Indigo carmine: A base and neutral electrolyte-mediated photoinitiator for 3D printing in high fidelity

Abstract

Volumetric additive manufacturing with light is an advanced technology in diverse conventional fields. However, with the raising awareness of environmental concerns and the growing interest in biomedical applications, the safety and water solubility of the existing photoinitiators are challenged. Herein, we developed a photoinitiating system based on a blue food colorant, i.e., indigo carmine. The indigo carmine-based photoinitiating system induced a rapid photochemical reaction and photobleaching under blue and green LEDs in the alkaline medium. The unprecedented photoinitiation ability of the indigo carmine-based photoinitiating system in terms of rate of photopolymerization and the final monomer conversion was achieved under the irradiation of low-intensity light sources. Subsequently, a sophisticated 3D printing in high fidelity was carried out and a 2D seashell was designed and printed with the function of 2D–3D reversible switching. These findings demonstrated that the indigo carmine-based photoinitiating system could resolve the safety and water solubility challenges and be involved in the 3D printing of biomedical materials.