SERS Detection of Hg²⁺ using Rhenium Carbonyl Labelled Nanoparticle Films

Abstract

Modified silver nanoparticles with a self‐assembled disulfide functionalized 2,2'‐bipyridine (L1 and L2) monolayer, and the corresponding rhenium complex [Re(L2)(CO)3Br] are shown to provide a method to position the nanoparticles at a water/dichloromethane interface forming a lustrous metal‐like‐liquid film (MeLLF) with a unique SERS response. The film formed using L2 showed divergent behaviour in the presence of a range of metal ions whilst bound to the surface. [Re(L)(CO)3Br] (where L=2,2'‐bipyridine, L1 and L2) in solution demonstrates a selective interaction with Hg2+, observed by UV‐vis, emission and 1H NMR spectroscopy, attributed to abstraction of the bromide. This interaction was demonstrated by subtle changes in the characteristic Raman Re‐CO stretch at 510 cm−1 both with the MeLLF, and when the film is immobilized in a PVA surface‐exposed‐nano‐sheet (SENS). The work provides proof of concept that the organometallic complexes can be employed as “labels” to generate SERS‐active nanoparticle films that possess detection capabilities.

Advancements in mercury detection using surface-enhanced Raman spectroscopy (SERS) and ion-imprinted polymers (IIPs): a review

“…74 instance, Lea et al developed a silver NP (AgNP)-based SERS platform, pioneering the use of a tethered rhenium carbonyl complex as a Raman reporter for Hg 2+ detection. 75 In a recent study, magnetic Fe 3 O 4 @SiO 2 @Au core/shell NPs modified with 4-mercaptopyrindine (4-MPY) served a dual role of a Raman reporter and a mercury-specific ligand. This strategic configuration was used as a SERS sensor for detecting Hg 2+ in water and macrophage cells.…”

“…Furthermore, supports like polymers possess necessary multifunctional characteristics such as mechanical strength and flexibility, in addition to cost-effectiveness, optical transparency, and metalloading capability, which make them suitable for hosting and enriching metal nanostructures while providing tunable sensing outcomes. 75,93 The supports do not contribute typically to the SERS effect as they do not absorb or scatter light.…”

“…In studies aimed at detecting mercury species in environmental samples, gold and silver NPs have been favored for decorating support surfaces due to their excellent plasmonic and light scattering properties, as well as their ability to conjugate recognition ligands or directly bind with targets for improving selectivity. 75 Another study illustrated the detection and quantitation of Hg 2+ ions in water samples containing Pb(II) and Cd(II) interferents, achieving an LOD of 0.51 pM. 12 This was accomplished using a SERS sensor composed of gold nanostructures deposited on a gold support substrate.…”