G-Quadruplex-Modulated Fluorescence Detection of Potassium in the Presence of a 3500-Fold Excess of Sodium Ions

Abstract

A label-free detection of K(+) was developed using G-quadruplex DNA (c-Myc) modulated fluorescence enhancement of tetrakis-(diisopropylguanidino) zinc phthalocyanine (Zn-DIGP). Upon the addition of increasing concentrations of potassium, a detection limit of 0.8 μM for K(+) was easily achieved. Comparative titrations using sodium, lithium, ammonium, transition metal, or alkali earth salts revealed that the fluorescence enhancement was highly specific for potassium ions. This system has, for the first time, provided a means for detecting 40 μM of K(+) even in the presence of a 3500-fold excess of Na(+) ions.

Label-Free Fluorescent Detection of Ions, Proteins, and Small Molecules Using Structure-Switching Aptamers, SYBR Gold, and Exonuclease I

“…This assay time is comparable to other reported methods. 7,19,20 K + under extracellular conditions coexists with Na + ions. Typically, in blood, the concentration of K + is 3.5−5.3 mM, whereas that of Na + is 135−148 mM.…”

Superior fluorescent probe for detection of potassium ion

“…Instrumental K þ analysis methods including electrochemistry [2,3], fluorescence [4][5][6][7][8][9][10][11], and colorimetry [12] suffer from low selectivity, low sensitivity (in ranges of μM to mM), and the requirement of nonaqueous conditions. Thus the sensitive and selective detection of K þ in an aqueous medium has become critical for biological health.…”

“…To address these challenges, significant efforts have been made to develop a label-free and simple method for fluorescent detection of various target molecules. Several label-free aptamerbased approaches have been reported by utilizing DNA structure selective fluorescent dyes [5,9,30,31] or conjugated polymers [8,20] to report conformational change of aptamers upon binding to targets. However, in order to control the binding sites between the dyes and DNA, the requirement of the extensive optimization of oligonucleotide limits the generalization of the methods for other targets [32].…”

Label-free Detection of Zn2+ Based on G-quadruplex

“…[21][22][23][24] G4s not only play vital roles in cancer research, but are also regarded as robust tools in analytical chemistry and biomedicine. [25][26][27][28] A number of sensors have been developed based on G4s for the detection of metal ions, such as K + , 29,30 Pb 2+ , 31,32 Ca 2+ , 33 Cu 2+ , 34 Hg 2+ , [35][36][37] Ag + , [38][39][40][41] Sr 2+ . 42 Herein, we first developed a label-free detecting strategy for the assay of Zn 2+ based on G4s; Zn 2+ can induce the structural transition of the human telomere sequence AG3(T2AG3)3 (denoted hereafter as H22) from a random coil to an antiparallel G4 structure.…”