A theoretical and experimental study of polyaniline/GCE and DNA G-quadruplex conformation as an impedimetric biosensor for the determination of potassium ions

An electrochemical aptasensor has been developed to determine K+ using electrochemical impedance spectroscopy. The polyaniline (PANI) coating was first electrodeposited on a GCE. Then, the potassium-selective aptamer [G(3)(T(2)AG(3))(3)] was adsorbed through an electrostatic force between PANI and aptamer. In the presence of K+, the single-stranded DNA is folded into the G-quadruplex configuration, which acts as a barrier against electron transfer at the GCE surface. AFM and FE-SEM images characterize the surface morphology at each fabrication stage. As the K+ concentration increased, the charge transfer resistance (R-ct) increased, and the plot of Delta Rct versus the logarithm of the K+ concentration is linear over a wide range of 10 pM-60 mu M with a low detection limit of 3.7 pM. Finally, the proposed sensor was used to determine K+ in water, serum, urine, and fruit samples. Moreover, the binding stability of the aptamer/PANI and K+/Aptamer/PANI and the interactions between the aptamer and PANI were analyzed through molecular dynamics simulation.

Automated summary

An electrochemical aptasensor has been developed to determine K+ concentration using electrochemical impedance spectroscopy. The sensor utilizes polyaniline (PANI) coating and potassium-selective aptamer to detect K+. The presence of K+ leads to the formation of a G-quadruplex configuration, which hinders electron transfer. The sensor has a wide detection range and low detection limit, and can be applied to various sample types.