title: An integrated dual functional recognition/amplification bio-label for the one-step impedimetric detection of Micro-RNA-21.
abstract: Alteration in expression of miRNAs has been correlated with different cancer types, tumour stage and response to treatments. In this context, a structurally responsive oligonucleotide-based electrochemical impedimetric biosensor has been developed for the simple and sensitive detection of miRNA-21. A highly specific biotinylated DNA/LNA molecular beacon (MB) probe was conjugated with gold nanoparticles (AuNPs) to create an integrated, dual function bio-label (biotin-MB-AuNPs) for both biorecognition and signal generation. In the presence of target miRNA-21, hybridisation takes place resulting in the "activation" of the biotin-MB; this event makes the biotin group, which was previously "protected" by the steric hindrance of the MB stem-loop structure, accessible. The activated biotin-MB-AuNPs/miRNA complexes become available for capture, via supramolecular interaction, onto a nentravidin-modified electrode for electrochemical transduction. The binding event results in a decrease of the charge transfer resistance at the working electrode/electrolyte interface. The biosensor responded linearly in the range 1-1000 pM of miRNA-21, with a limit of detection of 0.3 pM, good reproducibility (Relative Standard deviation (RSD) =3.3%) and high selectivity over other miRNAs (i.e. miRNA-221 and miRNA-205) sequences. Detection of miRNA-21 in spiked serum samples at clinically relevant levels (low pM range) was also demonstrated, thus illustrating the potential of the biosensor for point-of-care clinical applications. The proposed biosensor design, based on the combination of a neutravidin transducing surface and the dual-function biotin-MB-AuNPs bio-label, provides a simple and robust approach for detection of short-length nucleic acid targets, such as miRNAs.
authors.affiliation: Biosensors and Bioelectronics Centre, Department of Physics, Chemistry and Biology (IFM), Linköping University, S-58183 Linköping, Sweden; University of Sousse, Higher Institute of Applied Sciences and Technology of Sousse, GREENS-ISSAT, Cité Ettafala, 4003 Ibn Khaldoun Sousse, Tunisia.
authors.forename: Sawsen
authors.initials: S
authors.lastname: Azzouzi
authors.affiliation: Biosensors and Bioelectronics Centre, Department of Physics, Chemistry and Biology (IFM), Linköping University, S-58183 Linköping, Sweden. Electronic address: wing.cheung.mak@liu.se.
authors.forename: Wing Cheung
authors.initials: WC
authors.lastname: Mak
authors.affiliation: Biosensors and Bioelectronics Centre, Department of Physics, Chemistry and Biology (IFM), Linköping University, S-58183 Linköping, Sweden; Iranian National Institute for Oceanography and Atmospheric Science (INIOAS), P.O. Box 14155-4781 Tehran, Iran.
authors.forename: Kamalodin
authors.initials: K
authors.lastname: Kor
authors.affiliation: Biosensors and Bioelectronics Centre, Department of Physics, Chemistry and Biology (IFM), Linköping University, S-58183 Linköping, Sweden.
authors.forename: Anthony P F
authors.initials: APF
authors.lastname: Turner
authors.affiliation: University of Sousse, Higher Institute of Applied Sciences and Technology of Sousse, GREENS-ISSAT, Cité Ettafala, 4003 Ibn Khaldoun Sousse, Tunisia.
authors.forename: Mounir Ben
authors.initials: MB
authors.lastname: Ali
authors.affiliation: Biosensors and Bioelectronics Centre, Department of Physics, Chemistry and Biology (IFM), Linköping University, S-58183 Linköping, Sweden. Electronic address: valerio.beni@acreo.se.
authors.forename: Valerio
authors.initials: V
authors.lastname: Beni
mesh_terms: D015374:Biosensing Techniques / Q000379:methods; D001710:Biotin / Q000737:chemistry; D058266:Dielectric Spectroscopy / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D035683:MicroRNAs / Q000032:analysis / Q000097:blood*; D009693:Nucleic Acid Hybridization / Q000379:methods; D019095:Point-of-Care Systems; D015203:Reproducibility of Results
chemical_list: C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D001710:Biotin; D006046:Gold
keywords: Electrochemical impedance spectroscopy; Gold nanoparticles; MicroRNA-21; Molecular beacon