DNAzyme-based fluorescent microarray for highly selective and sensitive detection of lead(II)

A facile microarray-based fluorescent sensor for the detection of lead (II) was developed based on the catalytic cleavages of the substrates by a DNAzyme upon its binding to Pb(2+). The release of the fluorophore labelled substrates resulted in the decrease of fluorescence intensity. The sensor had a quantifiable detection range from 1 nM to 1 μM and a selectivity of >20 fold for Pb(2+) over other metal ions.     

A novel Pb(II)-imprinted IPN for selective preconcentration of lead from water and sediments

A novel adsorbent Pb(II)-imprinted interpenetrating polymer network (IPN) of epoxy resin-triethylenetetramine and lead methacrylate-acrylamide-1,4-butanedioldiacrylate (BDDA) was synthesized by the metal ionic imprinted polymer (MIIP) technique. The IPN was prepared by in situ sequential polymerization, and the coordination interaction of Pb(II) and functional groups of the IPN adsorbent was discussed using FT-IR spectra. The characters of the IPN were investigated by a series of experiments. The experimental results show that trace Pb(II) ions can be quantitatively preconcentrated at pH 4.0 with recoveries >95%. The maximum static adsorption capacity of the ion-imprinted adsorbent was 138.6?mg?g^?1. The imprinted IPN has a higher adsorption capacity and selectivity towards Pb(II). Moreover, the Pb(II)-imprinted IPN shows superior reusability and stability. The precision (R.S.D.) for 11 replicate adsorbent extractions of 20?ng?mL^?1 Pb(II) was 2.9%. The accuracy of the proposed procedure was verified by analysing three standard reference materials. The prepared ion-imprinted IPN adsorbent was applied to three natural samples and also yielded satisfactory results. That is to say, the Pb(II)-imprinted IPN is suitable for environmental Pb(II) ionic selective removal as an SPE adsorbent.     

A selective fluorescent sensor for Pb(II) in water

A new fluorescent sensor (1) containing bis(2-pyridylmethyl)amine group as a binding moiety for Pb²⁺ was developed. Compound 1 shows selective response to Pb²⁺ over other metal ions in pH 7.0 HEPES buffer solution. The fluorescence intensity enhancement was ascribed to the complex formation between Pb²⁺ and 1 which blocked the photo-induced electron transfer process.     

A colorimetric probe for the selective naked-eye detection of Pb(II) ions in aqueous media

A new colorimetric molecular probe based on a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye selectively binds Pb(II) ions in aqueous solutions, allowing for highly sensitive naked-eye detection.     

A novel selective fluorescent chemosensor for Cu（Ⅱ）

A novel fluorescence enhancement Cu~(2 ) chemosensor derived from coumarin was prepared.Emission study found that it exhibits evident Cu~(2 )-amplified fluorescence prior to Co~(2 ),Pb~(2 ),Mg~(2 ),Mn~(2 ),Ni~(2 ),Zn~(2 ),Fe~(3 ),Ag~ and Cd~(2 ),and the largest emission enhancement factor is about 9 at a ratio of 2:1 (chemosensor 1/Cu~(2 )).     

A selective, sensitive probe for mercury(II) ions based on oxazine-thione

A selective, sensitive probe for Hg(II) ions, 7-(diethylamino)-3-methyl-2H-benzo[b][1,4] oxazine-2-thione (1), is developed. Compound 1 behaves as a ratiometric probe, exhibiting a large blue shift of 100 nm in its absorption spectra upon exposure to Hg(II) ions. The dramatic color change of the solution made ‘naked-eye’ detection of Hg(II) ions possible. Emission spectra of 1 displayed a selective enhancement in intensity in the presence of Hg(II) ions. ESI⁺-MS analysis indicated that Hg²⁺-induced desulfurization caused the large absorption response.     

A sensitive and selective detection method for thiol compounds using novel fluorescence probe

In this work, a sensitive and selective detection method based on fluorescence resonance energy transfer (FRET) was developed for analyzing thiol compounds by using a novel fluorescent probe. The new fluorescent probe contains a disulfide bond which selectively reacts with nucleophilic thiolate through the thiol-disulfide exchange reaction. An obvious fluorescence recovery can be observed upon addition of the thiol compound in the fluorescent probe solution due to the thiol-disulfide exchange reaction and the destruction of FRET. This novel probe was successfully used to determine dithiothreitol (DTT), glutathione (GSH) and cysteine (Cys). The limits of detection (LOD) were 2.0 μM for DTT, 0.6 μM for GSH, and 0.8 μM for Cys. This new detection method was further investigated in the analysis of compound amino acid injection.     

