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Macroscopic volume change of dynamic hydrogels induced by reversible DNA hybridization.

ABSTRACT: Molecular recognition is fundamental to the specific interactions between molecules, of which the best known examples are antibody-antigen binding and cDNA hybridization. Reversible manipulation of the molecular recognition events is still a very challenging topic, and such studies are often performed at the molecular level. An important consideration is the collection of changes at the molecular level to provide macroscopic observables. This research makes use of photoresponsive molecular recognition for the fabrication of novel photoregulated dynamic materials. Specifically, a dynamic hydrogel was prepared by grafting azobenzene-tethered ssDNA and its cDNA to the hydrogel network. The macroscopic volume of the hydrogel can be manipulated through the photoreversible DNA hybridization controlled by alternate irradiation of UV and visible light. The effects of synthetic parameters including the concentration of DNA, polymer monomer, and permanent cross-linker are also discussed.

SUBMITTER: Peng L

PROVIDER: S-EPMC3407576 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature

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Macroscopic volume change of dynamic hydrogels induced by reversible DNA hybridization.

Peng Lu L You Mingxu M Yuan Quan Q Wu Cuichen C Han Da D Chen Yan Y Zhong Zhihua Z Xue Jiangeng J Tan Weihong W

Journal of the American Chemical Society 20120709 29

Molecular recognition is fundamental to the specific interactions between molecules, of which the best known examples are antibody-antigen binding and cDNA hybridization. Reversible manipulation of the molecular recognition events is still a very challenging topic, and such studies are often performed at the molecular level. An important consideration is the collection of changes at the molecular level to provide macroscopic observables. This research makes use of photoresponsive molecular recog ...[more]

PMID: 22742418

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Project description:The mechanical properties of the native extracellular matrix play a key role in regulating cell behavior during developmental, healing and homeostatic processes. Since these properties change over time, it may be valuable to have the capacity to dynamically vary the mechanical properties of engineered hydrogels used in tissue engineering strategies to better mimic the dynamic mechanical behavior of native extracellular matrix. However, in situ repeatedly reversible dynamic tuning of hydrogel mechanics is still limited. In this study, we have engineered a hydrogel system with reversible dynamic mechanics using a dual-crosslinkable alginate hydrogel. The effect of reversible mechanical signals on encapsulated stem cells in dynamically tunable hydrogels has been demonstrated. In situ stiffening of hydrogels decreases cell spreading and proliferation, and subsequent softening of hydrogels gives way to an increase in cell spreading and proliferation. The hydrogel stiffening and softening, and resulting cellular responses are repeatedly reversible. This hydrogel system provides a promising platform for investigating the effect of repeatedly reversible changes in extracellular matrix mechanics on cell behaviors. STATEMENT OF SIGNIFICANCE: Since the mechanical properties of native extracellular matrix (ECM) change over time during development, healing and homeostatic processes, it may be valuable to have the capacity to dynamically control the mechanics of biomaterials used in tissue engineering and regenerative medicine applications to better mimic this behavior. Unlike previously reported biomaterials whose mechanical properties can be changed by the user only a limited number of times, this system provides the capacity to induce unlimited alterations to the mechanical properties of an engineered ECM for 3D cell culture. This study presents a strategy for on-demand dynamic and reversible control of materials' mechanics by single and dual-crosslinking mechanisms using oxidized and methacrylated alginates. By demonstrating direct changes in encapsulated human mesenchymal stem cell morphology, proliferation and chondrogenic differentiation in response to multiple different dynamic changes in hydrogel mechanics, we have established a repeatedly reversible 3D cellular mechanosensing system. This system provides a powerful platform tool with a wide range of stiffness tunability to investigate the role of dynamic mechanics on cellular mechanosensing and behavioral responses.

Project description:Biomolecule-functionalized hydrogels have emerged as valuable cell culture platforms to recapitulate the mechanical and biochemical properties of the extracellular niche. The typical strategy to functionalize hydrogels with biomolecules involves directly tethering them to the hydrogel backbone resulting in a static material. Thus, this approach fails to capture the dynamic changes in biomolecule composition that occur during biological processes or that may be required for regenerative medicine applications. Moreover, it also limits the scope of biomolecules to simple peptides, as signaling proteins generally have poor stability under cell culture conditions and lose their bioactivity over time. To that end, we sought to develop a bioconjugation reaction that would enable reversible and repeatable tethering of signaling proteins to hydrogels, so that spent protein could be released on-demand and replaced with fresh protein as needed. Specifically, we designed an allyl sulfide chain-transfer agent that enables a reversible, photomediated, thiol-ene bioconjugation of signaling proteins to hydrogels. Upon addition of a thiolated protein to the allyl sulfide moiety, the previously tethered protein is released, and the "ene" functionality is regenerated. Using this approach, we demonstrate that protein patterning can be achieved in hydrogels through a thiol-ene reaction, and the patterned protein can then be released through a subsequent thiol-ene reaction of a PEG thiol. Importantly, this process is repeatable through multiple iterations and proceeds at physiologically relevant signaling protein concentrations. Finally, we demonstrate that whole signaling proteins can be patterned and released in the presence of cells, and that cells respond to their presentation with spatial fidelity. Combined, these data represent the first example of a methodology that enables fully reversible and repeatable patterning and release of signaling proteins from hydrogels.

Dataset Information

Macroscopic volume change of dynamic hydrogels induced by reversible DNA hybridization.

Publications

Macroscopic volume change of dynamic hydrogels induced by reversible DNA hybridization.

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