Preparation And Characterization Of CS/HAC Temperature-sensitive Gel For Socket Preservation

Objective :After tooth extraction,the alveolar bone progressive absorption atrophy causes implants implanted in difficulties,and will further affect the plant after repair of aesthetics and function.So if we can adopt alveolar ridge preservation after tooth extraction or before planting implant will effectively improve the planting effect.The existing alveolar ridge preservation material can’t get the body forming ability and mechanical strength at the same time.In order to obtain a novel alveolar ridge preservation material have body forming ability and mechanical strength,the main objective of this research was to develop a bone-like nano-hydroxyapatite/ multi-walled carbon nanotube(HAC)loaded chitosan(CS)/β-glycerophosphate(GP)injectable scaffold.Methods:1.A multi-step purification procedure,which includes calcination,HCl washing,mixed acid reflux,rinsed and length selection,vacuum drying was conducted to obtain the certain length,well-dispersed,preferably-modified O-MWNT,and the nanotubes was characterized by means of SEM,FTIR during the multi-step purification procedure.2.O-MWNT was dispersed in 10 ml of 10 m M HCl solutions by ultrasonic.By the wet-chemical in-situ precipitation,in turn to join the hydroxyapatite precursor solution in O-MWNT.Calcium phosphate ion self-assembly at sidewall defects and end of nanotubes obtained black precipitate.Centrifugal,washing,lyophilization,and the precipitate was qualitative and quantitative characterized by means of SEM,FTIR and XRD.3.The suspensions of HAC granules in different aqueous solutions of chitosan polymers,with a concentration ranging from 0.005 to 0.04 g ml-1,were prepared by mixing HAC solutions with a polymer solution.To the resulting solution,amounts of GP powder dissolved in 1 ml of distilled water,were carefully added drop by drop to obtain a clear and homogeneous liquid solution of HAC-loaded CS/GP.At 37℃ until chitosan solutions to turn into gel,characterization the composite materials in aspect of material application in bone tissue engineering.To evaluate each composite scaffold and finally confirmed the material for bone tissue engineering applications.Results :1.SEM image shows MWNT were efficiently cut and opened during the multi-step purification procedure,and many sidewall defects were generated along the resulting O-MWNT,and the sidewall is not smooth.The FTIR spectrum detect Carboxylation of O-MWNT.2.The composites by the self-assembly formed on the surface of O-MWNT determined by means of XRD,FTIR,ICP-OES,indicates that the formation of hydroxyapatite.SEM show achieved nanosized hydroxyapatite(nHAp).3.The HAC composite added thermo-sensitive chitosan solution,for the CS the gelation time,the porosity,the percentage weight loss is 18 min,92%,92%,respectively.When added CNT and HAC,the gelation time,the porosity,the percentage weight decrease gradually.The CS/HAC/10(HAC 10mg/ml),the gelation time,the porosity,the percentage weight loss is 12 min,84%,60%,respectively.The CS/HAC/20(HAC 20mg/ml)compared with CS/HAC/10,the gelation time increased to 14.5min;the porosity is 74%;the percentage weight loss is 56%.The CS/HAC/10(HAC 10mg/ml)compared with pure CS solution,the compressive strength of scaffold increased from 0.14 to 0.44 MPa.The CS/HAC/20 compressive strength is 0.3 MPa.Conclusions :1.The multi-step purification procedure can efficiently remove the impurity particles,open and cut nanotubes and produce many sidewall defects to MWNT.The length-selected(1μ m)and high carboxylic group containing O-MWNT exhibit a good dispersibility.2.The chemical precipitation of calcium and phosphate ions at the surface of O-MWNT,nucleation and growth leads to the self-assembly of HAC composites.As the deposition time extended,the sediment increased in carbon nanotube surface,and the volume increased,then the HA is nano-sizes.3.The CS/HAC/10 composite added thermo-sensitive chitosan solution,under the premise of the gel is not affected and certain porosity to improve the mechanical properties and controllable degradation rate,to shorten the clinical operation time.The HAC loaded CS/GP composite scaffolds developed in this study exhibited good formability and mechanical properties,could be a promising device for bone tissue engineering in material field.