Controllable Preparation Of Neuropeptide-modified Mesoporous Iron-doped Calcium Silicate/chitosan Fibrous Porous Scaffolds And Study Of Bone Repair Properties

AbstractBone defects caused by trauma,tumor resection,etc.,are difficult to heal by themselves.In addition to repairing damaged tissue,promoting bone formation and angiogenesis,bone therapy should further repair damaged nerves.Chitosan fiber(CS)has good biocompatibility,antibacterial,hemostasis,promoting wound healing and other properties,and is often used as wound dressing in the medical and health field.Therefore,the research on chitosan fiber(CS)has important value.In addition,mesoporous calcium silicate has properties such as biological activity,degradability,and drug loading/release,which can significantly promote cell attachment,proliferation,and differentiation.Therefore,the study of biological experiments in vivo and in vitro has far-reaching significance.In this paper,a neuropeptide NPFFmodified mesoporous iron-doped calcium silicate/chitosan fiber(OB/Fe-Si O?/NPFF)scaffold was designed.The scaffold was characterized by XRD,TEM and BET.The morphological structure,mechanical properties and pore structure of the material,and according to the results of in vitro cell experiments and in vivo animal experiments,revealed that chitosan fibers(CS)and neuropeptides(NPFF)in bone scaffolds have effects on biocompatibility,bone Mechanisms of effect on induction properties and neuroreparative properties.First,mesoporous iron-doped calcium silicate was prepared by self-assembly using P123 as surfactant;then,green and non-toxic genipin was used as cross-linking agent to combine chitosan fibers(CS)and organic substrate ?-Cyclodextrin(?-CD)was cross-linked with genipin;finally,a fibrous porous(OB/Fe-Si O?)scaffold was prepared by freeze-drying method.Mesoporous iron-doped calcium silicate is an ordered two-dimensional hexagonal symmetric mesoporous structure with an average pore size of about 5 nm.The OB/Fe-Si O? scaffold exhibits a porous structure with a pore size range of about 50-150 ?m.The OB/Fe-Si O? scaffold has a specific surface area of 68.1537 m2/g and a pore volume of 0.091815 cm3/g.The porous structure facilitates the transport of nutrients in cells and provides a favorable environment for cell proliferation.The results of the mechanical properties test showed that compared with the OB/Fe-Si O? scaffold without fibers,the OB/Fe-Si O? scaffold with fibers increased the compressive properties by 61% and the tensile properties by 134%.Theion release results showed that Fe,Si and Ca ions had a slow release effect along with the gradual degradation of the scaffolds.In vitro experiments on BSMCs cells showed that OB/Si O?,OB/Fe-Si O? and OB/Fe-Si O?/NPFF scaffolds all had good biocompatibility and no cytotoxicity,and in the control containing Fe ions The growth in the group was significantly better than that in the group without Fe ions,and the scaffolds in the group containing NPFF significantly promoted the proliferation and growth of cells.Furthermore,compared with OB/Si O? or OB/Fe-Si O? scaffolds,OB/Fe-Si O?/NPFF scaffolds significantly upregulated the expression levels of COL I,OCN,OPN and Osterix genes,which can be attributed to with the addition of the neuropeptide NPFF.By in vitro experiments on the migration and angiogenesis of HUVECs on the prepared scaffolds,the results showed that compared with OB/Si O? or OB/Fe-Si O? scaffolds,the OB/Fe-Si O?/NPFF scaffolds were more stable at 36 h.It significantly promoted wound healing and significantly up-regulated the gene expression levels of VEGF,PDGF,EGF,FGF,etc.,and promoted the angiogenesis of HUVECs.The experimental results of Neuro-2A cell neurite outgrowth indicated that NPFF induces Neuro-2A cell neurite outgrowth through the NPFF2 receptor.In vivo experiments of rat calvarial defect repair showed that the prepared OB/Fe-Si O?/NPFF,OB/Si O? and OB/Fe-Si O? scaffolds could promote the repair of rat calvarial defects.However,due to the presence of the neuropeptide NPFF,the repair effect of the OB/Fe-Si O?/NPFF scaffold group was significantly better than that of the OB/Si O? and OB/Fe-Si O? scaffolds.In conclusion,neuropeptide-modified mesoporous iron-doped calcium silicatechitosan fiber composite scaffolds have important application value in bone defects.