Fluorescent chemosensor based on Schiff base for selective detection of zinc(II) in aqueous solution

A chemosensor 1, based on the Schiff base, is easily prepared by reacting tryptophan and 2-hydroxy-1-naphthaldehyde in methanol. The optical properties of 1 are investigated in buffered aqueous solution, which displays specific recognition to Zn²⁺, and especially avoids the interference of Cd²⁺ when 1 is tested against a range of physiological and environmentally relevant metal ions. Such a novel fluorescent probe can also be used to detect Zn²⁺ in live cells.     

A simple pyridine-based colorimetric chemosensor for highly sensitive and selective mercury(II) detection with the naked eye

Two easily-prepared pyridine-based derivatives of (Z)-2-(4-amino-phenyl)-3-(pyridine-4-yl)acrylonitrile (I)and (Z)-2-phenyl-3-(pyridin-4-yl)acrylonitrile (II) were designed, synthesised and characterised. Due to the formation of a complex with Hg²⁺, hence leading to an enhanced ICT effect, I exhibits a visible colour change from light yellow to orange, rendering it suitable for use as a naked-eye sensor for rapid detection of Hg²⁺ in an aqueous ethanol solution. When mixed with Hg²+, I interacts with Hg²⁺ in a2:1 (Y1-Hg²⁺) stoichiometry via a coordination bond with an association constant of 7.7 × 10⁸ M^−2 (R² = 0.96). The present probe I exhibits excellent reproducibility, reversibility, sensitivity and selectivity with the presence of low concentration of Hg²⁺ (1.74 × 10^−10 M).     

A simple "molecular beacon"-based fluorescent sensing strategy for sensitive and selective detection of mercury (II)

A novel fluorescent sensor for the detection of Hg(2+) in aqueous media was developed. The method takes advantages of the highly selective thymine-Hg(2+)-thymine coordination and the sensitive "signal-on" structure-switching molecular beacon.     

A new fluorescent sensor bearing three dansyl fluorophores for highly sensitive and selective detection of mercury(II) ions

A novel fluorometric sensor bearing three dansyl moieties based on tris[2-(2-aminoethylthio)ethyl]amine was prepared by a simple approach using a conventional two-step synthesis. The sensor exhibits highly Hg²⁺-selective ON-OFF fluorescence quenching behavior in aqueous acetonitrile solutions and is shown to discriminate various competing metal ions, particularly Cu²⁺, Ag⁺, and Pb²⁺ as well as Ca²⁺, Cd²⁺, Co²⁺, Fe³⁺, Mn²⁺, Na⁺, Ni²⁺, and Zn²⁺, with a detection limit of 1.15 × 10⁻⁷ M or 23 ppb.     

A carbon nitride electrode for highly selective and sensitive determination of lead(II)

We have constructed a carbon nitride electrode modified with a bismuth film and show that it can be used for the electroanalysis of lead(II) by differential pulse anodic stripping voltammetry. The combination of such materials is shown to greatly improve the sensing capability of the electrode. Under the optimal conditions, the electrochemical response of the modified electrode is linearly related to the concentration of Pb(II) in the 6 – 1,000 nM concentration range (R = 0.9983). The detection limit is 2.0 pM (at an SNR of 3), and the sensitivity is 8 times better of that of respective graphite electrodes. The sensor enables rapid, highly sensitive, continuous, and environmentally friendly determination of trace levels of Pb(II) at affordable costs.

A highly selective and sensitive in vivo fluorosensor for zinc(II) without cytotoxicity

A highly selective and sensitive fluorescent Zn(2+) sensor, 2,6-bis(2-hydroxy-benzoic acid hydrazide)-4-methylphenol (1), was designed and synthesized. In aqueous THF (4 : 6 v/v) ligand 1 induces a 2 : 1 complex formation with respect to Zn(2+) at physiological pH. This probe features visible light excitation(390 nm) and emission (490 nm) profiles, excellent selectivity responses for Zn(2+)over other competing biological metal ions with K(d) < 1 pM(2), LOD < 1 ng L(-1) and about 680 fold enhancement in fluorescent intensity upon Zn(2+) binding. It also exhibits cell permeability and intracellular Zn(2+) sensing in A375 human melanoma cancer cell.     

Control over surface DNA density on gold nanoparticles allows selective and sensitive detection of mercury(II)

We have developed a new highly selective and sensitive technique for the detection of Hg(2+) using DNA-functionalized gold nanoparticles (Au NPs) and OliGreen. This system is the first that allows the detection of Hg(2+) based on the release of DNA molecules, induced by conformational changes on Au NP surfaces, and its sensitivity is highly dependent upon surface DNA density. When Hg(2+) ions interact with the thymidine units of the DNA molecules bound to the Au NPs through Au-S bonds, the conformations of these DNA derivatives change from linear to hairpin structures, causing the release of some of the DNA molecules from the surface of the Au NPs into the bulk solution to react with OliGreen. The fluorescence of OliGreen-DNA complexes increased with increasing concentration of Hg(2+), and Hg(2+) could be detected at concentrations as low as 25 nM. A linear correlation existed between the fluorescence intensity and the concentration of Hg(2+) over the range 0.05-2.5 microM (R(2) = 0.98). This simple and cost-effective probe was applied to determine the spiked Hg(2+) in the pond samples; the recoveries (96-102%) suggested low matrix interference and high sensitivity.     

