Preparation And Characterization Of Strontium Ferrite/Alginate Composite Hydrogel

Alginate has been widely used in bone, cartilage and vascular tissue engineering because of its moderate gelation condition and good biocompatibility. Magnetic stimuli have influences on the growth, proliferation, differentiation and arrangement of cell, and can improve the functionalization of cell and tissue in tissue reconstruction. Composite hydrogel based on magnetic particle and hydrogel is one of the research focuses in tissue engineering.Firstly, the influence of the ratio of Ca2+/COO- on the properties of alginate hydrogel was studied. The hydrogel showed the optimized performance when the ratio of Ca2+/COO- was 0.4. Based on the optimized ratio, alginate hydrogel with different crosslinking density were prepared. The obtained alginate hydrogel had the tensile strength ranged from 0.02 MPa to 0.2 MPa, the porosity and average pore size ranged from 70% to 90% and 100 to 300μm respectively. The process of cell culture in tissue engineering was simulated by lyophilizing the hydrogel and swelling it in DMEM. And the influences of cell culture process were investigated. After lyophilization and swelling in DMEM, the calcium ions were dissolved out of the hydrogel,which resulted in the decrease of tensile strength and yield strength.Secondly, magnetic particle/alginate composite hydrogel were prepared by mixing the SrFe12O19 particles with alginate. The remanence of composite hydrogel could be controlled by the content of magnetic particle. The addition of magnetic particle decreased the swelling ratio of hydrogel, but had little influence on mechanical property, rheological property and microstructure of hydrogel. Finally, the cytotoxicity of alginate hydrogel with endothelial cells and smooth muscle cells were investigated. And the endothelial cells were implanted into composite hydrogel scaffold. The results showed that alginate hydrogel and composite hydrogel have no cytotoxicity. The combination of magnetic field and magnetic particle could improve the metabolic activity of epithelial cells in hydrogel. All the research results above can provide experimental evidences for further applications of the composite hydrogel in soft tissue engineering.