DETERMINATION OF ADENOSINE TRIPHOSPHATE BY A TARGET INHIBITED CATALYTIC CYCLE BASED ON A STRAND DISPLACEMENT REACTION

A strand displacement reaction-based system was developed for the determination of adenosine triphosphate (ATP). It involved an entropy-driven catalytic cycle that directly employed the ATP aptamer as the catalyst. Introduction of ATP into the system induced the catalyst to form the G-quadruplex conformation and inhibited its catalytic activity. All intermediates in the catalytic cycle processes were identified by polyacrylamide gel electrophoresis analysis. When the oligonucleotides were labeled with a carboxyfluorescein fluorophore and a 4-([4-(dimethylamino)phenyl]azo)benzoic acid quencher, this strand displacement reaction-based catalytic system exhibited a switch-on response for ATP. Conditions for detecting ATP, such as the toehold length, concentrations of the catalyst and magnesium ion, and incubation temperature, were optimized to obtain a detection limit of 50nM and a linear response up to 1400nM of ATP. This target inhibited catalytic cycle provides an enzyme-free biosensing strategy and has potential application in aptamer-based biosensing.