Engineering gelatin-based alginate/carbon nanotubes blend bioink for direct 3D printing of vessel constructs

Nowadays 3D bioprinting, due to its high structural reconstruction and low cost, has been a promising technology and gained expectation in the treatment of vascular diseases. Although some studies have reported that 3D printing of large-sized blood vessels in the human body has been achieved, there are still some problems to be solved urgently, such as the unfulfilled microvascular simulation and inferior biocompatibility and mechanical strength of scaffold materials. In this paper, the hybrid bioink prepared with gelatin, sodium alginate and carbon nanotubes were manufactured into cylindrical scaffolds through the collaboration between the vertical directional extrusion of printing nozzle and axial rotation of stepper motor module. Mouse epidermal fibroblasts were inoculated into the inner and outer walls of hollow tubular scaffolds to fabricate engineered blood vessels. The internal diameters of the bionic circular tubes printed in batches were 3 mm with an average wall thickness of 0.5 mm and a length of 7-10 cm. Results demonstrated that the proper doping of carbon nanotubes could effectively increase the mechanical properties of the composite scaffolds. Also, quantitative experiments proved that a small amount of doping of carbon nanotubes had little effect on cytotoxicity, and the constructs could meet the requirements of biomimetic vascular.