Glutathione modified Ag nanoparticles as efficient detector for pyrimethanil

This work reports on glutathione modified Ag nanoparticles (GSH-Ag NPs) as a chemosensor for detecting pyrimethanil in an aqueous medium. The GSH-Ag NPs were expediently obtained by reducing AgNO₃ with NaBH₄ and modified with glutathione based on the Ag-S bond. The rapid discrimination for pyrimethanil from other pesticides exhibited the high selectivity of GSH-Ag NPs, then the selectivity was proved by ¹H NMR, FT-IR and computational simulation. Based on the good properties of localized surface plasmon resonance, the selective recognition was transformed to visible optical signal in colorimetric test. Additionally the quantitative detection was achieved with good sensitivity and could be applied to analyze practical samples. The experimental results have shown a good linear relationship with pyrimethanil concentration ranging from 10 μM to 1 mM and a low detection limit of 3.87 μM.

Green Synthesis of Silver Nanoparticles Stabilized with Mussel-Inspired Protein and Colorimetric Sensing of Lead(II) and Copper(II) Ions

This articles reports a simple and green method for preparing uniform silver nanoparticles (AgNPs), for which self-polymerized 3,4-dihydroxy-l-phenylalanine (polyDOPA) is used as the reducing and stabilizing agent in aqueous media. The AgNPs functionalized by polyDOPA were analyzed by UV-Vis spectroscopy, high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Raman spectrophotometry, and X-ray diffraction (XRD) techniques. The results revealed that the polyDOPA-AgNPs with diameters of 25 nm were well dispersed due to the polyDOPA. It was noted that the polyDOPA-AgNPs showed selectivity for Pb²⁺ and Cu²⁺ detection with the detection limits for the two ions as low as 9.4 × 10^-5 and 8.1 × 10^-5 μM, respectively. Therefore, the polyDOPA-AgNPs can be applied to both Pb²⁺ and Cu²⁺ detection in real water samples. The proposed method will be useful for colorimetric detection of heavy metal ions in aqueous media.

Highly stable antibacterial silver nanoparticles as selective fluorescent sensor for Fe³⁺ ions

Calix[4]resorcinarene polyhydrazide (CPH) protected water dispersible fluorescent silver nanaoparticles (AgNps) were prepared by one-pot method using water soluble CPH and AgNO₃. (CPH) bearing hydrazide group on its periphery acts as a reducing agent and its web type of structure as a stabilizing agent for the formation of calix protected silver nanoparticles (CPH-AgNps). CPH-AgNps were found to be highly stable over 120 days at room temperature and at varied pH. CPH-AgNps were characterized by UV/Vis-spectroscopy, particle size analyzer (PSA), transmission electron microscopy (TEM) and Energy dispersive X-ray analysis (EDX). Duly characterized nanoparticles were explored for their application as sensitive and selective fluorescent chemosensors for various metal ions. It was found that nanoparticles were selective and sensitive only for Fe(3+) ions with the linear range of detection from 0.1 μM to 10 μM. CPH-AgNps were also found to exhibit good antimicrobial activity when compared with standard Chloramphenicol. The selectivity and antimicrobial activity of CPH-AgNps suggests its potential use as a sensor for Fe(III) ions in ecosystems prone to industrial pollution and as an antimicrobial agent in biological applications.

Hyperbranched polyethylenimine-based sensor of multiple metal ions (Cu2+, Co2+and Fe2+): colorimetric sensing via coordination or AgNP formation

A commercially available HPEI polymer has been used as a single colorimetric probe for the selective colorimetric sensing of multiple metal ions in aqueous solution with distinguishable colors.

Bio-functionalized silver nanoparticles for selective colorimetric sensing of toxic metal ions and antimicrobial studies

Hibiscus Sabdariffa (Gongura) plant extracts (leaves (HL) and stem (HS)) were used for the first time in the green synthesis of bio-functionalized silver nanoparticles (AgNPs). The bio-functionality of AgNPs has been successfully utilized for selective colorimetric sensing of potentially health and environmentally hazardous Hg(2+), Cd(2+) and Pb(2+) metal ions at ppm level in aqueous solution. Importantly, clearly distinguishable colour for all three metal ions was observed. The influence of extract preparation condition and pH were also explored on the formation of AgNPs. Both selectivity and sensitivity differed for AgNPs synthesized from different parts of the plant. Direct correlation between the stability of green synthesized AgNPs at different pH and its antibacterial effects has been established. The selective colorimetric sensing of toxic metal ions and antimicrobial effect of green synthesized AgNPs demonstrated the multifunctional applications of green nanotechnology.

