Bromothymol Research Articles

A collagen-based theranostic wound dressing with visual, long-lasting infection detection capability

Continuous wound monitoring is one strategy to minimise infection severity and inform prompt variations in therapeutic care following infection diagnosis. However, integration of this functionality in therapeutic wound dressings is still challenging. We hypothesised that a theranostic dressing could be realised by integrating a collagen-based wound contact layer with previously demonstrated wound healing capability, and a halochromic dye, i.e. bromothymol blue (BTB), undergoing colour change following infection-associated pH changes (pH: 5–6 ➔ >7). Two different BTB integration strategies, i.e. electrospinning and drop-casting, were pursued to introduce long-lasting visual infection detection capability through retention of BTB within the dressing. Both systems had an average BTB loading efficiency of 99 wt% and displayed a colour change within 1 min of contact with simulated wound fluid. Drop-cast samples retained up to 85 wt% of BTB after 96 h in a near-infected wound environment, in contrast to the fibre-bearing prototypes, which released over 80 wt% of BTB over the same time period. An increase in collagen denaturation temperature (DSC) and red shifts (ATR-FTIR) suggest the formation of secondary interactions between the collagen-based hydrogel and the BTB, which are attributed to count for the long-lasting dye confinement and durable dressing colour change. Given the high L929 fibroblast viability in drop-cast sample extracts (92 %, 7 days), the presented multiscale design is simple, cell- and regulatory-friendly, and compliant with industrial scale-up. This design, therefore, offers a new platform for the development of theranostic dressings enabling accelerated wound healing and prompt infection diagnosis.

An intelligent label using sodium carboxymethyl cellulose and carrageenan for monitoring the freshness of fresh-cut papaya

A novel intelligent label (CNCB) was prepared by casting and drying a mixed solution of sodium carboxymethyl cellulose (CMC-Na) and carrageenan, to which bromothymol blue (BTB) was fixed as the pH indicator. The CNCB label can reply the freshness of fruit through color changes according to the CO2 concentration inside the package. Variations in the three label components were investigated using Fourier transform infrared spectroscopy. Furthermore, the label morphology and structure were evaluated using scanning electron microscopy and X-ray diffractometry. Lastly, the thermal stability of the labels was analyzed using a synchronous thermal analyzer. Carrageenan enhanced the water resistance of the CMC-Na label and improved the mechanical properties. Moreover, while the BTB dye was added to visually indicate color change, its addition improved not only the physical properties but also the thermal stability of the label. The CNCB label showed different color changes in response to different CO2 concentrations. When the CNCB label was stored with fresh-cut papaya, its color changed from blue to green, yellow-green, and eventually yellow-brown as the fruit lost its freshness, displaying a strong correlation with the CO2 concentration in the package. This label prepared from CMC-Na, carrageenan, and BTB, can be used as intelligent label in monitoring the freshness of fresh-cut papaya for the excellent pH sensitivity.

Development of a paper strip test for colorimetric detection of urea in raw materials for animal feed.

Aiming at developing an easily implementable method for on-site analysis to detect urea adulteration in feed ingredients, a simple and inexpensive paper strip for urea detection via colorimetric assay is herein presented. The paper strip can be simply fabricated by immobilizing urease with bromothymol blue (BTB) as a pH indicator on cellulose fiber. Upon dipping the paper strip into the target sample, the release of ammonia during the reaction between urea in the sample and urease on the paper strip causes a pH change that results in the development of a blue color, thus indicating the presence of urea. A semiquantitative detection method was developed on the basis of the color change on the paper strip, which can be detected by naked eyes and compared with a color chart made by spiking urea at concentrations varying from 0.10% to 1.0% (w/w) in animal protein and fishmeal samples. Moreover, quantitative data were obtained by taking a picture with a smartphone camera and measuring the color intensity using ImageJ software. A comparison between BTB and phenol red as pH indicators revealed that the former afforded better results in terms of resolution. Under optimal conditions, good linear responses of blue intensity were obtained in a concentration range of 0.10%-1.0% (w/w). The recovery was determined to range between 98.1% and 118.3% with a relative standard deviation of <5%. The developed paper strip assay was applied to determine urea in animal protein and fishmeal, finding good agreement with the official AOAC method (No. 967.07). The present paper strip is rapid and requires neither sophisticated devices nor skilled personnel, allowing its use by quality controllers for the routine on-site detection of the urea adulteration of raw materials.

