Fabrication of Patterned Hydrogel Interfaces: Exploiting the Maleimide Group as a Dual Purpose Handle for Cross-Linking and Bioconjugation.

Functional hydrogels that can be obtained through facile fabrication procedures and subsequently modified using straightforward reagent-free methods are indispensable materials for biomedical applications such as sensing and diagnostics. Herein a novel hydrogel platform is obtained using polymeric precursors containing the maleimide functional group as a side chain. The maleimide groups play a dual role in fabrication of functional hydrogels. They enable photochemical cross-linking of the polymers to yield bulk and patterned hydrogels. Moreover, the maleimide group can be used as a handle for efficient functionalization using the thiol-maleimide conjugation and Diels-Alder cycloaddition click reactions. Obtained hydrogels are characterized in terms of their morphology, water uptake capacity, and functionalization. Micropatterned hydrogels are obtained under UV-irradiation using a photomask to obtain reactive micropatterns, which undergo facile functionalization upon treatment with thiol-containing functional molecules such as fluorescent dyes and bioactive ligands. The maleimide group also undergoes conjugation through the Diels-Alder reaction, where the attached molecule can be released through thermal treatment via the retro Diels-Alder reaction. The antibiofouling nature of these hydrogel micropatterns enables efficient ligand-directed biomolecular immobilization, as demonstrated by attachment of streptavidin-coated quantum dots.

Designing functionalizable hydrogels through thiol-epoxy coupling chemistry.

A novel and modular strategy has been developed for the preparation of reactive and functionalized hydrogels. In this strategy, thiol-epoxy coupling chemistry was employed for the formation of a hydrophilic network. The hydroxyl groups, generated during the coupling process, were then engaged in anchoring a fluorescent probe to the hydrogel scaffold.