Research Of Carbon Nano-materials In Treatment Of Infected Bone Defect And Wound Scar After Open Fractures

With the rapid development of industry and transportation,the incidence of open fractures caused by high energy damage is increasing,which is vulnerable to infection and easily led to infected bone defect.As to the pathological features of infected bone defects,scholars mainly summarized them as the follow: 1)bacterial biofilm formation;2)antibiotics barely achieve effective local concentrations;3)Local blood circulation damage;4)bone regeneration difficulty.Therefore,the development of new bone graft material with antibacterial and osteogenic capacity is critical for the treatment of infected bone defect.Another complication that affects the prognosis of patients with open fractures is wound scars.In some open fractures caused by high energy damage,local soft tissue is severely damaged and irregularly wounded;even if the bone tissue of an open fracture can heal over a longer treatment period,if a hypertrophic scar formed,Patients may suffered from distress,loss of joint activity,and compromised postoperative satisfaction.The key to preventing scar formation includes the following aspects: inhibition of the excessive proliferation of fibroblasts;inhibition of collagen over-deposition,and promotion of regular growth of the fibrous tissue.However,the current treatment in reducing hypertrophic scar is not satisfactory.According to the requirements of open fracture and bone defect treatment,the advantages of carbon nano-materials as bone graft materials are as follows: 1.Improving the physical and chemical properties of scaffolds;2.Excellent biocompatibility;3.Promoting the osteogenic differentiation;4.With certain antibacterial properties itself;5.With special structural features which make it an ideal drug carrier.On the other hand,as another form of carbon nanomaterials,carbon nanotubes has been widely used in the biomedical field because of its unique one-dimensional structure and rich surface modification,Studies have shown that aligned carbon nanotubes can direct oriented growth of a variety of cells,Indicating the prospect of the alignation of carbon nanotubes(ACNTs)as a tissue engineering scaffold.The purpose of this study is to use the unique physical and chemical properties of carbon nanomaterials to prepare three-dimensional composite scaffolds with good osteogenic properties and antibacterial properties,which can be used for the treatment of open fracture and bone defect with anbiotics.The carbon nanotubes films were prepared facilitated by the plasticity of carbon nanomaterials.The effects of carbon nanomaterials on the wound scars were analyzed and the mechanism was further studied and discussed.As a whole to provide new ideas for the further applications of carbon nanomaterials in tissue engineering.(RGO-n HA)was synthesized via the method of self-assembly and ascorbic acid as reducing agent.The microstructures of RGO-n HA were observed by SEM,AFM and TEM.TGA and FTIR were used for evaluation of its physical and chemical properties;L929 and MC3T3 cells were used to evaluate the effect of scaffold on monoclonal formation and apoptosis.BMSCs were selected and the effects of scaffolds on cell adhesion and proliferation and cell morphology were evaluated by cell counting,fluorescence staining,SEM and CLSM;The osteogenic properties were evaluated by alizarin red staining and ALP activity assay.For antibacterial capacity,the composite scaffold was evaluated by colony counting and fluorescence staining;liquid medium culture and solid medium culture were also applied;blood compatibility was assessed by hemolysis test and SEM observation of the blood cells;By implanting the composite scaffolds into the subcutaneous tissue of mice,we assessed its absorption in vivo,and its toxicity to major organs were also evaluated;the model of infected bone defect in New Zealand rabbits was established,the composite scaffolds were implanted into New Zealand Rabbit model and the capacity of the scaffold in infection control and bone regeneration was evaluated via blood biochemistry,Imaging analysis and histological assessmentAdditionally,ACNTs were successfully synthesized by chemical vapor deposition(CVD).The results showed that ACNTs could effectively inhibit the proliferation of fibroblasts,guide the growth of cells,inhibit collagen deposition,with ideal cytocompatibility.Mechanisms analysis showed that ACNTs play a major role in altering cell proliferation,cytoskeleton,cell motility,and collagen-related gene expression.Finally,we used the rabbit ear scar model to evaluate its biological effect,indicating that ACNTs can effectively inhibit the formation of hypertrophic scars.In conclusion,with the unique physicochemical and biological properties of carbon nanomaterials(graphene and carbon nanotubes),we introduce them into the treatment of infected bone defects and wound scars caused by open fractures.With In vitro and in vivo experiments,the above nanomaterials were proved as ideal tissue engineering scaffolds for the treatment of infected bone defects and wound scars,which provides a new strategy to solve clinical problems with new carbon nanomaterials.