Cyanide Sensitivity Research Articles

Cyanide sensitivity in direct electron transfer-type bioelectrocatalysis by membrane-bound alcohol dehydrogenase from Gluconobacter oxydans

An overexpression system of membrane-bound alcohol dehydrogenase (ADH) from Gluconobacter oxydans was constructed to examine its bioelectrocatalytic characteristics. The effects of cyanide (CN−) addition on the kinetics of direct electron transfer (DET)-type bioelectrocatalysis by ADH were analyzed. CN− enhanced the bioelectrocatalytic activity, while the catalytic activity in the solution remained unchanged, even in the presence of CN−. Electrochemical methods and electron spin resonance spectroscopy showed the detailed electron transfer pathway in the DET-type bioelectrocatalysis by ADH. Briefly, ADH is suggested to communicate with an electrode via a CN−-insensitive and H+-sensitive heme c in DET. These characteristics of ADH with respect to CN− suggest the involvement of ADH in CN−-insensitive respiration in G. oxydans.

BODIPY-modified silica-coated magnetite nanoparticles/Copper (II) complex as fluorescent chemosensor for cyanide anions detection in aqueous medium

ABSTRACT A novel fluorescent BODIPY-modified silica-coated magnetite nanoparticles/Copper (II) complex was developed for cyanide detection in aqueous ethanol solution. The sensing abilities of the prepared fluorescent copper (II) complex towards cyanide anions was examined by fluorescence spectroscopy, and displays high selectivity and sensitivity for cyanide among the all tested anions in H2O/EtOH (v/v = 2:8) at the neutral pH range and with LOD of 0.57 μM.

A Novel Material Fluorescence Probe Based on Covalently Functionalized Graphene Oxide by Aminocoumarin for Detection of CN−

Owing to the hazardness, the sensitive and selective detection of cyanide (CN−) in water or water-containing systems has still been a puzzle plaguing scientists all around the world. In this paper, a novel fluorescence probe based on covalently functionalized graphene oxide (GO) by aminocoumarin for highly selective detection of CN− in deionized water was prepared under the action of EDC/NHS. This probe bears aminocoumarin group as the recognition site and fluorophore, and its fluorescence quantum yield is increased by 0.07. Simultaneously, by loading on GO, the dispersibility, selectivity and reversibility were soundly improved, which facilitated the detection process. The fluorescence spectra showed that the probe has high selectivity and sensitivity for cyanide, and has potential application in real water.

A chemodosimeter approach for selective colorimetric and fluorimetric cyanide detection using coumarin based fluorescent dyes

New coumarin based allylidenemalononitrile-aminophenyl conjugated fluorescent dyes having donor-π-acceptor-donor (D-π-A-D) system (Dyes 1, 2 and 3) were synthesized and characterized using 1H/13C-APT NMR and HRMS. Interestingly, dye 3 (diacetamide derivative) was obtained as a mixture of E/Z isomer. Dye 3 was investigated by 1H NMR within two solvents with different polarity (DMSO-d6 and Chl-d1) and exposed UV irradiation to observe any configurational changes. The absorption and emission properties of the dyes were determined in various solvents with different polarity. The anion sensitivity and selectivity of the dyes were studied with various anions in DMSO, and their interaction mechanisms were evaluated by spectrophotometric and 1H NMR titration techniques. All three dyes only interacted with cyanide via Michael reaction and the main absorption maxima showed hypsochromic shifts and emission intensity quenched. Moreover, investigation of cyanide sensitivity of the dyes was studied in aqueous media as a mixture of DMSO:water (7:3, v/v). Also, all these results can be detected with the naked eye due to the observed color of the dyes changes from pink to yellow. Additionally, DFT and TDDFT studies were performed to support structural and absorption spectral properties of the dyes.

