A rapid method for the detection of humic acid based on the poly(thymine)-templated copper nanoparticles

A label-free fluorescent method for sensitive detection of humic acid based on poly(thymine)-templated copper nanoparticles is reported.     

Fluorescence “turn-on” chemosensor for the selective detection of zinc ion based on Schiff-base derivative

N,N′-phenylenebis(salicylideaminato) (L) has been used to detect trace amounts of zinc ion in acetonitrile–water solution by fluorescence spectroscopy. The fluorescent probe undergoes fluorescent emission intensity enhancement upon binding to zinc ions in MeCN/H₂O (1:1, v/v) solution. The fluorescence enhancement of L is attributed to the 1:1 complex formation between L and Zn(II), which has been utilized as the basis for selective detection of Zn(II). The linear response range for Zn(II) covers a concentration range of 1.6 × 10^?7 to 1.0 × 10^?5 mol/L, and the detection limit is 1.5 × 10^?7 mol/L. The fluorescent probe exhibits high selectivity over other common metal ions, and the proposed fluorescent sensor was applied to determine zinc in water samples and waste water.     

A voltammetric sensor for simultaneous determination of lead,cadmium and zinc on an activated carbon fiber rod

A simple, low cost and sensitive voltammetric sensor was developed for the simultaneous detection of Pb²⁺, Cd²⁺, and Zn²⁺ based on a disposable carbon fiber rod (CFR). The important factors to enhance the sensing property were creation of a clean surface by dealing with CFR at a high potential and electrochemical deposition of Bi film to improve the accumulation of heavy metal ions.     

A fast,highly selective and sensitive dansyl-based fluorescent sensor for copper (II) ions and its imaging application in living cells

Since the copper ions (Cu²⁺) play a fatal role in many foundational physiological processes, it is important to develop a simple, highly sensitive and selective sensor for Cu²⁺ detection in living systems. Herein, an intramolecular charge transfer (ICT) and dansyl-based fluorescent chemosensor 1 was designed, synthesized and characterized for the sensitive and selective quantification of Cu²⁺. It exhibited remarkable fluorescence quenching upon addition of Cu²⁺ over other selected metal ions, attributed to the complex formation between 1 and Cu²⁺ with the association constant 6.7 × 10⁵ M^?1. The sensor 1 showed a fast and linear response towards Cu²⁺ in the concentration range from 0 to 12.5 × 10^?6 mol L^?1 with the detection limit of 2.5 × 10^?7 mol L^?1. This detection could be carried out in a wide pH range of 5.0–14. Furthermore, sensor 1 can be used for detecting Cu²⁺ in living cells.     

A simple highly sensitive and selective turn-on fluorescent chemosensor for the recognition of Pb2+

A simple highly sensitive and selective turn-on fluorescent chemosensor L based on bis-Schiff-base for Pb²⁺ ions was synthesized and characterized by spectroscopic techniques. L having high binding affinity towards Pb²⁺ ions of 2.10 × 10⁴ M^?1 selectively detects Pb²⁺ ions with almost no interference among various competitive ions by a 11-fold fluorescent enhancement in CH₃CN/H₂O (95:5, v/v) solution over a wide pH range. Moreover, sensor L displayed a lower detection limit of 3.80 × 10^?7 M, which is low enough for sensing sub-millimolar concentration of Pb²⁺ encountered practically.     

A simple and highly selective fluorescent sensor for palladium based on benzofuran-2-boronic acid

Benzofuran-2-boronic acid could be used as a fluorescent sensor for the detection of Pd²⁺ because it was rapidly converted to highly fluorescent derivative after mixing with Pd²⁺ under basic condition at room temperature. We found that dimerization of benzofuran was occurred to form fluorescent derivative by the catalytic activity of palladium. The fluorescence intensity at 360 nm increased with increasing the concentration of Pd²⁺. The excellent selectivity for Pd²⁺ was demonstrated among other metal ions. Based on this findings, we successfully applied benzofuran-2-boronic acid to develop a microplate-based assay for high-throughput measurement of Pd²⁺. The detection limit (blank + 3SD) for Pd²⁺ of the proposed assay was 9.8 nM.     

Toward a highly sensitive and selective indole-rhodamine-based light-up probe for Hg2+ and its application in living cells

We herein designed and synthesized a light-up fluorescent probe L1 for Hg²⁺ species, which is based on indole derivative and Rhodamine fluorophore. The new probe can show a linear response to Hg²⁺ with high sensitivity and selectivity. As the Hg²⁺ concentration changed from 0 to 450 μM, the fluorescence intensity of L1 at 575 nm changed from 50 to 6181 (～120-fold). The detection limit of the probe was 5.0 × 10^?8 M. Besides, we have successfully applied L1 to monitor Hg²⁺ species in living MCF-7 cells by way of fluorescence imaging.     

