L-cysteine Concentration Research Articles

An Efficient Method of Agrobacterium-Mediated Genetic Transformation and Regeneration in Local Indian Cultivar of Groundnut (Arachis hypogaea) Using Grafting

Groundnut (Arachis hypogaea L.) is an industrial crop used as a source of edible oil and nutrients. In this study, an efficient method of regeneration and Agrobacterium-mediated genetic transformation is reported for a local cultivar GG-20 using de-embryonated cotyledon explant. A high regeneration 52.69 ± 2.32 % was achieved by this method with 66.6 μM 6-benzylaminopurine (BAP), while the highest number of shoot buds per explant, 17.67 ± 3.51, was found with 20 μM BAP and 10 μM 2,4-dichlorophenoxyacetic acid (2,4-D). The bacterial culture OD, acetosyringone and L-cysteine concentration were optimized as 1.8, 200 μM and 50 mg L(-1), respectively, in co-cultivation media. It was observed that the addition of 2,4-D in co-cultivation media induced accumulation of endogenous indole-3-acetic acid (IAA). The optimized protocol exhibited 85 % transformation efficiency followed by 14.65 ± 1.06 % regeneration, of which 3.82 ± 0.6 % explants were survived on hygromycin after selection. Finally, 14.58 ± 2.95 % shoots (regenerated on survived explants) were rooted on rooting media (RM3). In grafting method, regenerated shoots (after hygromycin selection) were grafted on the non-transformed stocks with 100 % survival and new leaves emerged in 3 weeks. The putative transgenic plants were then confirmed by PCR, Southern hybridization, reverse transcriptase PCR (RT-PCR) and β-glucuronidase (GUS) histochemical assay. The reported method is efficient and rapid and can also be applied to other crops which are recalcitrant and difficult in rooting.

Design of an optical sensor for the determination of cysteine based on the spectrophotometric method in a triacetylcellulose film: PC-ANN application

An optical sensor was developed for measuring the concentration of L-cysteine (Cys) based on the immobilization of an ARS–Cu complex to a transparent triacetylcellulose film. The spectrophotometric studies of the sensing films clearly indicate that the absorption enhances at 438 nm and decreases at 535 nm in acetate buffer solution pH 5.0 as a result of the interaction of Cys with Cu2+ of the copper–ARS complex and the reduction of Cu2+ to Cu+ which cause the release of ARS. With the optode membrane described, Cys in a sample solution can be determined with the linear range of 47.8 to 637.0 μM which was improved to 18.9–672.0 μM by applying the PC-ANN algorithm. The proposed optode obtained a limit of detection equal to 7.32 μM and its response time was about 16 min, depending on the concentration of Cys. The measurements of Cys in a real sample via the new optical sensor have shown an excellent correlation with values obtained for the same samples using HPLC as a standard method.

Comparison of Modifiers for Mercury Speciation in Water by Solid Phase Extraction and High Performance Liquid Chromatography–Atomic Fluorescence Spectrometry

Diethyldithiocarbamate and 2-mercaptoethanol modifiers were compared for the preconcentration of mercury species in water by C18 solid phase extraction (SPE). The recovery values of mercury species were determined by high performance liquid chromatography–atomic fluorescence spectrometry. The eluent type, pH, chloride ion concentration, humic acid concentration, and storage time were evaluated to compare the preconcentration efficiency. L-cysteine was employed to elute the mercury compounds. Less eluent was needed for 2-mercaptoethanol modified SPE than for diethyldithiocarbamate modified SPE at an L-cysteine concentration of 0.12%. Diethyldithiocarbamate modified SPE could be used over a wider pH range and higher humic acid concentrations, whereas 2-mercaptoethanol modified SPE was less affected by the chloride concentration. Both modified SPE systems stored mercury species for 5 days, but diethyldithiocarbamate modified SPE could be stored longer. Diethyldithiocarbamate SPE provided limits of detections of 3.5, 2.5, and 4 ng · L−1 and average recoveries of 90.78 ± 3.37%, 96.79 ± 5.12%, and 84.88 ± 5.37% for mercury(II), methylmercury, and ethylmercury, respectively. The relative standard deviation was less 6.5%. For 2-mercaptoethanol modified SPE, the limits of detection were 1.4, 1, and 1.6 ng · L−1 and the recoveries were of 87.66 ± 8.45%, 86.70 ± 2.61%, and 91.31 ± 6.98% for mercury(II), methylmercury, and ethylmercury, respectively, with a relative standard deviation below 9.7%. Water should be characterized for its physical and chemical characteristics before mercury preconcentration to choose the most suitable method.

