Microstructured Elastomer‐PEG Hydrogels via Kinetic Capture of Aqueous Liquid–Liquid Phase Separation

• Published in: Advanced science Vol. 5; no. 6; pp. 1701010 - n/a
• Main Authors: Lau, Hang Kuen, Paul, Alexandra, Sidhu, Ishnoor, Li, Linqing, Sabanayagam, Chandran R., Parekh, Sapun H., Kiick, Kristi L.
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01.06.2018; John Wiley and Sons Inc; Wiley
• Subjects: Cell growth; Emulsion polymerization; Gene expression; Grants; Hydrogels; Kinetics; liquid-liquid phase separation; Mechanical properties; micromechanical; Microscopy; Microstructure; Molecular weight; Polymers; Polypeptides; resilin; Software; Statistical analysis; Stem cells; Tissue engineering; Delaware; micromechanical; hydrogels; liquid–liquid phase separation; resilin; polypeptides
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.201701010

Heterogeneous hydrogels with desired matrix complexity are studied for a variety of biomimetic materials. Despite the range of such microstructured materials described, few methods permit independent control over microstructure and microscale mechanics by precisely controlled, single‐step processing methods. Here, a phototriggered crosslinking methodology that traps microstructures in liquid–liquid phase‐separated solutions of a highly elastomeric resilin‐like polypeptide (RLP) and poly(ethylene glycol) (PEG) is reported. RLP‐rich domains of various diameters can be trapped in a PEG continuous phase, with the kinetics of domain maturation dependent on the degree of acrylation. The chemical composition of both hydrogel phases over time is assessed via in situ hyperspectral coherent Raman microscopy, with equilibrium concentrations consistent with the compositions derived from NMR‐measured coexistence curves. Atomic force microscopy reveals that the local mechanical properties of the two phases evolve over time, even as the bulk modulus of the material remains constant, showing that the strategy permits control of mechanical properties on micrometer length scales, of relevance in generating mechanically robust materials for a range of applications. As one example, the successful encapsulation, localization, and survival of primary cells are demonstrated and suggest the potential application of phase‐separated RLP‐PEG hydrogels in regenerative medicine applications. Microstructured elastomer‐poly(ethylene glycol) hydrogels can be formed by select photochemical capture of phase separation in solutions of a highly elastomeric resilin‐like polypeptide and poly(ethylene glycol). The evolution of chemical composition and micromechanical properties are correlated, and the matrices show high cell compatibility. These studies offer simple approaches for the production of microstructured elastomers of controlled compositions.