Detection In Aqueous Solution Research Articles

Sensitive Coatings for Luminescence Detection of Cu(II) in Solutions

Here we present a simple technique for copper (II) detection in aqueous solutions by luminescent dye doped polymeric film. In this study the photoluminescent dye lumocupferon was first embedded in thin films of polysaccharide chitosan. The sensor response is forming by quenching the dye luminescence. This technique can offer a rapid detection of Cu2+ with a dynamic range up to 350 μM.

Systematic Investigation of High-Sensitivity Luminescent Sensing for Polyoxometalates and Iron(III) by MOFs Assembled with a New Resorcin[4]arene-Functionalized Tetracarboxylate.

A new family of resorcin[4]arene-based metal-organic frameworks (MOFs), namely, [Eu(HL)(DMF)(H2 O)2 ]⋅3 H2 O (1), [Tb(HL)(DMF)(H2 O)2 ] 3 H2 O (2), [Cd4 (L)2 (DMF)4 (H2 O)2 ] 3 H2 O (3) and [Zn3 (HL)2 (H2 O)2 ] 2 DMF⋅7 H2 O (4), have been constructed from a new resorcin[4]arene-functionalized tetracarboxylic acid (H4 L=2,8,14,20-tetra-ethyl-6,12,18,24-tetra-methoxy-4,10,16,22-tetra-carboxy-methoxy-calix[4]arene). Isostructural 1 and 2 exhibit charming 1D motifs built with the cup-like HL(3-) anions and rare earth cations. Compounds 3 and 4 show a unique sandwich-based 2D layer and a fascinating 3D framework, respectively. Remarkably, compounds 1 and 2 display intensive red and green emissions triggered by the efficient antenna effect of organic ligands under UV light. More importantly, systematic luminescence studies demonstrate that Ln-MOFs 1 and 2, as efficient multifunctional fluorescent materials, show highly selective and sensitive sensing of Fe(3+) , polyoxometalates (POMs), and acetone, which represents a rare example of a sensor for quantitatively detecting three different types of analytes. This is also an exceedingly rare example of Fe(3+) and POMs detection in aqueous solutions employing resorcin[4]arene-based luminescent Ln-MOFs. Furthermore, the possible mechanism of the sensing properties is deduced.

A fluorescent aptasensor for amplified label-free detection of adenosine triphosphate based on core-shell Ag@SiO2 nanoparticles.

The novel, facile and universal aptamer-based methods for the highly sensitive and selective fluorescence detection of important biomolecules have attracted considerable interest. Here, we present a label-free aptasensor for adenosine triphosphate (ATP) detection in aqueous solutions by using an ultra-sensitive nucleic acid stain PicoGreen (PG) as a fluorescent indicator and core-shell Ag@SiO2 nanoparticles (NPs) as a metal-enhanced fluorescence (MEF) platform. In the presence of ATP, the complementary DNA (cDNA)/aptamer duplexes confined onto the Ag@SiO2 NPs surface can release their aptamers into the buffered solution, causing a significant reduction in fluorescence intensity. By virtue of the amplified fluorescence signal, this aptasensor toward ATP can achieve a detection limit of 14.2 nM with a wide linear range and exhibit a good assay performance in complex biological samples. This sensing approach is cost-effective and efficient because it avoids the fluorescence labeling process and the use of any enzymes. Hence, this method may offer an alternative tool for determining the concentrations of ATP in biochemical and biomedical research.

Water-compatible surface imprinting of ‘Saccharin sodium’ on silica surface for selective recognition and detection in aqueous solution

In this work, a saccharin sodium imprinted nanoparticles composite material has been successfully synthesized in aqueous solution. This molecular imprinted material has promising practical utility in the detection of saccharin sodium. First, we synthesized SiO2 nanoparticles, followed by the modification of functional amino group. Then we used functionalized SiO2@NH2 as the cores, saccharin sodium as the template, acrylic acid (AA) as the functional monomer and ammonium persulphate (APS) as the initiator. Molecularly imprinted nanoparticles (MIPs) were synthesized by surface-imprinted polymerization under airtight tubes at 60°C for 12h. MIPs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA). The binding experiments were shown to have relatively high adsorption capacity (8.965mgg−1) and selective recognition ability over structurally related compounds. Therefore, MIPs provide a sensitive and selective approach and offer the potential to become a new key for the detection of saccharin sodium.

