Preparation And Properties Of Nano-Hydroxyapatite/Chitosan Composite Scaffolds

Currently,autologous bone sources are limited,especially when multiple traumas of the whole body occur.Additionally,transplant rejection of allograft and xenograft largely impedes their clinical application.Therefore,it is necessary to design a better bone regeneration scaffold.Biopolymers have a wide range of sources,good biocompatibility,degradability and plasticity.Moreover,chitsoan(CS)is a natural polysaccharide with antibacterial ability,which might do a favor to control the inflammatory and infectious risk after surgical operation,and to improve the success of bone regeneration.However,CS is a kind of materials with low mechanical strength.Nanomaterials are often used to modify the CS to improve its mechanical properties.Hydroxyapatite(HAp),the main ingredient of organism skeleton,is commonly used as bone replacement materials because of its biocompatibility,biological activity,and mechanical strength similar to natural bone.Compared with HAp,smaller size,larger surface area and surface energy of nano hydroxyapatite(nHAp)make it available as particle coating to improve the mechanical properties and osteogenic activity of CS scaffolds.Currently,in the field of alveolar bone repair,the appropriate dosage ratio of nHAp/CS composite scaffolds is not clear.Therefore,this study intends to use nHAp to modify CS scaffolds,and to determine the effects of nHAp with different concentrations on the physicochemical and biological properties of nHAp/CS composite scaffolds,in order to develop a suitable bone defect repair material.ObjectiveThe purpose of this study was to screen out an appropriate combination of CS and nHAp for composite scaffold of bone tissue engineering(BTE).MethodsFirstly,CS-based scaffolds with different molecular weights were prepared,and the appropriate CS molecular weight was screened out by physical and chemical detection,such as surface morphology,pore size,and porosity;then,different masses of nHAp were introduced into the target CS scaffolds to prepare different concentration gradients of nHAp/CS composite scaffolds.Then,the appropriate nHAp concentration was screened out through the macroscopic and microscopic morphology,degradation rate and other physical and chemical properties.Finally,human dental pulp stem cells(hDPSCs)were inoculated with nHAp/CS composite scaffold and their self-renewal and osteogenic differentiation were deteceted,so as to comprehensively evaluate the biological properties of the composite scaffold.ResultsScanning electron microscopy(SEM)showed that CS scaffold with 700 kDa presented a large degree of buckling and folding of the pore wall,with porosity of 88.13±7.46%,pore diameter of 142.86±13.12 μm and elastic modulus of 0.0438±0.0015 MPa.In the nHAp/CS-10%group,nHAp was evenly distributed on the surface of the scaffold pore wall under SEM,with porosity of 78.47±2.56%,elastic modulus of 0.1101±0.0103 MPa,water absorption rate of 1298.55±98.34%,and 21-day degradation rate of 10.70±1.92%.hDPSCs were inoculated with nHAp/CS-10%scaffold,and the inoculation rate was 71.89±4.82%after being cultured for 16 h.CCK-8 results on day 5 and 7 were significantly higher than those in the control group,and ALP activity was significantly higher than that in the control group after 14 days of osteogenic induction.ConclusionsPure CS scaffolds with different molecular weights and nHAp/CS composite scaffolds with different concentration gradients were prepared by physical blending method and Freeze-Drying technology.Through relevant physical and chemical detection and cytological experiments,the results concluded that the nHAp modified 700 kDa CS scaffold with a mass fraction of 10%has good mechanical strength and biological activity,and has great application potential in the field of BTE.