Universal Strategy for Regulating Protein-Based High Internal Phase Emulsions as 3D Printing Materials

Protein-stabilized high internal phase emulsions (HIPEs), which are pseudoplastic fluids with shear thinning and high viscoelasticity, are suitable for 3D printing inks. However, owing to the lack of a universal approach to the 3D printing of HIPEs, existing printing materials are unable to meet the developmental, biocompatibility, and safety requirements of various applications. Herein, it is demonstrated that post-acidification of protein HIPEs enhances 3D printing performance. This method has the advantage of breaking through protein limitations, pH, and other environmental factors. The self-supporting property required for 3D printing is achieved through the self-assembly of continuous-phase proteins into particle aggregates, and interfacial stability is maintained owing to the constant interfacial tension and contact angle. The acid-induced protein aggregates in the continuous phase do not affect the stability of the modified HIPEs. This work provides a valuable new idea for advancing the application of protein HIPEs in 3D printing through a post-acidification strategy.