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Label‐Free, Electrochemical Quantitation of Potassium Ions from Femtomolar Levels
Author(s) -
Zhu Bicheng,
Booth Marsilea A.,
Woo Han Young,
Hodgkiss Justin M.,
TravasSejdic Jadranka
Publication year - 2015
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201500313
Subject(s) - aptamer , detection limit , dielectric spectroscopy , electrode , polypyrrole , electrochemistry , polymer , analyte , transducer , materials science , linear range , conductive polymer , chemistry , analytical chemistry (journal) , chromatography , organic chemistry , genetics , physics , quantum mechanics , biology
In this communication, a label‐free and sensitive electrochemical method to detect potassium ions is proposed. The conducting polymer polypyrrole was used as both an anchor for the probe and a transducer of the detection event. A K + ‐specific G‐rich aptamer was applied as a recognition element, which folded into the G‐quadruplex structure in the presence of K + , and this resulted in an increase in the electrode impedance. The combination of the K + ‐selective aptamer and the porous conducting polymer as a signal transducer afforded a successful sensor platform. The sensor responded approximately logarithmically over a wide dynamic range of K + concentrations from 20 f m to 1 m m , with a very low detection limit of 14.7 f m and excellent discrimination against other ions. Additionally, electrochemical impedance spectroscopy was used to study the kinetics of K + binding at the conducting polymer–immobilized aptamer surface, which indicated strong binding between the two. This work demonstrates a powerful approach for the sensitive, selective, and direct electrochemical detection of metal ions based on the switching conformation of G‐rich aptamers attached to a porous conducting polymer surface. This assay scheme can be expanded to the detection of a wide range of targets by modifying the aptamer structure as a recognizing moiety.