Tunable synthesis of multi-shaped PbS via l-cysteine assisted solvothermal method

Lead sulfide (PbS) with multi-morphologies were synthesized via solvothermal route under the assistance of l-cysteine. Reaction conditions such as concentration of l-cysteine, reacting temperature, reacting time and solvents have been systemically investigated in order to obtain shape-controlled PbS micro-crystals. A series of morphologies, such as cubic, Dendritic Hierarchical, Octagonal Hierarchical flowerlike and Vertebration shapes were obtained successfully. Self-assembly and a hypothesis based on Boltzmann distribution were introduced for illustration of morphology evolution obtained under different reacting temperatures, and the effect of the solvents and the role of l-cysteine were also discussed in detail. To testify the effects of different morphologies on the optical properties of PbS, the absorption spectra of some samples were measured. These results demonstrated that our work offers an effective way to develop the tunable synthesis of multi-shaped PbS for various applications.

Application of 3,4-dihydroxycinnamic acid as a suitable mediator and multiwall carbon nanotubes as a sensor for the electrocatalytic determination of L-cysteine

A highly sensitive electrochemical sensor was prepared for the determination of L-cysteine using a modified multiwall carbon nanotubes paste electrode in the presence of 3,4-dihydroxycinnamic acid (3,4-DHCA) as a mediator, based on an electrocatalytic process. The results indicate that the electrode is electrocatalytically efficient for the oxidation of L-cysteine in the presence of 3,4-DHCA. The interaction between the mediator and L-cysteine can be used for its sensitive and selective determination. Using chronoamperometry, the catalytic reaction rate constant was calculated to be 2.37 × 102 mol−1 L s−1. The catalytic peak current was linearly dependent on the L-cysteine concentration in the range of 0.4–115 μmol/L. The detection limit obtained by linear sweep voltammetry was 0.25 μmol/L. Finally, the modified electrode was examined as a selective, simple, and precise new electrochemical sensor for the determination of L-cysteine in real samples.

DNA Sensors and Aptasensors Based on the Hemin/G‐quadruplex‐Controlled Aggregation of Au NPs in the Presence of L‐Cysteine

L-cysteine induces the aggregation of Au nanoparticles (NPs), resulting in a color transition from red to blue due to interparticle plasmonic coupling in the aggregated structure. The hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme catalyzes the aerobic oxidation of L-cysteine to cystine, a process that inhibits the aggregation of the NPs. The degree of inhibition of the aggregation process is controlled by the concentration of the DNAzyme in the system. These functions are implemented to develop sensing platforms for the detection of a target DNA, for the analysis of aptamer-substrate complexes, and for the analysis of L-cysteine in human urine samples. A hairpin DNA structure that includes a recognition site for the DNA analyte and a caged G-quadruplex sequence, is opened in the presence of the target DNA. The resulting self-assembled hemin/G-quadruplex acts as catalyst that controls the aggregation of the Au NPs. Also, the thrombin-binding aptamer folds into a G-quadruplex nanostructure upon binding to thrombin. The association of hemin to the resulting G-quadruplex aptamer-thrombin complex leads to a catalytic label that controls the L-cysteine-mediated aggregation of the Au NPs. The hemin/G-qaudruplex-controlled aggregation of Au NPs process is further implemented for visual and spectroscopic detection of L-cysteine concentration in urine samples.