Biosynthesis of gold nanoparticles by Penicillium rubens and catalytic detoxification of ochratoxin A and organic dye pollutants.

The environmental pollution caused by chemical dyes is a growing concern nowadays. Limitations of traditional methods opened the route for nanotechnology; owing to the versatile properties of nanomaterials, gold nanoparticles (AuNPs) became a potential strategy for different applications. In the present study, biosynthesis of gold nanoparticles (BioAuNPs) was carried out by reacting chloroauric acid (HAuCl4) with cell-free filtrate of Penicillium rubens sp. nov. NCIM 1937. The AuNPs were then characterized by UV-visible spectroscopy, HR-TEM, FTIR, and DLS analysis to further examine their efficacious biosynthesis and morphological properties including size, shape, and stability. The biogenic AuNPs are polydisperse in nature, with a mean size of 14.92 ± 5nm. These AuNPs exhibited promising antimicrobial activity against Escherichia coli NCIM-2065, Bacillus subtilis NCIM-2010, and Penicillium verrucosum MTCC 4935. In vitro quantitative HPLC results revealed that BioAuNPs significantly inhibited the biosynthesis of ochratoxin A (OTA). Microbial fuel cells (MFCs) are intriguing for power generation and wastewater treatment since they can directly transform chemical energy stored in organic matter to electricity by extracellular electron transfer (EET) via membrane proteins. AuNPs also showed excellent potential for dye degradation of organic pollutants, viz., methylene blue (MB), phenol red (PR), bromothymol blue (BTB), Congo red (CR), and 4-nitrophenol (4-NP). All dye removal efficiencies were estimated and fitted to pseudo-first-order processes using kinetic rate constants (Ka).The present study reveals a simple, original, and eco-friendly method for the synthesis of multifunctional biogenic AuNPs that could be effective in OTA detoxification in food products and organic pollutant removal during wastewater treatment for a sustainable environment.

Potential of Titanium Dioxide to Remove Bromothymol Blue (BTB) in Aqueous Solution by Batch Mode Adsorption–Kinetic, Isotherm and Thermodynamic Studies

Potential of Titanium Dioxide to Remove Bromothymol Blue (BTB) in Aqueous Solution by Batch Mode Adsorption–Kinetic, Isotherm and Thermodynamic Studies

Smart Colorimetric Determination of Ionic Surfactants with Bromothymol Blue at the Presence of Nonionic Surfactant Triton X-100

The application of digital colorimetry for the determination of ionic surfactants, moderately hydrophobic medicinal substances of ionic nature in the system with bromothymol blue (BTB) in aqueous solutions using a smartphone has been shown. The influence of the solution nonionic surfactant Triton X-100 (TX-100) on the parameters of the colorimetric determination of bromothymol blue has been studied. It was established that the addition of TX-100 improves the linearity of the graduation dependence of the colorimetric signal of bromothymol blue (r ˃ 0.99) and reduces the detection limit of the dye by 15 %. The optimal conditions for the colorimetric determination of the cationic surface-active substance cetylpyridinium chloride (CPC), reagent concentration, and pH were established (LOD = 2.5·10-6 mol L-1, Sr ˂ 2 %). The spike recovery method checked the trueness of the results obtained in the model solutions analysis. The procedure for determining CPC in the drug "Septolete Total" was verified by the addition technique. The ability of a nonionic surface-active substance to stabilize the colloidal chemical state of solutions of hydrophobic counterions associates was used for the colorimetric determination of the anionic surfactant sodium dodecyl sulfate (r = 0.99; LOD = 7.5·10-7 mol L-1) and the less hydrophobic indomethacin (LOD = 6.6·10-6 mol L-1) with the BTB-TX-100-CPC reagent system.

