Homogeneously ultrasensitive electrochemical detection of adenosine triphosphate based on multiple signal amplification strategy.

An ultrasensitive electrochemical aptasensor was successfully fabricated for the detection of adenosine triphosphate (ATP). For the first time, one detection system combined several elements: magnetic aptamer sequences for target recognition and separation, a DNAzyme assisted cyclic signal amplification strategy, layer-by-layer (LBL) quantum dots (QDs) composites for promoting square wave anodic stripping voltammetric (SWASV) analysis and Bi, Nafion (Nf) and three-dimensional ordered macroporous polyaniline-ionic liquid (Bi/Nf/3DOM PANI-IL) film modified glassy carbon electrode (GCE) for monitoring enhanced SWASV signal. The modification of Nf/3DOM PANI-IL on GCE showed that the preconcentration efficiency was improved by the electrostatic absorption of Cd(2+) with negative Nf layer with the enhanced analytical sensitivity due to a large active surface area of 3DOM structure. The increased SWASV peak current values of the label (CdS)4@SiO2 composites were found to be proportional to the logarithmic value of ATP concentrations in the range of 1pM-10nM and 10nM-1µM, with the detection limit as low as 0.5pM. The proposed aptasensor has shown an excellent performance such as high sensitivity, good selectivity and analytical application in real samples. The results demonstrated that the multiple signal amplified strategy we developed was feasible for clinical ATP assay and would provide a promising model for the detection of other small molecules.