Regulation Of Self-assembly Behavior Of Natural Collagen

Collagen is one of the most abundant proteins in the body.It is widely found in animal skin,bone,achilles tendon and other tissues.It is also one of the main components of processing wastes(fish skin,fish scales,beef achilles tendon,pig skin,etc.)in aquatic and animal husbandry industries.Due to its excellent biocompatibility,good biodegradability and low immunogenicity,natural collagen has been widely used in food science,medical cosmetology,biological materials and other fields.Self-assembly is one of the most important molecular behavioral characteristics of natural collagen.In vivo,collagen first forms microfibers through intermolecular hydrophobic action,hydrogen bond,ionic bond and other interactions,and the microfibers further aggregate into collagen fibers,thus providing strong biomechanical properties for skin,achilles tendon,valve and other tissues.In vitro,collagen with triple helix structure can also self-assemble to form collagen fiber or collagen gel under ideal concentration,temperature,p H and other conditions,and the products formed by self-assembly have significantly improved mechanical properties,thermal stability and biological properties.Therefore,the cognition of collagen self-assembly behavior and the construction of products have attracted great attention of scientists.In recent years,collagen fibers and collagen gels constructed by natural collagen self-assembly molecular behavior have been successfully applied in food science,biomaterials,medical cosmetology and other fields.However,different application fields of collagen have different requirements for its performance.Thus,it is very important to realize the regulation of collagen self-assembly molecular behavior and then regulate the performance of self-assembly products.Chirality is one of the basic properties of nature.From elementary particles,atomic nuclei,simple inorganic molecules and advanced biological macromolecules to human body structure,celestial bodies and the vast universe,matter is closely related to molecular chirality in its form and mode of motion.Numerous studies have shown that molecular chirality plays an important role in nucleic acid assembly,protein adsorption and cell adhesion,growth and proliferation.However,the regulatory role of molecular chirality in natural collagen self-assembly is poorly understood.In view of this,we investigated the regulation of molecular chiral behavior of natural collagen self-assembly molecules through the introduction ofD(L)-glutamate using bovine achilles tendon collagen as a template.The results showed that the self-assembly rate of bovine achilles tendon collagen in the presence of D-glutamate was faster than that of the corresponding L-glutamate system.At the same time,the self-assembled collagen fibers in the L-glutamate system exhibited a larger diameter.Furthermore,compared with L-glutamic acid system,collagen gel in D-glutamic acid system has better thermal stability and better mechanical properties.Nanometer size is one of the important properties of nanomaterials and the main factor affecting the properties of nanomaterials.Research shows that the nanometer size has an important impact on the application prospect and performance of nanomaterials in the fields of targeted drug delivery,biosensors,biological imaging and biological coding.However,the effect of nano-size on the self-assembly behavior of bovine achilles tendon collagen is not clear.Based on this,this part will take bovine achilles tendon collagen as the research object,and use the size adjustable of graphene(GO)to carry out the research on the influence of nano size on the self-assembly molecular behavior of collagen.The results showed that the introduction of GO inhibited collagen self-assembly,and the inhibition effect of GO was stronger in larger size.At the same time,the introduction of larger-sized GO resulted in collagen fibers with better thermal stability and better water absorption than those with smaller-sized GO.Furthermore,the collagen gel constructed by self-assembly of bovine achilles tendon collagen in the presence of small-sized GO has better mechanical properties.These results indicate that molecular chirality and nanometer size are expected to be new means for the regulation of molecular behavior and product properties of natural collagen self-assembly,and help to expand the application scope of collagen.