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A Sensitive Near-Infrared Fluorescent Probe for Detecting Heavy Metal Ag+ in Water Samples
摘要： Silver is a common catalyst in industrial production, and the frequent use of Ag+ can cause water pollution. Thus, the detection of Ag+ in the environment is necessary to determine the level of pollution from silver. In this work, we designed a new, highly selective near-infrared (NIR) fluorescent probe QCy to detect Ag+. The probe exhibits 'turn-off' fluorescence quenching responses at 760 nm towards Ag+ over other relevant cations, with outstanding sensitivity and a low detection limit (0.03 μM), which is considerably lower than the standard of the World Health Organization (WHO) for drinking water (0.9 μM). Meanwhile, QCy showed a very good linearity at a low concentration of Ag+ with a 'naked eye' visible color change of solution from blue to red. The probe has been applied successfully for the detection of Ag+ in real water samples.
关键词： selectivity,fluorescence probe,Ag+,sensitivity,water samples
更新于2025-09-23 15:22:29
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Development of a turn-on graphene quantum dot-based fluorescent probe for sensing of pyrene in water
摘要： Polycyclic aromatic hydrocarbons (PAHs) are potentially harmful pollutants that are emitted into the environment from a range of sources largely due to incomplete combustion. The potential toxicity and carcinogenic effects of these compounds warrants the development of rapid and cost-effective methods for their detection. This work reports on the synthesis and use of graphene quantum dots (GQDs) as rapid fluorescence sensors for detecting PAHs in water. The GQDs were prepared from two sources, i.e. graphene oxide (GO) and citric acid (CA) – denoted GO-GQDs and CA-GQDs, respectively. Structural and optical properties of the GQDs were studied using TEM, Raman, and fluorescence and UV-vis spectroscopy. The GQDs were then applied for detection of pyrene in environmental water samples based on a “turn-off-on” mechanism where ferric ions were used for turn-off and pyrene for turn-on of fluorescence emission. The fluorescence intensity of both GQDs was switched on linearly within the 2–10 × 10?6 mol L?1 range and the limits of detection were found to be 0.325 × 10?6 mol L?1 and 0.242 × 10?6 mol L?1 for GO-GQDs and CA-GQDs, respectively. Finally, the potential application of the sensor for environmental water samples was investigated using lake water and satisfactory recoveries (97–107%) were obtained. The promising results from this work demonstrate the feasibility of pursuing cheaper and greener environmental monitoring techniques.
关键词： Polycyclic aromatic hydrocarbons,Pyrene detection,Graphene quantum dots,Fluorescence sensors,Environmental water samples
更新于2025-09-23 15:21:01
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One-step electrosynthesized molecularly imprinted polymer on laser scribed graphene bisphenol a sensor
摘要： Bisphenol A (BPA) is a toxic chemical used by industries for production of containers for storage of food and beverages leading to possible health risks. In this work, we present a simple, mask-free, low-cost imprinted sensor based on laser scribed graphene (LSG) technology combined to molecularly imprinted polymers (MIPs) for BPA determination. CO2 laser was used in production of LSG electrodes with high resistivity 58 Ω/square on flexible polyimide sheet leading to the high active surface area of the sensor. LSG device was functionalized with imprinted polypyrrole with a known amount of BPA as template molecule to develop the sensor. The bare LSG, LSG-MIP, LSG-NIP sensors were characterized using Raman spectroscopy, SEM, XRD, AFM. The electrochemical measurements were carried out using cyclic voltammetry and differential pulse voltammetry. Experimental conditions were optimized, including the concentration of pyrrole monomer, the number of polymerization cycles, the concentration of BPA as template and the incubation time. We evaluated the sensitivity of the LSG-MIP sensor in the concentration range between 0.05 μM and 20 μM with a limit of detection of 8 nM. The proposed sensor exhibits high selectivity towards BPA compared to its structural analogs and good reusability. The developed sensor was successfully applied for the detection of BPA in tap, mineral water and in plastic samples. The developed sensor was integrated into a PMMA case connected to the potentiostat to achieve complete isolation and a practical measurement system.
