Elastomeric Polyurethane Porous Film Functionalized With Gastrodin For Peripheral Nerve Regeneration

Objective:The polyurethane nerve films functionalized with different contents of Gastrodin were prepared.Compared to PU,we investigated the physico-chemical properties and biocompatibility of Gastrodin/PU film.And the potency of Gastrodin/PU as a scaffold material for nerve tissue engineeringis discussed.Methods:PU was successfully fabricated using the in situ polymerization method.The PCL2000 and IPDI as raw materials and the Lys·OEt-2HCl as a chain extender to get the prepolymer,then the different content of Gastrodin was added into the mixture to form four different contents of scaffolds.According to the theoretical weight ratio of Gastrodin in polymer chain(set as 0%,0.5%,1%,5%),the samples were named as PU,0.5Gastrodin/PU,1 Gastrodin/PU and 5Gastrodin/PU.Subsequently,PU was dissolved with an organic solvent 1,4-dioxane and NaCl particles(<50 ?m)as porogen were added into the solution(Wsample:WNaCl=12).The nerve film was constructed via Salt leaching technique.The functional structure and chemical composition of films were investigated by means of Fourier transform infrared spectroscopy(FTIR)and 1H nuclear magnetic resonance(1H NMR);The morphology of films was observed by scanning electron microscopy(SEM);The tensile mechanical properties of the films were determined using a universal testing machine;the thermal stability analysis of the films was tested on a thermo gravimetric analysis(TGA);the molecular weight and molecular weight distribution of films was tested by(Gel permeation chromatography,GPC).The surface contact angles of films were obtained using a contact angle measurement instrument.PC12 cells were seeded on the film,and the adhesion,spread,and proliferation of cells on the material surface were observed using SEM and Live/Dead stain.The cell viability was investigated by Cell Counting Kit-8(CCK-8).The gene expression of brain-derived neurotrophic factor(BDNF)and glial cell derived neurotrophic factor(GDNF)were determined using a quantitative real-time polymerase chain reaction(RT-qPCR).Results:The nerve film has a highly interconnected porous structure and the pore with a size of 10?60 ?m.The Young' modulus,thermal stability and hydrophilic property of 5Gastrodin/PU significantly increased compared with PU.Gastrodin/PU film was more conducive to cell adhesion,spreading and proliferation,indicating that the scaffolds had no cytotoxicity.In addition,5Gastrodin/PU could significantly up-regulate the expression of BDNF and GDNF.Conclusion:The porous nerve film of Gastrodin/PU has well flexibility and supporting mechanical strength,as well as excellent hydrop ilicity and biocompatibility,which can be further made into nerve conduit for nerve repair and egeneration.