PH-assisted shape-controlled synthesis of homogeneous hybrid CdS-cystine composites

Homogeneous hybrid CdS-cystine composites with different shapes such as side spindle-like, bundle-like, laminar and egg-like have been fabricated in mild conditions using CdS QDs as inorganic unit and l-cysteine as organic unit, in which l-cysteine was oxidated to generate cystine as an organic matrix. It is demonstrated that the morphologies of composites were controllable with pH of reactant solution and concentration of l-cysteine. The morphological evolution and photoluminescence properties of composites have also been explored.

SENSITIVE L-CYSTEINE AMPEROMETRIC SENSOR BASED ON A GLASSY CARBON ELECTRODE MODIFIED BY MnO2 NANOPARTICLES

A sensitive amperometric sensor for the determination of L-cysteine was fabricated by electrodeposition of modified MnO2 nanoparticles on a glassy carbon electrode. The morphology of the nanoparticles was characterized by scanning electron microscopy. Cyclic voltammetry was applied to investigate the mechanism of film formation and the electrochemical properties of the MnO2 nanoparticle-modified electrode. The results of electrochemical experiments showed that the modified electrode had a favorable catalytic ability for the electrochemical oxidation of L-cysteine. Under optimized conditions, the MnO2 nanoparticle-modified electrode exhibited a linear dependence on the concentration of L-cysteine from 1.0 × 10−6 to 6.4 × 10−4 M, and a detection limit of 8.0 × 10−7 M (signal/noise = 3). The modified electrode was highly resistant towards typical inorganic salts and some biomolecules. In addition, the sensor was applied for the determination of L-cysteine in human serum with high accuracy, demonstrating its potential for practical applications.

Microwave-assisted green synthesis of ultrasmall fluorescent water-soluble silver nanoclusters and its application in chiral recognition of amino acids

In this article, we established a fluorescent chiral recognition and detection method for cysteine based on the L-glutathione (L-GSH)-stabilized Ag nanoclusters (AgNCs) with high selectivity and sensitivity. A fast and green microwave (MW)-assisted strategy has been employed for synthesizing water-soluble fluorescent L-GSH-AgNCs. The reaction time was shortened from hours to several minutes. The synthetic process utilized L-glutathione as a stabilizing agent and a reducing agent without any other toxic reducing agent, such as NaBH4 or N2H4. The method is environmental friendly. Due to the different responses to AgNCs from chiral cysteine, we found d-cysteine hardly affects the fluorescence intensity of the AgNCs, whereas L-cysteine distinctly weakened its fluorescence intensity. This experiment indicated that fluorescence quenching efficiency of AgNCs was proportional to the concentration of L-cysteine in the range from 0.025 to 50 μmol L(-1).

Characterisation of gold agglomerates: size distribution, shape and optical properties

The slow agglomeration of gold colloids of approximate diameter 30 nm in the presence of a small concentration of L-cysteine·HCl has been followed by multiple techniques, namely particle tracking analysis (PTA), differential centrifugal sedimentation (DCS), UV-visible spectroscopy (UV), second order spectroscopy (SOS) and transmission electron microscopy (TEM). The citrate-stabilized Au nanoparticles were characterized by PTA, DCS, UV and dynamic light scattering (DLS) prior to exposure to the cysteine. Hydrodynamic forces during centrifugation can cause the disintegration of weakly held agglomerates. TEM reveals small linear agglomerates that become open linked chains of fractal-like structures after several hours of agglomeration. Second order Rayleigh scattering observed at the harmonic wavelength of 680 nm was resonantly enhanced by surface plasmon excitation of the growing agglomerates. During the initial stage of the agglomeration process, when chainlike or quasi-chainlike agglomerates were the dominant species, the SOS signal goes up by a factor of about three before reaching saturation. This study of a model nanoparticle system provides insights into the information obtained from a range of measurement techniques, with recommendations for characterisation of agglomerating nanoparticles under end-use conditions.