关键词： Molecularly imprinted polymers,Water samples,Electropolymerization,Electrochemical devices,Bisphenol A,Laser scribed graphene
更新于2025-09-23 15:21:01
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β-Cyclodextrin protected gold nanoparticle based cotton swabs as an effective candidate for specific sensing of trace levels of cyanide
摘要： In recent work, we demonstrate a rapid colorimetric and easy visual determination of cyanide ions (CNˉ ions) in water based on gold nanoparticles stabilized with β-cyclodextrin (β-CD). Optical detection of CNˉ ions were carried out using β-CD-AuNPs by tracking the changes in the SPR band and colorimetric nature of the β-CD AuNPs. This colorimetric nanosensor capably and ultra sensitively distinguishes the CNˉ ions owing to the capacity of etching the β-CD AuNPs surface and form a stable water soluble Au-CN complex. Under investigational conditions, the colorimetric assay demonstrated a steady response for CNˉ ions over a concentration arrays from 4.50 × 10-6 to 99.00 × 10-6 mol dm-3 with R = 0.994. Lowest limit of detection of this economical, naked eye visual approach is 93.00 × 10-9 mol dm-3, which is under the tolerant limit value (1.90 × 10-6 mol dm-3) described by the World health organization in drinking water. Specificity of β-CD-AuNPs based optical platform for the detection of CNˉ ions is superb evaluated with the various potential interfering anions. Furthermore, the proposed β-CD-AuNPs nanoprobe is effectively applied to quantify the CNˉ ions in tap and drinking water samples. For convenient use, we have designed a very stable β-CD-AuNPs containing cotton swab and it revealed good sensitivity against CNˉ ions in the environment with only bare eye.
关键词： cotton swab,Colorimetric analysis,drinking water samples,cyanide ions,nanosensor
更新于2025-09-10 09:29:36
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Fluorometric determination of hydroquinone by using blue emitting N/S/P-codoped carbon dots
摘要： N/S/P-codoped carbon dots (CDs) are shown to be a viable fluorescent probe in a turn-off-on fluorometric assay for hydroquinone (HQ). The preparation of CDs was carried out using a one-step hydrothermal reaction starting with glyoxal and isocarbophos. The method is based on the formation of ground state complexes between CD and Fe(III) which leads to quenching of blue fluorescence (with excitation/emission peaks at 363/448 nm). On addition of HQ, it will be oxidized by Fe(III) upon which fluorescence recovers. This turn-off-on system can be utilized to quantify HQ. A linear relationship exists between fluorescence recovery and HQ concentration in range between 0.56 and 375 μM. The limit of detection is 0.16 μM. The assay was successfully applied to the determination of HQ in spiked water samples and developer samples.
关键词： Developer samples,Blue emission,1,4-dihydroxybenzene,Glyoxal,Fluorescence turn-off-on system,Heteroatoms,Carbon dots,Water samples,Hydrothermal reaction,Fe(III)
更新于2025-09-09 09:28:46
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Enhanced Quenching Effect of Neonicotinoid Pesticides on Time-Resolved Terbium Luminescence in Presence of Surfactants
摘要： A luminescence analytical method for the quantification of neonicotinoid pesticides (acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid, and thiamethoxam) in water samples is proposed. The method is based on the quenching effect that these analytes produce on the time-resolved luminescence signal of terbium ions (excitation/emission wavelengths of 256/545 nm/nm). An enhancement on the analytical signal is observed when surfactants are used in the system. The use of a 0.01 mol·L?1 sodium dodecyl sulfate produced approximately a 30% increase in the sensitivity of the method. Under the optimum conditions, the method presented detection limits between 0.03 and 0.23 μg·mL?1. Interference studies were performed for ions commonly present in waters, observing no interferences. In addition, recovery experiments were performed in different waters, well, spring, and swamp, observing recovery yields close to 100%, with relative standard deviations lower than 4% in all cases. No sample treatment except a filtration step was required. Hence, this method may represent an alternative to other existing methods for the quick and simple analysis of these ubiquitous insecticides in environmental waters.
关键词： neonicotinoid pesticides,surfactants,time-resolved luminescence,terbium luminescence,water samples
更新于2025-09-04 15:30:14