An electrochemical aptasensor for detection of lead ions using a screen-printed carbon electrode modified with Au/polypyrrole composites and toluidine blue

An aptasensor based on the aptamer of lead(II) ions and the composites of Au nanoparticles and polypyrrole (Au@Py) was successfully fabricated. An Au@Py modified screen-printed electrode surface was employed to amplify the current signal. Complementary strands were successfully immobilized on the electrodes to combine with aptamers. The aptasensor with toluidine blue served as a redox indicator which was confirmed by electrochemical cyclic voltammetry methods as well as the differential pulse voltammetry technique in phosphate buffer solution (pH 7.4). Under optimal conditions, Pb2+ was detected in the range of 0.5–25 ppb with a low detection limit of 0.6 ppb (S/N = 3). Moreover, this electrochemical aptasensor was successfully applied to detect Pb2+ in soil. This electrochemical aptasensor exhibited satisfactory reproducibility, and is considered to possess great potential in developing an environmental monitoring platform.