Fluorescence quenching of triazatruxene-based glycocluster induced by peanut agglutinin lectin

A novel triazatruxene-based fluorescent glycocluster was synthesized and its selective binding interactions with PNA lectin were investigated by fluorescence spectroscopy,CD spectroscopy,and a turbidity assay.The glycocluster exhibited a strong binding affinity for PNA lectin with a Stern-Volmer quenching constant of 5.8×10⁵ mol^-1L     

Highly sensitive fluorescent sensor targeting CuCl2 based on thiophene attached anthracene compound (TA)

A novel thiophene attached anthracene (TA) based fluorescent compound was designed and synthesized. The TA showed a high quantum yield (Qy = 0.34) in regard to fluorescence. We applied this TA compound to detect specific metal compound and found that it could identify CuCl₂ from other metals through dramatic fluorescence change at λ_max = 460 nm. It showed strong quenching fluorescence property with CuCl₂ while with other metal compounds it exhibited strong blue fluorescence emission. UV/Vis absorption spectroscopy clearly demonstrated that the quenching property of TA at λ_max = 460 nm was due to overlapping of the fluorescence peak of TA at λ_max = 460 nm and the absorption band of CuCl₂ (from 190 nm to 525 nm). Binding constant (K′), which was 0.0895 mM^?2, indicated a complexation ratio between TA and CuCl₂ as 1:2 and this interaction induced quenching property.     

A benzothizole-based fluorescent probe for Hg2+ recognition utilizing ESIPT coupled AIE characteristics

A new benzothizole-based fluorescent probe 1 for Hg²⁺ recognition utilizing “ESIPT+AIE” strategy has been developed. In THF/H₂O (1:1, v/v, PBS 20 mM, pH = 8.5) mixed solution, probe 1 displays rapid fluorescence responses to Hg²⁺ ions with high selectivity and sensitivity through Hg²⁺-triggered releasing of a compound possessing “ESIPT+AIE” characteristics. Cell imaging investigations indicate that probe 1 is cell permeable with low toxicity to MCF-7 cells, and applicable to detect Hg²⁺ ions in living MCF-7 cells.     

A lysosomal targeting fluorescent probe and its zinc imaging in SH-SY5Y human neuroblastoma cells

A fluorescent probe based PET mechanism was designed, and the probe could image endogenous release of Zn²⁺ upon H₂O₂ stimulation in SH-SY5Y cells.     

A fluorescent sensor for Al3+ based on a photochromic diarylethene with a hydrazinobenzothiazole Schiff base unit

A new fluorescent turn-on chemosensor for Al³⁺ based on a diarylethene unit was designed and synthesized. Photochromism, fluorescence switch, and metal ion recognition behaviors of this diarylethene derivative were investigated by absorption and fluorescence emission spectra. It shows an outstanding fluorometric sensing ability toward Al³⁺ ion, and the detection limit was measured to be 9.3 × 10^?8 mol L^?1 via fluorescence methods. Based on these interesting properties, a combinational logic circuit was constructed successfully.     

Preparation of core-shell magnetic Fe3O4@SiO2-dithiocarbamate nanoparticle and its application for the Ni2+, Cu2+ removal

A typical superparamagnetic nanoparticles-based dithiocarbamate absorbent (Fe₃O₄@SiO₂-DTC) with core-shell structure was applied for aqueous solution heavy metal ions Ni²⁺, Cu²⁺ removal.     

A borondipyrrolemethene-based turn-on fluorescent probe for silver ion with high sensitivity and selectivity and its application in water samples and living cells

A borondipyrrolemethene-based compound (1) is synthesized and used as a “turn-on” fluorescent probe for silver ions (Ag⁺). The probe displays highly sensitive fluorescence response toward Ag⁺ with a 40-fold fluorescence enhancement when 60 μM of Ag⁺ is added. The fluorescence intensity of the probe is linearly dependent on Ag⁺ concentration ranging from 0.05 to 60 μM. And the detection limit (LOD) can reach 0.02 μM, which complies with the standard of World Health Organization (WHO) for drinking water (0.9 μM). Moreover, the probe shows remarkable selectivity for Ag⁺ over other metal ions. Furthermore, the response behavior of 1 toward Ag⁺ is pH independent in the neutral range from 6.0 to 8.0. The response of 1 toward Ag⁺ is fast (response time is less than 2 min) and reversible chemically. What’s more, the sensing mechanism of probe 1 toward Ag⁺ is verified by mass spectra (MS) and density functional theory (DFT) calculations. In particular, the probe is applied for detection of Ag⁺ in water samples and living cells successfully.     

