| Bio-3D printing is an advanced manufacturing technology that has shown great potential for tissue engineering applications in its early research stages,and many in vitro and even in vivo experiments have hinted at the feasibility of bioprinting artificial organs.The application of bio-3D printing is rapidly expanding due to its advantages in microscale,high throughput,and cell deposition.Biological 3D printing has emerged as a powerful manufacturing tool with significant potential for creating complex microand macro-biomedical systems.Cartilage tissue engineering is a key application area of bio-3D printing technology.The main objective of this paper is to prepare SA-XG-HA(sodium alginatexanthan gum-hydroxyapatite)composite hydrogel porous cartilage scaffold by 3D printing technology,which can be used for chondrocyte attachment and proliferation to promote cartilage damage repair,and can be naturally degraded in human body.First,by reading a large amount of relevant literature,the advantages and disadvantages of various types of biological 3D printing materials were summarized,and a method based on SA-XG-HA(sodium alginate-xanthan gum-hydroxyapatite)composite hydrogel for 3D printing of cartilage tissue was proposed.To study the printing performance of the composite gel,the viscosity and rheology of SA and XG and the mixed slurry at different ratios were analyzed,and HA powder was added to the co-blend.After several experiments,the optimal ratio of 7% concentration SA solution,3% concentration XG solution and HA powder mixed with a mass ratio of5:5:1 was determined.Secondly,this paper constructs a mathematical model based on the rheological properties of the blended slurry based on power-law fluid blending,in which the air pressure size,needle motion speed and fiber line spacing of hydrogel are important parameters affecting the printing performance of the composite.An elastic suspension line model is proposed to compensate for the collapse of the scaffold and the lack of porosity caused by the mobility of the hydrogel material during the printing process,resulting in a better porous structure.The finite element simulation of the constructed mathematical model is carried out to determine the range of parameters to be set for printing the scaffold.Third,based on the finite element simulation,the 3D printing process parameters were optimized by combining with the actual printing process.The optimal printing parameters of the composite hydrogel were determined(air pressure of 1 bar,moving speed of 9 mm/s,straight line shape inside the stent,and line spacing of 1.6 mm).Fourth,the hydrogel scaffolds were printed with a 3D-Bioplotter printer and examined for compressive properties,degradation properties,cytotoxicity and biocompatibility.The results showed that the novel composite hydrogel scaffolds prepared in this study had good mechanical and biological properties.The Young’s modulus of the composite hydrogel scaffold reached 130 KPa and was able to maintain a low degradation rate in SBF solution for more than one month,and the scaffold could be accelerated in SBF solution at a later stage.The scaffold leach solution was noncytotoxic and the activity of ATDC-EGP-5 chondrocytes in the leach solution was over120%.By inoculating and culturing chondrocytes on the surface of the scaffold,it was found that chondrocytes could proliferate on the surface of the scaffold in large numbers and the survival rate of chondrocytes could reach more than 90%,in a CO2 incubator at 37℃ and 5% CO2 concentration.The composite hydrogel scaffold prepared in this study has low cytotoxicity and good biocompatibility,and its porous structure can facilitate the growth of chondrocytes,which has good prospects for application in articular cartilage and other areas. |
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