稳定性等）的研究，为全面提升胶原蛋白膜等可食膜性能提供应用基础理论与技术改良手段。