Deep Eutectic Solvent-Based 3D Printable Zein Ink

3D printing of materials allows rapid and cost-effective fabrication of complex geometries and customized features in product design. With increasing focus on sustainability and circularity, natural biopolymers have gained attention as eco-friendly alternatives for developing 3D printing inks. Among these, zein, a prolamin-rich protein derived as a byproduct from corn processing, is desirable due to its biodegradability, biocompatibility, and availability in large scale. However, native zein ink prepared in aqueous ethanolic solution suffers from poor printability, structural infidelity, nozzle clogging, and solvent evaporation, which significantly compromise its usability. In this study, deep eutectic solvents (DES) are used to prepare zein inks for 3D printing applications. Rheological studies confirmed shear-thinning behavior of the formulated eutectic zein inks with tan δ < 1, indicating a favorable viscoelastic profile for 3D printing. Optimized printing conditions for the formulated ink are found to be 20 mm/s speed, 90 kPa pressure, 45% infill, and 22G (0.41 mm) nozzle diameter. Further, the formulated inks exhibited improved performance, such as increased filament stability, reduced collapse, and enhanced structural integrity over the native zein inks. In addition to ink compliance for 3D printing, cell adhesion studies revealed excellent biocompatibility and fibroblast proliferation, underscoring the material’s potential for biomedical applications. The findings of the study present a promising material formulation for sustainable and eco-friendly 3D printable bioinks in biomedical applications.