γ-aminobutyric acid (GABA) is an important inhibitory neurotransmitter in the brain with many physiological functions. Therefore, this work establishes an efficient biosynthesis process to achieve ...the high production of food-grade GABA. Firstly, we adopted a directional colorimetric screening method and then obtained the strain Lactobacillus brevis (Lb. brevis) CGMCC 24975 with 22.61 g/L GABA in shake flasks, much higher than Lb. brevis ATCC 367 (3.07 g/L) due to its more efficient and stable expression of its glutamate decarboxylase (GAD) system. After exploring the effects of optimal fermentation conditions and oxygen on GABA production, we found that anaerobic fermentation could increase GABA production by up-regulating gad operon expression and activating GADase. Finally, we developed an oil-sealed anaerobic fermentation process with 157.90 g/L GABA in a 5 L bioreactor, which was 6.98-fold of that in shake flasks. This work includes a complete process from screening GABA-producing strains to developing efficient fermentation processes, laying the foundation for producing food-safe GABA.
Display omitted
•A directional colorimetric screening method with bromocresol green was built.•Lactobacillus brevis CGMCC24975 with the highest A620 and GABA yield was selected.•This study has developed an oil-sealed anaerobic fermentation process.•The GABA production was 157.90 g/L in a 5 L bioreactor, which increased to 698%.
Display omitted
•Zafirlukast (ZST) is a vital cysteinyl leukotriene receptor antagonist.•Four spectrophotometric methods for the determination of ZST in solid dispersion’s.•Pharmaceutical analysis is ...oriented on ZST ion complexation with chromogens.•Sensitive, precise, accurate results as recommended by ICH guidelines.
The purpose of present work was to develop a novel analytical method for orally given leukotriene antagonist Zafirlukast (ZST), present in Meglumine and Eudragit EEPO based solid dispersion formulation. Four simple, extraction-free, fast, and economical methods based on charge transfer complexation among nitrogen of ZST with sulfonyl group comprising chromogenic mediator bromophenol blue (BPB-Method B), bromothymol blue (BTB-Method C) and bromocresol green (BCG-Method D). The first method (A) is based on the analysis using 0.1 M HCl as a solvent at λmax 242 nm while chromogenic methods yield color complex at λmax 415 nm (BPB-Method B), λmax 420 nm (BTB-Method C) and λmax 435 nm (BCG-Method D). The Beer’s Law stayed linear in the concentration ranges of 1–10, 10–75, 5–40 and 15–100 μg/ml for methods A, B, C and D, respectively. The spectral and thermodynamic characterization of each method was carried out by the application of Molar Absorptivity, LOD, LOQ, Association Constant and Gibbs free energy (ΔGo). The methods were statistically optimized and evaluated by F-Distribution Value, P-Value, Shapiro-Wilk P-Value, regression analysis, Q-Q plot, prediction interval, residual histogram and plots. Various experimental conditions affecting the complexation and stability of chromogenic complexes are cautiously studied including optimal temperature, chromogenic agent volume, color stability, recovery, precision and accuracy. All the measurements were executed under ICH guidelines. It can be established that proposed would be an appropriate prospective analytical approach for estimation of ZST in pure bulk, solid dispersions and dosage forms.
Display omitted
•One-step hydrothermal synthesis of PEI-coated SPIONs•Matrix-dispersed PEI-coated SPIONs for removal of anionic dyes from wastewater•Simultaneous spectrophotometric assay of BCG and ...BPB triphenylmethanes dyes•Studying adsorption thermodynamics and kinetics•TEM images revealed matrix-dispersed structures
Textile industries produce a massive amount of wastewater that should be cleaned from toxic substances such as fats, colors and any chemicals used during the production steps. Water-treatment methods should be facile, economic, fast and efficient. Here, we report the synthesis, characterization and application of matrix-dispersed superparamagnetic iron oxide nanoparticles (SPIONs) for the removal of anionic dyes from wastewater released from textile industrial plants. The matrix-dispersed SPIONs were synthesized via a solvothermal method in which a polyethyleneimine (PEI) shell was deposited onto SPIONs in order to add positive charges to their surfaces. TEM images revealed that the size of PEI-coated and uncoated SPIONs is 30–50 and 15–30 nm, respectively. Moreover, TEM images depicted that the as synthesized PEI-coated SPIONs show matrix-dispersed structures. Furthermore, the particle size obtained with DLS measurements was found to be 87.93 and 158.9 nm for uncoated and PEI-coated SPIONs, respectively. Bromophenol blue (BPB) and bromocresol green (BCG), two triphenylmethanes, were used as model anionic dyes. FTIR spectroscopy revealed the interaction between the PEI surface coating and the anionic dyes. The apparent ζ-potential measurements showed that the surface negative charges decreased from −13.5 to −4.03 mV upon coating with PEI. In order to investigate the anionic dyes removal/entrapment efficiency of SPIONs, a new derivative visible spectrophotometric method was developed for the simultaneous quantification of BPB and BCG before and after treatment where the linear ranges were 6.98–27.9 and 6.70–26.8 μg/mL and the recovery values were in the ranges of 98.10–101.7% and 99.55–104.8% for BCG and BPB, respectively. It was found that the uptake/adsorption capacity of PEI-coated SPIONs is ca.15.5 and 11.3 mg/g for BCG and BPB, respectively. The calculated thermodynamic parameters for the adsorption of BCG (ΔH = 37.08 J/mol and ΔS = 120.89 J/mol K) and BPB (ΔH = 181.26 J/mol and ΔS = 596.46 J/mol K) and the negative ΔG values indicate that the adsorption is thermodynamically favored. The adsorption processes were found to follow the pseudo-second-order kinetic model with r2 values of 0.9982 and 0.9956 for BCG and BPB, respectively.
