Hofmeister Effect‐Assisted One Step Fabrication of Ductile and Strong Gelatin Hydrogels

Abstract

Hydrogels with high strength and ductility are normally prepared from synthetic polymers, and most protein-based hydrogels are soft and brittle. Here, a strong, ductile gelatin hydrogel is prepared by simply soaking a virgin gelatin gel in an ammonium sulfate solution. The polymer chains in the covalent, crosslink-free network can freely move to homogeneously distribute stress, and more importantly, the highly kosmotropic ammonium sulfate ions greatly enhance the hydrophobic interactions and chain bundling within the gelatin gels. As a result, the treated hydrogels have an extraordinary ultimate strength (compressive and tensile strains of over 99% and 500%, respectively, and stresses of 12 and 3 MPa) superior to that of common protein gels. The physical crosslinks introduced by the Hofmeister effect can rapidly absorb energy and sustain large deformations via decrosslinking and dissociation, which result in energy dissipation and antifatigue properties. The effects of the gelatin and (NH 4 ) 2 SO 4 concentrations on the hydrogel mechanics are evaluated, and the possible strengthening mechanism is discussed. The effect of various ions in the Hofmeister series on the gelatin hydrogel is also investigated. Kosmotropic ions enhance the mechanical properties, whereas chaotropic ions soften and dissolve the gel.

Salt‐Assisted Toughening of Protein Hydrogel with Controlled Degradation for Bone Regeneration

“…Gelatin, derived from collagen, is considered a suitable base component of potential bone replacement materials with a 3D structure . Recently, Wang et al prepared a tough gelatin hydrogel with extraordinary ultimate strength; whereas, the gelatin hydrogel degraded quickly, as ions (CO 3 2− , Cl − , I − ) could render the gel soft and melted within 1 h. Neither slowly nor quickly degrading materials may be suitable for biomedical applications in tissue reconstruction.…”

Precisely Controlled Delivery of Abaloparatide through Injectable Hydrogel to Promote Bone Regeneration

“…[16,17] Gelatin is a denatured form of the protein collagen which can be used for tissue repair and controlling drug delivery systems. [18][19][20][21][22] Furthermore, gelatin shows no antigenity and is completely resorbable in vivo. [23] In order to further enhance or modify the performance of gelatin hydrogels, especially the mechanical properties, methacrylic anhydride (MA) was used to modify gelatin.…”

Hofmeister Effect‐Aided Assembly of Enhanced Hydrogel Supercapacitor with Excellent Interfacial Contact and Reliability

“…Furthermore, the increased intensity of the CO stretching vibrations (1670 cm −1 ) suggests the enhanced chain bundling. [28] All evidences confirmed the Hofmeister effect on PVA molecules within hydrogel.…”

“…Wang et al reported a tough and ductile gelatin hydrogel by immersing the prepared gelatin gel into an ammonium sulfate solution, this treated hydrogel has an extraordinary ultimate strength of 12 MPa based on Hofmeister effect. [28] Similarly, Kouwer et al tuned both the thermoresponsive behavior and mechanical properties of polyisocyanides hydrogel by utilizing the Hofmeister series. [29] While these studies have nothing to do with electrochemical energy storage devices, they provide us abundant experience to design tough hydrogel electrolyte for reliable devices.…”