A mitochondria-targeted ratiometric fluorescent probe for endogenous cyanide in biological samples

Various fluorescence probes for cyanide anions in water solution have been reported, but the investigation for endogenous cyanide recognition in plant tissues and mammalian cells is still limited. Here, a mitochondria-targeted cyanide fluorescent probe Mito-CP with colorimetric and ratiometric response was developed. The detection for cyanide was performed via the nucleophilic addition of cyanide to carbon-carbon double bond between coumarin moiety and pyridine moiety of the probe, which resulted in a color change from red to colorless and fluorescence change from red to blue. The probe showed high sensitivity (0.17 nM) and selectivity for cyanide over other common anion species and biothiols and could detect cyanide in real water samples with quantitative detection. Probe Mito-CP was successfully applied to detect endogenous cyanide in cassava root plant tissues. In addition, colocalization experiment showed that the probe has the property of targeting mitochondria with overlap coefficient being 0.93. A549 and HeLa living cells imaging experiment demonstrated the practical value of the probe in tracing CN− in biological systems. The probe also can detect endogenous cyanide change in mitochondria of rat pheochromocytoma (PC12) cells.

Selective colorimetric molecular probe for cyanide ion detection in aqueous solution

5-Nitro-2-hydroxybenzaldehyde (1) demonstrated to be a sensitive, and a selective molecular probe for cyanide ion (CN-) in aqueous media. In acetonitrile, compound 1 shows sensitivity and selectivity for cyanide, acetate and fluoride, in comparison to other investigated anions using both visual and spectroscopic means. In aqueous solution, the color becomes intense yellow upon addition of cyanide, while acetate showed this effect to a much lower extent. Significant spectral changes were also detected with the appearance of two new absorption bands at 358 and 387 nm. This was accompanied by concomitant intensity decrease for the band at 314 nm. Fluoride, dihydrogen phosphate, chloride, bromide, perchlorate, and azide showed negligible color and spectral changes for the probe in aqueous solutions. On the other hand, hydrogen sulfate caused fainting of the yellow color and gave a spectrum similar to that of the sensor in polar aprotic solvents. The cyanide ion was detected at micro molar levels in aqueous solutions with a stoichiometry of 1:1 for CN: probe in acetonitrile as the solvent. Cyanide, hydroxide, acetate, fluoride and dihydrogen phosphate showed identical changes to color and spectra, indicating a hydrogen bonding and a deprotonation mechanism.

A novel near-infrared ratiometric fluorescent probe for cyanide and its bioimaging applications.

A new near-infrared ratiometric type fluorescent probe was prepared. 3-formyl BODIPY derivatives without substituent group in the 2, 6-position was obtained through DDQ oxidation reaction. Furthermore, it reacted with indole salt to produce probe. This probe bears indolium group as the recognition site and the 3-formyl-BODIPY as fluorophore. The specific detection of cyanide was conducted the nucleophilic attack of cyanide toward the indolium group of the probe, breaking the intramolecular charge transfer (ICT) effect and generating a ratio change in the fluorescence signal. The probe has high selectivity and sensitivity for cyanide. Moreover, cell experiments indicated this probe was benign to HepG-2 cells, and has the potential application in imaging CN- in living HepG-2 cells.

A turn-on fluorescent chemosensor selectively detects cyanide in pure water and food sample

A turn-on fluorescent chemosensor (H-1) for cyanide anions based on dihydroxy phenazine was designed and synthesised. The sensor H-1 exhibits high sensitivity and good selectivity for cyanide in pure water. The CN− response mechanism involves a hydrogen bonding and deprotonation process in the sensor, which induced prominent fluorescence enhancement. The detection limit of the sensor toward CN− is 5.65×10−7M, and other anions had nearly no influence on the probing behavior. In addition, test strips based on the sensor were fabricated, which also exhibit a good selectivity to CN− in water. Notably, this sensor was successfully applied to detect CN− in food samples, which proves a very simple and selective platform for on-site monitoring of CN− in agriculture samples.

A simple chemosensor for the dual-channel detection of cyanide in water with high selectivity and sensitivity

By a deprotonated mechanism, the simple chemosensorHYshowed high sensitivity and selectivity for cyanide in aqueous media.

A pillar[5]arene-based cyanide sensor bearing on a novel cyanide-induced self-assemble mechanism

We have designed and synthesized a novel copillar[5]arene-based chemosensor, which employ 8-hydroxyquinoline group as a binding site and signal group. By a novel cyanide-induced self-assemble mechanism, the pillar[5]arene-based chemosensor shown high sensitivity and selectivity for cyanide in aqueous media. When cyanide was added to the solution of the chemosensor, a strong chartreuse fluorescence appeared. The detection limit of the fluorescent spectrum is 1.08 × 10−8 mol L−1 for cyanide. Moreover, test strips based on the sensor were fabricated, the chemosensor is a good cyanide test kits. In addition, we made life applications of cyanide detected, the chemosensor is also could detect cyanide in aqueous extracts from sprouting potatoes. It is worth mentioning that cyanide-induced self-assemble mechanism is a novel strategy for the design of pillararene based chemosensor. Moreover, to the best of our knowledge, it's the first example of pillararene based cyanide chemosensors.

