A simple non-enzymatic strategy for adenosine triphosphate electrochemical aptasensor using silver nanoparticle-decorated graphene oxide

In this work, a sensitive electrochemical aptasensor for the detection of adenosine triphosphate (ATP) has been introduced. A simple and non-enzymatic signal amplification strategy is utilized using silver nanoparticledecorated graphene oxide (AgNPs-GO) as a redox probe. The modified electrode surface was characterized by scanning electron microscopy, FTIR and UV-Vis spectroscopy, and electrochemical impedance spectroscopy. GO provides an excellent substrate for the presence of the large number of AgNPs, so the monitored oxidation signal of AgNPs has been amplified. ATP-specific DNA aptamer is split into two fragments (F-1 & -F-2) in order to design a sandwich-type assay. For the construction of the sensor, the surface of a graphite screen-printed electrode is modified with electrodeposited gold nanoparticles followed by selfassembling a monolayer of 3-mercaptopropionic acid on the electrode surface. The first amino-labeled fragment, F-1, is immobilized on the modified electrode via carbodiimide chemistry. The synthesized AgNPs-GO interacts with F-1 via pi-pi stacking. In the presence of ATP, the second fragment of the aptamer, F-2, forms an associated complex with the immobilized F-1 and causes AgNPs-GO to leave the surface. Consequently, a remarkable decrease in the oxidation signal of the AgNPs is observed. The percentage of this decrease has been monitored as an analytical signal, which is proportional to ATP concentration, and delivers a linear response over the range of 10.0 (+/- 0.6) to 850 (+/- 5) nM with a detection limit of 5.0 (+/- 0.2) nM.