Development of the Spectrophotometric Method for the Determination of Metoprolol in Tablets by using Bromothymol Blue

A simple, eco-friendly, rapid, and economic spectrophotometric method for the determination of metoprolol tartrate in tablets has been developed. The procedure for metoprolol determination is based on a reaction with bromothymol blue (BTB) in acetonitrile medium. The maximum formation of the colored product was observed in acetonitrile at the absorption maximum at a wavelength of 402 nm. The stoichiometry of molecular complexes was determined by Job's method and it was found to be 1 to 1. The optimal concentration of BTB was 1.6·10-4 M. The linear relationship between absorbance at λmax and concentration of analyte ranging 16.00-24.00 μg mL-1 was found. Regression analysis of Beer’s law plot at 402 nm yielded the regression equation, y = 0.0199x + 0.0721. High values of correlations coefficient R2 = 0.9990 and small values of intercept validated the linearity of calibration curve and obedience to Beer’s law. The calculated LOD and LOQ values were 1.90 and 5.78 μg mL-1, respectively. The proposed green spectrophotometric method is simple, rapid, and suitable for routine pharmaceutical analysis.

Spectrophotometric Methods for Determination of Clopidogrel in Bulk and in Pharmaceutical Formulations

The present article reports three simple, sensitive, and accurate spectrophotometric methods which have been progressed for monitoring of clopidogrel bisulphate (CG) in bulk and in pharmaceutical formulations. The three methods are depended on the production of yellow ion-pair complexes between the investigated drug and bromophenol blue (BPB), bromthymol blue (BTB), and bromocresol purple (BCP) as dyes in a universal buffer of pH range (2.0- 4.0). The chloroform was used for formed complexes extraction and measured at 421 nm, 414 nm, and 409 nm, respectively for the three systems. The best conditions of the reactions were tested and optimized. Beer’s law was obeyed in the concentration ranges 2.0 – 18.0 µg mL-1 with molar absorptivity of 4.4 × 104 , 6.4 × 104 and 6.9 × 104 L mol-1cm-1, for the BPB, BTB and BCP methods, respectively. Sandell’s sensitivity, correlation coefficient, quantification and detection limits are also studied. The investigated methods have been achieved successfully for the determination of the drug in pure form and in pharmaceutical formulations. Interference between common pharmaceutical excipients and additives was disappeared. Statistical comparison of the results with those observed by the HPLC method exhibits excellent agreement and shows no significant difference in terms of accuracy and precision.

Reimagining an old photosynthesis classic: Quantifying the effects of different factors on photosynthetic rates using the dye bromothymol blue

Reimagining an old photosynthesis classic: Quantifying the effects of different factors on photosynthetic rates using the dye bromothymol blue

Fabrication of Printable Colorimetric Food Sensor Based on Hydrogel for Low-Concentration Detection of Ammonia

With the increasing market share of ready-to-cook foods, accurate determination of the food freshness and thus food safety has emerged as a concern. To commercialize and popularize food sensing technologies, food sensors with diverse functionalities, low cost, and facile use must be developed. This paper proposes printable sensors based on a hydrogel-containing pH indicator to detect ammonia gas. The sensors were composed of biocompatible polymers such as 2-hydroxyethyl methacrylate (HEMA) and [2-(methacryloyloxy)ethyl] trimethylammonium chloride (MAETC). The p(HEMA-MAETC) hydrogel sensor with bromothymol blue (BTB) demonstrated visible color change as a function of ammonia concentration during food spoilage. Furthermore, polyacrylonitrile (PAN) was added to improve transport speed of ammonium ions as the matrix in the sensors and optimized the viscosity to enable successful printing. The color changed within 3 min at ammonia concentration of 300 ppb and 1 ppm, respectively. The sensor exhibited reproducibility over 10 cycles and selective exposure to various gases generated during the food spoilage process. In an experiment involving pork spoilage, the color change was significant before and after exposure to ammonia gas within 8 h in ambient conditions. The proposed sensor can be integrated in bar codes and QR codes that are easily mass produced.

