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 μM with a limit of detection (3σ) of 1.66 μM, 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.