An ultra-sensitive electrochemical aptasensor for simultaneous quantitative detection of Pb2+ and Cd2+ in fruit and vegetable

Abstract

An electrochemical aptasensor based on aptamer was designed for the first time to simultaneously detect Cd²⁺ and Pb²⁺ in fruit and vegetable. The double-stranded DNA including aptamers were immobilized on the electrode via Au-S bond. Due to the specific binding of aptamer and metal ions, the aptamers labelled with methylene blue or ferrocene were competed off the gold electrode, and the electrochemical signal was decreased. Under the optimal conditions, the electrochemical aptasensor showed linear response to Cd²⁺ and Pb²⁺ in the range of 0.1 to 1000 nmol/L, and the detection limits of Cd²⁺ and Pb²⁺ achieved 89.31 and 16.44 pmol/L (3σ), respectively. Excellent stability and reproducibility were exhibited with RSD 2.27% (Cd²⁺) and 3.61% (Pb²⁺). The digested fruit and vegetable were also tested, and the recoveries were in the range of 90.06% to 97.24%. Thus, this strategy held great potential in monitoring cadmium and lead pollution.

Keywords: Aptamer; Cadmium ion; Electrochemical aptasensor; Fruit and vegetable; Heavy metal ions detection; Lead ion.