Microflow injection potassium bioassay based on G‐quadruplex DNAzyme‐enhanced chemiluminescence

By taking advantage of microflow injection chemiluminescence analysis, we developed a distinctive microfluidic bioassay method based on G‐Quadruplex DNAzyme‐enhanced chemiluminescence for the determination of K + in human serum. AGRO100, the G‐rich oligonucleotide with high hemin binding affinity was primarily selected as a K + recognition element. In the presence of K + , AGRO100 folded into G‐quadruplex and bound hemin to form DNAzyme, which catalyzed the oxidation of luminol by H 2 O 2 to produce chemiluminescence. The intensity of chemiluminescence increased with the K + concentration. In the study, the DNAzyme showed both long‐term stability and high catalytic activity; other common cations at their physiological concentration did not cause notable interference. With only 6.7 × 10 −13  mol of AGRO100 consumption per sample, a linear response of K + ranged from 1 to 300 µmol/L, the concentration detection limit 0.69 µmol/L (S/N = 3) and the absolute detection limit 1.38 × 10 −12  mol were obtained. The precision of 10 replicate measurements of 60 µmol/L K + was found to be 1.72% (relative standard deviation). The accuracy of the method was demonstrated by analyzing real human serum samples. Copyright © 2014 John Wiley & Sons, Ltd.