title: Hairpin-based DNA electrochemical sensor for selective detection of a repetitive and structured target codifying a gliadin fragment.
abstract: High selectivity of genosensors is crucial for certain applications such as those involving species with high genetic variability. This is an unresolved problem when dealing with long target sequences that is further complicated when the target contains repetitive sequence domains. As a model for this situation, the problem of detecting gluten in food with identification of the source is studied. In order to discriminate the specific DNA sequence that encodes the wheat prolamin (gliadin) from rye and barley prolamins, the exquisite selectivity of a rationally designed hairpin capture probe is proposed and compared to a nonstructured capture probe. An electrochemical sandwich assay is proposed, involving capture probes chemisorbed on Au surfaces and biotinylated-signaling probes in combination with streptavidin-peroxidase labeling conjugates. As a result, a genosensor with similar sensitivity to that observed with linear probes but with complete specificity against closely related species was achieved. The surface-attached DNA stem-loop yields a device capable of accurately discriminating wheat DNA from rye and barley with a limit of detection of 1 nM.
authors.affiliation: Sección Departamental de Química Analítica, Facultad de Farmacia, Universidad Complutense de Madrid, Pz. Ramon y Cajal s/n, 28040, Madrid, Spain.
authors.forename: Begoña
authors.initials: B
authors.lastname: Martín-Fernández
authors.forename: Noemí
authors.initials: N
authors.lastname: de-Los-Santos-Álvarez
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Lobo-Castañón
authors.forename: Beatriz
authors.initials: B
authors.lastname: López-Ruiz
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000295:instrumentation* / Q000379:methods*; D005903:Gliadin / Q000032:analysis* / Q000235:genetics; D001467:Hordeum / Q000737:chemistry / Q000235:genetics; D057230:Limit of Detection; D015335:Molecular Probes / Q000737:chemistry*; D008969:Molecular Sequence Data; D012434:Secale / Q000737:chemistry / Q000235:genetics; D012680:Sensitivity and Specificity; D019809:Streptavidin / Q000737:chemistry; D014908:Triticum / Q000235:genetics
chemical_list: D015335:Molecular Probes; D004247:DNA; D005903:Gliadin; D019809:Streptavidin