2.3. Fabrication of gel filaments
Under sterile conditions, the prepared ink was transferred to a printing stock syringe to be extruded through a nozzle with an inner diameter of 1 mm and deposited in an ion cross-linking solution to produce a 3D long gel filament with a diameter of about 1 mm. The printing speed was adjusted to print different types of inks with ideal printability. The gel fibre was soaked in deionised water for 10 min, rinsed, freeze-dried, frozen for 6 h, and then dried for 4 h before use.