Anion sensing with cobalt corrinoid grafted quartz crystal microbalances

Corrin macrocycles are well known for their interesting and multifaceted coordination chemistry at the axial positions of the cobalt center. In this work, the use of such cobalt corrinoids as sensitive elements for sorption based chemical sensors like the quartz crystal microbalance (QCM) is described for the first time. This approach of fast and reversible ion detection extends the versatility and applicability of this class of metal-containing ionophores and colorimetric indicators. QCMs were grafted with aquacyano and dicyano cobalt corrinoids and assessed in their sensing characteristics during exposure to cyanide, thiocyanate, and other ionic species as well as selected organic compounds. The liquid sensing characteristics of the corronoids were found to be excellent. Sensors reach equilibrium in <3s from the stable baseline after analyte exposure and the responses are fully reversible. Sensors of high sensitivity and selectivity for cyanide have been obtained with detection limits at 1μM. At the same time, the sensitivities to common organic compounds are negligible. The results demonstrate that corrin grafted QCMs exhibit enormous potential as chemical sensors for the detection of anions, especially cyanide, in aqueous samples.

A ratiometric fluorescent probe based on benzo [e] indolium for cyanide ion in water

A new ratiometric fluorescent cyanide probe bearing a benzo [e] indolium moiety as a fluorophore and binding site was developed. The detection of cyanide was performed via the nucleophilic attack of cyanide toward the benzo [e] indolium group of the probe, resulting in a prominent fluorescence ratiometric change and a color change. The probe was invested in water with high selectivity and sensitivity for cyanide. A simple paper test strip system for the rapid monitoring of cyanide was developed.

Responses of glomus cells to hypoxia and acidosis are uncoupled, reciprocal and linked to ASIC3 expression: selectivity of chemosensory transduction

Carotid body glomus cells are the primary sites of chemotransduction of hypoxaemia and acidosis in peripheral arterial chemoreceptors. They exhibit pronounced morphological heterogeneity. A quantitative assessment of their functional capacity to differentiate between these two major chemical signals has remained undefined. We tested the hypothesis that there is a differential sensory transduction of hypoxia and acidosis at the level of glomus cells. We measured cytoplasmic Ca(2+) concentration in individual glomus cells, isolated in clusters from rat carotid bodies, in response to hypoxia ( mmHg) and to acidosis at pH 6.8. More than two-thirds (68%) were sensitive to both hypoxia and acidosis, 19% were exclusively sensitive to hypoxia and 13% exclusively sensitive to acidosis. Those sensitive to both revealed significant preferential sensitivity to either hypoxia or to acidosis. This uncoupling and reciprocity was recapitulated in a mouse model by altering the expression of the acid-sensing ion channel 3 (ASIC3) which we had identified earlier in glomus cells. Increased expression of ASIC3 in transgenic mice increased pH sensitivity while reducing cyanide sensitivity. Conversely, deletion of ASIC3 in the knockout mouse reduced pH sensitivity while the relative sensitivity to cyanide or to hypoxia was increased. In this work, we quantify functional differences among glomus cells and show reciprocal sensitivity to acidosis and hypoxia in most glomus cells. We speculate that this selective chemotransduction of glomus cells by either stimulus may result in the activation of different afferents that are preferentially more sensitive to either hypoxia or acidosis, and thus may evoke different and more specific autonomic adjustments to either stimulus.

