title: Miniaturized lead sensor based on lead-specific DNAzyme in a nanocapillary interconnected microfluidic device.
abstract: 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.
authors.affiliation: 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.
authors.forename: In-Hyoung
authors.initials: IH
authors.lastname: Chang
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Tulock
authors.forename: Juewen
authors.initials: J
authors.lastname: Liu
authors.forename: Won-Suk
authors.initials: WS
authors.lastname: Kim
authors.forename: Donald M
authors.initials: DM
authors.lastname: Cannon
authors.forename: Yi
authors.initials: Y
authors.lastname: Lu
authors.forename: Paul W
authors.initials: PW
authors.lastname: Bohn
authors.forename: Jonathan V
authors.initials: JV
authors.lastname: Sweedler
authors.forename: Donald M
authors.initials: DM
authors.lastname: Cropek
mesh_terms: 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*
chemical_list: D021881:DNA, Catalytic; D007220:Industrial Waste; D012722:Sewage; D014874:Water Pollutants, Chemical; D007854:Lead