title: Aptamer biosensor for label-free impedance spectroscopy detection of potassium ion based on DNA G-quadruplex conformation.
abstract: Herein, a label-free and highly sensitive electrochemical impedance spectroscopy (EIS) aptasensor for the detection of potassium ion (K⁺) was developed based on a conformational change in which a K⁺-stabilized single stranded DNA (ssDNA) with G-rich sequence was used as the recognition element. In the measurement of K⁺ ions, the change in interfacial electron transfer resistance (R(ct)) of the sensor using a redox couple of [Fe(CN)₆]³⁻/⁴⁻ as the probe was monitored. In the presence of K⁺, the G-rich DNA folded into the G-quadruplex structure, and then K⁺ can bind to the G-quadruplex structure, leading to an increase in the R(ct). The Rct increased with K⁺ concentration, and the plot of R(ct) against the logarithm of K⁺ concentration is linear over the range from 0.1 nM to 1 mM with a detection limit of 0.1 nM. Other metal ions, such as Ca²⁺, Mg²⁺, Na⁺, Li⁺, Al³⁺, Zn²⁺, Cu²⁺, and Ni²⁺ caused no notable interference on the detection of K⁺. The scheme reported herein is applicable to the detection of other kinds of G-rich aptamer-binding chemicals and biomolecules.
authors.affiliation: Department of Chemistry, Capital Normal University, Beijing 100048, China. czb979216@sina.com
authors.forename: Zhengbo
authors.initials: Z
authors.lastname: Chen
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: He
authors.initials: H
authors.lastname: Ma
authors.forename: Tong
authors.initials: T
authors.lastname: Zhou
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Li
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods; D002414:Cations, Monovalent / Q000652:urine; D004277:DNA, Single-Stranded / Q000737:chemistry*; D058266:Dielectric Spectroscopy / Q000379:methods*; D054856:G-Quadruplexes; D006801:Humans; D057230:Limit of Detection; D011188:Potassium / Q000652:urine*
chemical_list: D052157:Aptamers, Nucleotide; D002414:Cations, Monovalent; D004277:DNA, Single-Stranded; D011188:Potassium