Silk fibroin-based colorimetric microneedle patch for rapid detection of spoilage in packaged salmon samples

Spoiled salmon can cause foodborne diseases and severely affects human health. Herein, we report a pH-responsive colorimetric microneedle (MN) patch fabricated from bromothymol blue (BTB) and silk fibroin meth acryloyl (SilMA) (BTB/SilMA@MN patch) for sensing salmon spoilage. The needle tips of MN could penetrate food cling film and insert into fish to extract tissue fluids directly and transport the extracted fluids to the backing layer for color displaying. The color change of BTB/SilMA@MN patches depended on the pH variation resulting from the increase of total volatile basic nitrogen in salmon during storage. The color of MN patches changed from yellow to yellowish green and to final green, indicating salmon changed from fresh to medium fresh and then to putrefied, respectively. Salmon spoilage can be rapidly determined via naked eye recognition and also analyzed on a smartphone in a nondestructive way, allowing consumers to estimate food quality easily and reliably.

Fabricating κ-carrageenan/carboxymethyl cellulose films encapsulating bromothymol blue fixed rice straw fiber for monitoring meat freshness

Intelligent films monitoring food quality are potential to use in people’s life. The safety and sensitivity are of great importance. In this study, a dual synergistic design was developed to construct a safely and sensitively smart film in which quaternary ammonium groups modified rice straw fiber (CRSF) attached bromothymol blue (BTB) was embedded into an anion κ-carrageenan/carboxymethyl cellulose (CMC) matrix. SEM results revealed the good interfacial compatibility between the matrix and the modified fiber. Substitution degree (DS) of quaternary ammonium groups and addition amount of CRSF-BTBs interestingly affected the properties of the film. That containing 1% CRSF-BTB with DS of 19.3% exhibited distinguishable colorimetric response in only 3.0 s at humidity of 75.0% with 0.8 mL of ammonia, and lower BTB release rate of 2.87% in 95% ethanol solution. The film displayed visible color changes from yellow to dark-blue as meat freshness decreased. This study provides a novel strategy to develop a highly smart film for insuring the food safety.

Highly elastic halochromic fibers capable of reversible sensing of acidic/basic vapor for use in wearable textiles

Halochromic sensors, which allow users to visually recognize exposure to acid/base chemicals that are harmful to the human body, are routinely used in a wide range of industries, such as pharmaceuticals, biotechnology, cosmetics, and environmental/human monitoring systems. In this study, halochromic fibers that operate stably, even when exposed to rain or sweat and repeated stretching–releasing, were investigated. While the halochromic mesoporous silica was synthesized using tetraethylorthosilicate and cetyltrimethylammonium bromide, methyl yellow (MY) and bromothymol blue (BTB) as halochromic dyes were added so that MY and BTB were chemically or physically immobilized on the siloxane network structure of the halochromic mesoporous silica. Using the swelling and shrinking properties of the polymer, the halochromic mesoporous silica was embedded in a highly elastic spandex fiber composed of multiple strands. Because of the strong ionic and hydrogen bonding between the dye and the silica matrix, the dyes can be immobilized even in an aqueous solution without the leaching of the dyes. The stretchable halochromic fiber reversibly changed its color even after repeated exposure to acidic/basic conditions five times and could sense acid/base concentrations in the range of 0.5–10 wt %. In addition, because the halochromic mesoporous silica is tightly adhered between the stands of spandex fibers, stable color conversion properties were maintained even after stretching to 150% of the fibers and repeated 100 times. Because the halochromic fiber can be applied to lab coats, work clothes, and gloves, it is expected to be used as a wearable colorimetric sensor for daily life and industrial applications.