Temporo-Spectral Imaging of Intrinsic Optical Signals during Hypoxia-Induced Spreading Depression-Like Depolarization

Spreading depression (SD) is characterized by a sustained near-complete depolarization of neurons, a massive depolarization of glia, and a negative deflection of the extracellular DC potential. These electrophysiological signs are accompanied by an intrinsic optical signal (IOS) which arises from changes in light scattering and absorption. Even though the underlying mechanisms are unclear, the IOS serves as non-invasive tool to define the spatiotemporal dynamics of SD in brain slices. Usually the tissue is illuminated by white light, and light reflectance or transmittance is monitored. Using a polychromatic, fast-switchable light source we now performed temporo-spectral recordings of the IOS associated with hypoxia-induced SD-like depolarization (HSD) in rat hippocampal slices kept in an interface recording chamber. Recording full illumination spectra (320–680 nm) yielded distinct reflectance profiles for the different phases of HSD. Early during hypoxia tissue reflectance decreased within almost the entire spectrum due to cell swelling. HSD was accompanied by a reversible reflectance increase being most pronounced at 400 nm and 460 nm. At 440 nm massive porphyrin absorption (Soret band) was detected. Hypotonic solutions, Ca2+-withdrawal and glial poisoning intensified the reflectance increase during HSD, whereas hypertonic solutions dampened it. Replacement of Cl- inverted the reflectance increase. Inducing HSD by cyanide distorted the IOS and reflectance at 340–400 nm increased irreversibly. The pronounced changes at short wavelengths (380 nm, 460 nm) and their cyanide sensitivity suggest that block of mitochondrial metabolism contributes to the IOS during HSD. For stable and reliable IOS recordings during HSD wavelengths of 460–560 nm are recommended.

A simple, sensitive and selective detection of cyanide in organic as well as aqueous media by fluorene-based chromogenic host

A receptor bearing fluorene as spacer, urea as a binding site and nitrophenyl as signalling unit was designed and synthesised. Designed receptor has displayed good selectivity and sensitivity for cyanide over other anions such as F− , Cl− , Br− , I− , , , CH3COO− , , SCN− , , , OCN− , , and PhO− by visual as well as spectroscopic methods. Naked-eye detection of cyanide in natural environment extends its practical applicability in real-time monitoring.

Control of Respiration by Cytochrome c Oxidase in Intact Cells

Metabolic control analysis was applied to intact HepG2 cells. The effect on the control coefficient of cytochrome c oxidase (CcOX) over cell respiration of both the electrical (Delta psi) and chemical (Delta pH) component of the mitochondrial transmembrane proton electrochemical gradient (Delta mu(H(+))) was investigated. The overall O(2) consumption and specific CcOX activity of actively phosphorylating cells were titrated with cyanide under conditions in which Delta psi and Delta pH were selectively modulated by addition of ionophores. In the absence of ionophores, CcOX displayed a high control coefficient (C(IV) = 0.73), thus representing an important site of regulation of mitochondrial oxidative phosphorylation. A high control coefficient value (C(IV) = 0.85) was also measured in the presence of nigericin, i.e. when Delta psi is maximal, and in the presence of nigericin and valinomycin (C(IV) = 0.77), when Delta mu(H(+)) is abolished. In contrast, CcOX displayed a markedly lower control coefficient (C(IV) = 0.30) upon addition of valinomycin, when Delta psi is converted into Delta pH. These results show that Delta psi is responsible for the tight control of CcOX over respiration in actively phosphorylating cells.

Oxidative stress response of Mycosphaerella fijiensis, the causal agent of black leaf streak disease in banana plants, to hydrogen peroxide and paraquat

Mycosphaerella fijiensis causes black leaf streak disease in banana and plantain. This fungus is usually attacked by reactive oxygen species secreted by the plant or during exposure to fungicide, however, little is known about the antioxidant response of the fungus. In this study, mycelia were observed to totally decompose 30 mmol/L of hydrogen peroxide (H2O2) within 120 min, liberating oxygen bubbles, and also to survive in concentrations as high as 100 mmol/L H2O2. The oxidative stress responses to H2O2, paraquat, and hydroquinone were characterized in terms of the activities of catalase and superoxide dismutase (SOD). Two active catalase bands were seen in native PAGE induced by H2O2. Band I had monofunctional activity and band II had bifunctional catalase-peroxidase activity. Two isozymes of SOD, distinguishable by their cyanide sensitivity, were found; CuZnSOD was the main one. The combination of H2O2 and 3-aminotriazole reduced the accumulation of biomass up to 40% compared with exposure to H2O2 alone, suggesting that catalase is important for the rapid decomposition of H2O2 and has a direct bearing on cell viability. The results also suggest that the superoxide anion formed through the redox of paraquat and hydroquinone has a greater effect than H2O2 on the cellular viability of M. fijiensis.

