Fluorescent Probe For Mercury Ions Research Articles

Highly Efficiency Fluorescent Probe for Mercury Ions Based on (N, S)‐Co‐Doped Carbon Dots

AbstractThis work demonstrates the preparation of (N, S)‐co‐doped fluorescent carbon dots (N, S‐CDs) for mercury ions (Hg2+) detection. This new fluorescent probe based on N, S‐CDs using dopamine hydrochloride (DA) and L‐cysteine (L‐Cys) as raw materials was reported for the first time. The resulting N, S‐CDs exhibited excellent specificity and selectivity towards Hg2+ and could distinguish them from 26 anions and cations, including Cd2+, Pb2+, and Cr2O72−. The sensor demonstrated high‐intensity fluorescence quenching at ∼457 nm under the Hg2+ presence and the ability to detect Hg2+ in the 0.05‐0.5 μM range with a 9.37 nM detection limit. The innovations of this work are to offer a method for rapid monitoring of Hg2+ in the environment, besides inventing a new fluorescent probe based on N, S‐CDs.

Theoretical insights into sensing performances of rhodamine‐contained two‐photon fluorescent probes for mercury ion

AbstractActing as a caustic element with high cellular toxicity, mercury may cause serious damage to the neurological and endocrine systems of the living body. Hence, the rapid detection of mercury ions is of significant importance. In this work, photoabsorption and photoemission properties of a series of newly synthesized mercury ion chemosensors based on rhodamine is investigated using the time‐dependent density functional theory. It shows that the fluorescent peaks of the probes are greatly redshifted from about 450 nm to about 530 nm with 5 to 12 times the fluorescence enhancement after reacting with mercury ions. Special attention has been paid to understanding the response mechanism of the probes, and the recognition of mercury ions controlled by the fluorescence resonance energy transfer process is verified theoretically. More importantly, the quadratic response theory has been used to calculate two‐photon absorption properties of these novel chemosensors. With the presence of mercury ion, a two‐photon absorption cross section for the studied probes increases from 35, 19, and 20 GM (1GM=10‐50cm4s/photon) to 155, 147, and 63 GM, respectively, indicating the feasibility of the probes to be used in two‐photon fluorescent microscopy imaging. The investigations demonstrate the donor effect on sensing performance of the sensors, which helps people to understand the structure‐property relationships and further design more effective two‐photon fluorescent probes for mercury ions.

Highly selective and sensitive fluorescent probe for mercury ions based on a novel rhodol-coumarin hybrid dye

A fluorescent probe RCHg based on a novel rectilinear π-extended rhodol-coumarin hybrid dye has been designed and synthesized for the detection of Hg2+ ions. Via a specific Hg2+-promoted ring-opening and desulfurization cascade reaction, RCHg shows high selectivity and sensitivity for Hg2+ detection and with a detection limit down to the nanomolar range. At the same time, the probe RCHg is living cell membrane permeable and should be suitable for practical application in vitro.

A FRET-based fluorescent probe for mercury ions in water and living cells

On the basis of fluorescence resonance energy transfer (FRET), a new rhodamine derivative (DRh) was synthesized as a ratiometric fluorescent probe for detecting Hg2+ in water and living cells samples. The recognition properties of the probe DRh with metal ions had been investigated in H2O/CH3CN (9:1, v/v; Tris-HCl 50mmolL−1; pH=7.0) solution by the UV–Vis spectrophotometry and the fluorescence spectrophotometry. The results showed that the probe DRh exhibited the selective recognition of Hg2+. Upon the addition of Hg2+, the spirolactam ring of probe DRh was opened. The 1:1 stoichiometric structure between DRh and Hg2+ were supported by Job's plot, MS and DFT theoretical calculations. The linearly fluorescence intensity ratio (I582/I538) is proportional to the concentration of Hg2+ in the range 0–30μmolL−1. The limit of detection (LOD) of Hg2+ is 0.008μmolL−1 (base on S/N=3). The present probe was applied to the determination of Hg2+ in neutral water samples and gave recoveries ranging from 104.5 to 107.9%. Furthermore, the fluorescent probe also can be applied as a bioimaging reagent for Hg2+ detection in HeLa cells.

Selective and “turn-off” fluorimetric detection of mercury(II) based on coumarinyldithiolane and coumarinyldithiane in aqueous solution

In this work, five novel coumarin-based fluorescent probes for mercury ions were developed. The recognition of mercury ions was performed via the mercury(II)-promoted desulfurization of the probes and a reasonable reaction mechanism was proposed and verified by thin layer chromatography (TLC), 1H nuclear magnetic resonance (1H NMR) and fluorescence intensity measurements. All the probes showed excellent optical properties and exclusively distinguish mercury ions from various metal ions in aqueous solutions at pH 7.4. The linear response of the fluorescence emission intensity for all the probes to the concentration of mercury ions was obtained over a wide range of 0.06–1.5μM (0.06–0.9μM for probe 3e). In addition, the biological toxicity and the confocal fluorescence images of probe 3a were also tested on MCF-7 cells.

