Study On The Preparation And Properties Of Mg And Sr Containing Bioactive Glass/Chitosan/Alginate Composite Scaffolds

Bone tissue engineering scaffold as an alternative to bone graft materials for repairing bone injuries is receiving increasing attention due to the limited source and immunogenicity of bone repair materials such as autologous and allogeneic bone.The sol-gel bioactive glass with good bioactivity,biodegradability,biocompatibility,strong osteoconductivity and osteoinduction ability is regarded as promising candidates for bone regeneration.However,the sol-gel bioactive glasses are mostly powder granules,which cannot be directly used as bone repair materials,and usually need to be compounded with polymer materials to obtain bone tissue engineering scaffolds.In this paper,magnesium and strontium co-containing bioactive glass/chitosan/alginate composite scaffolds were produced by freeze-drying technique,with magnesium and strontium co-containing bioactive glass derived from sol-gel method,chitosan and sodium alginate as raw materials.60SiO₂-31CaO-4P₂O₅-xMgO-(5-x)SrO(x=0,1,2,3,4 and 5 mol%)bioactive glasses were prepared by sol-gel method using ethyl orthosilicate,triethyl phosphate,calcium nitrate tetrahydrate,magnesium nitrate hexahydrate and strontium nitrate as raw materials.The effects of different doping amounts of Mgand Srelements on the physicochemical properties,phase composition and in vitro mineralization of bioactive glasses were analyzed.The results showed that the bioactive glasses were mainly amorphous in structure and had high specific surface area,but when the Srdoping amount was 2 mol%and Mgdoping amount was 3 mol%,Sr₂SiO₄ crystal diffraction peak was observed and the intensity of the crystal diffraction peak increaseed with the increase of Srdoping amount.After 3 days of immersion in SBF solution,XRD diffraction peaks and FTIR absorption peaks of hydroxyapatite were observed in all samples,indicating the formation of hydroxyapatite deposits.The bioactive glass had higher hydroxyapatite formation rate when Srwas added at 1 mol%and Mgwas added at 4 mol%,and the amount of hydroxyapatite production increased with the increase of immersion time.The composite scaffolds were prepared by freeze-drying technique using60SiO₂-31CaO-4P₂O₅-4MgO-SrO bioactive glasses powders derived from sol-gel method and chitosan as raw materials,and the properties were characterized.The results showed that the composite scaffolds were honeycomb-shaped with three-dimensional through porous structures and uniform pore size distributions.With increasing addition of bioactive glass powders,the porosity and average pore size of the composite scaffolds decreased,the thermal stability increased,the swelling ratio decreased and the degradation rate decreased.The compressive modulus of the composite scaffolds first increased and then decreased,and reached the maximum value of 1.12±0.019 Mpa when the mass ratio of bioactive glass to chitosan was 1:2,which was 4.67 times of that of the pure chitosan scaffold.After 3 days of immersion in SBF solution,the pure chitosan scaffold had no hydroxyapatite,and the bioactive glass improved the hydroxyapatites'formation ability of the composite scaffolds,and the more hydroxyapatite deposits were formed with the increase of the bioactive glass addition.The magnesium and strontium co-containing bioactive glass/chitosan/alginate composite scaffolds were produced by freeze-drying technique using60SiO₂-31CaO-4P₂O₅-4MgO-SrO bioactive glasses powders,chitosan and sodium alginate as raw materials,and the properties were characterized.The results showed that the composite scaffolds had three-dimensional through porous structure.With the increase of sodium alginate,the porosity and average pore size of the composite scaffolds decreased,the thermal stability increased,the swelling ratio decreased,the degradation rate decreased and the compressive modulus increased.when the mass ratio of sodium alginate to chitosan was 1:1,the compressive modulus reached the maximum value of 5.66±0.219 MPa.After 3 days of immersion in SBF solution,the composite scaffolds had the formation of hydroxyapatite,indicating the composite scaffold had good bioactivity and met the requirements of bone tissue engineering scaffold.