Bingham Fluid-Assisted Fabrication of 3D Vascular-Like Constructs of Interpenetrating Network Hydrogel

Organ printing, which utilizes advanced manufacturing technologies to fabricate three-dimensional (3D) functional organs based on layer-by-layer mechanism, is emerging as a promising solution to solve the organ donor shortage problem affecting all over the world. One of the biggest challenges for fabrication of functional and effective thick tissues/organs is the engineering of vascular networks. This paper introduces a Bingham fluid (Carbopol gel) to assist fabrication of 3D vascular-like constructs of interpenetrating network (IPN) hydrogels. Carbopol gel as a Bingham fluid exhibits a characteristic yield stress behavior. As the nozzle moves inside Carbopol, the shear stress is larger than the yield stress and the Carbopol gel behaves like a viscous fluid with a specific viscosity. After the nozzle moves away, the shear stress decreases below the yield stress and the Carbopol gel rapidly solidifies behaving like a solid. This unique rheological property is utilized to support and maintain the shape of the fabricated 3D structures, although the fluid printed is not crosslinked. Finally, the fabricated structures are subject to a two-step gelation process to successfully form 3D vascular-like constructs of IPN hydrogels. This novel approach enables effective and efficient fabrication of complex vascular network of IPN hydrogels.