Miniaturized lead sensor based on lead-specific DNAzyme in a nanocapillary interconnected microfluidic device

In Hyoung Change, Joseph J. Tulock, Juewen Liu, Won Suk Kim, Donald M. Cannon, Yi Lu, Paul W. Bohn, Jonathan V. Sweedler, Donald M. Cropek

Research output: Contribution to journalArticlepeer-review


A miniaturized lead sensor has been developed by combining a lead-specific DNAzyme with a microfabricated device containing a network of microfluidic channels that are fluidically coupled via a nanocapillary array interconnect. A DNAzyme construct, selective for cleavage in the presence of Pb2+ and derivatized with fluorophore (quencher) at the 5́ (3́) end of the substrate and enzyme strands, respectively, forms a molecular beacon that is used as the recognition element. The nanocapillary array membrane interconnect is used to manipulate fluid flows and deliver the small-volume sample to the beacon in a spatially confined detection window where the DNAzyme is interrogated using laser-induced fluorescence detection. A transformed log plot of the fluorescent signal exhibits a linear response (r2 = 0.982) over a Pb2+ concentration range of 0.1-100 μM, and a detection limit of 11 nM. The sensor has been applied to the determination of Pb 2+ in an electroplating sludge reference material, the result agreeing with the certified value within 4.9%. Quantitative measurement of Pb2+ in this complex sample demonstrates the selectivity of this sensor scheme and points favorably to the application of such technologies to analysis of environmental samples. The unique combination of a DNAzyme with a microfluidic-nanofluidic hybrid device makes it possible to change the DNAzyme to select for other compounds of interest, and to incorporate multiple sensing systems within a single device for greater flexibility. This work represents the initial steps toward creation of a robust field sensor for lead in groundwater or drinking water.

Original languageEnglish (US)
Pages (from-to)3756-3761
Number of pages6
JournalEnvironmental Science and Technology
Issue number10
StatePublished - May 15 2005

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry


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