A label-free aptasensor for highly sensitive ATP detection by using exonuclease I and oligonucleotide-templated fluorescent copper nanoparticles

Abstract

In this work, we developed a simple and highly sensitive fluorescence method for the determination of ATP based on a designed multifunctional oligonucleotide, which holds the ability of synthesizing fluorescent copper nanoparticles (CuNPs) as well as recognizing ATP molecules. In the absence of ATP, this multifunctional probe containing an ATP aptamer and poly T strand can be digested upon the addition of Exo I, which leads to the failure of synthesizing poly T-templated fluorescent CuNPs, whereas in the presence of ATP, the ATP aptamer folds into a G-quadruplex structure, which makes it resistant to digestion by Exo I. Accordingly, the poly T strand is reserved and can be used as an efficient template for the formation of CuNPs with strong fluorescence. Thus, the concentration of ATP could be identified very easily by observing fluorescence changes of this sensing system. This signal-on assay exhibits high sensitivity to ATP with a detection limit of 500 nM in the range of 1–80 μM. Further specificity investigation and real sample anti-interference experiments show that this assay also has high selectivity and anti-interference ability.