Cation-induced shape programming and morphing in protein-based hydrogels

• Published in: Science advances Vol. 6; no. 18; p. eaba6112
• Main Authors: Khoury, Luai R., Slawinski, Marina, Collison, Daniel R., Popa, Ionel
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 01.05.2020
• Subjects: Applied Sciences and Engineering; Life Sciences; Materials Science; SciAdv r-articles
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.aba6112

Dosing protein hydrogels with divalent cations allows for programming of complex shapes and shape morphing. Smart materials that are capable of memorizing a temporary shape, and morph in response to a stimulus, have the potential to revolutionize medicine and robotics. Here, we introduce an innovative method to program protein hydrogels and to induce shape changes in aqueous solutions at room temperature. We demonstrate our approach using hydrogels made from serum albumin, the most abundant protein in the blood plasma, which are synthesized in a cylindrical or flower shape. These gels are then programmed into a spring or a ring shape, respectively. The programming is performed through a marked change in stiffness (of up to 17-fold), induced by adsorption of Zn 2+ or Cu 2+ cations. We show that these programmed biomaterials can then morph back into their original shape, as the cations diffuse outside the hydrogel material. The approach demonstrated here represents an innovative strategy to program protein-based hydrogels to behave as actuators.