2.8 Fabrication of the complete biomimicking trilayer tissue engineering scaffolds
BMSC-laden GelMA/Gel bioinks were used to fabricate the cell-laden hydrogel layer on S+F-PDA@E2 bilayered scaffolds via 3D bioprinting for the construction of designed biomimicking trilayer tissue engineering scaffolds. In the current study, GelMA/Gel inks were homogeneously mixed with BMSCs at room temperature. The resulting cell-laden bioinks were subsequently transferred to a cartridge in a 3D bioprinter. The printing parameters were set as: the inner diameter of the printing nozzle was 210μm, the printing temperature was 20℃, and the printing speed was 6mm/s. After adjusting the height between the S+F-PDA@E2 scaffold and printing nozzle, BMSC-laden GelMA/Gel hydrogels were 3D printed on S+F-PDA@E2 scaffolds. Subsequently, a UV light (wavelength: 365 nm; power: 365 mW) was used to crosslink the hydrogel layer for 2 min. The trilayer tissue engineering scaffolds thus produced were transferred to 6-well cell culture plate and cultured with DMEM at 37 ℃. The printability of BMSC-laden GelMA/Gel bioinks was evaluated by using the following formula:
Printability = L2/16A (1)
where L is the perimeter and A is the area of the pore. If the Printability value is close to 1, it signifies the square shape of the pores, suggesting good printability of the ink or bioink[21].