Development of a label-free electrochemical aptasensor based on diazonium electrodeposition: Application to cadmium detection in water

In this study we have developed a new aptasensor for cadmium (Cd2+) detection in water. Gold electrode surface has been chemically modified by electrochemical reduction of diazonium salt (CMA) with carboxylic acid outward from the surface. This was used for amino-modified cadmium aptamer immobilization through carbodiimide reaction. Chemical surface modification was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). This latter was also used for Cd2+ detection. The aptasensor has exhibited a good linear relationship between the logarithm of the Cd2+ concentration and the impedance changes in the range from 10(-3) to 10(-9) M with a correlation R-2 of 0.9954. A high sensitivity was obtained with a low limit of detection (LOD) of 2.75*10(-10) M. Moreover, the developed aptasensor showed a high selectivity towards Cd2+ when compared to other interferences such as Hg2+, Pb2+ and Zn2+. The developed aptasensor presents a simple and sensitive approach for Cd2+ detection in aqueous solutions with application for trace Cd2+ detection in spring water samples.

Automated summary

In this study, a new aptasensor for detecting cadmium (Cd2+) in water was developed. The sensor showed a good linear relationship between the Cd2+ concentration and impedance changes, with a high sensitivity and selectivity towards Cd2+ compared to other interferents. The developed aptasensor provides a simple and sensitive approach for trace Cd2+ detection in aqueous solutions.