The Study Of Self-Assembled Structure Of Collagen And Its Specific Ions Effect

In recent years, collagen has attracted considerable attention in food industries,leather making process, biomedical materials and cosmetics applications, because ofits superior properties like biocompatibility, biodegradable, non-toxic and antigenicity.In order to further develop and exploit the abundant natural resource of collagen, andapply to relevant materials, it is need to further improve and enhance theirperformance such as strength characteristics. Controlling of collagen moleculeassembly on the nanoscale has positive significance on the materials characteristicsand its applications. Thus many reseachers have been attracted to investigate thestructure of collagen molecule and the process of collagen self-assembly. Currently,most studies of collagen assembly focused on collagen concentration, duration, pH,electrolyte, substrate, etc. However, there are little studies focused on metal ions ordispersion medium, which actually influence the assembly of collagen. Moreover,specific anions effect has almost been neglected. In this work, we investigated theassembly of collagen in different dispersion medium. Many different metal salts wereemployed in our research to study specific ions effect on collagen assembly. The maincontents of the study are as follows:1. Effect of different dispersion medium. AFM was used to study the structure ofcollagen assembly. We have investigated collagen assemblies changing with differentdispersion by controlling the concentration of collagen in0.2mol/L acetic acid,ultrapure water or0.2mol/L phosphate buffered saline. Collagen membrane wasobtained and grown with increased concentration in acetic acid dispersion. Collagenfibrils was obtained and grown with increased concentration in PBS. This research ishelp for our further studies about specific ions effect on collagen assembly.2. Specific anions effect in the process of collagen assembly on mica. We haveinvestigated anions effect on collagen assembly for the first time, employing differentsalts such as chloride, sulphate and acetate. Hoffmeister anions series was employedfor specific explanations. Cl-is the typical chaotropic ion, tending to act as thecollagen denaturant and increasing collagen solubility. In this case, collagenmolecules assembled on mica in a different pattern. In our experiment, both sulphateand acetate ion are kosmotropes, but collagen assemblies with them were different. 3. Various metal ions were used for the collagen assembly mediating, such asCo²⁺, Ag⁺, Mg²⁺, Zn²⁺and Ni²⁺. Collagen network with uniform mesh structure wereassembled on mica surface by using cobalt acetate, and we investigated thedependence of collagen mesh structure on cobalt concentration. Besides, well-orderedcollagen fibrils were also obtained in the presence of Mg²⁺, Zn²⁺and Ni²⁺. Therelationship between ions strength and collagen assemblies was also studied. Collins’conception was considered to interpret the interactions between different ions andcharged groups.