A “donor-two-acceptor” sensor for cyanide detection in aqueous solution

A “donor-two-acceptor” cyanide sensor L based on 3-ethyl-2-methyl-1,3-benzothiazol-3-ium iodide and 5-nitrosalicylaldehyde has been designed and prepared. This structurally simple sensor displays rapid response for cyanide over other common anions (F−, Cl−, Br−, I−, AcO−, H2PO4−, HSO4−, ClO4−, S2−, N3− and SCN−) in aqueous solution. A large blue shift (87nm) was also observed in the absorption spectra in response to CN−. The bleaching of the color could be clearly observed by the naked eye. By the nucleophilic attacking of CN− to the benzothiazol C-2 atom of the sensor, the Intramolecular Charge Transfer progress was blocked with color changed and fluorescence quenched. The mechanism of the reaction of the sensor with the cyanide ion was established by using 1H NMR and mass spectrometry.

Interaction of Citrate-Capped Gold Nanoparticles with the Selected Amino Thiols for Sensing Applications

The amino thiols, methionine, cysteine, and homocysteine are considered to be important biomarkers for various diseases. In the present study, the authors have demonstrated that the interactions of synthesized citrate-capped gold nanoparticles with these amino thiols at different pH values can be used to develop simple colorimetric methods for their detection in aqueous solutions. The aggregation of the gold nanoparticles by interactions with the thiol group was found to depend strongly on the pH of the amino thiols. At pH 10, the detection of cysteine was possible in the presence of homocysteine at low concentration and similarly homocysteine could be detected in the presence of cysteine at low concentration by thiol-induced aggregation of the gold nanoparticles. Cysteine and methionine were specifically detected by monitoring the aggregation of the gold nanoparticles through the UV–Visible spectra at pH 7 and pH 10 respectively. The increase in the mean hydrodynamic diameter of the particles confirmed the thiol-induced aggregation of the particles both at pH 7 and pH 10. The specific pH-based interactions can form a basis to design simple colorimetric sensors for the amino thiols using as-synthesized citrate-capped gold nanoparticles without further functionalization.

Fundamental Study of Electrospun Pyrene-Polyethersulfone Nanofibers Using Mixed Solvents for Sensitive and Selective Explosives Detection in Aqueous Solution.

Fluorescent pyrene-polyethersulfone (Py-PES) nanofibers were prepared through electrospinning technique using mixed solvents. The effects of mixed solvent ratio and polymer/fluorophore concentrations on electrospun nanofiber's morphology and its sensing performance were systematically investigated and optimized. The Py-PES nanofibers prepared under optimized conditions were further applied for highly sensitive detection of explosives, such as picric acid (PA), 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) in aqueous phase with limits of detection (S/N = 3) of 23, 160, 400, and 980 nM, respectively. The Stern-Volmer (S-V) plot for Py excimer fluorescence quenching by PA shows two linear regions at low (0-1 μM) and high concentration range (>1 μM) with a quenching constant of 1.263 × 10(6) M(-1) and 5.08 × 10(4) M(-1), respectively. On the contrary, S-V plots for Py excimer fluorescence quenching by TNT, DNT, and RDX display an overall linearity in the entire tested concentration range. The fluorescence quenching by PA can be attributed to the fact that both photoinduced electron transfer and energy transfer are involved in the quenching process. In addition, pyrene monomer fluorescence is also quenched and exhibits different trends for different explosives. Fluorescence lifetime studies have revealed a dominant static quenching mechanism of the current fluorescent sensors for explosives in aqueous solution. Selectivity study demonstrates that common interferents have an insignificant effect on the emission intensity of the fluorescent nanofibers in aqueous phase, while reusability study indicates that the fluorescent nanofibers can be regenerated. Spiked real river water sample was also tested, and negligible matrix effect on explosives detection was observed. This research provides new insights into the development of fluorescent explosive sensor with high performance.

Fluorescent probes for detection of picric acid explosive: A greener approach

Green materials with advantages of low cost and high sensitivity are important from the perspective of human health, environment and homeland security. Herein, we have reported two cost effective modified biomaterials as fluorophores for detection of Picric acid in aqueous state. The biomaterials Scutellarin–Hispiduloside and Curcumin have been modified with green solvent glycerol for Picric acid detection in aqueous solution. The limit of detection for Picric acid by Scutellarin–Hispiduloside–glycerol and Curcumin–glycerol are 9.1×10−8M and 6.03×10−8M respectively. These luminescence based sensors have also been able to detect Picric acid in real samples with high efficiency. The fluorescence quenching efficiency of Scutellarin–Hispiduloside–glycerol has been found to be 99% while that for Curcumin–glycerol, it is 88.9% for 0.5µM Picric acid in aqueous state. In both the cases, the quenching is governed by FRET between the fluorophore and the quencher and the FRET efficiency has been found to be 0.968 and 0.792 respectively. In addition, both the systems show excellent selectivity towards PA in presence of other nitroaromatic compounds and are also statistically accessible. The utilization of readily available cheap biomaterials without using multistep protocol for synthesis and devoid of any kind of sophisticated equipments for the processs further enhances the utility of the method.

