Preparation And Biological Properties Of Heterogeneous Coaxial Collagen Fiber Materials

In recent years,tissue engineering technology and related research have developed rapidly.As the most representative tissue engineering materials,fiber or spinning materials have attracted wide attention from all walks of life.Due to its good biocompatibility,low immunogenicity,biodegradability and wide sources,and its unique fiber-forming properties,collagen has become an excellent raw material for fiber spinning materials.Common collagen-based coaxial fiber materials are often mixed with other different types of raw materials to construct the inner and outer layers,so as to make the finished materials have high biocompatibility of collagen-based materials and other materials.However,the introduction of other materials tends to increase the risk of immune rejection caused by non-biocompatibility,limiting the proliferation of grafted cells or tissue cells.Therefore,we tried to use two kinds of natural collagen with different structures and properties to construct a fibrous material with nuclear layer and shell layer.By controlling the preparation process and the internal performance difference between the two kinds of collagen,the differentiated performance of coaxial material in the body was realized,and it was used as a new functional material to guide the directional proliferation of tissue cells.The specific idea is to take bovine Achilles tendon collagen and grass carp collagen as raw materials to prepare homologous coaxial collagen fibers and heterologous coaxial collagen fibers,respectively.Among homologous coaxial fibers,differences in collagen concentration and ultraviolet(254 nm)external irradiation were used to amplify the differences in enzyme-resistant degradation performance between coaxial coaxial collagen fibers’ nuclear and shell layers,so as to realize the step-by-step degradation of collagen fibers in tissues.In the heterogeneous coaxial collagen fibers,the difference in the anti-enzyme degradation performance of bovine Achilles tendon collagen and grass carp collagen was utilized to realize the stepwise degradation.The main research contents and results are summarized as follows:(1)Preparation and characterization of self-assembled collagen uniaxial fiber:collagen fiber was prepared by wet spinning with high concentration of bovine Achilles tendon collagen hydrochloric acid solution and high concentration of PBS buffer solution as a fixed bath.The thermal stability and tensile properties of collagen fiber were optimized by adjusting the concentration of collagen stock solution andPBS.The results showed that the concentration of 20 mg/m L collagen solution and 30×PBS were the better conditions for the preparation of collagen fiber,and the results of sem analysis showed that the collagen fiber prepared by this method had a fibrotic self-assembled microstructure.On this basis,the effect of uv irradiation(254 nm)cross-linking on the properties of collagen filaments was investigated.The results showed that uv irradiation could enhance the thermal stability and enzyme degradation resistance of collagen filaments,but weaken their tensile properties.The results of the cell compatibility experiment showed that the collagen filaments had good cell compatibility and the ability to induce the directed growth of cells.Ultraviolet irradiation would weaken the ability of the collagen filaments to promote the proliferation of cells.The irradiation time of 5 minutes was considered as the appropriate irradiation time.(2)Preparation and characterization of coaxial coaxial collagen fiber: coaxial collagen fiber was successfully prepared by coaxial wet spinning with 20 mg/m L bovine Achilles tendon collagen as the shell layer and 2 mg/m L bovine Achilles tendon collagen as the core layer.The double-layer structure of coaxial collagen fiber was confirmed by sem and HE staining.On this basis,ultraviolet irradiation was further used to enhance the performance difference of coaxial collagen fiber core-shell double layers.The results showed that ultraviolet irradiation could enhance the thermal stability of coaxial collagen fiber and the difference of enzyme-resistant degradation performance between coaxial collagen fiber and shell layers,but weaken the tensile performance of coaxial collagen fiber.The results of paraffin embedding section experiment and laser confocal experiment of cell compatibility showed that NIH/3T3 fibroblasts could grow well in the shell and core layers of coaxial collagen fibers,and the cells could grow directionally along the coaxial collagen fibers..(3)Preparation and characterization of heterogeneous coaxial collagen fiber:heterogeneous coaxial collagen fiber was prepared by coaxial wet spinning with 20mg/m L bovine Achilles tendon collagen as the shell layer and 2 mg/m L grass carp collagen as the core layer.The results showed that the differences in the structure and performance of core-shell filaments could be further regulated by adjusting the preparation temperature.The turbidity test results indirectly proved that the double-layer structures of heterogenous coaxial collagen filaments prepared at 30℃all had fibrosis self-assembled microstructure.The results of in vitro enzymatic degradation experiments show that there are significant differences in the enzymaticdegradation resistance of the inner and outer layers of the heterologous coaxial filaments,which can realize the design of directionally induced regeneration structure for distributed degradation.The confocal analysis of cell compatibility showed that NIH/3T3 fibroblasts could grow well in the upper and lower surface and core of the heterogenous coaxial collagen fiber,and the frozen section experiment showed that the cells could grow directionally along the heterogenous coaxial collagen fiber,and the heterogenous coaxial collagen fiber had a good potential of inducing tissue oriented regeneration.