Potassium-induced G-quadruplex DNAzyme as a chemiluminescent sensing platform for highly selective detection of K+

A simple and highly selective chemiluminescence (CL) detection method for K+ was developed based on a K+-stabilized G-qaudruplex DNAzyme, which catalyzes a luminol-H2O2 reaction system. Herein, a G-quadruplex DNAzyme stemming from a common guanine-rich DNA sequence named PS2.M is introduced as a catalyst. Upon the addition of K+, PS2. M is induced to fold into G-quadruplex as a cofactor binding with hemin, effectively catalyzing the redox reaction of luminol-H2O2. The reaction generates a CL emission and allows the DNAzyme to show a good horseradish peroxidase (HRP) mimicking-enzyme activity. The intensity of CL shows a linear dependence on the concentration of K+ within the range of 2-120 mu M with a limit of detection (3 sigma) of 1.66 mu M, giving a vital clue to quantify K+ content in urine samples. This strategy firstly opens up CL as an effective and facile approach to detect K+ with high selectivity.