A reversible and selective luminescent probe for Cu2+ detection based on a ruthenium(II) complex in aqueous solution

A turn-off luminescent probe RuHPIP for Cu2+ detection in aqueous solution has been developed through reversible and selective complexation. Cu2+ can specifically bind with the ligand of 2-hydroxyphenyl imidazo in the RuHPIP structure and induce luminescence quenching of the sensor instantaneously under a physiological environment. The probe enabled rapid and reversible detection of Cu2+ with detection limit of 7.23×10−8M, and it can image Cu2+ in live pea aphids.

Synthesis of highly selective and sensitive magnetic targeted nanoprobe for Cr3+ detection in aqueous solution and its application in living cell imaging

The magnetic targeted probes based on rhodamine B (RB)-polyethylene glycol dicarboxylic acid (PEG)-polyacrylic acid (PAA)-comodified Fe3O4 nanoparticles (RB-PEG-PAA-MNPs) have been successfully synthesized for Cr3+ detection. The RB-PEG-PAA-MNPs have many favorable properties, including biocompatibility, robustness and magnetic response. Importantly, the fluorescence changes of the probes are remarkably specific for Cr3+ in the presence of other cations, and the limit of detection (LOD) for Cr3+ in MeOH-H2O (3:2, v:v, pH 7.4) solution is lower (0.131μM) than the value of the U.S. EPA, which meet the selective and sensitive requirements for practical application. Furthermore, the experiments of RB-PEG-PAA-MNPs for monitoring Cr3+ inside HUVE cells reveal that the probes have low cytotoxicity and can effectively detect Cr3+ in a short time. In general, all the results presented in this study show that the proposed probes have significant potential for targeted detection of Cr3+ in many environmental and biomedical applications.

DNA-functionalization gold nanoparticles based fluorescence sensor for sensitive detection of Hg2+ in aqueous solution

We have developed a sensitive, selective, and simple fluorescence spectrometric sensor for Hg2+ detection in aqueous solution by using thiol-DNA-functionalized gold nanoparticles (Au NPs). This sensor is based on the Hg2+-induced conformational change of single-stranded DNA (ssDNA) with an enhanced fluorescence resonance energy transfer (FRET) process between the energy donor (fluorescein, FAM) and the energy acceptor (Au NPs). In the presence of Hg2+, a formation of a hairpin structure for ssDNA originates from thymine-Hg2+-thymine (T-Hg2+-T) coordination, resulting in notable fluorescence quenching in comparison to the random coil. In order to improve the stability and sensitivity of the sensor, we adopt short “helper” oligonucleotides to increase the density of DNA on the surface of Au NPs. The assay enables the detection limit for the detection of Hg2+ is 8nM, and is extremely specific for Hg2+ even in the presence of high concentrations of other metal ions. Toward the goal for practical applications, this sensor was applied to monitor Hg2+ in tap water samples and showed low matrix interference and high sensitivity.

Synthesis, optical properties of multi donor–acceptor substituted AIE pyridine derivatives dyes and application for Au3+ detection in aqueous solution

A series of multi donor–acceptor substituted pyridine derivative dyes were synthesed by three-component catalyst-free domino reaction in methanol aqueous at room temperature. The pyridine derivative dyes with thermally stable fluorescence exhibit aggregation-induced emission (AIE) in both aqueous solution and solid state due to the restricted intramolecular rotation as well. Furthermore, the family of molecule dyes showed nearly the full range of color emitters from blue to green and to orange. Moreover, the importance of dyes for heavy and transition metal ion species detection applications was demonstrated via the “turn off” detection of Au3+ in aqueous solution with the simple synthetic approach and high selectivity and sensitivity.

A new spectrofluorometric method for pyrophosphate assay based on the fluorescence enhancement of trypsin-stabilized copper clusters

A new method for pyrophosphate detection in aqueous solution has been developed based on the fluorescence enhancement of trypsin-stabilized CuNCs.

A water-soluble tetraphenylethene based probe for luminescent carbon dioxide detection and its biological application

A water-soluble tetraphenylethene derivative (TPE-ONa) was developed for luminescent carbon dioxide detection in aqueous solution and porous film, which is able to monitor the variation of external CO2concentration of living cells.

A fluorescent light-up platform with "AIE + ESIPT" characteristics for multi-target detection both in solution and on paper strip.

