Highly sensitive DNAzyme sensor for selective detection of trace uranium in ore and natural water samples

Abstract

A new single labelled DNAzyme sensor was developed for trace UO22+ detection based on the fact that the four consecutive guanines at the 5′-end of DNAzyme quenches the fluorescence of fluophor-tetramethyl-6-carboxyrhodamine (TAMRA) modified at the 3′-end of substrate. When UO22+ coexisted with DNAzyme sensor, UO22+ catalyzed the phosphoester cleavage reaction at the rA position of the substrate accompanied by the fluorescence emission significantly increased. The detection limit of the new DNAzyme sensor is 0.41nmol/L, which is sensitive enough for UO22+ detection in drinking water as the toxic UO22+ level in drinking water defined by the U.S. Environmental Protection Agency (EPA) is 130nM. Moreover, the new DNAzyme sensor could discriminate the ores with and without UO22+, and the exact content of trace UO22+ in ores and natural water samples could also be quantified. In the foreseeable future, the new DNAzyme sensor will be extensively applicable in field environmental monitoring, uranium mining and process control in virtue of portable fluorometers.