title: Electronic transduction of DNA sensing processes on surfaces: amplification of DNA detection and analysis of single-base mismatches by tagged liposomes.
abstract: Tagged, negatively charged, liposomes are used to amplify DNA sensing processes. The analyses of the target DNA are transduced electrochemically by using Faradaic impedance spectroscopy, or by microgravimetric measurements with Au-quartz crystals. By one method, a probe oligonucleotide (1) is assembled on Au-electrodes or Au-quartz crystals. The formation of the double-stranded assembly with the analyte DNA (2) is amplified by the association of the 3-oligonucleotide-functionalized liposomes to the sensing interface. The target DNA is analyzed by this method with a sensitivity limit that corresponds to 1 x 10(-12) M. A second method to amplify the sensing of the analyte involves the interaction of the 1-functionalized electrode or Au-quartz crystal with the target DNA sample (2) that is pretreated with the biotinylated oligonucleotide (4). The formation of the three-component double-stranded assembly between 1/2/4 is amplified by the association of avidin and biotin-labeled liposomes to the sensing interfaces. By the secondary association of avidin and biotin-tagged liposomes, a dendritic-type amplification of the analysis of the DNA is accomplished. The analyte DNA (2) is sensed by this method with a sensitivity limit corresponding to 1 x 10(-13) M. The biotin-tagged liposomes are also used to probe and amplify single-base mismatches in an analyte DNA. The 6-oligonucleotide-functionalized Au-electrode or Au-quartz crystal was used to differentiate the single-base mismatch (G) in the mutant (5) from the normal A-containing gene (5a). Polymerase-induced coupling of the biotinylated-C-base to the double-stranded assembly generated between 6 and 5 followed by the association of avidin and biotin-tagged liposomes is used to probe the single base mismatch. The functionalized liposomes provide a particulate building unit for the dendritic amplification of DNA sensing.
authors.affiliation: Contribution from the Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: F
authors.initials: F
authors.lastname: Patolsky
authors.forename: A
authors.initials: A
authors.lastname: Lichtenstein
authors.forename: I
authors.initials: I
authors.lastname: Willner
mesh_terms: D020137:Base Pair Mismatch; D001483:Base Sequence; D004247:DNA / Q000032:analysis* / Q000737:chemistry; D004566:Electrodes; D008081:Liposomes; D010084:Oxidation-Reduction
chemical_list: D008081:Liposomes; D004247:DNA