title: Comprehensive study of interactions between DNA and new electroactive Schiff base ligands. Application to the detection of singly mismatched Helicobacter pylori sequences.
abstract: N,N'-Bis(3,4-dihydroxybenzylidene)-1,2-diaminobenzene (3,4-DHS) and N,N'-bis(2,5-dihydroxybenzylidene)-1,2-diaminobenzene (2,5-DHS) have been used as electrochemical probes in DNA sensing. These ligands, containing ortho and para quinone functional groups, respectively, as well as planar aromatic domains, are capable of binding to double stranded DNA (ds-DNA) more efficiently than to single stranded DNA (ss-DNA). Emphasis has been placed on the elucidation of the nature of the interaction by combining spectroscopic and electrochemical techniques. From spectrophotometric titration experiments, the binding constants of 3,4-DHS and 2,5-DHS with ds-DNA were found to be (9.0+/-0.3) x 10(3) and (3.3+/-0.2) x 10(3)M(-1), respectively. These values are consistent with a binding mode dominated by interactions with the minor groove of ds-DNA. The electroactivity of the quinone moiety in 3,4-DHS bound to DNA could be employed as an electrochemical indicator to detect hybridization events in DNA biosensors. These biosensors have been constructed by immobilization of a thiolated capture probe sequence from Helicobacter pylori onto gold electrodes. After hybridization with the complementary target sequence, 3,4-DHS was accumulated within the double stranded DNA layer. Electrochemical detection was performed by differential pulse voltammetry over the potential range where the quinone moiety is redox active. Using this approach, complementary target sequences of H. pylori can be quantified over the range of 8.9-22.2 microM with a detection limit of 8.3+/-0.4 microM and a linear correlation coefficient of 0.989. In addition this approach is capable of detecting hybridization of complementary sequences containing a single mismatch.
authors.affiliation: Departamento de Química Analítica y Análisis Instrumental, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Revenga-Parra
authors.forename: Tania
authors.initials: T
authors.lastname: García
authors.forename: Encarnación
authors.initials: E
authors.lastname: Lorenzo
authors.forename: Félix
authors.initials: F
authors.lastname: Pariente
mesh_terms: D020137:Base Pair Mismatch / Q000235:genetics*; D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D016480:Helicobacter pylori / Q000235:genetics*; D017403:In Situ Hybridization / Q000379:methods*; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D012545:Schiff Bases / Q000737:chemistry*; D017422:Sequence Analysis, DNA / Q000379:methods
chemical_list: D004269:DNA, Bacterial; D012545:Schiff Bases