title: On-chip transduction of nucleic acid hybridization using spatial profiles of immobilized quantum dots and fluorescence resonance energy transfer.
abstract: The glass surface of a glass-polydimethylsiloxane (PDMS) microfluidic channel was modified to develop a solid-phase assay for quantitative determination of nucleic acids. Electroosmotic flow (EOF) within channels was used to deliver and immobilize semiconductor quantum dots (QDs), and electrophoresis was used to decorate the QDs with oligonucleotide probe sequences. These processes took only minutes to complete. The QDs served as energy donors in fluorescence resonance energy transfer (FRET) for transduction of nucleic acid hybridization. Electrokinetic injection of fluorescent dye (Cy3) labeled oligonucleotide target into a microfluidic channel and subsequent hybridization (within minutes) provided the proximity for FRET, with emission from Cy3 being the analytical signal. The quantification of target concentration was achieved by measurement of the spatial length of coverage by target along a channel. Detection of femtomole quantities of target was possible with a dynamic range spanning an order of magnitude. The assay provided excellent resistance to nonspecific interactions of DNA. Further selectivity of the assay was achieved using 20% formamide, which allowed discrimination between a fully complementary target and a 3 base pair mismatch target at a contrast ratio of 4:1.
authors.affiliation: Chemical Sensors Group, Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, Ontario L5L 1C6, Canada.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Tavares
authors.forename: M Omair
authors.initials: MO
authors.lastname: Noor
authors.forename: Charles H
authors.initials: CH
authors.lastname: Vannoy
authors.forename: W Russ
authors.initials: WR
authors.lastname: Algar
authors.forename: Ulrich J
authors.initials: UJ
authors.lastname: Krull
mesh_terms: D001483:Base Sequence; D015342:DNA Probes; D031541:Fluorescence Resonance Energy Transfer; D044085:Microfluidics / Q000295:instrumentation; D009693:Nucleic Acid Hybridization; D045663:Quantum Dots
chemical_list: D015342:DNA Probes