Microfluidic/nanofluidic sensors using catalytic DNA for heavy metal detection

ENVR 157

Tulika S. Dalavoy, tdalavoy@uiuc.edu1, Jonathan V. Sweedler1, Paul W. Bohn, pbohn@nd.edu2, Yi Lu, yi-lu@uiuc.edu1, Mark A. Shannon, mshannon@uiuc.edu3, and Donald Cropek, Donald.M.Cropek@erdc.usace.army.mil4. (1) Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, (2) Department of Chemical and Biomolecular Engineering, University of Notre Dame, 301 Cushing Hall, Notre Dame, IN 46556, (3) Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green, 140 Mechanical Engineering Building, Urbana, IL 61801, (4) Environmental Processes Branch, USA CERL, 2902 Newmark Dr, Champaign, IL 61826
Non-biodegradable lead can accumulate in the environment and produce numerous toxicological effects. Despite the recognized adverse effects of lead, its presence is not actively monitored due to the lack of a field product that meets all requirements for in situ measurement of lead in ground water, i.e., rugged, reliable, sensitive, selective, and remotely operable. Microfluidic systems have become an important trend in environmental monitoring due to its potential to reduce cost, provide portability, and increase analysis speed. Combinations of biosensing with a microfluidic device can provide rapid and reliable determination of lead at trace levels.

In order to develop a reliable and sensitive device for in situ measurement of lead in ground water, a microchip-based lead sensor is being developed that employs lead-specific catalytic DNA as the recognition element. Lead-specific catalytic DNA (DNAzyme) cleaves its complementary substrate DNA strand in the presence of only cationic lead (Pb2+). Fluorescent tags on the substrate DNA transduce the Pb2+ concentration to a measurable optical signal. Microfluidic devices are being fabricated using PMMA to create a chip that can be used to controllably inject a sample analyte plug containing many metallic species through a molecular gate, i.e., Nanocapillary Array membrane (NCAM) into a microfluidic separation channel.

Strategies to immobilize DNAzyme on PMMA using biotin-streptavidin interaction are being explored both on planar PMMA and on the PMMA walls of the microfluidic channel. Pb(II) solution can be controllably injected from the separation channel through the NCAM into the detection channel containing immobilized DNAzyme, where it can be detected and quantified. Work on the immobilization of Pb-specific DNAzyme in the PMMA microfluidic devices and the study of the Pb detection activity in the microchannel using fluorescence microscopy will be presented.

 

Sensors for Detection and Quantification of Contaminants in Drinking Water and the Environment
8:30 AM-12:10 PM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 235, Oral

Division of Environmental Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008