ACC/ACP-Collagen Composite Scaffolds: Preparation, Characterization And Application In Bone Defect Repairing

Background and Objectives:Bone grafts are commonly used to repair bone defects,such as those caused by traumatic injuries,resection of osteosarcoma or osteomyelitis.An autologous bone graft is still the gold standard for the repair of bone defects,but it has the problems of availability of graft material and donor-site morbidity.Allograft can be used to obviate the limitation of autologous bone graft,but is limited by the immunogenicity and transmitting pathogens.Therefore,a large number synthetic bone graft substitutes have been investigated such as demineralized bone matrix and calcium phosphate-based materials.However,the pure material is often difficult to meet the currently high requirement of tissue repair/tissue engineering scaffolds.Thus,a variety of composite materials which can give multifunctional properties has become a hot research filed.Calcium carbonate and calcium phosphate are the main components of bio-minerals.Among all of the forms of bio-minerals,amorphous calcium phosphate(ACP)and amorphous calcium carbonate(ACC)are the most important forms because they play a key role in the process of bio-mineralization.Therefore,it is significant to develop biomaterials with high bioactive using ACP and ACC.Methods and results:In this study,we synthesized ACC and ACP nanospheres using a facile microwave-assisted wet-chemical method.The samples were characterized by using X-ray powder diffraction(XRD),fourier transform infrared(FTIR),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Then the ACC/ACP materials with a nano structure have been blended with collagen to fabricate a composite porous scaffold by freeze drying.The physic-chemical characterization,in-situ mineralization and in vitro cytotoxicity of ACC/ACP-collagen composite scaffolds have been investigated.We have cultured the bone marrow mesenchymal stem cells(BMSCs)on the as-prepared porous composite scaffold to investigate the interaction of cells and scaffolds.Finally,the in vivo bone defect repair properties of the ACC/ACP-collagen composite scaffold have been investigated.ResultsThe as prepared ACC/ACP-collagen composite scaffolds exhibit good morphologies and favorable behaviors of mineralization in simulated body fluid(SBF).The ACC/ACP nanospheres play the key role in the process of mineralization.The ACC/ACP-collagen composite scaffolds also showed good biocompatibility,when the BMSCs seeded and cultured on the scaffolds.Finally,the in vivo bone defect repair properties have been studied.From the result of histological analysis,ACC/ACP-collagen composite scaffolds display favorable properties for the repair of bone defects.ConclusionIn summary,the as-prepared ACC/ACP nanomaterials and its composite scaffolds have shown favorable properties in the structure,chemical/physical properties and bioactivity,and have shown potential for applications in bone tissue engineering.