Assessment of Appropriate L-cysteine Concentration for Boar Semen Cryopreservation by Using Flow Cytometry

Assessment of Appropriate L-cysteine Concentration for Boar Semen Cryopreservation by Using Flow Cytometry

A novel electrochemical sensor based on metal-organic framework for electro-catalytic oxidation of L-cysteine

A novel electrochemical sensor based on Au-SH-SiO2 nanoparticles supported on metal-organic framework (Au-SH-SiO2@Cu-MOF) has been developed for electrocatalytic oxidation and determination of L-cysteine. The Au-SH-SiO2@Cu-MOF was characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction and cyclic voltammetry. The electrochemical behavior of L-cysteine at the Au-SH-SiO2@Cu-MOF was investigated by cyclic voltammetry. The Au-SH-SiO2@Cu-MOF showed a very efficient electrocatalytic activity for the oxidation of L-cysteine in 0.1M phosphate buffer solution (pH 5.0). The oxidation overpotentials of L-cysteine decreased significantly and their oxidation peak currents increased dramatically at Au-SH-SiO2@Cu-MOF. The potential utility of the sensor was demonstrated by applying it to the analytical determination of L-cysteine concentration. The results showed that the electrocatalytic current increased linearly with the L-cysteine concentration in the range of 0.02–300μM and the detection limit was 0.008μM. Finally, the sensor was applied to determine L-cysteine in water and biological samples.

Is the poly (methylene blue)-modified glassy carbon electrode an adequate electrode for the simple detection of thiols and amino acid-based molecules?

This paper describes the preparation, characterization, and use of poly (methylene blue) (PMB)-modified glassy carbon electrodes (GCE) (GCE–PMB) in the detection of the thiols L-cysteine (L-CySH) and N-acetyl cysteine (Acy), and the herbicide glyphosate (GLYP) in pH 5.3 aqueous solution. The polymer film prepared by electropolymerization showed different characteristics such as robustness, stability, and redox properties satisfactorily. The surface coverage concentration (Γ) of PMB was found to be 7.90×10−9molcm−2. Moreover, we observed strong adhesion of the polymer film to the electrode surface. The results using GCE–PMB as a sensor indicated that this modified electrode exhibited electrocatalytic activity toward the detection of thiols and glyphosate in 0.1molL−1 KCl (pH 5.3). Meanwhile, strong adsorption of the analytes on the GCE–PMB electrodes was also observed. Otherwise, using a low concentration (1×10−4molL−1) of L-cysteine and N-acetyl cysteine and 8.9×10–6molL−1 of glyphosate, separately, it was possible to observe a well-defined electrochemical response, thus providing an opportunity to further understand the applicability of PMB as a sensor for amino acid-based molecules.

Optimization of enzymatic treatment of polyamide fabrics by bromelain

In this study, we investigated the effects of enzymatic hydrolysis on polyamide fabrics by using bromelain as an enzyme. The hydrolytic activity of bromelain was evaluated on the basis of the number of carboxylic groups formed on the surface of the polyamide fabrics, and it was measured using the reactive dye absorbance. In addition, 2,4,6-trinitrobenzenesulfonic acid was added as an indicator to measure the number of amino groups released into the treatment liquid by the changes in color of the liquid. The optimum treatment conditions were bromelain pH of 6.0, treatment time of 120 min, temperature of 50 °C, concentration of 10 % (owf), and L-cysteine concentration of 70 mM. The weight loss in the fabric after treatment with bromelain facilitated by L-cysteine significantly improved; however, the tensile strengths of the polyamide fabrics did not show any differences. Bromelain hydrolysis of the polyamide fabrics thus improved hydrophilicity without damaging the fabrics’ strength.

