Construction, Mechanical And Biological Properties Of Chitosan Fiber/Bioceramic Three Dimensional Porous Scaffolds

Three dimensional porous scaffolds are urgently developped to repair and regenerate large segmental bone defects suffering from trauma and surgery. An ideal scaffold should have the similar chemical composition and pore structure to nature bones, and exhibit the suitable mechanical properties that match well with human bone tissue. In this paper, with chitosan fiber scaffold(CSs) as matrix, a chitosan fiber/bioglass 3D porous scaffold(CS/BGs) and a chitosan fiber/nano-hydroxyapatite 3D porous scaffold(CS/HAs) have been prepared by dip-coating method and needle-punching process, respectively.The morphologies, phases and pore structure of the scaffolds were studied by means of SEM, TEM, EDS, XRD, FTIR, and Capillary Flow Porometer. The mechanical properties including compression, tensile and flexure experiments for the scaffolds are characterized by using universal mechanical testing method. In addition, we reveal the influence of chemical composition and microstructure on the biocompatibility and bioactivity of the scaffolds by in vitro cell culture experiments and in vivo experiments on animals.First, we have developed a new method to fabricate chitosan/bioglass 3D porous scaffold(CS/BGs) according to the following steps:(i) preparation of chitosan fiber scaffold(CSs) by needle-punching process and(ii) deposition of BG on the above CSs by dip-coating technique. The CS/BGs has interconnected porous structure with a porosity of 77.52 % and a pore size of about 50 μm. Water absorption values of CSs and CS/BGs are 570 % and 59 %, respectively. The BG in the CS/BGs significant decreases the swelling behavior of CS fibers, and thus improves the stability of scaffold structure. The CS/BGs possesses good mechanical properties with a compression strength of 6.60 ± 0.80 MPa and an elastic modulus of 0.40 ± 0.05 GPa, which are well-matched with those of trabecular bones. In vitro cell assay results demonstrate that the CS/BGs has good biocompatibility, which can facilitate the spreading and proliferation of human bone marrow stromal cells(h BMSCs).Then, chitosan fiber/nano-hydroxyapatite 3D porous scaffold(CS/HAs) has been fabricated according to following steps:(i) deposition of brushite/CS on CS fibre porous scaffold by dip-coating method; and(ii) formation of hybrid nanostructured CS/HAs composite scaffold by a bioinspired mineralization process. The CS/HAs possesses three-dimensional(3D) interconnected pores with a pore size of 30-80 μm. The HA nanorods with a length of ~200 nm and width of ~50 nm are perpendicularly oriented to the CS fibres. Hybrid nanostructures make the composite scaffold possess exhibit good mechanical properties with compression strength of 9.41 ± 1.63 MPa and elastic modulus of 0.17 ± 0.02 GPa, which are well-matched to those of trabecular bone. The influences of CS/HAs on cells have been investigated by using human bone marrow stem cells(h BMSCs) as cell model and the CSs as control sample. The CS/HAs not only supports the adhesion and proliferation of h BMSCs, but also improve the osteoinductivity. The alkaline phosphatase activity and mineralization deposition on the CS/HAs are higher than those on the CSs. Moreover, the CS/HAs can promote the formation of new bone formation in rat calvarial defects as compared with the CSs. The excellent biocompatibility, osteoinductivity, bone regeneration and mechanical properties suggest that the CS/HAs has great potential for bone tissue engineering.