Pluronic 40% (w/v) was loaded into two separate 3 cc syringe barrels (Nordson EFD, Fluid Dispensing system, USA) at room temperature and centrifuged in an Avanti J-26 XPI centrifuge (Beckman Coulter, USA) at 1600 rpm for 5 min to remove air bubbles. The syringe barrel was connected to a nozzle (red gauge 25 and pink gauge 20) and loaded on an Allevi 3D bioprinter (Allevi, USA). Printing speed and path plan was controlled by programmed G-code.