12-hour phase-shift of mice kidney rhodanese (thiosulfate sulfurtransferase) activity in the first two months of life

This study aimed to investigate and compare variation of renal rhodanese activity at 2nd, 4th and 8th weeks of post-natal development (PND) in mice. The enzyme activity increased with age and was higher in females compared to males in all studied groups. Cosinor analysis revealed significant circadian rhythms (with period τ = 24 h) of enzyme activity in both genders with peak time shift during the PND. At the 2nd week of PND (pre-weaning time), the circadian rhythm peaked at the beginning of light span, more precisely ≅1 HALO (Hours After Light Onset). A week after weaning (4th week of PND), the peak time was located at the second half of photophase (≅9 HALO) in both genders. Four to six weeks later, about the 8th week of PND, the circadian peak time was then recorded at ≅13 HALO. These findings suggest that rhodanese level and rhythm stabilization were age-dependent. Moreover, gender-related differences may stimulate discussions on the relationship between renal rhodanese and cyanide sensitivity.

Host-Plant Selectivity of Rhizobacteria in a Crop/Weed Model System

Belowground microorganisms are known to influence plants' performance by altering the soil environment. Plant pathogens such as cyanide-producing strains of the rhizobacterium Pseudomonas may show strong host-plant selectivity. We analyzed interactions between different host plants and Pseudomonas strains and tested if these can be linked to the cyanide sensitivity of host plants, the cyanide production of bacterial strains or the plant identity from which strains had been isolated. Eight strains (four cyanide producing) were isolated from roots of four weed species and then re-inoculated on the four weed and two additional crop species. Bacterial strain composition varied strongly among the four weed species. Although all six plant species showed different reductions in root growth when cyanide was artificially applied to seedlings, they were generally not negatively affected by inoculation with cyanide-producing bacterial strains. We found a highly significant plant species x bacterial strain interaction. Partitioning this interaction into contrasts showed that it was entirely due to a strongly negative effect of a bacterial strain (Pseudomonas kilonensis/brassicacearum, isolated from Galium mollugo) on Echinochloa crus-galli. This exotic weed may not have become adapted to the bacterial strain isolated from a native weed. Our findings suggest that host-specific rhizobacteria hold some promise as biological weed-control agents.

CHARACTERIZATION AND PARTIAL PURIFICATION OF THE RAT AND HUMAN ENZYME SYSTEMS ACTIVE IN THE REDUCTION OFN-HYDROXYMELAGATRAN AND BENZAMIDOXIME

The enzymic basis for intracellular reduction of N-hydroxylated amidines to their corresponding amidines, and hydroxylamines to their corresponding amines, is unknown. The hydroxylated amidines can be used as prodrug moieties, and an understanding of the enzyme system active in the reduction can contribute to more efficient drug development. In this study, we examined the properties of this enzyme system using benzamidoxime and N-hydroxymelagatran as substrates. In rats and humans, the hepatic enzyme system was localized in mitochondria as well as in microsomes, using preferably NADH as cofactor. Potassium cyanide, N-methylhydroxylamine, p-hydroxymercuribenzoate, and desferrioxamine were efficient inhibitors, whereas typical cytochrome P450 (P450) inhibitors were ineffective. In rats, the highest specific activity was found in liver, adipose tissue, and kidneys, whereas in humans, the specific activity in the preparations of adipose tissue examined was lower. A sex difference was observed in rat liver, where 4-fold higher activity was seen in microsomes from female rats. No gender differences were present in any other tissue investigated. Partial purification of the hepatic system was achieved using polyethylene glycol fractionation followed by Octyl Sepharose chromatography at low detergent concentrations, whereas the enzyme was denatured after complete solubilization. The unique appearance of the enzyme activity in adipose tissue, together with the cyanide sensitivity and the failure of typical P450 inhibitors to impede the reaction, indicates that the enzyme system active in reduction of benzamidoxime and N-hydroxymelagatran formation is not of cytochrome P450 origin, but likely consists of an NADH-dependent electron transfer chain with a cyanide-sensitive protein as the terminal component.