Preparation And Characterization Of Mesoporous Bioactive Glass/Protein Bionic Bone

It’s well known that bone is one of the most complicated biomedical composites in nature,which plays an important role in human body. However, bone defects caused by trauma,congenital malformation or tumor are still a problem in bone tissue engineering in recent years.Although the striking achievements have been gained in the study of the bone repairing materials,there are still some problems that remain to be solved in this field, such as structure differentfrom cancellous bone. Therefore, it is imperative for researchers to prepare newer and bettermaterials for bone repairing.Natural cancellous bone is a composite composed of hydroxyapatite and collagen. Andhydroxyapatite has an orderly and evenly deposition within collagen fibroin. This structureprovides significant strategies and ideas for designing novel bone repairing materials-Preparationand study of inorganic/organic composite materials. Mesoporous bioactive glass possesses a highspecific surface area, pore volume and highly ordered mesopore channel structure. Besides, thiskind of material can effectively induce the formation of hydroxyapatite. Collagen is the maincomponent of extracellular matrix (ECM) and plays an important role in tissue structure; silkfibroin as a class of collagen can better simulate bone collagen in structure and property.Therefore, from bionic perspective, collagen and silk fibroin are the preferred materials for bonescaffold materials.Based on the structure of cancellous bone, the mesoporous bioactive glass/protein bionicbone scaffold materials were prepared using the demineralized bone matrix as a template. Themain research contents and results were obtained as follows:1. Preparation and study of the mesoporous bioactive glass58S/demineralized bone matrixcomposite bionic bone scaffolds. Mesoporous bioactive glass (M58S) with a highly orderedmesopore channel was synthesized by a two-step acid-catalyzed self-assembly process combinedwith hydrothermal treatment; demineralized bone matrix (DBM) three-dimensional scaffoldmaterials were obtained after treating natural cancellous bones with HCl. This material withporosity about71%was mainly composed of collagen and the pore size was200to600μm. Combining the super osteogenic property of mesoporous bioactive glass with the supportingeffect of demineralized bone matrix, mesoporous bioactive glass/demineralized bone matrixcomposite bionic bone scaffolds were prepared using immersion method. The pore sizesdecreased strikingly and the porosity was about40%, however, the compressive strength wasabout (8.49±2.14) MPa. And this value was significantly higher than that of demineralized bonematrix (1.10±0.31) MPa, which could meet the need of cancellous bone. In vitro bioactivity testshowed that composite scaffolds could effectively induce the formation of hydroxyapate and hadgood bioactivity. In vitro degradation test showed that weight loss of the scaffolds increased withthe extension of degradation time. After immersion in PBS for15days, the degradation ratio ofscaffolds was10.54%. Therefore, the scaffolds showed good degradability in PBS. During initialimmersion period, the composite scaffolds showed lower water absorption. However, the waterabsorption increased with the extension of time. Mesoporous bioactive glass58S/demineralizedbone matrix composite bionic bone scaffolds are new materials, which have potential applicationin bone tissue engineering.2. Preparation and study of the mesoporous bioactive glass58S bionic bone scaffolds. Theprepared natural demineralized bone matrixes were used as macroporous templates and P123were used as mesoporous templates. Combining template technology with sol-gel process, pureinorganic bioactive glass scaffolds were obtained after calcinations process using mufflefurnaces. The results showed that inorganic bioactive glass scaffolds not only had highly orderedmesoporous structure but also had macroporous structure which were similar to the calcinedbones. The pore size was200to500μm. However, the compressive strength of M58S scaffoldswas only about (0.19±0.08) MPa which was obviously lower than that of the calcined bones.Therefore, this low strength limited its applications in bone tissue engineering. In vitrobioactivity test showed that mesoporous bioactive glass scaffolds could effectively induce theformation of hydroxyapatite and showed super bioactivity. In vitro degradation test showed thatpure inorganic mesoporous bioactive glass scaffolds had rapid degradation rate which hardly metthe need of the bone tissue engineering.3. Preparation and study of the mesoporous bioactive glass58S/silk fibroin compositebionic bone scaffolds. The composite scaffolds were fabricated by immersing the preparedmesoporous bioactive glass scaffolds into aqueous silk fibroin solutions (3%,6%,8%). The results showed that the composite scaffolds had interconnected macroporous network and silkfibroin solutions with different concentrations had no obvious effect on pore size. However, thecompressive strength increased with the increase of silk fibroin concentration. In vitro bioactivitytest showed that all composite scaffolds had good bioactivity and could induce the formation ofhydroxyapatite. In vitro degradation test showed that the composite scaffolds had gooddegradation property. Therefore, the scaffolds with different porosities, compressive strengthsand degradation performance could be obtained in order to be used in bone tissue regenerationengineering.From the above studies, mesoporous bioactive glass/protein bionic bone scaffolds weresuccessfully prepared in this study and both of them showed good performance. This kind ofscaffolds expects to become a new bone defect repair material which expands the source of thebone scaffolds.