Preparation Of Xanthan Gum/Graphene Composite Hydrogel And Its Application In Spinal Cord Injury Repair

Spinal cord injury can interrupt the connection between the brain and peripheral nerves,resulting in partial or total loss of sensory and motor function and even life-threatening injuries.However,the self-healing ability of the spinal cord is limited,so the effective repair of the damaged spinal cord is still one of the difficult problems in the medical field.With the continuous development of tissue engineering,the use of spinal cord injury repair scaffolds to promote regeneration of the damaged spinal cord is now a very promising approach.For spinal cord injury repair scaffolds,the soft properties and high electrical conductivity similar to the spinal cord are very beneficial to the repair of the spinal cord.In addition,porous structure similar to the extracellular matrix can also promote nerve cell regeneration after spinal cord injury.And this inspired us to design a soft,conductive and porous scaffold for spinal cord injury repair.However,combining multiple properties simultaneously in a single scaffold remains a challenge.In this work,a reduced graphene oxide(r GO)composite xanthan gum(XG)spinal cord injury repair scaffold(XG/r GO)was constructed using freeze-drying technique.Reduced graphene oxide and xanthan gum were polymerized together by ionic cross-linking and hydrogen bonding.Xanthan gum exhibits excellent biocompatibility and can be cross-linked into soft hydrogels.And r GO with excellent electrical conductivity has been shown to promote neuronal differentiation in vivo.Combining these two materials,a soft,conductive,and porous repair scaffold was prepared by freeze-drying technology.(1)The microscopic morphology,internal structure and physical properties of the obtained XG/r GO gel scaffold were characterized.The scaffold showed a porous structure inside with a porosity of 73.15% and an average pore size of 42.14 μm.This porous internal structure can provide enough space for nerve cells to grow.The scaffold exhibited a high dissolution rate of 1577.25%.And the scaffold showed soft mechanical properties matching the spinal cord tissue,with a modulus of elasticity of 7.68±0.26 k Pa.It can provide physical support to the spinal cord without causing secondary damage to the spinal cord when it is implanted.Furthermore,the scaffold exhibited high electrical conductivity similar to that of the spinal cord,with an electrical conductivity of 2.07±0.16 S/m,which transmits bioelectrical signals and stimulates the differentiation of neural stem cells to neurons after implantation in the spinal cord.And the scaffold has the various properties required for spinal cord injury repair and can be used for spinal cord injury repair experiments.(2)The cytotoxicity of the XG/r GO gel scaffold was investigated,and it was demonstrated that the scaffold was non-cytotoxic and could be implanted into rats.In vivo,the scaffold was implanted into the rats,and the repair effect of XG/r GO gel scaffold was assessed by immunofluorescence staining,histological staining and behavioral scoring after6 weeks.The scaffold was shown to fill the spinal cord cavity,guide the orderly growth of regenerating nerve fibers,and inhibit the formation of glial scarring.Behavioral experiments showed that the XG/r GO gel scaffold promoted the recovery of motor function in rats.In summary,it is foreseen that this scaffold showed great potential in the field of spinal cord injury repair and provided important reference significance for the design of spinal cord injury repair scaffolds.