An electrochemical sensing method based on an oligonucleotide structure for ultrasensitive detection of malachite green

Abstract

Herein, a simple electrochemical aptasensor with the implementation of an oligonucleotide structure is introduced for determination of malachite green (MG) as a fungicide. The oligonucleotide structure is composed of MG aptamer (Apt) and its two complementary strands (CSs). Benefiting from physical barrier and high negatively charged of the oligonucleotide structure, the proposed sensing strategy indicated improved selectivity and sensitivity for MG detection with a detection limit of 0.15 nM. Addition of MG leads to conformational change of Apt sequence, its release from the electrode surface and dismantlement of the oligonucleotide structure. So, [Fe(CN)6]3−/4− as redox marker has high accessibility to the gold electrode surface and the peak current remarkably increases. Also, the aptasensor exhibited great potential for MG detection in tap water. The designed sensing method opens a simple way for ultrasensitive detection of MG in a relatively short time.