A new bodipy/pillar[5]arene functionalized magnetic sporopollenin for the detection of Cu(II) and Hg(II) ions in aqueous solution.

In this study, a new bodipy/pillar[5]arene functionalized magnetic MS-Sp-P[5]-bodipy microcapsule sensor was prepared based on the use of environmentally friendly for the selective and sensitive detection of Cu(II) and Hg(II) ions in aqueous media. SEM results used in the characterization process of the materials synthesized at each stage confirmed the structural and morphological changes in the pore structure, while other characterization results (FT-IR and XRD) elucidated the role of pillar[5]arene compound and bodipy dye in the synthesis of magnetic microcapsule sensors. The colloidal solution of MS-Sp-P[5]-bodipy (water/ethanol)) showed two fluorescence bands centered at 402 and 540 nm. The detection limits of MS-Sp-P[5]-bodipy for Hg(II) and Cu(II) were calculated to be 0.06 µM and 2.27 µM, respectively (at 540 nm). The linear range of the magnetic sensor for Hg(II) and Cu(II) was found to be in the range of 1-150 µM and 10-150 µM, respectively. The experimental results (response time, pH, temperature, sensitivity and selectivity) demonstrated the applicability and potential of the prepared magnetic microcapsule sensor for the detection of Cu(II) and Hg(II) in water and tap water samples containing heavy metal ions.

A highly sensitive fluorescent sensor for fenamiphos detection in vegetable samples and living cells based-on an enzyme free system.

Fenamiphos (Fena), an organophosphorous pesticide, is widely used in agricultural soils to control nematodes and thrips. This nematicide is harmful to fish, birds and humans and, causes several diseases. Therefore, the determination of the nematicide is crucial. Fena has been generally detected by enzyme-based systems which require specific conditions. Herein, we integrated a xanthene moiety and a pyrimidine moiety to obtain an enzyme-free detection system for Fena and, a fluorescent sensor (N-(6-(diethylamino)-9-(pyrimidin-5-yl)-3H-xanthen-3-ylidene)-N-ethylethanaminium hexafluorophosphate(V)) (RosPm) was easily prepared. The colorimetric and spectroscopic properties of RosPm were investigated using the UV-vis and fluorescence spectroscopy. RosPm exhibited a high selectivity and sensitivity to Fena over all the metal ions, the anions and pesticides tested in acetonitrile (ACN)/water (H2O) (v:v, 1:1) solution. RosPm showed a clear visual change from purple to light-purple resulting fluorescent quenching with Fena. This sensor could be preferred for detecting Fena in vegetable samples such as tomato, pepper, and cucumber, and visualizing Fena in living MFC-7 cells.

Highly selective fluorescent probe with an ideal pH profile for the rapid and unambiguous determination of subcellular labile iron (III) pools in human cells.

A convenient tool for detecting iron ions in subcellular structures is desired for better understanding its roles in biological systems. In this work, a new Fe3+ sensor, 2-(2-((1-(6-acetylpyridin-2-yl)ethylidene)amino)ethyl)-3',6'-bis(diethylamino)spiro[isoindoline-1,9'-xanthen]-3-one (RhPK), which operates across the entire cellular pH range and is capable of unambiguously detecting Fe3+ ion in live human cells at subcellular resolution, is reported. The sensor exhibits high selectivity and sensitivity toward Fe3+ with a rapid fluorescence response and a 12-fold increase in intensity upon the addition of 1 equivalent Fe3+ at pH 7.3. RhPK forms a 1:1 complex with Fe3+ with an apparent binding constant 1.54 × 107 M-1 and a detection limit of 50 nM. The sensor is stable between pH 4.2 and 9.0 and operates across the whole cellular pH range. Cell imaging demonstrates the ability of the sensor to unambiguously detect basal level Fe3+ as well as its dynamic changes in real-time in live cells at subcellular resolution, with one labile Fe3+ pool identified in mitochondria in human primary fibroblast (ws1) cells for the first time and two Fe3+ pools confirmed in mitochondria and endo/lysosomes in human SH-SY5Y neuroblastoma cells, suggesting different cell types have distinctive Fe3+ storage in subcellular compartments. The RhPK probe is powerful for rapid and sensitive bioimaging of Fe3+ at subcellular level, enabling the unambiguous detection of labile Fe3+ pools at the entire cellular pH range, which is of great significance to understand the biological chemistry of Fe3+ and its roles in physiological processes and diseases.

A rapid responsive coumarin-naphthalene derivative for the detection of cyanide ions in cell culture.

Cyanide ion (CN-) is widely used in many industrial processes; however, it causes several diseases in humans. Therefore, rapid and accurate detection of CN- is very important and urgent. In this study, a CN- sensor (MH-2) which was capable of detecting CN- ions in living cell was developed. MH-2 gives a rapid color change, absorbance and fluorescence response to CN- in the presence of the anions tested in the working system. The binding ratio between the sensor and CN- was demonstrated by some spectrophotometric methods and the sensing mechanism was investigated by NMR titration experiments, suggesting that MH-2 gives response to CN- via the nucleophilic addition reaction. The fluorescence detection limit and the absorbance detection limit were calculated as 0.056 µM and 0.11 µM, respectively. Both of these detection limits are below the tolerable limit recommended by WHO for CN- in the drinking water (1.9 µM). MH-2 was also applied to living cells for bio-imaging and the results showed that the sensor penetrates the cells and can detect cyanide ions in living cells.

A reaction-based system for the colorimetric detection of glyphosate in real samples.