One-pot green synthesis of nitrogen-doped carbon nanoparticles as fluorescent probes for mercury ions

Herein, a simple, green, and low-cost way was developed in the synthesis of fluorescent nitrogen-doped carbon nanoparticles (FNCPs) with nitrogen content of 6.88%, using one-pot hydrothermal treatment of strawberry juice. The as-prepared FNCPs exhibited a maximum emission at 427 nm with a quantum yield of 6.3%, which could be specifically quenched by Hg2+. This phenomenon was used to develop a fluorescent method for facile detection of Hg2+ with a linear range from 10 nM to 50 μM and a detection limit of 3 nM (S/N = 3), and further extended to measure environmental water samples with satisfactory recovery. This study provides a green strategy in the synthesis of FNCPs to detect Hg2+ with good performance.

Synthesis of π‐Extended Coumarins and Evaluation of Their Precursors as Reactive Fluorescent Probes for Mercury Ions

AbstractAn efficient synthetic route to π‐extended coumarin derivatives and their precursors that contain amino substituents has been developed. The synthesis involves monosubstitution of 2,7‐dihydroxynaphthalene with dimethylamine through the Bucherer reaction. The extended coumarins emit at much longer wavelengths and with higher quantum yields relative to a related coumarin. Two vinyl ethers, precursors of the extended coumarins, were prepared and evaluated as reactive probes for Hg2+ ions. The vinyl ethers undergo hydrolysis promoted by Hg2+ ions to produce the extended coumarins at physiological pH (pH 7.4) and room temperature, which is accompanied by fluorescence in the “turn‐on” mode. The vinyl ethers do not respond to various other metal species. The extended coumarins and their precursors are versatile sensing platforms for Hg2+ ions, as well as for the development of related reaction‐based sensing systems.

FRET-Based Ratiometric Detection System for Mercury Ions in Water with Polymeric Particles as Scaffolds

Mercury pollution is a global problem, and the development of stable and sensitive fluorescent probes for mercury ions in the water phase has long been sought. In this work, a novel fluorescence resonance energy transfer (FRET)-based ratiometric sensor for detecting Hg(2+) in pure water was demonstrated. Polymeric nanoparticles prepared by miniemulsion polymerization of methyl methacrylate and acrylic acid were used as the scaffold for the FRET-based sensor. A hydrophobic fluorescent dye nitrobenzoxadiazolyl derivative (NBD) was embedded in the nanoparticles during the polymerization and used as the donor. A spirolactam rhodamine derivative SRHB-NH(2) was synthesized and then covalently linked onto the particle surface and used as an ion recognition element. The presence of Hg(2+) in the water dispersion of nanoparticles induced the ring-opening reaction of the spirolactam rhodamine moieties and led to the occurrence of the FRET process, affording the nanoparticle system a ratiometric sensor for Hg(2+). The nanoparticle sensor can selectively detect the Hg(2+) in water with the detection limit of 100 nM (ca. 20 ppb). It has been found that the FRET-based system with smaller nanoparticles as the scaffold exhibited higher energy transfer efficiency and was more preferred for the accurate ratiometric detection. Moreover, the FRET-based sensor was applicable in a relatively wide pH range (pH 4-8) in water; thus, this approach may provide a new strategy for ratiometric detection of analytes in environmental and biological applications.

A selective fluorescence probe for mercury ion based on the fluorescence quenching of terbium(III)-doped cadmium sulfide composite nanoparticles

A fluorescent probe for mercury(II) ions, based on the quenching of fluorescence of terbium(III) ions doped in CdS nanoparticles, has been developed. The terbium(III)-doped cadmium sulfide composite nanoparticles were successfully synthesized through a straightforward one-pot process, with the biomolecule glutathione (GSH) as a capping ligand. In addition, the terbium(III) ions were observed an enhancement of emission intensity, owing to fluorescence energy transfer from the excited CdS particles to the emitting terbium(III). Because of a specific interaction, the fluorescence intensity of terbium(III)-doped CdS particles is obviously reduced in the presence of mercury(II) ions. The fluorescence quenching phenomenon of terbium(III) can be attributed to the fact that the energy transfer system was destroyed by combining with mercury(II). Under the optimal conditions, the fluorescent intensity of terbium(III) ions at 491 nm decreased linearly with the concentration of mercury(II) ions ranging from 4.5 nmol L −1 to 550 nmol L −1. The limit of detection for mercury(II) was 0.1 nmol L −1. This method is simple, practical, relatively free of interference from coexisting substances and can be successfully applied to the determination of mercury(II) ions in real water samples. In addition, the probable mechanism of reaction between terbium(III)-doped CdS composite nanoparticles and mercury(II) was also discussed.

Host–guest assembly of squaraine dye in cucurbit[8]uril: its implication in fluorescent probe for mercury ions

The binding interactions between SQ2 squaraine dye and cucurbit[8]uril (CB8) effectively removes the aggregation of SQ2 in aqueous solution by forming a 1 : 1 inclusion complex. The resulting SQ2.CB8 complex exhibits highly selective fluorescence quenching by Hg(2+) ions, as a result of the synergetic binding between CB8, SQ2 and metal cation.