Detection Of Silver Ions Research Articles

Self-Cascade System Based on Cupric Oxide Nanoparticles as Dual-Functional Enzyme Mimics for Ultrasensitive Detection of Silver Ions

Artificial enzyme mimics based on nanomaterials have attracted sustained attention owing to their multiple advantages compared with natural enzymes. However, there are a few enzyme self-cascade systems for the highly sensitive detection of analytical targets. Herein, we have described a self-cascade catalytic system based on single-component cupric oxide nanoparticles (CuO NPs) for an ultrasensitive fluorescent detection toward glutathione (GSH) and Ag+ ions. The limit of detection is lower for nanomolar (nM) and picomolar (pM) levels for GSH and Ag+, respectively. To the best of our knowledge, for the first time, we find that CuO NPs possess the intrinsic GSH-oxidase and peroxidase-like activity as a dual-functional nanozyme, coupling with terephthalic acid (TA) and GSH to construct a self-cascade fluorescent system. The turn-on fluorescence signal of oxidation hydroxyterephthalate (TAOH) is generated in the presence of GSH. Then, the fluorescence of a reaction mixture is quenched after the addition of A...

A facile synthesis of cysteine-based diketopiperazine from thiol-protected precursor.

l-Cysteine is one of the most promising biomass-based building blocks with great potential applications. Herein, we report a versatile synthetic route to produce cysteine-based 2,5-diketopiperazine (DKP) with good yield from the thiol-ene click reaction of l-cysteine and commercially available acrylates, followed by dimerization of the amino acid intermediates. The achieved DKP diastereomers were successfully separated and fully characterized by spectroscopic methods. Moreover, the chiroptical property of DKP in the presence of various metal ions was investigated by circular dichroism spectroscopy. The potential application of the optically active cysteine-based DKP as a chiral probe for detection of silver ion in water has been demonstrated.

Reaction-based colorimetric and ratiometric fluorescent probe for highly selective detection of silver ions

A novel colorimetric and ratiometric fluorescent probe CHa based on Ag+-induced hydrolysis of hydrazone was designed and synthesized. To the best of our knowledge, this is the first time the ratiometric sensing of Ag+ based on a chemical reaction has been accomplished. When Ag+ was added to a solution of CHa, a visible color change from yellow to colorless and a fluorescence color change from yellow to blue were observed. Probe CHa displayed a 203-fold enhancement of the fluorescence intensity ratio (I450nm/I520nm) toward Ag+ with outstanding sensitivity, high selectivity and a low detection limit (LOD 61 nM). Moreover, CHa was successfully applied to the ratiometric imaging of Ag+ in HepG2 and HeLa cells.

A Rapid and Sensitive Colorimetric Sensor for Detection of Silver Ions Based on the Non-aggregation of Gold Nanoparticles in the Presence of Ascorbic Acid

In the present work, we have developed a label free, colorimetric and non aggregation based gold nanoparticle (Au NPs)/Ascorbic acid (AA) probe without employing any aggregation agents for detection of trace amounts of silver ions (Ag+ ions) in aqueous solution and water samples. This detection probe can be prepared by simply mixing Au NPs with AA. The sensing mechanism is based on the reduction of Ag+ to Ag0 on the surface of Au NPs by AA. The addition of Ag+ ions to Au NPs/AA probe resulted in the enhancement and simultaneous blue shift of surface plasmon resonance band of Au NPs at 512 nm and it is accompanied by the appearance of a new peak around 385 nm. These observations are attributed to the deposition of Ag0 on the surface of Au NPs. This method could selectively detect Ag+ ions and showed a good linearity over the range of 2–28 μM (LOD = 0.85 μM). This sensing strategy avoids complex surface modification of Au NPs and it is cost effective.

