3D Printing Hydrogel As An Immobilized Carrier For Biological Processes

Three-dimensional?3D?bioprinting is a hot pot for 3D printing,mostly used in tissue engineering and rarely used in enzyme-catalyzed processes.In this paper,sodium alginate/polyacrylamide/hydroxyapatite?SA/PAM/HA?mixed interpenetrating polymer network SA-AM-HA hydrogel was prepared and optimized for its application.First,sodium alginate-calcium chloride?SA-CaCl₂?,polyacrylamide?PAM?single-network hydrogel,SA-AM and SA-AM-HA double-network hydrogel were prepared,which were confirmed by SEM and FTIR.The synthesis of SA-AM hydrogels demonstrates the advantages of SA-AM-HA hydrogels as immobilized carriers by their degree of swelling,SEM,mechanical properties,and rheological properties.The compressive modulus of the SA-AM-HA hydrogel?7.16 MPa?is 14 times higher than that of the SA-AM hydrogel,and the maximum storage modulus of the SA-AM-HA hydrogel is 31960 Pa.Then,the ratio of SA/PAM/HA components is optimized.The best ratio of SA-AM-HA hydrogel preparation is SA:HA=1.2:1,AM:SA=4:1 decided by swelling degree,SEM,mechanical properties,rheological properties,porosity.In enzyme catalyzed applications,the non-catalytic properties of immobilized matrices have high importance.We use a one-pot method for immobilized enzymes based on extrusion-based bio-3 D printing technology.Next,we used different types of immobilized glucose oxidase/catalase to synthesize gluconic acid.With the porosity of the immobilized enzyme,the catalytic efficiency is improved.In addition,the immobilized enzyme exhibits operational stability.Finally,after 4 batches of re-use,a high conversion of 97%was maintained.These results indicate that the preparation of one-pot immobilized enzyme by 3D bioprinting has great application prospects due to high stability and conversion rate.Finally,considering the degradability of tissue engineering scaffolds,three different pore size Gel-SA-HA gel scaffolds were used to culture the ADTC5 mouse chondrocytes.It was found that the cells could proliferate on the scaffold and the cells could be The proliferation was extended to OD values of 0.5 and above in 3 days and 5 days,and the cells in the 9-well scaffold had the best proliferation effect.With the increase of time,the cell inhibition rate increased gradually and even reached more than 20%on the 7th day,and the 9-well scaffold had the highest cell inhibition rate.