•On-package colorimetric sensing label was developed for fish freshness.•Label was based on bromocresol green indicator and sol-gel matrix layer.•A Hue Saturation Value model was used to correlate ...the response of sensing label.•Three kinds of fish fillets showed intense color change during the spoilage trial.
Fish freshness monitoring is important for consumers. This study aims to develop an colorimetric sensing label based on bromocresol green (BCG) and a sol-gel matrix layer coated onto filter paper to monitor fish freshness. Characterization results showed that the sol-gel layer was successfully coated, and the coating yield was 14.25%. The fish freshness could be detected clearly by the naked eye as the color of the sensing label changed. A Hue Saturation Value (HSV) model was used to correlate the response of the sensing label to the freshness of fish samples. Hue (H) values showed a linear response to the total volatile basic nitrogen (TVB-N) concentration in the range of 16.4–23.11 mg/100 g at room temperature, and in the range of 9.28–24.12 mg/100 g at a chilled temperature. The sensing label was applied to other types of fish, and showed an intense color change during the spoilage trial.
Display omitted
Cross-linked multilayer thin films assembled using weak polyelectrolytes with specific functional groups are useful materials in solid phase extraction techniques. Herein, we report a ...facile strategy to modify silica microparticle surfaces for the separation of two anionic dyes Congo red (CR) and Bromocresol green (BCG). Different multilayer films, consisting of poly(ethyleneimine) (PEI) and poly(vinyl amine) (PVAm), as weak polycations, and poly(acrylic acid) (PAA), as a weak polyanion, were deposited onto silica using a layer-by-layer technique. The amount of anionic dyes sorbed onto the composite surface depended on the nature of polycation, deposition conditions, number of polycation layers, cross-linker concentration and on the nature of dyes. The degree of crosslinking by glutaraldehyde (GA) of the composite microparticles strongly influenced the extraction of PAA chains from multilayer during strong basic treatment and subsequently, the sorbed amount of dye and selective desorption capacity of composite. Daisogel//(PEI/PAA)4.5 cross-linked with 1.00% GA, can be used succesfully as a solid support in sorption and selective desorption of two anionic dyes (BCG and CR) only by pH tuning.
Electrocatalytic oxidation of UA, DA and AA at poly(bromocresol green) modified glassy carbon electrode were investigated by differential pulse voltammetry. The peak currents of UA, DA and AA ...increased significantly, and the peak potentials shifted negatively at PBG/GCE, moreover, the peak of DA and AA separate significantly, demonstrating that the proposed methods enhanced the kinetics of the electrochemical process as an efficient promoter.
DPVs for 10μM UA, 0.5μM DA and 70μM AA in 0.1M PBS (pH 6.0) at PBG/GCE (a) and bare GCE (b), and PBG/GCE in blank pH 6.0 PBS (c). Display omitted
•A poly(bromocresol green) modified glassy carbon electrode was simply prepared.•The modified electrode was applied for simultaneous determination of UA, DA and AA.•The modified electrode exhibited good electrocatalytic activity to UA, DA and AA.
A glassy carbon electrode modified with poly(bromocresol green) was prepared by electropolymerization process for simultaneous determination of uric acid, dopamine and ascorbic acid. The interface morphology and structure of poly(bromocresol green) film were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The simultaneous determination of uric acid (UA), dopamine (DA) and ascorbic acid (AA) in 0.1M phosphate buffer solution (pH 6.0) was carried out by differential pulse voltammetric technique. Under optimum conditions, the results show that the peaks of three species were well separated. The proposed sensor exhibited linear responses to UA, DA and AA in the ranges of 0.5–200, 0.05–10 and 0.5–1000μM, respectively. Moreover, the poly(bromocresol green) modified electrode has been successfully applied to determine UA, DA and AA in human serum samples and vitamin C tablets.