Dual colorimetric sensing of mercury and iodide ions by steroidal 1,2,3-triazole-stabilized silver nanoparticles

Bile acid-based 1,2,3-triazole ligands have been synthesized, which show excellent ability to stabilize silver nanoparticles. These AgNPs have been found to exhibit highly selective dual colorimetric sensing of Hg²⁺ and I⁻ ions.

Green synthesized silver nanoparticles for selective colorimetric sensing of Hg2+ in aqueous solution at wide pH range

In the present study, the syntheses of crystalline silver and gold nanoparticles (NPs) has been demonstrated in a green and environmentally friendly approach using citrus fruit extracts (lemon, Citrus limon (Cl-1) and sweet orange, Citrus limetta (Cl-2)). In addition, potentially hazardous metal ion sensing properties of these NPs in aqueous solution has been explored. Cl-1 and Cl-2 that predominantly contained citric and ascorbic acid, exhibited different reducing abilities towards silver and gold ions into NPs. Cl-1 reduces silver ions into AgNPs only in the presence of sunlight whereas AuNPs from gold ions were formed without exposure to sunlight. In contrast, Cl-2 converts both silver and gold ions into the corresponding NPs in the absence of sunlight. The colorimetric sensor studies of these green synthesized AgNPs (Cl-1-AgNPs) showed selective sensing of the potentially hazardous Hg(2+) ion in water at micromolar concentrations. More importantly, green synthesized Cl-1-AgNPs sensor systems detected Hg(2+) ions in water in a wide pH range (3.2 to 8.5).

A selective, sensitive, and chromogenic chemodosimeter for cyanide based on the 1,1'-binaphthyl scaffold

A highly selective chemodosimeter 1 for cyanide based on the 1,1'-binaphthyl skeleton is described which demonstrated significant visual change and a low limit of detection. Interestingly, a reversible process triggered successively by CN(-) and Au(3+) is also observed and determined by fluorescence, UV-vis spectra, (1)H NMR titration, and ESI-MS.

Lead (II) ion detection in surface water with pM sensitivity using aza-crown-ether-modified silver nanoparticles via dynamic light scattering

In this paper, we reported ultrasensitive lead ion detection in environmental water with pM sensitivity using aza-crown-ether-modified silver nanoparticles (ACE-Ag NPs) through dynamic light scattering (DLS). The colorimetric method based on ACE-Ag NPs is not capable of detecting Pb2+ ions over other metal ions (Fe3+, Co2+, Cu2+, Hg2+, Cd2+, Ag+, Li+, Na+, K+ and Cs+) with high sensitivity. But DLS has improved the selectivity and sensitivity of the Pb2+ detection system (50-fold or more) over colorimetric method, and its detection limit is 0.25 pM (1.03 ppt). The Pb2+ DLS assay can be applied to detect Pb2+ in the environmental water, such as in Yangtze and East Lake water samples with a detection limit of 0.20 and 0.22 pM, which is much lower than the maximum contamination level of 4.8×10(-8) M for lead in surface water defined by the national environmental quality standards of China (GB 3838-2002). Also, this method has a good performance in the determination of Pb2+ in drinking water, which is much lower than the maximum contamination level (MCL) of 72 nM for lead as defined by the US Environmental Protection Agency (EPA).

Cooperative binding of bifunctionalized and click-synthesized silver nanoparticles for colorimetric co(2+) sensing

Bifunctionalized silver nanoparticles (triazole-carboxyl Ag NPs) were synthesized through a click reaction and have a cooperative effect on recognition of Co(2+), resulting in appreciable changes in color and absorption properties over other metal ions tested, including Fe(2+), Mn(2+), Hg(2+), Ni(2+), Cd(2+), Cu(2+), Zn(2+), Pb(2+), Li(+), Na(+), K(+), Cs(+). The functionalized silver nanoparticles became aggregated in solution in the present of Co(2+) through cooperative metal-ligand interaction. The colorimetric sensor allows a rapidly quantitive assay of Co(2+) down to the concentration of 7.0 x 10(-6) M. Moreover, the triazole-carboxyl AgNPs can be capable of evaluating the exceeding standard of Co(2+) in drinking water.