Hydrophilic surface modification of cyclic olefin copolymer microfluidic chips using sequential photografting

Timothy B. Stachowiak, Dieudonne A. Mair, Tyler G. Holden, L. James Lee, Frantisek Svec, Jean Frechet*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

76 Scopus citations


The plastic material known as cyclic olefin copolymer (COC) is a useful substrate material for fabricating microfluidic devices due to its low cost, ease of fabrication, excellent optical properties, and resistance to many solvents. However, the hydrophobicity of native COC limits its use in bioanalytical applications. To increase surface hydrophilicity and reduce protein adsorption, COC surfaces were photografted with poly(ethylene glycol) methacrylate (PEGMA) using a two-step sequential approach: covalently-bound surface initiators were formed in the first step and graft polymerization of PEGMA was then carried out from these sites in the second step. Contact angle measurements were used to monitor and quantify the changes in surface hydrophilicity as a function of grafting conditions. As water droplet contact angles decreased from 88° for native COC to 45° for PEGMA-grafted surfaces, protein adsorption was also reduced by 78% for the PEGMA-modified COC micro-channels as determined by a fluorescence assay. This photografting technique should enable the use of COC microdevices in a variety of bioanalytical applications that require minimal nonspecific adsorption of biomolecules.

Original languageEnglish (US)
Pages (from-to)1088-1093
Number of pages6
JournalJournal of Separation Science
Issue number7
StatePublished - May 1 2007


  • Cyclic olefin copolymer
  • Microfluidic device
  • Photografting
  • Poly(ethylene glycol) methacrylate
  • Surface modification

ASJC Scopus subject areas

  • Analytical Chemistry
  • Filtration and Separation


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