Detection Of Silver Ions Research Articles

One-step synthesis of mitochondrion-targeted fluorescent carbon dots and fluorescence detection of silver ions

Silver ions (Ag+) are the most representative harmful ions found in polluted water and widely used in many industries; excessive ingestion of Ag+ in the human body may result in interaction with different metabolites in the human body and in aquatic microorganisms, leading to many diseases. Therefore, there is a great desire to develop good fluorescent probes for Ag+. Herein, a kind of mitochondrion-targeted fluorescent carbon dot was developed. These carbon dots exhibit 29.5% fluorescence quantum yield in water, good photostability and thermal stability. The as-fabricated carbon dots can quickly detect Ag+ in 100% water solution with good selectivity and anti-interference ability. Further, the carbon dots have been successfully applied to monitor Ag+ in living cells via the dual-channel method.

Electrochemical detection of silver ions by using sulfur quantum dots modified gold electrode

Sensitive and low-cost determination of Ag+ is important due to the potential risk of Ag+ increasingly applied in various fields. In this work, we report an extremely simple electrochemical sensor for the Ag+ determination based on the sulfur quantum dots (SQDs) modified Au electrode. The SQDs were synthesized by a top-down method through alkali etching of bulk sulfur powder, which were then directly used for Au electrode surface modification due to the high affinity between Au and S atoms. The strong binding between Ag and S makes the modified electrode highly sensitive for Ag+ sensing. The theoretical investigation was carried out by calculating the bond length and binding strength between Ag and S. Since the non-conductive nature of the SQDs, the amount of modifier is a crucial factor for the sensing performance. Under optimum condition, the proposed sensor showed a linear detection range of 0.1 nM to 3 μM with a detection limit of 71 pM.

Fluorescence Anisotropy Reduction of An Allosteric G-Rich Oligonucleotide for Specific Silver Ion and Cysteine Detection Based on the G-Ag+-G Base Pair.

Silver is a common heavy metal, and the detection of silver ion (Ag+) is of great importance because of its wide application and hazardous effect on the environment and human health. However, it is a great challenge to produce a large fluorescence anisotropy (FA) change for small molecules (e.g, Ag+). Herein, we describe a novel fluorescence anisotropy reduction approach for the sensitive and specific detection of Ag+. The feasibility of this method is demonstrated through screening a number of guanine-rich oligonucleotide probes. By selectively labeling the oligonucleotides with a single fluorophore tetramethylrhodamine (TMR), the reduction in FA response is associated with the conformation change from the unfolded to a hairpin-like folded structure by inducing formation of the intermolecular G-Ag+-G base pair, which diminishes the interaction between guanine and TMR by photoinduced electron transfer (PET). The change in FA allows the selective detection of Ag+ at a concentration as low as 0.5 nM with a dynamic range from 2.0 to 100 nM. The interference from the other 14 metal ions with a 100-fold even to a 1000-fold excess amount is negligible. This simple and cost-effective probe was further explored to determine cysteine (Cys) based on competing with a guanine-rich oligonucelotide for Ag+-binding.

Photothermal Microfluidic Sensing Platform Using Near-Infrared Laser-Driven Multiplexed Dual-Mode Visual Quantitative Readout.

The application of different sensing principles in microfluidic devices opens up further possibilities for the development of point-of-care testing (POCT). Herein, the photothermal sensing principle is introduced in microfluidic paper-based analytical devices (μPADs) to develop a photothermal microfluidic sensing platform using near-infrared (NIR) laser-driven multiplexed dual-mode visual quantitative readout. Prussian blue (PB) as the analyte-associated photothermal agent was in situ synthesized in thermoresponsive poly(N-isopropylacrylamide) hydrogels to serve as the on-chip photothermal sensing element. TheNIR laser-driven photothermal effect of PB triggered not only on-chip dose-dependent heat generation but also phase transition-induced dye release from the hydrogels, simultaneously enabling both thermal image- and distance-based dual-mode visual quantitative readout of the analyte concentration in a multiplexed manner. Both the on-chip temperature elevation value of the hydrogels and the traveling distance of released dye solutions were proportional to the concentration of PB. With the detection of silver ions in environmental water as a proof-of-concept study, the photothermal μPAD can detect silver ions at a concentration as low as 0.25 μM with high selectivity and satisfactory accuracy. The photothermal microfluidic sensing platform holds great potential for POCT with promising integratability and broad applicability, owing to the combination of synergistic advantages of the photothermal sensing principle, μPADs, and photothermally responsive hydrogels.

