An electrochemical aptasensor based on bifunctional Fe3O4@Au nanocomposites for adenosine triphosphate assay

We describe a label-free electrochemical aptasensor for adenosine triphosphate (ATP) assay based on bifunctional Fe 3 O 4 @Au nanocomposites. Due to the introduction of Au nanoparticles, the resulting bifunctional Fe 3 O 4 @Au nanocomposites can be easily modified with ATP-specific aptamer molecules through Au–S interaction to build the nanoprobe and used to immobilize on a glassy carbon electrode simply with the assistance of a magnet. Once exposed to the target ATP, the current signal obtained at nanoprobe-containing magnetic glassy carbon electrode decreases immediately. The decrease in sensor current is a result of the less methylene blue adsorbed on the aptamer caused by the fact that the ATP-specific aptamer prefers to bind with ATP rather than with methylene blue. The decrease in sensor current can be used for electrochemical determination of ATP, for example, to determine ATP in human serum samples.