Study On Nreparation And Nroperties Of Conductive Fiber Scaffold Materials

Peripheral nerve damage is a common and serious disease,each year millions of patients worldwide have suffered from peripheral nerve damage which may affect patients quality of life and bring heavy burden to individuals and society.How to prepare scaffold materials consistent with neurite re-physiological properties is a scientific issue that many researchers are concerned about.At present,research on neural tissue mainly focuses on several aspects such as scaffold structure,nerve factor and electrical signal.Simulate physical and electrical signals in body can enhance cell adhesion and proliferation,guide directed growth and migration of cells,and promote peripheral nerve regeneration and functional recovery.Based on material morphology and electrical properties,three different conductive fiber scaffold materials were prepared from biomaterials such as polyaniline(PANI),silk knitted fabric,graphene oxide(GO),poly(lactic-co-glycolic acid)(PLGA)and collagen.By controlling process parameters in electrostatic self-assembly,in-situ polymerization and electrospinning,optimal GO,aniline(ANI)and PANI concentration were selected.On this basis,different methods were used to prepare conductive fiber scaffold materials and their physicochemical properties such as surface morphology,fiber diameter and orientation,surface chemical composition,mechanical properties,hydrophilic properties and thermal properties were studies and characterized to provide a certain experimental basis and new research ideas for preparation of peripheral nerve regeneration scaffold.The main research contents and experimental conclusions are as follows:(1)Comparing electrical conductivity and surface morphology of PANI/silk knitted fabrics obtained by in-situ polymerization and of RGO/PANI/silk fiber knitted fabrics prepared by electrostatic self-assembly,a two-step electrostatic self-assembly method of "GO dipping-reduction" and "aniline polymerization in situ" was selected,and a conductive RGO/PANI/silk fiber knitted fabric was prepared by hydrogen bonding and electrostatic adsorption between amino,GO and PANI.The best GO/ANI concentration combination was selected by testing effects of a series of different GO/ANI concentrations on RGO/PANI/silk fabrics surface morphology and electrical conductivity.The research showed that when GO concentration was 1 g/L and the ANI was 0.4/0.6/0.8 mol/L,RGO/PANI/silk fabric has good electrical conductivity and conductivity stability which ranged from 0.62×10-3 to 1.72×10-3 S/cm,and cutting-stitching and different physical stress(tiling,folding,twisting)had little effect on scaffold conductive performance;Conductive silk fabric had evenly distributed PANI particles,good thermal stability,suitable mechanical properties that could provide good support for cell growth,but its degradation performance still needed to be improved;The conductive silk fabric had an ordered coil,fiber structure and a large pore size with an average pore diameter of 40-70 ?m.(2)PLGA nanofiber films with different mixing compositions were prepared by electrospinning technology and their basic properties were tested.On this basis,PANI coated nanofiber films with good conductivity were selected using in-situ polymerization by controlling ANI concentration.The research showed that PLGA blended fiber film had a smooth fiber surface and a uniform fiber diameter;Compared with pure PLGA fiber film,after blending MWCNT and GO,fiber fineness was reduced,the ultimate strength,Young's modulus and hydrophilic properties of fiber film were enhanced to some extent,in which PLGA/MWCNT had better fiber orientation,ultimate strength and Young's modulus;Accordingly,PLGA and PLGA/MWCNT fiber films were selected for aniline in situ polymerization,indicating that with increase of ANI concentration,fiber diameter increased,fiber surface was coated with a uniform and dense PANI particle,and conductivity showed a trend of rising first and then decreasing;When ANI concentration was 0.4 mol/L,electrical conductivity reached the maximum value,and electrical conductivity of PANI/PLGA fiber film was significantly larger than that of PANI/PLGA/MWCNT fiber film,which were 1.56×10-2 S/cm and 6.06×10-3 S/cm,respectively;Fiber film had excellent electrical and thermal stability.(3)Shell-core nanofiber film with PANI/PEO as shell layer and PLGA/collagen as core layer was prepared by coaxial electrospinning,and electrical conductivity was provided by shell layer,mechanical support and biocompatibility was provided by core layer.The concentration of PANI in shell solution was adjusted to study effect of PANI concentration on surface morphology and electrical conductivity of fiber film;Rotation speed of electrospinning receiving roller was changed to adjust fiber orientation of different fiber layers in film material.The results showed that surface of shell-core conductive fiber membrane was rough and had irregular PANI particles,which diameter and electrical conductivity were increased with increase of PANI concentration,and conductive fiber film had good conductivity stability and thermal stability which conductivity could be up to 4.69×10-4 S/cm;Fiber orientation and fiber pore diameter could be increased by increasing rotation speed of receiving roller;pore diameter of bottom fiber was significantly larger than that of upper layer;As PANI concentration increased,pore diameter of fiber film decreased,and gap between pore diameters of upper and lower layers decreasedIn summary,three different conductive fiber scaffold materials have good electrical conductivity and special fiber structure with its own advantages,that can be applied to preparation of peripheral nerve regeneration scaffold after further biological properties research.Through this study,it can not only provide a certain experimental basis for preparation of conductive fiber scaffold materials in peripheral nerve conductive scaffolds,but also provide a new research idea for design of nerve conductive scaffold.