Colorimetric Iodide Recognition and Sensing by Citrate-Stabilized Core/Shell Cu@Au Nanoparticles

Abstract

In the light of the significance and urgency for the recognition and sensing of anions specifically, especially those of biological relevance, herein, we wish to demonstrate a novel colorimetric avenue for highly selective iodide recognition and sensing using simple citrate-stabilized core/shell Cu@Au nanoparticles. No other ions than iodide can induce an appreciable color change of the Cu@Au nanoparticles solution from purple to red by transforming the interconnected, irregularly shaped nanoparticles to the single, separated, and nearly spherical ones, as confirmed by the transmission electron microscopy (TEM). On the basis of the optical spectra and TEM studies, a mechanism of iodide-induced aggregating/fusion, fragmentation, and reorganization of atoms is proposed. With this strategy, 6 μM (0.76 ppm) of iodide can be recognized within 20 min by naked-eye observation. This sensitive and selective colorimetric assay opens up a fresh insight of facile, rapid, and reliable detection of iodide and may find its future application in the analysis of the total iodine in edible salt as well as the clinical diagnosis of urinary iodide.

A colorimetric assay for measuring iodide using Au@Ag core–shell nanoparticles coupled with Cu2+

“…Base on these properties, a series of metal NPs based colorimetric methods has been developed to detect I - [10][11][12][13][14][15][16][17][18]. For example, Zhang et al synthesized citrate-stabilized Cu@Au core-shell NPs and used them as colorimetric probes for the recognition of I -through the I --induced transformation of irregular shaped NPs to nearly spherical ones [10].…”

A selective sensor for cyanide ion (CN−) based on the inner filter effect of metal nanoparticles with photoluminescent carbon dots as the fluorophore

“…Recently, the application of plasmonic or fluorescent nanoparticles provides another effective measure in the fabrication of sensitive sensors for a couple of anions, including halides [17,18], sulfide [19,20], sulfite [21,22], sulfate [23], nitrite [24], hypochlorite [25], and cyanide [26]. Cyanide (CN -) is an extremely toxic anion that can directly cause the death of human, animals, and aquatic lives by inhibiting the function of cytochrome c oxidase and finally damaging the central nervous system [27].…”

Incorporation of the fluoride induced SiO bond cleavage and functionalized gold nanoparticle aggregation into one colorimetric probe for highly specific and sensitive detection of fluoride

“…Various metal ions were detected by monitoring the color changes occurring upon aggregation of ligand-functionalized AuNPs through specific molecular interactions [26][27][28][29][30]. However, studies on colorimetric anion recognition and sensing anions by AuNPs are limited [31][32][33][34][35][36]. Up to now, the thioglucose modified AuNPs had been developed for colorimetric detection of F − based on interparticle crosslink induced aggregation [37].…”