Label-Free, Electrochemical Quantitation of Potassium Ions from Femtomolar Levels

Bicheng Zhu, Marsilea A. Booth, Han Young Woo, Justin M. Hodgkiss, Jadranka Travas-Sejdic

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


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 fm to 1mm, with a very low detection limit of 14.7fm 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.

Original languageEnglish
Pages (from-to)2169-2175
Number of pages7
JournalChemistry - An Asian Journal
Issue number10
Publication statusPublished - 2015 Oct 1
Externally publishedYes


  • aptasensors
  • electrochemistry
  • kinetics
  • polymers
  • potassium

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry


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