Coaxial Scale‐Up Printing of Diameter‐Tunable Biohybrid Hydrogel Microtubes with High Strength, Perfusability, and Endothelialization

Although great progress has been made in coaxial extrusion printing toward generating microtubes for mimicking tubular tissues, these microtubes with insufficient mechanical properties and uncontrollable inherent swelling attribute severely hinder their utilization as load-bearing tubular tissue. Herein, a high-strength microtube is constructed by coaxial printing with a customized biohybird hydrogel ink consisting of nanoclay, H-bonding monomer N-acryloyl glycinamide, and gelatin methacryloyl. The physical interpenetration between nanoclay and polymer chains endows this ink with excellent printability and structural stability, thus facilitating the precise deposition of scalable microtubes with tunable small-diameters and large-scale lengths. After photocrosslinking, 3D-printed biohybrid hydrogel microtube demonstrates marvelous mechanical properties with a tensile strength (approximate to 22 MPa), a stretchability (approximate to 500%), a Young's modulus (approximate to 21 MPa), an anti-fatigue performance (approximate to 200 cycles), a burst pressure (approximate to 2500 mmHg), and a suture retention strength (approximate to 280 gf) in swelling equilibrium state, which are far superior to the previously printed microtubes and generally satisfy the requirements of tubular tissues. Additionally, this obtained microtube also displays favorable biological features that support adhesion, spreading, and endothelialization of human umbilical vein endothelial cells. This study successfully develops a biohybrid hydrogel ink to fabricate a scalable high-strength microtube with enormous potential in regeneration of tube-like tissues.