Preparation and Electrochemical Behaviour of Silver Pentacyanonitrosylferrate Film Modified Glassy Carbon Electrode and Its Electrocatalytic Oxidation to L‐cysteine

AbstractA glassy carbon (GC) electrode modified with silver pentacyanonitrosylferrate (AgPCNF) film as a redox mediator was fabricated. Cyclic voltammetry was used to study the redox property of AgPCNF modified electrode. The modified electrode showed a well‐defined redox couple due to [AgIFeIII/II(CN)5NO]1‐/2‐system. The effects of scan rates, supporting electrolytes and solution pHs were studied on the electrochemical behavior of the modified electrode. The feasibility of using the AgPCNF modified electrode to measure L‐cysteine was investigated. It showed an excellent electrocatalytic activity towards the oxidation of L‐cysteine and the anodic currents were proportional to the L‐cysteine concentration in the range of 0.1 μM to 20 μM, the linear regression equation is Ipa(μA) = ‐68.58 ‐ 5.78CL‐cysteine (μM), with a correlation coefficient 0.998 for N = 23. The detection limit was down to 3.5 × 10‐8 M (three times the ratio of signal to noise).

Direct Selective Extraction of Actinides (III) from PUREX Raffinate using a Mixture of CyMe4BTBP and TODGA as 1-cycle SANEX Solvent

Within the framework of our research activities related to the partitioning of spent nuclear-fuel solutions, the direct selective extraction of trivalent actinides from a simulated PUREX raffinate was studied using a mixture of CyMe4BTBP and TODGA (1-cycle SANEX). The solvent showed a high selectivity for trivalent actinides with a high lanthanide separation factor. However, the coextraction of some fission product elements (Cu, Ni, Zr, Mo, Pd, Ag, and Cd) from a simulated PUREX raffinate was observed, with distribution ratios up to 30 (Cu). The extraction of Zr and Mo could be suppressed using oxalic acid but the use of the well-known Pd complexant N-(2-Hydroxyethyl)-ethylendiamin-N,N′,N′-triacetic acid (HEDTA) was unsuccessful. During screening experiments with different amino acids and derivatives, the sulfur-bearing amino acid L-Cysteine showed good complexation of Pd and prevented its extraction into the organic phase without influencing the extraction of the trivalent actinides Am (III) and Cm (III). The optimization studies included the influence of the L-Cysteine and HNO3 concentration and the kinetics of the extraction. The development of a process-like extraction series showed very promising results in view of further optimizing the process. A strategy for a single-cycle process is proposed within this article.

Sensitive and selective electrochemical sensing of l-cysteine based on a caterpillar-like manganese dioxide–carbon nanocomposite

A novel one-dimensional (1-D) caterpillar-like manganese dioxide-carbon (MnO(2)-C) nanocomposite has been synthesized by a direct redox reaction between carbon nanotubes (CNTs) and permanganate ions for the first time. The as-prepared nanostructured MnO(2)-C composite mainly consisting of ε-MnO(2) nanoflakes had a unique microstructure, high specific surface area (200 m(2) g(-1)) and favourable conductivity. The nanostructured MnO(2)-C composite, added as a modification to the glassy carbon (GC) electrode via a direct electrochemical co-deposition process with a chitosan hydrogel, was found to exhibit excellent catalytic activity toward L-cysteine electro-oxidation because the specific interaction between the -SH group of L-cysteine and solid MnO(2) occurred to form surface complexes. A determination of L-cysteine at the MnO(2)-C/chitosan/GC (MnO(2)-C/chit/GC) electrode was carried out by amperometric measurement. Under the optimum experimental conditions, the detection response for L-cysteine was fast (within 7 s). The logarithm of catalytic currents shows a good linear relationship with that of the L-cysteine concentration in the range of 0.5-680 μM (R = 0.9986), with a low detection limit of 22 nM. The MnO(2)-C/Chit/GC electrode exhibited excellent stability (without any decrease of the response signal after 1 month) and admirable resistance against interference like glutathione and other oxidizable amino acids (tryptophan, tyrosine, L-lysine and methionine).