A highly sensitive and selective fluorescent molecular sensor for Pb(II) based on a calix[4]arene bearing four dansyl groups

A new fluorescent molecular sensor based on a calix[4]arene bearing four dansyl groups exhibits very efficient binding in acetonitrile-water for lead and the changes of emission properties allows a detection limit of 4 microg L(-1).     

A highly selective and sensitive fluorescent PET (photoinduced electron transfer) chemosensor for Zn(II)

The naphthalimide derivative 1 was designed as a fluorescence PET sensor for Zn(II); 1 showed excellent selectivity for Zn(II) at pH 7.4, even in the presence of other competitive cations, the emission, being pH independent above pH 3.5, was switched on upon Zn(II) recognition.     

A novel cationic triazatetrabenzcorrole: selective detection of mercury(II) by nucleic acid-induced aggregation

In the present work, a novel water-soluble cationic triazatetrabenzcorrole compound was synthesised. Its aggregation and fluorescence quenching properties are demonstrated by serval methods, such as UV-vis and fluorescence spectroscopic studies and naked-eye visualization. Unlike the traditional Hg(2+) sensor based on thymine-Hg(2+)-thymine, we use a novel approach, exploiting the high affinity of Hg(2+) for sulfur in phosphorothioate DNA. Based on the S-Hg(2+)-S pairs, we designed the phosphorothioate DNA T4G4-S3 as an Hg(2+) sensor, which can detect Hg(2+) sensitively and selectively in aqueous solution. And this sensing system is fairly fast and convenient.     

Pallatriazo — A sensitive and selective reagent for the spectrometric determination of palladium(II)

Summary Based on an investigation of the functional and active analytical groups, a new trisazo derivative, pallatriazo, is proposed as a reagent for determining Pd(II) spectrometrically. This reagent shows high sensitivity, allowing palladium determination in the concentration range 0.05–4g Pd(II)/ml even if platinum is present up to the ratio Pd(II)Pt(IV)=130.

---

Pallatriazo — ein empfindliches und selektives Reagens für die spektrometrische Bestimmung von Palladium(II) (Vorläufige Mitteilung)

Zusammenfassung Auf der Grundlage einer Untersuchung der funktionellen und analytischaktiven Gruppen wurde ein neues Trisazo-Derivat, Pallatriazo, als Reagens für die spektrometrische Bestimmung von Pd(II) vorgeschlagen. Es zeigt hohe Empfindlichkeit und gestattet die Pd-Bestimmung im Gebiet 0,05–4g Pd(II)/ml, auch wenn Platin in 30fachem Überschuß anwesend ist.

     

基于杂交链式反应和共价有机框架的新型荧光传感器用于ctDNA的高灵敏和选择性检测

共价有机框架是近年来发展起来的一种高度结晶的多孔聚合物,由有机单元连接形成。由于其优异的孔隙率,模块性,结晶性和生物相容性,在传感领域显示出良好的应用前景。本文开发了一种基于杂交链式反应 (HCR) 和共价有机框架的新型荧光传感平台,用于高灵敏的检测循环肿瘤DNA (ctDNA)。ctDNA可以作为HCR的激活剂,通过触发发夹1 (H1) 和发夹2 (H2) 的自主交叉打开,激活HCR形成延伸的有缺口的双链DNA,导致荧光信号的变化,从而实现ctDNA的定量检测。HCR产物和荧光信号分别采用琼脂糖凝胶电泳和荧光光谱进行表征。ctDNA浓度在0-10 nM范围内,ctDNA的浓度与荧光信号呈良好的线性关系,检测限为1.3 nM。该方法对ctDNA具有满意的选择性,并在人类血清样品中显示出良好的性能。该荧光传感平台为ctDNA的检测提供了新思路,在癌症早期诊断中显示出潜在的应用前景。     

A highly selective fluorescence chemosensor for Pb(II) in neutral buffer aqueous solution

A 3,4-dimethylthieno[2,3-b]thiophene-based fluorogenic probe bearing benzo[d]-thiazole-2-thio unit (sodium 3,4-bis ((benzo[d]thiazol-2-ylthio)methyl) thieno [2, 3-b]thio-phene-2, 5-dicarboxylate) was developed as a novel fluorescent chemosensor with high selectivity towards Pb(II) over other cations tested. The new probe exhibited good water solubility and only sensed Pb(II) among metal ions examined in neutral 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer solution. The selectivity and sensitivity of fluorogenic probe to Pb(II) were discussed on the basis of experimental results.