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 H2 O2 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.