Influence of L-Cysteine Concentration on Oxidation-reduction Potential and Biohydrogen Production

The effects of L-cysteine concentration on biohydrogen production by Enterobacterium Bacterium M580 were investigated in batch cultivation. The experimental results showed that L-cysteine could enhance the cell growth, hydrogen production rate and hydrogen yield when its concentration was less than 500 mg·L −1, while it had negative effects when its concentration was higher than 500 mg·L −1. The hydrogen production was the highest [1.29 mol·mol −1 (H 2/glucose)] when 300 mg·L −1 L-cysteine was added into the culture, and the yield was 9.4% higher than that in the control. The oxidation-reduction potential (ORP), which was influenced by L-cysteine, also affected hydrogen production. The ORP values were in the range (300 mV to (150 mV when the L-cysteine concentration was higher than 500 mg·L −1. Although the ORP in this range was favorable for hydrogen production, it was not suitable for the biomass growth. Hence, less hydrogen was produced. When the L-cysteine concentration was lower than 500 mg·L −1, the ORP was more suitable for both biomass growth and hydrogen production. In addition, at least 91% glucose was consumed when L-cysteine was added to the culture media, compared to the 97.37% consumption without L-cysteine added.

A Multilayer Film for Bifunctional Electrocatalyst and Electrochemical Sensor Based on Polyoxometalate and Tris(1,10-Phenanthroline)Ruthenium

The multilayer films containing tris(1,10-phenanthroline) ruthenium(II) Ru(phen)3Cl2 (abbr. Ru(phen)3, phen = 1,10-phenanthroline) and polyoxometalate [P2W18O62]6− (abbr. P2W18) through a layer-by-layer (LBL) process were fabricated. UV–vis absorption spectra showed that the subsequent growth of the multilayer film was regular and highly reproducible from layer to layer. X-ray photoelectron spectra (XPS) confirmed the incorporation of Ru(phen)3 and P2W18 into the film. The result of atomic force microscopy (AFM) revealed a relatively uniform surface morphology of the multilayer film. The multilayer film exhibited remarkable electrocatalytic activities toward the reduction of $$ {\text{IO}}_{3}^{ - } $$ and the oxidation to l-cysteine. The value of I pc was as a function with the concentration of iodate and l-cysteine, which indicated that the film can be a candidate for bifunctional electrocatalyst and electrochemical sensor.

Supplemental effect of varying L-cysteine concentrations on the quality of cryopreserved boar semen

Cryopreservation is associated with the production of reactive oxygen species, which leads to lipid peroxidation of the sperm membrane and consequently a reduction in sperm motility and decreased fertility potential. The aim of this study was to determine the optimal concentration of L-cysteine needed for cryopreservation of boar semen. Twelve boars provided semen of proven motility and morphology for this study. The semen was divided into four portions in which the lactose-egg yolk (LEY) extender used to resuspend the centrifuged sperm pellet was supplemented with various concentrations of L-cysteine to reach 0 mmol L(-1) (group I, control), 5 mmol L(-1) (group II), 10 mmol L(-1) (group III) and 15 mmol L(-1) (group IV). Semen suspensions were loaded in straws (0.5 mL) and placed in a controlled-rate freezer. After cryopreservation, frozen semen samples were thawed and investigated for progressive motility, viability using SYBR-14/EthD-1 staining and acrosome integrity using FITC-PNA/EthD-1 staining. There was a significantly higher (P < 0.01) percentage of progressive motility, viability and acrosomal integrity in two L-cysteine-supplemented groups (group II and group III) compared with the control. There was a biphasic effect of L-cysteine, with the highest percentage of progressive motility, viability and acrosomal integrity in group III. In conclusion, 5 or 10 mmol L(-1) was the optimum concentration of L-cysteine to be added to the LEY extender for improving the quality of frozen-thawed boar semen.