A novel method for the detection of silver ions with carbon dots: Excellent selectivity, fast response, low detection limit and good applicability

With the extensive application of silver containing materials in industry, the issue of release of silver ions has attracted increasing attention due to toxic effect of silver ions on the human health and environment. Traditionally, silver ions can be detected by atomic absorption spectroscopy, atomic emission spectrometry etc., which needed expensive and elaborate instruments and were high energy consumption. Therefore, economic and convenient methods are required for the effective determination of silver ions. Herein, two types of carbon dots (CDs-1 and CDs-2) have been prepared through a solvothermal synthesis method by using sucrose or citric acid and tris(hydroxymethyl)aminomethane as precursor, respectively. Then, CDs-1 were developed for the detection of silver ions through a colorimetric method. The detection mechanism was based on the reduction of silver ions and the formation of silver nanoparticles, which possess unique surface plasma resonance properties. CDs-1 could both act as reductants and stabilizers during the reaction for determination of silver ions. This CDs-1 based detection system could quantitatively determine silver ions in 3 min with a limit of detection (LOD) of 26 nmol/L (2.81 ppb). Interestingly, this strategy could also realize the detection of silver ions by CDs-2. Furthermore, the sensing assay is applicable to detecting silver ions in lake water and silver sulfadiazine cream samples.

DNA-functionalized gold nanoparticle-based fluorescence polarization for the sensitive detection of silver ions.

Despite their practical applications, Ag+ ions are environmental pollutants and affect human health. So the effective detection methods of Ag+ ions are imperative. Herein, we developed a simple, sensitive, selective, and cost-effective fluorescence polarization sensor for Ag+ detection in aqueous solution using thiol-DNA-functionalized gold nanoparticles (AuNPs). In this sensing strategy, Ag+ ions can specifically interact with a cytosine-cytosine (CC) mismatch in DNA duplexes and form stable metal-mediated cytosine-Ag+-cytosine (C-Ag+-C) base pairs. The formation of the C-Ag+-C complex results in evident changes in the molecular volume and fluorescence polarization signal. To achieve our aims, we prepared two complementary DNA strands containing C-base mismatches (probe A: 5'-SH-A10-TACCACTCCTCAC-3' and probe B: 5'-TCCTCACCAGTCCTA-FAM-3'). The stable hybridization between probe A and probe B occurs with the formation of the C-Ag+-C complex in the presence of Ag+ ions, leading to obvious fluorescence quenching in comparison to the system without AuNP enhancement. The assay can be used to identify nanomolar levels of Ag+ within 6 min at room temperature, and has extremely high specificity for Ag+, even in the presence of higher concentrations of interfering metal ions. Furthermore, the sensor was successfully applied to the detection of Ag+ ions in environmental water samples and showed excellent selectivity and high sensitivity, implying its promising application in the future.

Synthesis and fluorescence characteristics of selective ratiometric fluorescent sensors for silver ions based on 3-indolyl-4-indazolyl maleimide derivatives

Selective ratiometric fluorescent sensor b for detection of silver ions and its counterparts (sensor a and c) were efficiently synthesized based on 3-indolyl-4-indazolyl maleimide, and their photophysical properties and activities towards metal ions were examined. The experimental results were verified by density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The results demonstrated that sensor b could selectively and sensitively recognize Ag+ compared with other competing metal ions in tetrahydrofuran (THF). It probably forms a 1:1 complex with Ag+, displaying a 52-nm bathochromic shift of the fluorescence emission spectrum. Moreover, the binding mechanism was investigated using binding stoichiometry titration and 1H, 13C nuclear magnetic resonance (NMR).