Ultra-fast pH determination with a new colorimetric pH-sensing hydrogel for biomedical and environmental applications

In this study that demonstrates many firsts in the literature, the acrylate derivative (BTBm) of bromothymol blue, retaining its indicator feature, was synthesized as a monomer via using an organic indicator bromothymol blue (BTB). After the structural characterization of BTBm synthesized by ourselves for the first time, copolymeric hydrogel systems were formed with three different commercial monomers in cationic (3-Acrylamidopropyl-trimethylammonium chloride / APTMACl), anionic (3-Sulfopropyl acrylate potassium salt / SPA) and neutral (acrylamide / AA) structures. Structural characterization of BTBm-based hydrogels, which was successfully synthesized by using a 0.5% methylene bisacrylamide (MBA) crosslinker, was elucidated by FT-IR spectroscopy. The morphological structures and elemental compositions of the hydrogels were examined by SEM and EDX elemental mapping analyses. The color changes of BTBm-based hydrogels, which are intended to be used as colorimetric pH sensors, were examined in different pH environments both with naked-eye and by using a UV–Vis spectrophotometer. It has been observed that APTMACl-BTBm hydrogel can be a more beneficial colorimetric pH sensor material than other BTBm-based hydrogels in terms of its ability to respond to pH changes in a wide color range, short response time, and mechanical strength performance.

Quantitative Evaluation of the Diffusion Coefficients of Aqua Ions in Hydrogels via Iron Corrosion

A method to quantitatively evaluate the diffusion coefficient of aqua ions, viz. protons and hydroxide ions, in hydrogels using iron corrosion was developed. In this paper, the locations of the anode and cathode formation, which dominate iron corrosion, were experimentally controlled using pseudosacrificial corrosion protection with conductive anticorrosion ink. First, hydrogen (atomic) generation during the process was confirmed by a chromic gel with iron-doped tungstic acids. Then, the diffusion of aqua ions generated from them was visualized using a BTB-agar hydrogel with BTB (bromothymol blue), and the diffusion coefficient of aqua ions was evaluated using Fick’s law by reading the time variation of luminance. The temperature dependence of the diffusion coefficient was also examined, and the activation energies were evaluated as 19.0 ± 5.9 and 25.9 ± 3.3 kJ/mol for hydroxide ions and proton, respectively. Furthermore, the experimentally evaluated diffusion coefficients of aqua ions were used in a computer simulation to solve the diffusion equation to predict the pH distribution. The diffusion behaviors of aqua ions by the experiment are almost consistent with the simulation results and demonstrate the feasibility of the present method.

Development of the spectrophotometric method for the determination of atorvastatin in tablets by using bromothymol blue

The aim of the work was to develop a simple, economic, fast, reliable, and eco-friendly spectrophotometric method for the determination of atorvastatin in tablets based on the reaction with bromothymol blue (BTB).&#x0D; Material and methods. A double–beam Shimadzu UV-Visible spectrophotometer, with spectral bandwidth of 1 nm wavelength accuracy ±0.5 nm, Model –UV 1800 (Japan), Software UV-Probe 2.62 was used to measure absorbance of the resulting solution. Pharmacopeial standard sample of atorvastatin calcium and BTB were provided by Sigma-Aldrich (≥98 %, HPLC). The used dosage forms of atorvastatin: tablets Atorvastatin 10 mg and 20 mg.&#x0D; Results and discussion. The method of spectrophotometric determination of the quantitative content of atorvastatin calcium based on its reaction with BTB in ethyl acetate medium has been developed. The stoichiometric ratios of the reactive components as 1:1 were obtained by the methods of continuous changes and the saturation method. Linearity regression equation was y=0.0017x+0.0496 and the obtained correlation coefficient was R2=0.9993. The linear relationship was found between absorbance at λmax and concentration of medicine in the range 15.48–154.80 µg/mL. The LOD and LOQ values were calculated to be 4.85 µg/mL and 14.71 µg/mL respectively. Spectrophotometric method for the determination of atorvastatin in tablets using BTB was developed in accordance with GAC principles.&#x0D; Conclusions. A simple, economic, fast, reliable and eco-friendly spectrophotometric method was developed for the determination of atorvastatin calcium in tablets based on the reaction with BTB and validated according to the standardized validation procedure by the standard method. It was proved that according to such validation characteristics as linearity, precision, accuracy, and robustness the proposed method met the requirements of SPhU