Glyphosate is widely used herbicides and causes several diseases in humans. Therefore, the detection of glyphosate is curial and urgent. Studies on the detection of glyphosate in literature are often based on inhibition of the enzyme acetylcholinesterase. In this study, we developed two simple colorimetric sensors, BP-Cl and CP-Cl, by linking 3-chloro-4-methylpyridine with 4-(dimethylamino)cinnamaldehyde or 4-(dimethylamino)benzaldehyde in a one-step reaction. The colorimetric and optical sensing properties of these compounds were investigated by the naked-eye and UV-Vis spectrophotometer in ACN/HEPES buffer (5 mM pH 8.0, 1:1 v/v). The sensors displayed high sensitivity and selectivity for glyphosate by color changes, which ranged from colorless to yellow for BP-Cl and yellow to orange for CP-Cl. The detection limits of BP-Cl and CP-Cl by the naked-eye detection were found as 15 µM and 10 µM. On the other hand, the detection limits of BP-Cl and CP-Cl via UV-Vis measurements were calculated as 0.847 µM and 1.23 µM, respectively. Moreover, the sensors were able to monitor glyphosate in water samples using the naked-eye, UV-Vis spectroscopy, and filter paper strips.

A novel near-infrared turn-on and ratiometric fluorescent probe capable of copper(ii) ion determination in living cells.

A near-infrared ratiometric fluorescent probe CR-Ac based on a coumarin-benzopyrylium platform has been developed for selective detection of Cu2+. The cell imaging data revealed the capabilities of CR-Ac in monitoring the dynamic changes of subcellular Cu2+ and the quantification of Cu2+ levels in living cells.

Colorimetric cadmium ion detection in aqueous solutions by newly synthesized Schiff bases.

Two newly synthesized Schiff bases DMCA and DMBA were used for selective detection of Cd2+ over a wide range of other metal ions in acetonitrile (ACN)/ Tris-HCl buffer (10 mM, pH 7.32, v/v 2:1). The sensors can detect Cd2+ ions by colour changes from colourless to orange for DMBA and yellow to reddish for DMCA. Response of the probes towards metal ions was investigated by using UV-vis spectroscopy. The complex stoichiometry between the sensors, DMBA and DMCA, and Cd2+ was found to be 2:1 and the binding constants were calculated to be 2.65 ×1012 M-2 and 4.95 ×1012 M-2, respectively. The absorbance-based detection limits of DMBA and DMCA were calculated as 0.438 µM and 0.102 µM, respectively. The sensors were also successfully applied to real samples.

Reaction-based turn-on fluorescent probes with magnetic responses for Fe(2+) detection in live cells.

Iron is the most abundant nutritionally essential transition metal found in the human body. It plays important roles in various biological processes such as oxygen delivery, electron transport, enzymatic reactions and DNA synthesis and repair. However, iron can also catalyze the production of free radicals, which are linked to quite a few diseases such as cancer, neurodegenerative diseases, and cardiovascular diseases. Both iron deficiency and iron overload are related to various health problems. Thus, precisely monitoring iron ions (Fe(2+) and Fe(3+)) in biological systems is important in understanding the detailed biological functions of iron and its trafficking pathways. However, effective tools for monitoring labile Fe(2+) in biological systems have not yet been established. Reported herein are turn on, reaction-based coumarin and rhodamine-linked nitroxide probes (Cou-T and Rh-T) for selective detection of Fe(2+) in solution and in living cells. Rh-T displayed a unique change in the EPR signal as well as enhancement of the fluorescence signal resulting from a specific redox reaction between the probe and Fe(2+). The turn-on fluorescence response towards Fe(2+) allows the subcellular imaging of endogenous Fe(2+) as well as imaging under conditions of external iron supplementation or depletion, with a labile Fe(2+) pool located in the mitochondria of human fibroblast primary cells. The detection and mechanism were verified by the magnetic properties of the probe via electron paramagnetic resonance (EPR) spectroscopy in solution and in cells.

A turn-on fluorescent sensor for imaging labile Fe(3+) in live neuronal cells at subcellular resolution.

An eye for an iron: A highly sensitive, selective and reversible turn-on Fe(3+) sensor for imaging labile Fe(3+) in live cells at subcellular resolution is reported. The sensor can respond to changes in intracellular Fe(3+) levels and was used to image endogenous chelatable Fe(3+) in live human neuroblastoma SH-SY5Y cells, with two Fe(3+) pools being identified in mitochondria and endosomes/ lysosomes for the first time.

Determination of uric acid and creatinine in human urine using hydrophilic interaction chromatography.

Uric acid is the end-product of purine metabolism and a major antioxidant in humans. The concentrations of uric acid in plasma and urine are associated with various diseases and routinely measured in clinical and biomedical laboratories using enzymatic conversion and colorimetric measurement. In this study a hydrophilic interaction chromatographic (HILIC) method was developed for simultaneous determination of uric acid and creatinine, a biomarker of urine dilution and renal function, in human urine. Urine samples were pretreated by dilution, protein precipitation, centrifugation and filtration. Uric acid and creatinine were separated from other components in urine samples and quantified using HILIC chromatography. A linear relationship between the ratio of the peak area of the standards to that of the internal standard and the concentration of the standards was obtained for both uric acid and creatinine with the square of correlation coefficients >0.999 for both analytes. The detection limits were 0.04 µg/mL for creatinine and 0.06 µg/mL for uric acid. The described HILIC method has proved to be simple, accurate, robust and reliable.