Internal standard-based SERS aptasensor for ultrasensitive quantitative detection of Ag+ ion

A ratiometric surface-enhanced Raman scattering (SERS) aptasensor based on internal standard (IS) methods was proposed for the ultrasensitive and reproducible quantitative detection of silver ion (Ag+) with Au@Ag core-shell nanoparticle (Au@Ag NP) substrate. In principle, the thiolated 5′-Rox C-containing labeled aptamer probe (Rox-aptamer) is firstly immobilized on the SERS substrate surface and then hybridizes with the complementary DNA (cDNA) to form a rigid double-stranded DNA (dsDNA), in which the Rox Raman labels is used to produce the Raman signal. Furthermore, the pyridine is employed as an IS element to provide the ratiometric determination of target. In the presence of Ag+, the Rox-aptamer is turned into the cytosine (C)-Ag+-C mediated hairpin structure, which remarkably reduces the distance between the Rox labels and the Au@Ag NP surface responsible for a measurable ‘turn-on’ signal change of Rox. This IS-based ratiometric SERS aptasensor exhibits a limit of detection of 50 pM for Ag+ with a linear detection range from 0.1 to 100 nM and the shortcoming of irreproducibility of SERS signal could be overcome. The proposed method provides a simple, robust, and rapid approach for the sensitive and reproducible quantitative detection of Ag+, and it could also be used for the detection of other metal ions which exhibits specific interactions with natural or synthetic bases.

Synthesis of carbon quantum dots from Broccoli and their ability to detect silver ions

Carbon quantum dots (CQDs) are promising nanomaterials with various industrial applications, including metal ion detection. Herein, a simple, green, and low-cost strategy was developed for the synthesis of fluorescent water-soluble CQDs for selective detection of Ag+ via one-step hydrothermal treatment of edible green plant, Broccoli. The functional group composition, morphology, and pH stability of the synthesized CQDs were investigated. In this study, the silver ions quenched the PL of the CQDs more strongly than other heavy metals, with a limit of detection (LOD) of 0.5 µM, which indicates that the synthesized CQDs can be effectively used as an Ag+ sensing tool.

Photoelectrochemical Stripping Analysis.

Electrochemical stripping analysis (ECSA) is a promising method for metal ions detection. However, the low sensitivity and poor reproducibility limits its practical applications. The combination with other powerful detection techniques to address these concerns is highly desirable. Herein, the anodic stripping method and photoelectrochemical (PEC) technique are integrated into a new detection platform of PEC stripping analysis (PECSA) with bismuth vanadate (BiVO4) as both optoelectronic material and an electrochemical enrichment candidate. The new PECSA strategy presents high sensitivity and excellent reproducibility; in addition, inherited from the ECSA, this strategy also offers new selectivity dimensions through the potential-dependent response and thus implements reproducible, sensitive, and selective detection of silver ion (Ag+) in real biological and environmental samples. The success of PECAS strategy shed light on the rational combination of various analysis techniques for versatile applications.

Paper-based visual detection of silver ions and l-cysteine with a dual-emissive nanosystem of carbon quantum dots and gold nanoclusters

The detection of silver ions and l-cysteine with a dual-emissive nanosystem of carbon quantum dots and gold nanoclusters.

Triazole-imidazole (TA-IM) derivatives as ultrafast fluorescent probes for selective Ag+ detection.

1,2,3-Triazole-imidazole derivatives (TA-IM) were prepared as fluorescent probes for silver ion detection. The design principle is the incorporation of an intramolecular H-bond between the imidazole and triazole moiety that enables a co-planar conformation to achieve fluorescence emission in the UV-blue range. Screening of different metal ions revealed excellent binding affinity of this new class of compounds toward silver ions in aqueous solution. The novel probe provided ultrafast detection (<30 s) even for a very low concentration of silver ions (in the nM range) with good linear correlation, making it a practical sensor for detection of silver ions.

Simple preparation and highly selective detection of silver ions using an electrochemical sensor based on sulfur-doped graphene and a 3,3',5,5'-tetramethylbenzidine composite modified electrode.

