Immobilization of multi-enzyme microreactors inside microfluidic devices

Won-Gun Koh, Michael Pishko

Research output: Contribution to journalArticle

88 Citations (Scopus)

Abstract

A simple method to fabricate enzyme-containing microscopic hydrogel structures in microfluidic devices for the potential use in micro total analysis systems (μ-TAS) is described. Poly(ethylene glycol)-based hydrogel microstructures were prepared inside microchannels by photolithography and enzymes conjugated to a pH sensitive fluorophore (SNAFL-1) were incorporated into these hydrogel microstructures. Because of the ratiometric pH-dependent nature of SNAFL fluorescence, hydrogel microstructures exhibited a different emission intensity ratio with pH and this intensity ratio changed almost linearly between pH 7 and 12. When alkaline phosphatase-containing microreactors were exposed to p-nitrophenylphosphate (pNPP) as a substrate, phosphoric acid was produced inside the microstructure by enzymatic-catalyzed hydrolysis of the substrate and subsequently decreased the microenvironment pH. Because of the relatively rapid mass transport of analyte through the hydrogel, enzyme-catalyzed reaction was easily detected by change in emission intensity ratio before and after exposure to substrates. Enzyme-catalyzed reactions were quite fast and reached 90% of maximum value within 10 min. Data were analyzed using a modified Michaelis-Menten equation and apparent Michaelis constants could be obtained. This system was also successfully applied to urea hydrolysis by urease.

Original languageEnglish
Pages (from-to)335-342
Number of pages8
JournalSensors and Actuators, B: Chemical
Volume106
Issue number1 SPEC. ISS.
DOIs
Publication statusPublished - 2005 Apr 29

    Fingerprint

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

Cite this