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A Polyaniline-based Sensor of Nucleic Acids
Published on: November 1, 2016
A Novel "On-Off-On" Electrochemiluminescence Biosensor from Multifunctional AuPt Triangular Nanoprisms/Carbon Nitride
Fang-Fang Xin1, Jingxian Li1,2, Futing Wang1
1Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo and Biosensing, College of Material Science and Engineering, College of Chemistry and Chemical Engineering, College of Biology, Hunan University, Changsha, Hunan410082, China.
Abstract:
In this study, a novel electrochemiluminescence (ECL) biosensor is constructed by employing multifunctional gold-platinum triangular nanoprisms decorated on carbon nitride nanosheets (AuPt/CN) and an exonuclease III (Exo III)-assisted target recycling amplification strategy for the ultrasensitive detection of miRNA-499 via an "on-off-on" readout. CN nanosheets work as an excellent ECL luminophore, while AuPt TNPs enhance catalytic activity and electron-transfer capability and boost ECL emission. The AuPt/CN-modified glassy carbon electrode (AuPt/CN/GCE) produces a strong initial ECL signal, i.e., "on" status. Subsequent binding of ferrocene (Fc)-labeled hairpin DNA (H-Fc) via Au-S bonds, brings the -Fc group close to AuPt/CN/GCE, resulting in the quenching of the ECL signal of H-Fc/AuPt/CN/GCE, i.e., "off" status. When miRNA-499 is present, the Exo III-assisted recycling amplification strategy is activated: miRNA-499 hybridizes with H-Fc to form miRNA-499/H-Fc/AuPt/CN/GCE, and Exo III selectively cleaves the blunt 3'-terminus of H-Fc. As a result, the Fc group is removed from the AuPt/CN/GCE surface, while miRNA-499 is released to trigger the next amplification cycle and restore the ECL signal, i.e., "on" status. The as-designed ECL biosensor can ultrasensitively detect miRNA-499 with a detection limit (LOD) of 0.07 fM (S/N = 3) in the range of 0.1 fM to 10 nM.