Display omitted
•An integrated paper-based platform is proposed for the HSA concentration detection.•BCG reagent and HSA concentration is induced albumin-BCG complex for RGB detection.•HAS ...concentration of 36 real-world human samples are measured.•The results are in excellent agreement of R2 = 0.9912 versus official method.
A rapid analytical platform composed of a paper-based chip (µPB-Chip) and a small analytic box is developed to determine the concentration of human serum albumin (HSA). In this study, a Bromocresol Green (BCG) reagent is dropped into the reaction area of the µPB-Chip, and the HSA concentration was derived from the R (red) value intensity of the albumin-BCG complex formed after a reaction process at 37 °C for 12 min. The effectiveness of the developed method is displayed using albumin concentrations ranging from 0 to 5 g/dL in HSA control samples. The measurement results acquired from 36 volunteer patient’s HSA samples are presented to be in good consistency with those obtained utilizing a conventional assay technique (R2 = 0.9912). Ultimately, the results show that the developed platform provides a convenient, economical and dependable method for HSA concentration detection.
According to statistics, craniocerebral injuries are often the cause of disability among the population. The choice of medicines for traumatic brain injuries is one of the most difficult problems in ...the complex treatment of such patients. Ademol (1-adamantylethyloxy-3-morpholino-2-propanol hydrochloride) is a promising medicinal substance that has a huge positive therapeutic effect of a protective act on the damaged brain and can be presented in medicinal preparations in different dosages. Therefore, the urgent task is the development of highly accurate, reliable, affordable, and fast methods of quantitative determination of ademol. The aim of the work is to study the optimal conditions for the “ademol – bromocresol green” reaction and to develop an express, sensitive and easy-to-implement method for the quantitative determination of ademol. Materials and methods. Bromocresol green (BCG) grade “chemically pure” and acetone grade “pure for analysis” were used as reagents and solvents. Analytical equipment: spectrophotometer Specord 200, electronic scales AVT-120-5DM, ultrasonic bath Elmasonic E 60H, class A measuring vessels. Results. A new method of quantitative determination of ademol by the spectrophotometric method was developed. The optimal conditions of the flow between the substance to be determined and the reagent have been studied, the concentration limits have been established, in which subordination to the basic law of light absorption is observed. A forecast of the complete uncertainty of the results of the specified method of quantitative determination was made to assess the correctness of the reproduction of the developed method in other laboratories. The proposed method is relevant according to the requirements of the State Pharmacopoeia of Ukraine. Conclusions. According to the experimental data, the method of quantitative determination of ademol can be correctly reproduced and suitable for use.
•Fe/Co-chalcogenide stabilizing Fe3O4 nanoparticles supported Mg/Al-layered double hydroxide high paramagnetic susceptibility.•The Fe3O4–SiO2/FeS-CoS/Mg/AL-LDH achieved excellent extraction ...performance towards anionic food colors.•Ion exchange, H-bond, large surface area and size-matching effect were possible mechanism.•The Fe3O4–SiO2/FeS-CoS/Mg/AL-LDH was used for the enrichment and analysis of anionic food colors in real samples.
Magnesium-aluminum layered double hydroxide (MgAl-LDH) supported on Fe3O4–SiO2 which stabilized and modified by CoS-FeS chalcogenide was prepared and characterized by FT-IR, XRD, FE-SEM, EDS and, VSM analysis. Subsequently, this prepared material was applied in a dispersive solid-phase extraction (DSPE) system for simultaneous preconcentration and determination of trace levels of disulfine blue (DSB) and bromocresol green (BCG) anionic dyes from aqueous solutions which method was followed by UV–vis spectrophotometry detection. Central composite design (CCD) was applied to optimize the contribution of operational parameters including pH, sorbent dosage, sonication extraction time, type, volume and eluent concentration on system performance. Under optimized conditions, detection and quantification limits were obtained to be 0.033 mg L−1 and 0.109 mg L−1 for DSB and 0.037 and 0.123 mg L−1 for BCG, respectively, as well as, good linearity was obtained. This novel and interesting extraction approach seem to be fast and efficient procedure for the extraction of anionic dyes from aqueous samples. The kinetics and the adsorption isotherms of dyes reveal their rapid adsorption, following a with a pseudo-first-order kinetics and Freundlich adsorption isotherm model.