We report a fluorescent light-up platform for multi-target detection in aqueous solution and on paper strip. The platform is based on a salicylaldazine fluorogen with aggregation-induced emission (AIE) and excited state intramolecular proton transfer (ESIPT) characteristics, which shows distinct advantages including ease of chemical modifications, free of self-quenching effect, excellent light-up ratio and large Stokes shift. To demonstrate the versatility of the platform, palladium cation and perborate anion, as well as UV light, were selected as the targets. The three representative probes, AIE-Pd, AIE-perborate and AIE-UV, light up specifically in the presence of the target both in aqueous solution and on paper strip. The immediate naked-eye response makes the probes ideal for instrument-free and power-free detection.

Towards Alpha Radiation Detection in Aqueous Solution: VLSI Technology Development for Diamond-Silicon Hybrid Sensors

ABSTRACTIn the presented work, we have developed VLSI technology processes for new prototype sensors based on the synthesis of boron doped nanocrystalline diamond (B-NCD) and silicon based commercial detectors. The process is based on commercial passivated implanted planar silicon (PIPS) devices of PD450 and CAM450 types (CANBERRA). A layer of B-NCD of several hundred nanometers thickness and boron concentration up to 1021 atoms/cm3 is grown on the SiOx passivation layer in an ellipsoidal plasma enhanced chemical vapor deposition (PECVD) reactor at temperatures from 520-750°C, in hydrogen atmosphere. . The diamond electrode is dry chemically structured and aluminum electrodes are realized before mounting in a three-fold housing for measurements in aqueous solution. The prototype sensors show an alpha spectroscopy resolution of 100 keV for 241Am electroprecipitated from liquid solution.

Thiacalix[4]arene-functionalized vesicles as phosphorescent indicators for pyridoxine detection in aqueous solution

Luminescent DPPC vesicles, decorated by new amphiphilic tetracarboxylate derivatives ofp-tert-butylthiacalix[4]arene with Tb(iii) were used for the selective detection of pyridoxine hydrochloride.

An “off–on” optical sensor for mercury ion detection in aqueous solution and living cells

A rhodamine-based optical sensor Rh–3S has been developed for selective detection of Hg2+ in aqueous solution as well as in living cells. UV–vis and fluorescence spectroscopic studies reveal that Rh–3S shows marked sensitivity and selectivity to Hg2+ with a chelation-induced “off–on” response in acetonitrile (ACN)/MOPS buffer (10mM, pH7.3, v/v, 1:1). The Rh–3S sensor binds Hg2+ in a 1:1 stoichiometry with an apparent binding constant 3.71×106M−1 (log K=6.57) and displays a distinct change in color and fluorescence upon the alteration of free Hg2+ levels in solution with a reversible response and little interference with other biological relevant metal ions. Live cell confocal imaging studies demonstrate that the sensor is also capable of imaging the presence of Hg2+ ions as well as its dynamic changes in live cells.

High-sensitivity ring-down evanescent-wave sensing in fiber resonators.

We report on optical-fiber cavity ring-down spectroscopy (CRDS) in the liquid phase using a laser emitting at telecommunication wavelengths. A fiber-ring cavity, comprising a short evanescent-wave coupler for radiation-matter interaction, is used as a sensor while its resonance modes are frequency locked to the laser. Exploiting the intrinsic sensitivity and noise immunity of the CRDS technique, we show that liquid absorption can be detected down to a level that is nearly a factor of 20 above the shot noise limit. We provide a thorough comparison between the experimental results and various noise contributions and address different expressions that can be used to calculate the shot noise equivalent absorbance. As a proof of principle, polyamine detection in aqueous solutions is carried out demonstrating a minimum detectable absorbance of 1.8×10(-7) Hz(-1/2), which, to our knowledge, is the best sensitivity limit reported to date for evanescent-wave sensors.

A novel “Turn-On” fluorescent probe for F− detection in aqueous solution and its application in live-cell imaging

A novel probe incorporating quaternized 4-pyridinium group into a BODIPY molecule was synthesized and studied for the selective detection of fluoride ions (F−) in aqueous solution. The design was based on a fluoride-specific desilylation reaction and the “Turn-On” fluorescent response of probe 1 to F− was ascribed to the inhibition of photoinduced electron transfer (PET) process. The probe displayed many desired properties such as high specificity, appreciable solubility, desirable response time and low toxicity to mammalian cells. There was a good linearity between the fluorescence intensity and the concentrations of F− in the range of 0.1–1mM with a detection limit of 0.02mM. The sensing mechanism was confirmed by the NMR, electrospray ionization mass spectrum, optical spectroscopy and the mechanism of “Turn-On” fluorescent response was also determinated by a density functional theory (DFT) calculation using Gaussian 03 program. Moreover, the probe was successfully applied for the fluorescence imaging of F− in human epithelial lung cancer (A549) cells and alveolar type II (ATII) cells under physiological conditions.