A novel electrochemical sensor based on sulfur (S)-doped graphene (S-Gr) and a 3,3',5,5'-tetramethylbenzidine (TMB) composite (S-Gr-TMB) modified glassy carbon (GCE) electrode for highly selective quantitative detection of silver ions (Ag+) were fabricated. The S-Gr-TMB composite was first prepared via electrostatic interaction between TMB and S-Gr and then, the composite was coated on the surface of GCE. The resultant S-Gr-TMB/GCE electrode showed a significant voltammetric response to Ag+ at 0.3 V vs. Ag/AgCl due to the synergistic effect of S-Gr and TMB. The sensor showed good linearity from 50 μM to 400 μM with a detection limit of 2.15 μM towards the determination of Ag+. In addition, after the addition of Fe3+ and other metal ions, including Al3+, Ca2+, Cd2+, Co2+, Cu2+, K+, Mg2+, Na+, Ni2+, Pb2+ and Zn2+, in the same concentration, the current signal remained almost unchanged, revealing that the proposed electrochemical sensor exhibited a high selectivity for Ag+, which solves the nonselective problem of TMB as a spectral probe. This enhanced detection performance is attributed to two factors: (1) S-Gr has excellent electrical conductivity; (2) the coupling interactions between Ag-S are speculated to result in strengthened enrichment for Ag and good selective performance.

A portable fluorescence resonance energy transfer biosensor for rapid detection of silver ions

In this study, we employed CupR protein in the construct of a fluorescence resonance energy transfer (FRET)-based protein biosensor for the detection of silver ions. We fused the CFP and the YPet through a truncated CupR protein (containing a dimerization helix and a metal binding domain) to create a FRET-based biosensor for the detection of silver ions. Various aqueous media (including tap water and pond water) were examined to determine the matrix effects and agarose gel was used to increase the feasibility of this portable biosensors. The resulting biosensor has demonstrated high sensitivity and selectivity to silver ions.

Off-on fluorescence monitoring of intracellular Ag+ in single living cells using an Ag+-responsive probe

Detection of silver ions (Ag+) in living cells has becoming more and more attractive due to the important biological impact of Ag+ on cellular functions. Here, we put forward a new approach to realize the in situ fluorescence imaging and detection of Ag+ in single cells via an ultrasensitive Ag+-responsive probe, 3′,6′-bis (diethylamino)-2-(2-iodoethyl) spiro[isoindoline-1,9′-xanthen]-3-one (BDISIX). In the presence of Ag+, the fluorescence of the probe can be turned ‘on’, generating strong red fluorescence. Using breast cancer cells (MCF-7) as the example, we successfully realize the imaging of intracellular Ag+ through one-step incubation of the probe, which is especially convenient and fast for the in situ intact detection of Ag+ in living cells.

Determination of Zinc, Cadmium, Lead, Copper and Silver Using a Carbon Paste Electrode and a Screen Printed Electrode Modified with Chromium(III) Oxide.

In this study, the preparation and electrochemical application of a chromium(III) oxide modified carbon paste electrode (Cr-CPE) and a screen printed electrode (SPE), made from the same material and optimized for the simple, cheap and sensitive simultaneous determination of zinc, cadmium, lead, copper and the detection of silver ions, is described. The limits of detection and quantification were 25 and 80 µg·L−1 for Zn(II), 3 and 10 µg·L−1 for Cd(II), 3 and 10 µg·L−1 for Pb(II), 3 and 10 µg·L−1 for Cu(II), and 3 and 10 µg·L−1 for Ag(I), respectively. Furthermore, this promising modification was transferred to the screen-printed electrode. The limits of detection for the simultaneous determination of zinc, cadmium, copper and lead on the screen printed electrodes were found to be 350 µg·L−1 for Zn(II), 25 µg·L−1 for Cd(II), 3 µg·L−1 for Pb(II) and 3 µg·L−1 for Cu(II). Practical usability for the simultaneous detection of these heavy metal ions by the Cr-CPE was also demonstrated in the analyses of wastewaters.

