A Cu@Au Nanoparticle-Based Colorimetric Competition Assay for the Detection of Sulfide Anion and Cysteine

Abstract

As an extension of our previous work, which described the unique ability of the core/shell Cu@Au nanoparticle (NP) to selectively recognize iodide, (1) herein, we wish to report the development of an alternatively sensitive and selective colorimetric detection for sulfide anion and cysteine based upon the Cu@Au NP by a competition avenue. In the absence of sulfide anion or cysteine, iodide can induce an appreciable color change of the Cu@Au NP solution from purple to red by transforming the clusters of NP to single, nearly spherical, and larger ones. However, the transformation is severely interfered by the presence of sulfide or cysteine because of a higher binding strength of the S-Au bond than the I-Au one. As a result, the clear purple-to-red color change induced by iodide is affected as a correlation with the concentration of sulfide or cysteine. By taking advantage of this fact, we can detect a concentration of 3 μM for sulfide and 0.4 μM for cysteine with the naked eye or 0.3 μM (10 ppb) for sulfide and 50 nM (6 ppb) for cysteine aided by a UV/vis spectrometer. Given the detrimental effect of hydrogen sulfide and the biological importance of cysteine, the assay may become useful in the environment monitoring, water quality inspection and biomedical diagnosis as well.

Au/AgI Dimeric Nanoparticles for Highly Selective and Sensitive Colorimetric Detection of Hydrogen Sulfide

“…The lowest detectable concentrations of sulfide with naked‐eyes and UV–vis spectrophotometer were 5 × 10 −6 and 0.5 × 10 −6 m , respectively, which are comparable to or lower than those reported with other colorimetric methods. [2b,12,15,16] Such high sensitivity is attributed to the fact that the LSPR effect of the hybrid NPs is intimately associated with the composition and dimensional ratio of the two parts. A small amount of sulfide can readily change the composition of AgI, resulting in obvious color changes.…”

“…However, these Cu‐ and Ag‐based nanoprobes are susceptible to oxidation in the presence of coordination agents, limiting the selectivity of these probes and their use in real samples with complicated matrices. Zhang et al developed a Cu@Au core–shell NPs‐I − system for the colorimetric detection of sulfide, taking advantage of the inhibition of iodide‐induced etching by sulfide . However, biothiols like cysteine can also induce the same color change.…”

Carboxymethylagarose-AuNPs generated through green route for selective detection of Hg2+ in aqueous medium with a blue shift

“…However, most of these techniques require expensive instrumentation and complicated sample preparation in certain cases, which make them inappropriate for point of use applications. To overcome these drawbacks, a variety of colorimetric sensors based on gold nano particles (AuNPs) have been attempted for the simple and rapid detection of Hg 2+ Lee, Ulmann, Han, & Mirkin, 2008;Maity, Kumar, Gunupuru, & Paul, 2014;Xue, Wang, & Liu, 2008;Yu & Tseng, 2008;Zhang, Xu, Yuan, Yang, & Yang, 2011 The utilization of nontoxic chemicals, environmentally benign solvents and renewable materials are some of the key issues that merit important consideration in a green synthesis strategy (Poliakoff & Anastas, 2001;DeSimone, 2002;Raveendran, Fu, & Wallen, 2003). In literature natural polymers like starch and chitosan are reported to stabilize silver nanoparticles (Raveendran et al, 2003;Huang & Yang, 2004b).…”

“…Biopolymers like chitosan, carboxymethyl chitosan, heparin and hyaluronan are also reported in the literature for synthesis and stabilization of silver and gold nano particles (Huang & Yang, 2004a;Huang & Yang, 2004b;Kemp et al, 2009). Gold nanoparticles in both colloidal solutions and films respond to elemental mercury with blue shifts in localized surface Plasmon resonance (LSPR) wavelength (Chen et al, 2009;Jiang et al, 2012;Li et al, 2006;Lim et al, 2010;Liu et al, 2009;Lu et al, 2007;Rusin et al, 2003;Spãtaru et al, 2001;Zhang et al, 2011). The above reports indicates that there are no reports on the synthesis and stabilization of gold nanoparticles (AuNPs) using carboxymethylagarose.…”

Protein-based nanobiosensor for direct detection of hydrogen sulfide

“…Strong variations in SPR are generally observed when these plasmonic nanostructures aggregate as a result of the organic reaction between the coated molecules and analytes. For instance, Zhang et al reported a novel colorimetric probe for the detection of S − 2 and cysteine using simple citratestabilized core-shell Cu/GNPs through the S − 2 /cysteineinduced transformation of original and spherical clusters of large, single, spherical particles [18]. Recently fluorescent, DNA-templated Au/Ag nanocluster probes were used for the detection of S − 2 in a turn-off manner [19].…”