ACP-PLA Composite Nanoifbers For The Experiment Of Bone Defects Reconstruction

Backgrounds and Objectives:The most ideal scaffolds for tissue engineering should be bioactive, which canintroduce and guide tissue repair or regeneration. After native tissue regenerates, the scaffolds are designed to degrade naturally. calcium phosphate has been recognized as an attractive biomaterial due to its bioactivity and biocompatibility. In last decades, a variety of CaP based materials with different morphologies including nanorods, plate-like nanocrystals, nanoparticles, nanotubes and three-dimensional structureshave been prepared and used in many biomedical fields. Although many achievements have been made, there are still many deficiencies which do not meet the high requirements of biomaterials for the CaP based materials. For example, the structure,morphology-controllable synthesis and the further functionalization are long-term challenges. Electrospinning, as a facile method, has been considered to be a promising way to produce polymeric nanofibers for application in drug carriers and tissueengineering scaffolds. Electrospinning has shown unique adavantages over other methods by providing porous meshes which are quite similar to the native extracellularmatrix in biomedical field. Nanostructured CaP such as hydroxyapatite(HA), as a group of widely used bioactive inorganic materials, have been used to improve the biocompatibility of eletrospun nanofibers. ACP, which could be found in human bonetissue, usually appears as an intermediate phase during the formation process of other kinds of CaP including HA. Therefore, ACP and its composite has been widelyused as biomaterials with excellent biocompatibility and bioactivity.Methods and results:In this study, CaP nanospheres with a chemical phase of ACP were synthesized usinga simple wet precipitation method in aqueous solution, in the presence of a blockcopolymer of polylactide–block–monomethoxy(polyethyleneglycol)(PLA mPEG). Then,the as prepared ACP nanospheres were blended with poly(D,L-lactic acid)(PLA) toprepare ACP-PLA composite nanofibers through electrospinning. The physic-chemicalcharacterization, in-situ mineralization and in vitro cytotoxicity were performed withACP-PLA composite nanofibers. The results indicated that compared with the pure PLAnanofibers the biomineralization process was significantly accelerated when the ACPcontent was brought into the PLA to form a composite nanofiber. The CaP paly key role inthe biomineralization process and result in the formation of HA on the surface of ACP-PLA composite nanofibers. Thereafter, osteoblast-like cells, MG63, have been used to study thebiocompatibility of the composite nanofibers. The experiments indicated goodbiocompability and bioactivity of ACP-PLA composite nanofibers. Finally, the as-preparedACP-PLA composite nanofibers were implanted into defects of rabbits’ femoral condyle,which is5mm in diameter. The two dimensional CT images were observed in the4thweeks and the8th weeks, after surgery. Twelve weeks after surgery, the animals weresacrificed and the gross morphology and histomorphology of the formed bone wasanalysed. The as-prepared ACP-PLA composite nanofibers were beneficial for the bonerepair, and showed excellent biocompatibility with the degradation of the materials and theformation of new bone.Conclusion:Due to the facile fabricating process, fast biomineralization and good biocompatibility,the as-prepared ACP-PLA composite nanofibers have the potential for applications intissue engineering and other biomedical fields.