Study On The Conductive Composite Scaffold Of CS-g-PPy/hyaluronic Acid/functional Peptide For Nerve Tissue Engineering

Nerve cells are a kind of electrically active cells.When cultured on electrically active scaffolds in vitro,better growth,differentiation and neurite growth can be obtained.In this thesis,a composite scaffold with electrical activity and good biocompatibility was designed to provide a good microenvironment for promoting the growth of nerve cells,and the effects of electrical stimulation on neuronal axon growth and myelination were explored.In this paper,polypyrrole（PPy）was grafted onto chitosan（CS）to obtain conductive material,and was compounded with hyaluronic acid（HA）to form CS-g-PPy/HA composite scaffold.Zeta potential,FTIR,scanning electron microscopy,thermogravimetric analyzer,electrochemical workstation,resistivity tester,universal testing machine,such as testing instruments,explores the formation mechanism and characterization of the composite scaffold composite support structure,microstructure,thermal,electrochemical properties,mechanical properties,and the determination of the composite scaffold porosity,swelling degree and water retention.In order to further improve the biocompatibility of composite scaffolds,the effects of the addition of functional peptide（HGF）on the structure and properties of scaffolds were investigated in this paper.The cells were cultured in vitro and immunofluorescence staining was performed to observe the effect of CS-g-PPy/HA/HGF composite scaffold on dorsal root ganglia（DRG）with or without electrical stimulation（ES）,and the expression level of DRG-related m RNA was measured by Q-PCR.The results showed that the conductive material CS-g-PPy with different grafting rates was successfully prepared by chemical oxidation polymerization,and the CS-g-PPy/HA composite scaffold was formed with HA.Due to the different amount of graft of PPy,the properties of the composite scaffolds prepared are also different.When the mass ratio of CS and PPy was 5:1,the swelling degree,water retention rate,porosity and electrical conductivity of the composite scaffold formed were 7.29,1.41,72.31%and 3.49×10^-4 S/cm.The composite scaffold showed good electrochemical properties,and mechanical and thermal performance tests showed that it had good mechanical strength and thermal stability.Under these basic conditions,compared with the composite scaffold without HGF,the thermal stability of the CS-g-PPy/HA/HGF composite scaffold formed by adding HGF decreased,the electrochemical performance basically did not change,and the mechanical properties,swelling degree and water retention rate were improved.Immunofluorescence staining and Q-PCR results showed that the combination of CS-g-PPy/HA/HGF scaffold with ES promoted the growth and migration of dorsum root ganglion neurons（DRG）and Schwann cells（SC）,and promoted their myelination.This provides more possibilities for the application of conductive composite scaffolds in nerve tissue engineering.