Miniaturized lead sensor based on lead-specific DNAzyme in a nanocapillary interconnected microfluidic device.
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 5' (3') 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 microM, and a detection limit of 11 nM. The sensor has been applied to the determination of Pb2+ 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.
Chang
In-Hyoung
IH
Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
Tulock
Joseph J
JJ
Liu
Juewen
J
Kim
Won-Suk
WS
Cannon
Donald M
DM
Lu
Yi
Y
Bohn
Paul W
PW
Sweedler
Jonathan V
JV
Cropek
Donald M
DM
D015374:Biosensing Techniques / Q000295:instrumentation*; D021881:DNA, Catalytic; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D007220:Industrial Waste / Q000032:analysis; D007854:Lead / Q000032:analysis*; D044085:Microfluidics / Q000295:instrumentation*; D049329:Nanostructures; D012722:Sewage / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
D021881:DNA, Catalytic; D007220:Industrial Waste; D012722:Sewage; D014874:Water Pollutants, Chemical; D007854:Lead