Aptasensor based on cascaded fluorescent sensor assisted by exonuclease III for ultra-sensitive detection of Hg.

Construct a sensitive and rapid detection fluorescence biosensor with the assistance of exonuclease III to achieve efficient detection of Hg. Nucleic acid aptamer H0 specifically recognizes Hg, and under the action of exonuclease III, H0 bound to Hg is hydrolyzed, which in turn fails to trigger the catalytic hairpin self-assembly amplification reaction, resulting in a decrease in the number of double-stranded DNA bound to the fluorescent dye SYBR Green I in the solution, and a decrease in the fluorescence intensity. The results showed that the concentration of Hg showed a good linear relationship with the fluorescence intensity of the sensing system within the range of 3.8-10 pmol/L, and the detection limit was 0.53 pmol/L. The recoveries of Xiangjiang River water used for the analysis of the actual samples were in the range of 99.57-103.58%, and the relative standard deviations of the determined values were 2.4-3.7%. The method is simple, sensitive, specific, cost-effective and can be applied to water samples.