Facile fabrication of dual emissive nanospheres via the self-assembling of CdSe@CdS and zinc phthalocyanine and their application for silver ion detection

The far-red/near infrared photoluminescence of zinc phthalocyanines would be strongly quenched once they are aggregated, which will obviously hinder their wide applications in environmental, energy related and biomedical fields. Herein, the ultra-small sized semiconductor quantum dots with core-shell structures (CdSe@CdS) have been firstly synthesized and then assembled with a dendritic zinc phthalocyanine (ZnPc) in the H2O/DMF mixed solvent to obtain monodispersed nanospheres. Finally, it was found that the resultant ethanolic colloids can be employed as a sensitive and specific fluorescent nanoprobe for silver ions discrimination with a limit of detection (LOD) approaching to 10−8mol/L.

A ratiometric fluorescent nanosensor for the detection of silver ions using graphene quantum dots

A ratiometric fluorescent nanosensor was reported for the first time for the sensitive and selective analysis of Ag+ ions by employing graphene quantum dots (GQDs) as the reference fluorophore and o-phenylenediamine (OPD) as the specific recognition probe. Upon the addition of Ag+ ions, OPD could be oxidized to produce 2,3-diaminophenazine (DAP) with a strong fluorescence emission at 557nm, whereas the fluorescence of GQDs at 445nm would be simultaneously quenched by the so generated DAP through fluorescence resonance energy transfer (FRET). A ratiometric fluorescent Ag+ nanosensor was thus developed. The fluorescence intensity ratios of DAP to GQDs linearly increased with the increasing of Ag+ concentrations in the range of 0–115.2μM, with a detection limit down to 250nM. Furthermore, the feasibility of practical applications of the developed detection strategy for probing Ag+ ions in real water samples was demonstrated.

A microcantilever-based silver ion sensor using DNA-functionalized gold nanoparticles as a mass amplifier

Silver ions have been used to sterilize many products, however, it has recently been demonstrated that silver ions can be toxic. This toxicity has been studied over many years with the lethal concentration at 10 μM. Silver ions can accumulate through the food chain, causing serious health problems in many species. Hence, there is a need for a commercially available silver ion sensor, with high detection sensitivity. In this work, we develop an ultra-sensitive silver ion sensor platform, using cytosine based DNA and gold nanoparticles as the mass amplifier. We achieve a lower detection limit for silver ions of 10 pM; this detection limit is one million times lower than the toxic concentration. Using our sensor platform we examine highly selective characteristics of other typical ions in water from natural sources. Furthermore, our sensor platform is able to detect silver ions in a real practical sample of commercially available drinking water. Our sensor platform, which we have termed a ‘MAIS’ (mass amplifier ion sensor), with a simple detection procedure, high sensitivity, selectivity and real practical applicability has shown potential as an early toxicity assessment of silver ions in the environment.

Facile Colorimetric Detection of Silver Ions with Picomolar Sensitivity.

Although various colorimetric methods have been actively developed for the detection of Ag+ ions because of their simplicity and reliability, the limits of detection of these methods are confined to the nanomolar (nM) level. Here, we demonstrate a novel strategy for colorimetric Ag+ detection with picomolar (pM) sensitivity. This strategy involves the use of poly(vinylpyrrolidone)- (PVP-) capped Pt nanocubes as artificial peroxidases that can effectively generate a colored signal by catalyzing the oxidation of peroxidase substrates. In the presence of Ag+ ions, the colored signal generated by these Pt cubes is greatly diminished because of the specific and efficient inhibition of Ag+ toward the peroxidase-like activity of the Pt cubes. This colorimetric method can achieve an ultralow detection limit of 80 pM and a wide dynamic range of 10-2-104 nM. To the best of our knowledge, the method presented in this work shows the highest sensitivity for Ag+ detection among all reported colorimetric methods. Moreover, this method also features simplicity and rapidness as it can be conducted at room temperature, in aqueous solution, and requires only ∼6 min.