A highly selective Ag+ sensor based on 8-hydroxyquinoline functionalized graphene oxide -silica nanosheet and its logic gate behaviour

An 8-hydroxyquinoline functionalized graphene oxide-mesoporous silica nanocomposite (GS-Q) was synthesized and its fluorescence properties were studied to evaluate the sensing capability of GS-Q toward metal cations. By selection of the appropriate excitation wavelength as 360 nm, the aqueous suspension of GS-Q showed a broad emission peak around 480 nm that was influenced by some cations such as alkaline earth and transition metal ions. Besides, a second-order scattering (SOS) signal, amounting to twice the excitation wavelength 720 nm, was observed in the emission spectra that selectively responded to Ag+ ions in the presence of other metal ions. The linear response of the SOS signal to the concentration of Ag+ makes for a versatile and selective probe for the detection of silver ions based on the enhancement of the SOS signal. Furthermore, the remarkable dual-output signal effect of GS-Q was exploited to study the logic behavior of GS-Q in the aqueous media and consequently a solid support logic circuit was constructed by producing two optical outputs under the stimulation of Al3+, Fe3+ and Ag+ ions, as inputs.

TiO₂ Decorated Graphene as a Fluorescent Chemosensor for the Detection of Silver Ions.

In this report, a new design is proposed for the detection of silver ions using Graphene Oxide-Titanium oxide (GO/TiO₂) composite. The GO was synthesized by modified Hummers method and the composite is synthesized by chemical reflux method. The surface morphology of the composite was analyzed using a scanning electron microscope (SEM), and it is clearly observed that TiO₂ spheres are adsorbed on the surface of GO in a disordered manner. X-ray Diffraction (XRD) results confirm the presence of TiO₂ on GO. Photoluminescence (PL) spectra show the reduced recombination of charge carriers in the (GO/TiO₂) composite. The resulting composite selectively detects silver ions over other potentially competing metal ions with no notable interference monitored by fluorescence.

Fluorometric detection of silver(I) using cytosine-Ag(I)-cytosine pair formation, DNA assembly and theAND logic operation of amultiple-componentDNAzyme.

A nonenzymatic fluorometric assay is described for highly sensitive and selective detection of silver ion. It is making use of a controlled DNA assembly and an AND logic operation of amultiple-component DNAzyme (MNAzyme). It corresponds to an Ag(I)-responsive three-way junction (3-WJ) assembly. The tailored probes of the 3-WJ architecture were designed with complementary domains for subsequent assembly. Cytosine (C)-cytosine mismatches at one-way junction were set as the sensing element for Ag(I). Upon exposure to Ag(I) as an input, C-Ag(I)-C pairs are being formed. This enhances the binding energy between these separate probes and thus promotes the formation of a nanostructure that represents an AND logic assembly of MNAzyme with an amplified output signal. This results in an Ag(I)-induced increase in fluorescence which is measured best at excitation/emission maxima of 645/670nm. The method displays high selectivity and sensitivity, has a 5 pM detection limit at 3σ and a dynamic range that extends from 10 pM to 100nM. Graphical abstract Schematic presentation of a new fluorescence system for determining silver ion by making use of cytosine-Ag(I)-cytosine pair formation, precisely-controlled DNA assembly and "AND" logic operation of multiple components DNAzyme (MNAzyme).

Potential Application of Nitrogen-Doped Carbon Quantum Dots Synthesized by a Solvothermal Method for Detecting Silver Ions in Food Packaging.

