Preparation And Self-assembly Behavior Of Type I Collagen-based Composite Fibers

Collagen is an important renewable biopolymer in nature,which has excellent biocompatibility and biodegradability.However,it possesses several shortcomings,such as low mechanical strength,thermal degeneration and high degradation speed.In this work collagen fibers were fabricated by wet-spinning technique.To improve the mechanical performance of the collagen fibers,the crosslinking and blending modifications of the collagen fibers were carried out.In addition,self-assembly behavior of the collagen was studied,aiming at probing the forming rule of the collagen fibers and improving its comprehensive performance as well.The cross-linking of the collagen fibers with 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride(EDC)and N-Hydroxysuccinimide(NHS)was carried out.The optimum concentration of EDC/NHS was 10 mmol/L,and the optimum time was 12 h.The crosslinking mechanism of EDC/NHS was the reinforcement of interactions among collagen macromolecules without the formation of crosslinking bonds.Crosslinking could improve the thermal stability of the collagen fibers.The tensile strength of the crosslinked collagen fibers was improved by 38.89%compared with that before crosslinking.There was good compatibility between collagen and high molecular weight chitosan in a certain range because of the hydrogen bond interactions between them.The crystallinity of the composite fibers decreased with the increase of continuity of chitosan.When the content of chitosan was 20%,the tensile strength of the composite fibers was improved by 31.3%compared with the pure collagen fibers,and at this time their compatibility was the best.Cellulose nanocrystals(CNC)were used to enhance the mechanical properties of the collagen fibers.There were some hydrogen bonding interactions between collagen and CNC.Moreover,CNC could promote the nucleation and crystallization of the collagen macromolecules.The spinnability of the collagen/CNC composite fibers was improved with the addition of CNC.When the content of CNC was 0.8%,the tensile strength of the collagen/CNC composite fibers reached 1.08 cN/dtex,which was improved by 38.46%compared with the pure collagen fibers.Self-assembly behavior of the collagen occured when the collagen concentration reached a critical value.Collagen macromolecules formed oblique parallel lines on the mica surface under the atomic force microscope.With the increase of collagen concentration,the self-assembly morphology of the collagen macromolecules changed from parallel lines to network structures.Potassium ions had a certain role in promoting the self-assembly through the charge effect between the mica and collagen.With the increase of its concentration,the more obvious self-assembly behavior was observed.