title: Electrochemical DNA biosensors based on long-range electron transfer: investigating the efficiency of a fluidic channel microelectrode compared to an ultramicroelectrode in a two-electrode setup.
abstract: Here, we describe the transposition of an ultramicroelectrode (UME) setup into a microfluidic chip configuration for DNA biosensors. The hydrodynamic properties of the fluidic channel microelectrode were screened with an [Fe(iii)(CN)6]3-/[Fe(ii)(CN)6]4-redox couple by cyclic voltammetry to provide a basis for further biological processes. A 23-base DNA probe was self-assembled into a monolayer on gold microelectrodes both in classical configuration and integrated in a microfluidic setup. Special interest was focused on the DNA target mimicking the liver-specific micro-ribonucleic acid 122 (miRNA122). Long-range electron transfer was chosen for transducing the hybridization. This direct transduction was indeed significantly enhanced after hybridization due to DNA-duplex π-stacking and the use of redox methylene blue as a DNA intercalator. Quantification of the target was deduced from the resulting electrical signal characterized by cyclic voltammetry. The limit of detection for DNA hybridization was 0.1 fM in stopped flow experiments, where it can reach 1 aM over a 0.5 μL s-1flow rate, a value 104-fold lower than the one measured with a conventional UME dipped into an electrolyte droplet under the same analytical conditions. An explanation was that forced convection drives more biomolecules to the area of detection even if a balance between the speed of collection and the number of biomolecules collected has been found. The latter point is discussed here along with an attempt to explain why the sensor has reached such an unexpected value for the limit of detection.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 place Jussieu, F-75005, Paris, France. Jean.gamby@lpn.cnrs.fr and Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N - Marcoussis, 91460 Marcoussis, France.
authors.forename: M-C
authors.initials: MC
authors.lastname: Horny
authors.affiliation: UTCBS, U 1022 INSERM, UMR 8258 CNRS, Paris Sciences Lettres University, Ecole Nationale Supérieure de Chimie de Paris, 11 rue Pierre et Marie Curie, 75005 Paris, France and Sorbonne Paris Cité, Université Paris Descartes, Faculté de Pharmacie de Paris, 4 avenue de l'observatoire, 75006 Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Lazerges
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234, Laboratoire PHysico-chimie des Electrolytes et Nanosystèmes InterfaciauX (PHENIX), 4 place Jussieu, F-75005, Paris, France.
authors.forename: J-M
authors.initials: JM
authors.lastname: Siaugue
authors.affiliation: Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N - Marcoussis, 91460 Marcoussis, France.
authors.forename: A
authors.initials: A
authors.lastname: Pallandre
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 place Jussieu, F-75005, Paris, France. Jean.gamby@lpn.cnrs.fr.
authors.forename: D
authors.initials: D
authors.lastname: Rose
authors.affiliation: UTCBS, U 1022 INSERM, UMR 8258 CNRS, Paris Sciences Lettres University, Ecole Nationale Supérieure de Chimie de Paris, 11 rue Pierre et Marie Curie, 75005 Paris, France and Sorbonne Paris Cité, Université Paris Descartes, Faculté de Pharmacie de Paris, 4 avenue de l'observatoire, 75006 Paris, France.
authors.forename: F
authors.initials: F
authors.lastname: Bedioui
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 place Jussieu, F-75005, Paris, France. Jean.gamby@lpn.cnrs.fr.
authors.forename: C
authors.initials: C
authors.lastname: Deslouis
authors.affiliation: Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N - Marcoussis, 91460 Marcoussis, France.
authors.forename: A-M
authors.initials: AM
authors.lastname: Haghiri-Gosnet
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, 4 place Jussieu, F-75005, Paris, France. Jean.gamby@lpn.cnrs.fr and Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N - Marcoussis, 91460 Marcoussis, France.
authors.forename: J
authors.initials: J
authors.lastname: Gamby
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004247:DNA / Q000032:analysis* / Q000737:chemistry; D004563:Electrochemistry; D004579:Electron Transport; D056656:Lab-On-A-Chip Devices; D008839:Microelectrodes; D009693:Nucleic Acid Hybridization
chemical_list: D004247:DNA