Multi-level Construction And Performance Of A Novel Three-dimensional Porous Composite Bone Tissue Engineering Scaffold

The rapid development of tissue engineering provides a new method for clinical bone defect treatment.Scaffold plays an important role in bone tissue engineering.It serves as a framwork for bone tissue regeneration and its properties directly affect the survival,migration,proliferation and metabolic functions of cells.This study aims to build a new type of three-dimensional microsphere composite scaffold with multi-level structure.Calcium silicate(CS)and mesoporous silica(HMS)were used to added to PLGA microspheres to improve its biodegradation properties and biocompatibility.3D-Bioplotter was used to fabricated PLGA three-dimensional scaffolds and low temperature fusion technology was used to combine microspheres and scaffolds together.In addition,this paper also explored the forming mechanism of the porous microspheres which provided theoretical basis for further drug delivery.And the in vitro and in vivo biocompatibility were evaluated,which is of great significance for human body implantation.(1)At first,we prepared CS and HMS by chemical precipitation method and template agent removal,respectively.And then they were used to added to PLGA microspheres to fabricate PLGA/CS? PLGA/HMS and PLGA/CS/HMS composite microspheres with three different kinds of structures.XRD?IR?Zeta potential analysis ?SEM and other kinds of characterization methods were used to study their forming mechanism.The primary cause is the different hydrophily of CS and HMS.CS is more hydrophilic and mainly formed the surface pores of microspheres.And HMS tend to form the inner holes because it is more hydrophobic.The content of CS and HMS also influenced the size?quantity and distrbution of pores.(2)In addition to the surface morphology and pore structure,this paper also studied physical and chemical properties of the composite microspheres.To some extent,CS and HMS can buffer the acid which caused by PLGA degradation products and promote the proliferation of BMSCs in vitro.The composite microspheres have better suspension property in deionized water.Among the three kinds of composite microspheres above,the suspension property of PLGA/CS microspheres is the best.This property is helpful for further construction of composite scaffolds.(3)We prepared PLGA three-dimensional scaffolds by 3D-Bioplotter which is one of rapid portotyping techniques and studied the effect of the printing parameters.Three kinds ofscaffolds with different internal structure were prepared and their porosity and mechanical properties were tested.The scaffolds with inner fiber arrangement by 0° and 90° in turn have the largest porosity.Meanwhile,their compressive strength and compression modulus are also supreme.Compared with the traditional microspheres scaffolds prepared by sintering,the three-dimensional scaffolds prepared by 3D-Bioplotter have better biocompatibility and no obvious toxic effect on heart?liver?spleen?lung?kidney and other organs.(4)We built a new kind of three-dimensional microsphere composite scaffold with multi-level structure by low temperature fusion technology.The addition of microspheres makes the pore structure of scaffolds more diverse and mechanical performance greatly improved,and they can also regulate the degradation speed and the pH value of the surrounding environment.The results of in vitro and in vivo tests suggested that this kind of composite scaffolds have good biocompatibility.