Electrodeposition-based rapid bioprinting of 3D-designed hydrogels with a pin art device

Three-dimensional (3D) designed hydrogels are receiving considerable attention for use in tissue engineering. Herein, we present a novel method for bioprinting 3D hydrogels by electrodeposition with a pin art device. The device consists of a metal substrate and an array of electrode pins that can slide independently. To fabricate a 3D-hydrogel, pins are pushed from the rear with a 3D object to generate a 3D extruded-pin relief of the object; the extruded pins are then inserted into a chitosan/gelatin hydrogel. Due to H⁺ consumption at these pins, which collectively act as a cathode, the protonated amino groups of the chitosan become deprotonated, which results in the electrodeposition of the chitosan bound to the gelatin onto the extruded pins. The untreated hydrogel is removed by heating to provide the 3D-designed chitosan/gelatin hydrogel. As a proof of concept, hydrogels of various shapes were fabricated. In addition, cells were successfully cultured in a hydrogel, highlighting its biocompatibility. This method is useful for constructing 3D artificial tissue consisting of hydrogels and cells.