In this paper, nitrogen-doped carbon quantum dots (N-CQDs) were synthesized by a solvothermal method using 1,2,4-triaminobenzene as a carbon precursor. The surface of the synthesized N-CQDs was modified with amino functional groups. The results indicated that N-CQDs had various N-related functional groups and chemical bonds and were amorphous in structure. At the same time, the quantum yield of N-CQDs was 5.11%, and the average lifetime of fluorescence decay was 5.79 ns. The synthesized N-CQDs showed good selectivity for and sensitivity to Ag+. A linear relationship between N-CQDs detection efficiency and Ag+ concentration was observed for concentration ranges of Ag+ corresponding to 0–10 μM and 10–30 μM. In addition, N-CQDs were used for the detection of trace Ag+ in food packaging material. The silver ion content of the sample determined by the N-CQDs detection method was 1.442 mg/L, with a relative error of 6.24% with respect to flame atomic absorption spectrometry, according to which the Ag+ content was 1.352 mg/L. This indicates that the N-CQDs detection method is reliable. Therefore, the N-CQDs prepared in this paper can detect Ag+ rapidly, simply, and sensitively and are expected to be a promising tool for the detection of trace Ag+ in food packaging materials.

Target-triggered inhibiting oxidase-mimicking activity of platinum nanoparticles for ultrasensitive colorimetric detection of silver ion

The development of efficient methods for the detection of hazardous and toxic elements is extremely important for environmental security and public health. In this work, we developed a facile colorimetric assaying system for Ag+ detection in aqueous solution. Chitosan-stabilized platinum nanoparticles (Ch-PtNPs) were synthesized and severed as an artificial oxidase to catalyze the oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) and generate color signal. In the presence of Ag+, due to the strong metallophilic interactions between Ag+ and Pt2+ on the surface of Ch-PtNPs, Ag+ can weaken the affinity to the substrates and inactivate the catalytic activity of Ch-PtNPs, leading to decreased absorbance signal to varying degrees depending on Ag+ amount. Combing the specific binding between Ch-PtNPs and Ag+ with signal amplification procedure based on the Ch-PtNPs-catalyzed TMB oxidation, a sensitive, selective, simple, cost-effective, and rapid detection method for Ag+ can be realized. Ag+ ions in tap and lake waters have been successfully detected. We ensured that the proposed method can be a potential alternative for Ag+ determination in environmental samples.

The wound healing and antibacterial potential of triple-component nanocomposite (chitosan-silver-sericin) films loaded with moxifloxacin

AimThe current study reports the development and evaluation of chitosan-sericin-silver nanocomposite (CSSN) films without and with moxifloxacin (Mox). MethodologyThe film preparation method involved the in-situ synthesis of silver nanoparticles within the chitosan-sericin colloidal composite followed by preparation into a film by solvent casting technique. In-situ formation and the particle size analysis of the silver nanoparticles was performed via UV-Visible and zeta-size spectrometer. The prepared films were tested for swelling ratio, contents uniformity, in-vitro Mox release, and permeation analysis. The morphological (SEM), elemental (EDX), spectral (FT-IR), structural (XRD), and thermal (TGA and DSC) properties of the composites were also inspected. The antibacterial activity of the CSSN films was performed against seven pathogenic bacterial strains including five ATCC and two clinical strains. The potential wound healing activity of the composite films was evaluated on burn wound model induced in Sprague Dawley male rats. ResultsThe prepared films displayed good swelling profile with a sustained in-vitro Mox release and permeation profile; attaining maximum of 78.57% (CSSM3) release and 55.05% (CSSM1) permeation (CSSM1) in 24 h. The prepared films, particularly the Mox-loaded CSSN films displayed a promising antibacterial activity against all the tested strains with the activity being highest against MRSA (clinical isolates). The prepared films indicated a remarkable wound healing applications with successful fibrosis, collagen reorganization, neovascularization, and mild epidermal regeneration after 7 days of treatment with no silver ions detection in animal’s blood. ConclusionThe obtained findings strongly suggest the use of the prepared novel composite dressing for wound care applications.

One-Step Synthesis of Label-Free Ratiometric Fluorescence Carbon Dots for the Detection of Silver Ions and Glutathione and Cellular Imaging Applications.

