Adenosine triphosphate (ATP) monitoring in Escherichia coli bacterial samples by an electrochemical aptasensor

Adenosine triphosphate (ATP) is widely recognized as the cellular energy currency in organisms and a biomarker for the diagnosis and monitoring of various diseases. It is also a key indicator for evaluating environmental cleanliness, controlling food quality and safety, monitoring microbial contamination, and assessing cellular activity. Accordingly, in this study, an electrochemical aptasensor was developed for the detection of ATP extracted from lysed bacterial samples. To fabricate the aptasensor, the surface of a carbon paste electrode (CPE) was electrochemically modified with positively charged conductive polypyrrole (PPy). Subsequently, negatively charged gold nanoparticles (AuNPs) were incorporated onto the PPy-modified surface through electrostatic interactions to facilitate aptamer immobilization on the modified electrode surface. Ferro/ferricyanide redox couple [Fe(CN)₆^3-/4-] was used as an electrochemical probe. In optimal conditions, the fabricated aptasensor exhibited a linear detection range from 30.00 to 140.00 pM with a limit of detection (LOD) of 8.52 pM and a relative standard deviation (RSD) of 1.85%. Finally, the proposed biosensor was applied in the monitoring of ATP molecules in a real Escherichia coli (E. coli) bacterial sample.