Construction of a Graphene/Au-Nanoparticles/Cucurbit[7]uril-Based Sensor for Pb²⁺ Sensing

The development of highly sensitive and selective methods for the detection of lead ion (Pb²⁺) is of great scientific importance. In this work, we develop a new surface-enhanced Raman scattering (SERS)-based sensor for the selective trace measurement of Pb²⁺. The SERS-based sensor is assembled from gold nanoparticles (AuNPs) and graphene using cucurbit[7]uril (CB[7]) as a precise molecular glue and a local SERS reporter. Upon the addition of Pb²⁺, CB[7] forms stronger complexes with Pb²⁺ and desorbs from AuNPs, resulting in a sensitive "turn-off" of SERS signals. This SERS-based assay shows a limit of detection (LOD) of 0.3 nm and a linear detection range from 1 nm to 0.3 μm for Pb²⁺. The feasibility of the assay is further demonstrated by probing Pb²⁺ in real water samples. This SERS-based analytical method is highly sensitive and selective, and therefore holds promising applications in environmental analysis.