A novel electrochemical aptamer biosensor for lead (Ⅱ) ion detection utilizing GO/PAMAM @Au and Au/MB as dual signal amplifiers.

A competitive electrochemical aptamer biosensor for the selective detection of Pb2+ was developed in this study. The PAMAM@Au hybrid materials and the bioprobe MB-GNPs-ssDNA were synthesized with chemical methods. Modified electrode with carboxylated graphene oxide was prepared via electrodeposition. PAMAM@Au was immobilized on the modified electrode using the EDC/NHS crosslinker, and aptamer (Apt) was bound to PAMAM@Au hybrid materials using the glutaraldehyde crosslinker. The assembly of MB-GNPs-ssDNA/Apt/PAMAM@Au/GO/SPCE biosensors was achieved through immobilizing bioprobe onto electrodes, based on the theory of aptamer-complementary chain reactions. The fabricated biosensor was characterized through electrochemical experiments, SEM, AFM, TEM, XPS and FTIR. The biosensor's performance was evaluated in a series of Pb2+ aqueous solutions by differential pulse voltammetry (DPV), and the results demonstrated this biosensor had excellent repeatability, stability, and specificity. The detection range spanned from 0.5 pM/L to 500 nM/L, with a detection limit of 5 fM/L. Consequently, the proposed biosensor can serve as a reliable analytical tool for the sensitive detection of lead ions. • A novel competitive electrochemical aptamer biosensor for detecting lead ions was Designed. • The polyamidoamine (PAMAM) dendrimer encapsulated with nanogold was innovatively synthesized. • A biosignal probe MB-GNPs-ssDNA for enhancing the detection signal of biosensor was synthesized. • The redox property of methylene blue was employed to generate a detectable electrical signal. [ABSTRACT FROM AUTHOR]