Abstract
A new class of supramolecular hydrogels, cross-linked by host-guest interactions between β-cyclodextrin (βCD) and adamantane, were designed for the dynamic regulation of cell-substrate interactions. The initial substrate elasticity can be optimized by selecting the molar fraction of host- and guest monomers for the target cells. Moreover, owing to the reversible nature of host-guest interactions, the magnitude of softening and stiffening of the substrate can be modulated by varying the concentrations of free, competing host molecules (βCD) in solutions. By changing the substrate elasticity at a desired time point, it is possible to switch the micromechanical environments of cells. We demonstrated that the Young’s modulus of our “host-guest gels”, 4–11 kPa, lies in an optimal range not only for static (ex situ) but also for dynamic (in situ) regulation of cell morphology and cytoskeletal ordering of myoblasts. Compared to other stimulus-responsive materials that can either change the elasticity only in one direction or rely on less biocompatible stimuli such as UV light and temperature change, our supramolecular hydrogel enables to reversibly apply mechanical cues to various cell types in vitro without interfering cell viability.
Highlights
A new class of supramolecular hydrogels, cross-linked by host-guest interactions between β-cyclodextrin and adamantane, were designed for the dynamic regulation of cell-substrate interactions
We utilized a new class of hydrogel materials, cross-linked by host-guest interactions, and demonstrated the potential for the dynamic regulation of cell-substrate interactions
Taking the advantage of reversible, supramolecular cross-linkers based on βCD and adamantane, the substrate elasticity can be modulated by exchanging the culture medium with and without free host molecules
Summary
A new class of supramolecular hydrogels, cross-linked by host-guest interactions between β-cyclodextrin (βCD) and adamantane, were designed for the dynamic regulation of cell-substrate interactions. Through fine adjustment of cross-linker concentrations and the reaction time[6,7], one can control the bulk elasticity (Young’s modulus) of a given gel substrate “ex situ” Such materials have been used to gain insight into the vital role of elasticity compliance between cells and ECM in optimizing the cell morphology[8,9,10], regulating the migratory behavior[11,12], and controlling the stem cell differentiation[13,14]. Several recent studies demonstrated that the thiolated hyaluronic acid[26] and gelatin[27] form chemical gels via disulfide bonds, whose Young’s modulus decreased by adding dithiothreitol Such materials have a fundamental drawback: the change in the substrate stiffness by the cleavage of disulfide bonds goes only in one direction. Once a covalent bond is formed, it is very hard to cleave it
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