Agarose Acetate And Its Composites For Bone Regeneration

The degradable biomaterials are usually applied for bone regeneration,such as inorganic non-metallic materials containing tricalcium phosphate ceramics or polylactic acid or similar polymer.These materials with single component cannot fully meet the needs of clinical applications,so it is necessary to seek new biomaterials for bone regeneration.At present,many researches focus on seeking new materials for bone regeneration;on the other hand,we may composite two kind of biomaterials for obtaining composites with new functions.As we have known,natural bone tissue is composed of inorganic component hydroxyapatite and organic substance type Ⅰcollagen,which maintains the balance between high toughness and high strength.Therefore,the composites with organic and inorganic biomaterials are expected to meet the needs of bone regeneration.Previous studies had proved that agarose acetate had excellent biocompatibility,processability and biodegradability.Meanwhile agarose acetate degraded,without acidic produces as polylactic acid doing.But agarose acetate has less biomedical function,particularly less ability to guide bone regeneration.In order to further improve the osteogenic activity of agarose acetate material,in this paper,we composite agarose acetate with β-tricalcium phosphate for bone regeneration after knowing the preparation method,structure and properties of the composites.1,Base on the study of agarose acetate in the early stage of our research group,the ratio of agarose acetate to β-TCP was set.The composite scaffolds of agarose acetate/β-TCP with mass ratio of agarose acetate/β-TCP being 9:1,8:2,7:3 and 6:4were fabricated by solvent casting/particulate leaching method.There were porous interpenetrating network in the composite scaffolds.The β-TCP power promoted compressive modulus of the composite scaffolds.The compressive modulus and porosity of composite scaffolds with mass ratio of agarose acetate/β-TCP being 6:4were 0.87±0.09 MPa and(88.97 ± 0.09)%,respectively.The cell culture results showed that the composite scaffolds were non-toxic and had excellent cytocompatibility.The composite scaffold with mass ratio of agarose acetate/β-TCP being 6:4 significantly promoted the adhesion and proliferation of rat bone marrow mesenchymal stem cells(r BMSCs).The in vivo and in vitro degradation experiments demonstrated that the composite scaffold with mass ratio of agarose acetate/β-TCP being 6:4 degraded fast and had minimal inflammatory response.The in vivo results disclosed that the composite scaffold with mass ratio of agarose acetate/β-TCP being6:4 would significantly facilitate new bone formation in critical-sized cranial bone defect rat model after 12 w implantation,compared with the control group,by BV/TV quantitative analysis,micro-CT,H&E and masson staining.2,The composite fiber membranes of agarose acetate/β-TCP with β-TCP content of10%,20%,30% and 40% were prepared by electrospinning method.The diameter and roughness of fibers increased with raising content of β-TCP powder.When theβ-TCP content was 40%,the average diameter of the composite fiber membrane was776 ± 86 nm,and the tensile strength was 3.86 ± 0.75 MPa.The cell culture results showed that the composite fiber membranes with β-TCP content of 40% were favorable for the adhesion,proliferation and migration to internal fiber,osteogenic differentiation of r BMSCs,ALP expression,and synthesis of calcium nodules and extracelluar matrix.3,The antibacterium fiber membranes of agarose acetate with tinidazole content of2%,6%,12% and 24% were fabricated by electrospinning method.The fiber surface was smooth without beaded structures.The average diameter of fibers decreased with the increase of tinidazole content.When the tinidazole content was 24%,the average fiber diameter was 258 ± 32 nm,and it cumulative released 80% of tinidazole in 10 d,with long-leasing effect.In vitro antibacterial experiments showed that it effectively inhibited the growth of bacteria with bacteriostatic ring diameter of 37.3±05mm.Moreover,with the increase of tinidazole content zone of inhibition was increased.Further,the loaded tinidazole in the membrane did not affect the proliferation of NIH-3T3 cells.After 7d culture,NIH-3T3 cells were still grown on the surface of functional membrane while working as a fibroblastic barrier.4,The double-layer guided bone regeneration membrane(GBR membrane)was obtained by electrospinning with tinidazole containing surface layer for antibactrium and blocking penetration of tissues and β-tricalcium phosphate containing one for osteoconductivity.Mechanical testing found that GBR membrane had appropriate tensile strength in wetting,and close connection between the two layers.The in vivo SD rat test results indicated that the GBR membrane would significantly inhibit bacteria,reduce local inflammation,and effectively prevent connective tissue in growth,and facilitate new bone formation in a critical-sized mandible defect model by micro-CT,H&E and masson staining with SD rat mandibular model.In conclusion,Agarose acetate and its composites not only have good biocompatibility,and biodegradation with neutral degradable products,and good osteoconductivity,but also are easy to be processed with sufficient mechanical strength as bone regeneration scaffolds.The research also extends the clinical applications of agarose and its modification,one of seaweeds in biomedical engineering.