In situ crosslinked hydrogels formed using Cu(I)-free Huisgen cycloaddition reaction

Meredith Clark, Patrick Kiser*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Background: 'Click' chemistry, or the 1,3-dipolar cycloaddition of organic azides with alkynes, has been evaluated for many biomedical purposes; however, its utility in crosslinking hydrogels in situ is limited by the toxicity of the requisite copper(I) catalyst. We report the first use of catalyst-free Huisgen cycloaddition to generate crosslinked hydrogels under physiological conditions using multivalent azide-functionalized polymers and an electron-deficient dialkyne crosslinker. Results: Water-soluble azide-functionalized polymers were crosslinked with an electron-deficient dialkyne crosslinker to form hydrogels at physiological temperature without the addition of copper(I) catalyst. Crosslinking was confirmed using scanning electron microscopy, Fourier transform infrared and 1H NMR analyses. Flow by vial inversion and dynamic rheological methodologies were implemented to evaluate gelation kinetics at 37°C of variable polymer compositions, concentrations and stoichiometric ratios. Kinetic studies revealed gelation in as little as 12 h at 37°C, although strong gels that withstand inversion were observed by 1-8 days. Conclusion: The ability to form hydrogel networks under mild conditions demonstrates the potential viability of the catalystfree 'click' crosslinking chemistry for in situ gelling and other biological applications. Further chemical modifications in the crosslinking moieties, as well as polymer and crosslinker conformations, are expected to enhance gelation kinetics to a more biomedically practical rate.

Original languageEnglish (US)
Pages (from-to)1190-1195
Number of pages6
JournalPolymer International
Issue number10
StatePublished - Oct 2009


  • Catalyst Free
  • Click chemistry
  • Crosslinking
  • Cycloaddition
  • Hydrogels

ASJC Scopus subject areas

  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry


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