Selective Colorimetric Sensor for Hg²⁺ Ions Using a Mixture of Thiourea Derivatives and Gold Nanoparticles Stabilized with Adenosine Triphosphate

Abstract

The detection of Hg 2 + ions has attracted considerable attention in recent years because it is one of the most toxic elements on the planet and is a known environmental pollutant routinely released from coal-burning power plants, oceanic and volcanic emissions, gold mining, and solid-waste incineration. [1] As a result, numerous optical detection methods for Hg 2 + ions have been developed based upon several strategies, including fluorogenic and chromogenic organic dyes, functional polymers, oligonucleotides, and proteins. [2] In addition, nanomaterials, including carbon nanotubes, [3] silica nanoparticles, [4] quantum dots, [5] and gold nanoparticles, [6] have been recently studied as alternative detection methods for Hg 2 + ions. In particular, colorimetric chemosensors are attractive because they can be understood with the naked eye, in some cases at the point of use. Therefore, a lot of colorimetric sensors for Hg 2 + ions have been developed based upon chromogenic organic dyes and gold nanoparticles.Gold nanoparticles (AuNPs) are attractive scaffolds for the creation of a colorimetric sensing system of Hg 2 + ions owing to their optical properties. Gold nanoparticles are good chromophores because their extinction coefficients are 3-5 orders of magnitude higher than those of organic dye molecules. Gold nanoparticles also have unique distance-dependent optical properties that can be chemically programmed through the use of specific host compounds; DNA, etc. can induce a dramatic red-to-blue color change in the AuNPs. [7] So far, several strategies for the detection of Hg 2 + ions have been developed, including chemically modified AuNPs, [6a-b] DNA functionalized AuNPs, [6c-f] and a mixture of oligonucleotide and unmodified AuNPs. [6g-h] Chemi-cal modification methods utilize the interconnection of chemically modified AuNPs induced by the interaction between Hg 2 + ions and ligands on the AuNPs. The DNA-functionalized AuNP method and the mixture of oligonucleotides and AuNPs utilize thymine-Hg 2 + -thymine interactions; Hg 2 + ions can selectively bind in between two mismatched oligonucleotide thymines, and a measurable signal is transduced by the interaction. Unmodified AuNP-based colorimetric chemosensor methods are the simplest of these methods and can detect Hg 2 + ions in aqueous media with high sensitivity and selectivity. Most of unmodified AuNPbased colorimetric chemosensors have been utilized with the mixture of oligonucleotides and AuNPs and the high specificity of oligonucleotide interactions with Hg 2 + ions. [6] Therefore, it is desirable to develop another approach for unmodified AuNP-based chemosensors for Hg 2 + ions.Herein, we describe a new type of unmodified AuNPbased chemosensor for Hg 2 + ions in aqueous media with high sensitivity and selectivity using a Hg 2 + -promoted desulfurization reaction of a thiourea derivative and the reactivity of thiourea with gold nanoparticles. Thiourea is readily transformed into urea by a Hg 2 + -promoted desulfurization reaction owing to the strong...

Simple, Fast and Selective Detection of Adenosine Triphosphate at Physiological pH Using Unmodified Gold Nanoparticles as Colorimetric Probes and Metal Ions as Cross-Linkers

“…The ring nitrogen of hybrid aromatics and primary amines with electron-rich nitrogen atoms are more likely to be bound onto the surface of metal nanoparticles through the coordinating interactions with the electron-deficient surface of metal nanoparticles [43]. ATP with multiple binding sites, including one exocyclic amino group and/or two double-nitrogen hybrid rings, can strongly coordinate to AuNPs by ligand exchange with weakly surface-bound citrate ions [32]. Metal ions, especially Cu 2+ , Cd 2+ and Zn 2+ , can form dimeric metal-ATP complexes by coordinating to the triphosphate groups and an adenine ring nitrogen [39].…”

A fast and simple method to perform cyanide detection using ATP stabilized gold nanoparticles combined with the Cu(DDTC)2 complex

“…In the following experiments, the calibration curves did not show a good linearity at a measurement time of 6 min, which is the reason why measurements were nally performed 1 min aer the mixing of the reagents. This was a shorter time than that used in the experiments by Kim et al 33 ). Moreover, ophenanthroline reacts slowly with some metals and also tends to dissociate slowly, especially under acidic conditions.…”

“…Citric acid-stabilized nanoparticles were prepared by adding 10 mL of a 38.8 mM sodium citrate solution to 100 mL of boiling 1.0 mM HAuCl 4 $3H 2 O with vigorous stirring. 33 The solution was boiled and stirred for 15 minutes aer the appearance of a deep red color, and aerwards it was allowed to cool to room temperature with continuous stirring.…”

“…The phenanthroline became free when exposed to cyanide anions and caused the aggregation of the nanoparticles with a visible change in the color of the solutions. ATP stabilized particles are interesting for the detection of anions, 32 but methods have also been developed for the analysis of cations such as mercury 33 or for enzyme sensing assays. 34 The objective of this study is the development of an assay for cyanide using gold nanoparticles stabilized with adenosine triphosphate (ATP), and in the presence of the Cu(DDTC) 2 complex.…”

Optical Reading of Contaminants in Aqueous Media Based on Gold Nanoparticles

“…Therefore, Hg 2+ can bind thiourea prior to AuNPs, and then its thiophilic characteristic promotes the desulfurization fast with products of urea and HgS. Since the urea and thiourea did different behaviours toward AuNPs, a new type of unmodified AuNPs system for Hg 2+ detection was developed with the assistance of the naphthyl‐thiourea . Because thiol group (–SH) shows as similar log K f values with metal ions as SCN group, meaning only Hg 2+ can broke the Au‐S bond among common metal ions.…”