Hydrogel Synthesis

Hydrogels are three-dimensional, crosslinked hydrophilic polymer materials that have attracted widespread attention due to their key role in the development of drug-delivery systems, biomolecular sensors and scaffolds for tissue engineering. Traditional synthesis methods for hydrogels rely on photopolymerization of water-soluble monomers. These radical-based uncontrolled crosslinking procedures lead to the formation of non-uniform heterogeneous hydrogels that often suffer from poor mechanical and structural properties^[1]. Click chemistry is a novel method for hydrogel synthesis and offers the potential to overcome the above challenges.

Applications

• Hydrogel synthesis by CuAAC click reaction

As a classical click reaction, copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction has been widely applied to hydrogel synthesis. Recently, a novel hydrogel was synthesized via CuAAC click reaction between poly (dimethylacrylamide) functionalized with an alkyne moiety (copoly alkyne) and poly (ethylene glycol) bis-azide bearing azido groups at both ends (Scheme 1)^[2]. This hydrogel can be used as a novel sieving matrix for high performance DNA electrophoresis, and its resolution and separation efficiency were significantly improved compared with traditional cross-linked polyacrylamide hydrogels.

Scheme 1. Formation of the hydrogel by CuAAC click reaction.

• Hydrogel synthesis by nucleophilic thiol-yne click reaction

Nucleophilic thiol-yne click reaction has been demonstrated as an attractive reaction for biomaterial synthesis such as hydrogels. Macdougall et al^[3]. reported the synthesis of strong hydrogels with tunable properties by nucleophilic thiol-yne click reaction. Specifically, alkyne and thiol-terminated poly (ethylene glycol), PEG precursors with 2, 3, and 4 arms were prepared by simple Fischer esterification methodologies (Scheme 2). Formed PEG hydrogels were subsequently prepared by mixing solutions containing a 1:1 molar ratio of alkyne to thiol polymer precursors in phosphate buffered saline (PBS) solution at pH 7.4. Hydrogels prepared by nucleophilic thiol-yne click reaction have several advantages, including high equilibrium water content, flexible structure, large pores, and tunable stiffness.

Scheme 2. (a) Nucleophilic click reaction between an thiol and alkyne; (b) Schematic of the PEG
precursors synthesized for crosslinking; and (c) Schematic of exemplar hydrogel networks.

What Can We Do?

Alfa Chemistry has a strong research foundation in the field of hydrogel synthesis by click chemistry. We have ability to help you explore the various applications of click chemistry and provide you with related click chemistry reagents, technical advice and services. If you have problems, please don't hesitate to contact us.

References

1. Yigit, S.; et al. Fabrication and functionalization of hydrogels through "click"; chemistry. Chemistry-An Asian Journal. 2011, 6: 2648-2659.
2. Finetti, C.; et al. Synthesis of hydrogel via click chemistry for DNA electrophoresis. Journal of Chromatography A. 2017, 1513: 226-234.
3. Macdougall, L.J.; et al. Efficient in situ nucleophilic thiol-yne click chemistry for the synthesis of strong hydrogel materials with tunable properties. ACS Macro Letters. 2017, 6: 93-97.