The construction of ratiometric fluorescence assay has displayed fantastic advantages in improving semi-quantitative visualization capability by presenting successive color changes. Herein, long-wavelength emission nitrogen-doped carbon dots (N-CDs) were developed for intrinsic ratiometric detection of silver ions (Ag+) and glutathione (GSH), accompanied by visualization fluorescence variation of orange and green. The label-free N-CDs were favorably obtained through one-step hydrothermal synthesis and displayed single long-wavelength emission at 618 nm under the excitation wavelength of 478 nm. Interestingly, a ratio rising peak emerges at 532 nm and the emission at 618 nm decreases with the introduction of Ag+, which exhibits ratiometric fluorescence emission characteristics ( I618nm/ I532nm) in the range of 0-140 μM with significant fluorescence varying from orange to green. Furthermore, the fluorescence of CDs@Ag(I) can be effectively ratiometric recovered by virtue of a specific reaction of GSH with Ag+, which is accompanied by the fluorescence of the solution returning from green to orange. In addition, the N-CDs hold excellent biocompatibility which can be implemented as the visualization biosensing platform for intracellular determination of Ag+ and GSH, demonstrating that proposed N-CDs have tremendous potential in biological systems.

Methylene blue-based distinguishing DNA conformation for colorimetric detection of silver ions

A highly sensitive colorimetric sensing strategy based on the interaction between methylene blue (MB) and C-rich single-stranded DNA (ssDNA) (24C used here) has been developed for detection of Ag+. In the absence of target Ag+, the interaction between MB and 24C makes the color immediately change from blue to purple. However, specific C-Ag+-C pair forms when Ag+ ions are present in the aqueous solution containing 24C and MB, resulting in the desorption of MB from the surface of 24C into the solution. As a result, the color changes from purple to blue, and the absorbance values of MB at 660 and 605 nm gradually decrease. The detection limit can be as low as 1 nM, which satisfies the guideline concentration of Ag+ in drinking water set by the United States Environmental Protection Agency (EPA). The practical use of this method for Ag+ detection in river water samples is also demonstrated successfully.

Facile green and one-pot synthesis of purple perilla derived carbon quantum dot as a fluorescent sensor for silver ion

In this work, biomass-derived carbon quantum dots (CQDs) with excellent water solubility, strong fluorescence and favorable biocompatibility were synthesized via one-step hydrothermal treatment of purple perilla for the first time. The functional group composition, morphology, and pH stability of the synthesized CQDs were systematically investigated. And based on fluorescence quenching of CQDs, the as-prepared CQDs were innovatively developed as an effective “signal-off” fluorescent probe for selective and sensitive detection of silver ion (Ag+) with two linear ranges of 0–10 and 10–3000 nM, and a detection limit 1.4 nM. The specificity and selectivity of this fluorescent probe were also verified through challenging the detection by using similarmetallic cations or in real water samples. In addition, the as-prepared CQDs exhibit a low cytotoxicity and a good biocompatibility, revealing its potential bioimaging applications in living cells.

Facile preparation of orange-emissive carbon dots for the highly selective detection of silver ions

We have prepared orange-emissive carbon dots, which serve as a highly selective fluorescent method for the detection of silver ions.

Extremely sensitive and wide-range silver ion detection via assessing the integrated surface potential of a DNA-capped gold nanoparticle

With the rapid development of nanotechnology and its associated waste stream, public concern is growing over the potential toxicity exposure to heavy metal ions poses to the human body and the environment. Herein, we report an extremely sensitive Kelvin probe force microscopy (KPFM)-based platform for detecting nanotoxic materials (e.g. Ag+) accomplished by probing the integrated surface potential differences of a single gold nanoparticle on which an interaction between probe DNA and target DNA occurs. This interaction can amplify the surface potential of the nanoparticle owing to the coordination bond mediated by Ag+ (cytosine–Ag+–cytosine base pairs). Interestingly, compared with conventional methods, this platform is capable of extremely sensitive Ag+ detection (∼1 fM) in a remarkably wide-range (1 fM to 1 μM). Furthermore, this platform enables Ag+ detection in a practical sample (general drinking water), and this KPFM-based technique may have the potential to detect other toxic heavy metal ions and single nucleotide polymorphisms by designing specific DNA sequences.

