A sensitive Pb2+ testing method based on aptamer-functionalized peroxidase-like 3D-flower MoS2 microspheres

Abstract

Herein, we proposed an electrochemical Pb²⁺ sensor using peroxidase-like GR aptamer-functionalized 3D-flower MoS₂ microsphere (MoS₂–GR) hybrids as signal probes. AuPt nanoparticles and multiwalled carbon nanotube composites (AuPt–MCNTs) were successively modified on a glassy carbon electrode (GCE), which improved the electronic transfer rate as well as increased the amount of immobilized capture hairpin DNA (HP). In the presence of Pb²⁺, GR could be specifically cleaved at the ribonucleotide (rA) site, which produced the short MoS₂–GR to hybridize with HP immobilized on the surface of the GCE. Because of the mimic peroxidase property of MoS₂, an enzymatically amplified electrochemical signal was obtained to achieve the sensitive detection of Pb²⁺. In addition, benefiting from the Pb²⁺-dependent GR, the proposed assay could selectively detect Pb²⁺ in the presence of other metal ions. This method showed a good linear relationship between the current response and the Pb²⁺ concentration ranging from 0.03 to 500 nmol L⁻¹ with a detection limit of 0.015 nmol L⁻¹. The new, robust, and convenient assay systems can be widely utilized for the identification of other target molecules.