Ionochromism, solvatochromism and effect of dissolved gases on the spectral properties of bromothymol blue

The color of the pH indicator Bromothymol blue (BTB) changes from yellow to blue with increasing pH. The effect of some electrolytes (LiCl, NaCl, KCl, CsCl, KSCN and KClO3) and of D2O on the spectral properties of dilute solutions of BTB is explored. The results are interpreted in terms of dimerization of the dye molecules and of the different hydration that D2O induces.The effects of dissolved gases on the spectral properties of BTB is studied. Complete removal of dissolved gas is achieved. Surprising effects on the UV–vis spectra emerged. After degassing solutions, gases were re-admitted via bubbling. The gases He, Ar, N2, CO2 and CH4.were studied.The effects can be explained by presence or absence of nano- and microbubbles of gas in the solution. These allow formation of dimers and multiple association via adsorption and so affect the spectral properties of the dye molecules.

Development of a calcium hydroxide–dye kimchi ripening indicator and its application in kimchi packaging

Intelligent packaging that provides real-time information on food quality is useful for consumers. We developed a kimchi ripening indicator that can determine the ripeness of kimchi inside packaging and evaluated its applicability and limitations. The indicator was made using calcium hydroxide, which captures CO2, and four pH-sensitive dyes (cresol red, bromothymol blue, bromocresol purple, and methyl red). Fourier-transform infrared spectra of the prepared powders showed shapes similar to that of calcium hydroxide, and the dyes were evenly distributed on the calcium hydroxide surfaces. When the developed indicators were evaluated for kimchi packaging application, the indicator made from synthesized calcium hydroxide and bromothymol blue was the most reliable and clearly reflected useful kimchi ripening information. The indicator developed in this study is judged to be practically usable at temperatures of 4–15 °C. However, its usefulness is limited in that the seller cannot change the packaging capacity or kimchi capacity.

Fabrication and validation of CO2-sensitive indicator to monitor the freshness of poultry meat

Three-layer CO2-sensitive intelligent labels consisting of PET as transparent gas impermeable film, the color changing layer with pH dyes (bromothymol blue (BTB) and phenol red (PR)) immobilized with a cellulose-based binder, and a white PE film as the gas permeable inner layer. The intelligent labels were implemented in PA/PE bags for CO2 simulation at concentrations of 0–30 %, and color change (∆E and ∆RGB) was monitored at 4 °C and 25 °C for 24 h. Chicken breast was packaged with PA/PE bags integrated with the intelligent labels and the color change was monitored at 10 °C for 4 days. BTB-based indicators showed a higher color difference than PR-based indicators in simulation and poultry packaging. However, phenol red-based indicators showed a more distinct and noticeable color change. The increase in CO2 correlates well with the color change. PR and BTB-based pH sensitive dyes are successfully used to monitor poultry meat spoilage in real packaging conditions.

Novel indicator and stem-loop-primer assisted isothermal amplification for the visual semi-quantitative detection of Toxoplasma gondii

This study presents a simple, inexpensive, versatile, pH-dependent colorimetric assay, which for the first time combines the commercial colorimetric indicator bromothymol blue (BTB), and a simpler designed stem-loop-primer-assisted isothermal amplification (SPA) for the detection of Toxoplasma gondii. Compared with other existing indicators, the BTB indicator showed more obvious color change and larger data change, with yellow indicating positive and blue indicating negative. The assay can be applied to the reactions of different volumes (5–20 µL), with the color also obvious at 0.5 µL. The SPA method was further evaluated objectively, and its serious nonspecific amplification problem was resolved. Under optimal parameters, the method tolerates interference from other parasites and genomes of complex samples at extremely high concentrations. A detection limit as low as 0.072 T. gondii/µL was achieved in 90 min and 1 real fecal sample missed by PCR was detected. More accurate results can be obtained by using a smartphone based on the red signal value. Overall, this strategy not only provides a new option for signal output in conventional volume or microfluidic devices, but also the closed-tube naked-eye detection method fundamentally avoids contamination, and enables accurate and rapid detection of Toxoplasma gondii.