Research On Neuronal Growth Induced By Carbon Nanotube-Functional Self-Assembly Peptide Conductive Hydrogel In Combination With Electrical Stimulation

Objective: Neuronal cells have electroactivity,and electrical stimulation therapy has been widely used in the recovery process after nerve injury.It is a feasible strategy to create a microenvironment for neuronal growth based on biomaterials combined with exogenous electrical stimulation(ES).However,the development of biomaterials with specific responses still remains a challenge.The purpose of this study is to design a novel hydrogel with conductive property,and biocompatibility,which is used to construct a good growth environment for neural cells.The effects on axonal growth and myelination have also been studied.Method:(1)We designed three functional self-assembly peptides(SAP): HG,GF,and HGF.The microstructure and mechanical properties of the hydrogels self-assembled by the three functional peptides were examined by circular dichroism(CD),atomic force microscope(AFM),and rotary rheometer.(2)The pristine carbon nanotubes(pCNT)were mixed with HG,GF and HGF to form SAP/pCNTs composites.The microstructures of SAP/pCNTs composites were examined by AFM,CD,scanning electron microscope(SEM),transmission electron microscope(TEM),Raman spectroscopy properties(Ram).The mechanical properties of SAP/pCNTs composites were examined by rotary rheometer.The electrochemical properties of SAP/pCNTs composites were examined by electrochemical workstation.(3)Immunofluorescence staining was employed to investigate dorsal root ganglion(DRG),growth within HGF/pCNTs and HGF hydrogels under ES.We also tested the expression level of DRG myelin basic protein m RNA by Q-PCR.(4)IMARIS software was used to construct a visualized microscopic 3D structure to observe the impact on DRG,and the neurite could be observed directly.Results:(1)Three functional self-assembly nanofiber hydrogels(HG,GF and HGF)were successfully synthesized.(2)pCNTs were surface-modified by HG,GF and HGF,forming SAP/pCNTs composite hydrogel.The loading of pCNTs reached to 13.7%,showing good injectability and electrochemical properties.(3)Cell immunofluorescent staining results showed that HGF/pCNTs composite hydrogel combined with ES were conducive for the migration of Schwann cells(SC)and axonal growth.(4)Further reconstruction studies showed that there were close relations between the Schwann cells and the neurites.Conclusion: The self-designed functional hydrogel and pCNT formed SAP/pCNTs composites with excellent physical and chemical properties,good injectability,electrochemical property and biocompatibility,and can promote DRG neurite growth as well as the formation of remyelination in combination with ES.