Fully Degradable Protein Gels with Superior Mechanical Properties and Durability: Regulation of Hydrogen Bond Donors.

Abstract

Protein gels hold great promise in various applications due to their high biocompatibility, biodegradability, and abundant sources. However, most existing protein gels suffer from low strength, stiffness, and toughness because conventional solvent within gels usually weakens crosslinked network structure. Here, strong, stiff, and tough protein gels are developed by using deep eutectic solvents (DESs) with tunable hydrogen bond donors (HBDs) as the dispersion medium. The DESs not only facilitate protein chain-chain interaction, but also form abundant non-covalent crosslinks between protein chains through protein chain-solvent interaction. More importantly, these crosslinked interactions can be tailored by varying HBDs, further toughening the gels. As a result, the obtained protein gels exhibit excellent mechanical properties, including tensile strength of 10.25 ± 1.28 MPa, tensile strain of 892.51 ± 39.66%, elastic modulus of 24.57 ± 0.27 MPa, toughness of 17.34 ± 0.46 MJ m-3, and fracture energy of 6.76 ± 0.99 kJ m-2, which surpass the previously reported protein gels. Despite their enhanced mechanics, they retain key advantages such as adhesiveness, retrievability, environmental durability, and full degradability. This work presents a novel strategy for designing robust, multifunctional protein gels, expanding their potential in emerging technologies that demand both mechanical toughness and functional versatility.