A sensitive tetraphenylethene-based fluorescent probe for Zn2+ ion involving ESIPT and CHEF processes

A new tetraphenylethene-based fluorescent probe 2-(quinolin-8-yliminomethyl)-4-triphenylvinyl-phenol (HL) for detecting Zn²⁺ ion through the excited state intramolecular proton transfer (ESIPT) and chelation enhanced fluorescence (CHEF) processes has been designed and synthesized. The results show that HL emits relatively strong blue fluorescence at 460 nm without Zn²⁺ ion, however, probe HL displays highly pink fluorescent emission at 600 nm when adding Zn²⁺ ion. The fluorescent emission of HL appears an extremely large Stokes shift, which effectively reduces the interference of background signal. The limit of detection of HL for Zn²⁺ ion can reach to 9.0 × 10^–8 M.     

Highly selective fluorescence turn-on determination of fluoride ions via chromogenic aggregation of a silyloxy-functionalized salicylaldehyde azine

A novel fluorescent chemsensor TBS-protected salicylaldehyde azine (TSAA) for fluoride ion was developed based on aggregation-induced emission (AIE). The probe TSAA was prepared by the reaction of salicylaldehyde azine (SAA) with tert-butyldimethylsilyl chloride (TBS-Cl) via an unusual synthetic methodology and shows only non-emission. Upon treatment with fluoride in aqueous MeCN solution, the TBS protective group of probe TSAA was removed readily and the fluorescence of the probe was switched on, which resulted in a new fluorescence peak around 543 nm. The fluorescent intensity at 543 nm increases linearly with fluoride ion concentration in the range 1–50 μmol L^?1. This proposed probe shows excellent selectivity toward fluoride ion over other common anions and cations.     

In-line Raman spectroscopy and advanced process control for the extraction of anethole and fenchone from fennel (Foeniculum vulgare L. MILL.)

Plants are a desirable source for molecules of all kinds and for every purpose. Besides traditional techniques for extraction, plants are challenging for modern process engineering due to great variations because of their natural origin. One way to ensure high quality and low costs, as well as highly resource-efficient extraction, is in-line monitoring and process control. This study demonstrates the use of in-line Raman spectroscopy for monitoring the extraction of anethole and fenchone from fennel seed as a typical example. A partial least square calibration model with high accuracy was created. (Anethole: R² = 0.99, root mean square error of calibration (RMSEC) = 0.01256 g/L, root mean square error of validation (RMSEV) = 0.02608 g/L, and calibration range up to 2 g/L. Fenchone: R² = 0.98, RMSEC = 0.01188 g/L, RMSEV = 0.01945 g/L, and calibration up to 0.75 g/L.) These data are directly linked to a physicochemical process model to control the extraction process in real time and to perform predictive simulations while processing. The added value of this approach for modern phytoextraction is highlighted and exemplified as a major step toward sustainable Green Extraction processes.     

A novel fluorescence sensor for K+ based on bis-Bodipy: The ACQ effect controlled by cation complexation of pseudo crown ether ring

Three novel bis-Bodipy 3a–3c bridged with crown ether chain were prepared in yields of 70–78%. Their complexation absorption and fluorescent spectra for fourteen metal ions suggested that compound 3b exhibited the selective response for K⁺ with obvious ACQ effect. The association constant of compound 3b with K⁺ was 4.3 × 10⁵ M^?1 and 1:1 complex mode was deduced. The complexation mechanism of ACQ effect controlled by cation complexation of pseudo crown ether ring was confirmed by the fluorescent titrations, complexation FT-IR spectra, complexation ¹H NMR spectra, complexation ESI-MS spectra and contrast experiment of similar mono-Bodipy derivative. The K⁺ was binded in the cavity of a pseudo crown ether ring, leading to the closed distance for two Bodipy units and then enhancing the ACQ effect obviously. Both the structure of the crown ether chain and two Bodipy units were decisive factors for the selective fluorescence sensor for K⁺.     

Development of 1,3a,6a-triazapentalene-labeled enterobactin as a fluorescence quenching sensor of iron ion

1,3a,6a-Triazapentalene (TAP)-labeled enterobactin was developed as an iron ion sensor. 3-Acetylated-TAP was successfully introduced to the catechol ring of enterobactin, a well-recognized siderophore secreted by various Gram-negative bacteria. The fluorescence of TAP-labeled enterobactin decreased gradually as the amount of Fe³⁺ ion as an additive was increased, and 1.2 equiv of Fe³⁺ ion completely quenched the fluorescence. In clear contrast, when other metal ions were used, the fluorescence of TAP-labeled enterobactin remained even at 5.0 equiv.     

Design,synthesis, and fungicidal activity of novel 1,3,4-oxadiazole derivatives

Employing the intermediate derivatization method (IDM), a series of 1,3,4-oxadiazole derivatives containing arylpyrazoloxyl moiety were designed and synthesized. In vitro bioassays showed that these compounds have moderate to significant fungicidal activity against rice sheath blight and sorghum anthracnose. Furthermore, compound 20 is a promising fungicide for further development.