Silver Ions Detection via Nucleolipids Self-Assembly.

A novel hybrid bioinspired amphiphile featuring a cytosine moiety, which self-assembles into liposomes can be used to detect silver ions in aqueous media. The coordination of Ag+ ions by the nucleotide moiety increases membrane rigidity, which enhances the fluorescence of a common reporter, Thioflavin T. Ag+ can be sensed even at trace concentrations (3 ppb) with great specificity over other metals ions. These nucleotide based supramolecular structures can be used to detect silver ions in drinking water, demonstrating the robustness of this approach.

Fabrication of a nanomaterial-based fluorescence sensor constructed from ligand capped CdTe quantum dots for ultrasensitive and rapid detection of silver ions in aqueous samples.

In this study, CdTe QDs were prepared in aqueous medium and then capped with a synthetic heterocycle ligand (CdTe/L QDs) via surface modification method. Characterization of synthesized CdTe/L QDs was carried out through various analytical techniques including fluorescence spectroscopy, transmission electron microscopy (TEM), UV-Vis spectrophotometry, thermo-gravimetric (TG) analysis and Fourier transform infrared (FTIR). The fluorescence intensity of the CdTe/L QDs at 520 nm (excitation at 380 nm) was selectively quenched in the presence of trace amounts of silver ions. CdTe/L QDs were utilized as an ultrasensitive and selective fluorescent sensor for determination of trace concentrations of silver ions with a detection limit of 6.12 ± 0.11 × 10-10 mol L-1 and a linear range of 2.04 ± 0.10 × 10-9 mol L-1-3.63 ± 0.12 × 10-7 mol L-1. The fabricated optical sensor was also used for the measurement of silver ions in real water samples which yielded satisfactory analytical results. These results were also evaluated with inductively coupled plasma emission spectroscopy (ICP-OES). This study shows that CdTe/L QDs could have potential applications in selective and sensitive analysis of different water samples for detection of silver ions.

Changes of Parameters of Mixed Monolayers Based on Photosensitive Crown Ether in the Presence of Silver Ions

The use of the achievements attained in colloid chemistry and other fields of chemical sciences allows us to develop new nanoscale systems for chemosensorics. Mixed monolayers consisting of a new chemosensory amphiphilic dithia-18-crown-6, which contains a dye of 4-alkylpyridine series with polyvinyl stearate at the water–air interface, are obtained and studied. The influence of various concentrations of silver ions on these mixed monolayers is studied. A promising method for the detection of silver ions in water using the given nanoscale systems based on chemosensory amphiphilic dithia-18-crown-6 is proposed.

Gallotannin functionalized gold nanoparticles for rapid, selective and sensitive colorimetric detection of Ag+ in aqueous medium: Approach to eco-friendly water analysis

We have prepared gallotannin (GT) capped gold nanoparticles (AuNPs) for rapid, sensitive and naked eye colorimetric detection of silver ion (Ag+) in aqueous medium. Amongst the 21 different metal ion studied for absorption titration, only Ag+ ion induces the change in color and spectral properties of GT capped AuNPs. The formation of GT capped AuNPs and its interaction with Ag+ were discussed with change in pink to yellowish brown color, hypsochromic spectral shift in absorption maximum wavelength, decrease in zeta potential and increase in particle size. The sequential addition of Ag+ to the colloidal suspension of GT capped AuNPs simultaneously increases the absorbance along with hypsochromic shift in wavelength maxima. The absorption titration results were fits well to calibration plot in linearity range of 0–1 ng/mL of Ag+ showing correlation coefficient (R2) of 0.9983. The lower detection limit estimated for Ag+ is 0.22 ng/mL (2.05 nM) that shows sensitivity and selectivity of present analytical method towards detection of Ag+ in aqueous solution. The present method includes practical application for quantitative determination of Ag+ in real environmental water samples. Thus, the present study offers simple, cost-effective, selective, sensitive, speedy, profitable and naked eye detection of Ag+ in aqueous medium.

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...