| In traditional bone tissue engineering for the treatment of bone defects,the use of bone-implant scaffolds in clinics is limited by the disadvantages such as difficult porosity control,single scaffold style,and insufficient functionality of scaffolds.Therefore,the current research focuses on the preparation of implanted scaffolds with meticulous structure and versatility.With the development of science and technology,rapid prototyping technology(also known as 3D printing technology)has become a hot research topic in recent years.As a representative of direct writing technology,extrusion deposition technology has a wide range of material applicability,and has huge advantages in nanomaterial forming,which provides a strong guarantee for the forming of the scaffolds.A variety of materials and ways combined with hydroxyapatite to form composites make up for the deficiency of pure hydroxyapatite materials,and provide research ideas for achieving the versatility of scaffold materials.For the purpose of meeting the repair of different types of bone defects,while satisfying the diversified functions of bone implant materials.In this paper,commercial nano-hydroxyapatite(n HA)was used innovatively to fabricate two morphologies of HA implanted scaffolds with uniform morphology and well controlled pores by using our experimentally modified 3D printing technique of pneumatic extrusion and ionic gelation method,which solved the defects of uneven scaffolds and uncontrollable pores in traditional ways.The macroscopic and microscopic morphology,degradability,and biological properties of the scaffold were explored through material science and biological tests.The optimization effects of different modification methods on HA scaffolds are summarized.The response of morphology of the microsphere scaffolds to different forming process parameters was explored by the discontinuous extrusion method.A set of better slurry preparation schemes were obtained(1%SA and 20%HA).The average diameter of the microspheres printed in batches is 2.08±0.32 mm,ranging from 1.7 to 2.3 mm.Different metal cations combined with ion gelation were used to prepare HA microspheres doped with different cations,and sintered with a gradient temperature from 800 to 1200~oC.The analysis showed that the Cu and Zn ion-doped microspheres could produce a second phase in Ha microspheres,and the grain size was also slightly larger than that of Ca and Sr ion-doped ha microspheres.The in vitro degradation experiments showed that the biphasic microspheres could achieve 21.21%degradation rate for 4 weeks,which was significantly higher than that of single ha phase microspheres,which was beneficial to provide growth space during the new bone formation.The results of antibacterial experiments showed that HA combined with functionalized metal ions(Cu,Zn)gave the microsphere scaffold good antibacterial properties.The self-assembled silk fibroin(SF)-HA porous scaffolds were prepared by continuous extrusion.The scaffold has a good pore structure(300-400μm),which is conducive to the growth of cells and the exchange of nutrients.The rough structure of the surface makes the cells adhesion more easily.SF combined with HA can promote cell proliferation and differentiation.This study demonstrates that bone tissue engineering scaffolds with multiple morphologies can be prepared with pneumatic extrusion 3D printed technology to obtain differently functionalized HA implanted scaffolds by ion doping and physical blending.It provides an experimental basis for the diversification of clinical bone repair and enriches biomanufacturing methods. |
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