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OBJECTIVES: This study aims to present a method for the determination of the aluminum in antiperspirant products (APPs) by chelating it with quercetin before its detection by smartphone digital image colorimetry (SDIC). MATERIALS AND METHODS: Samples were prepared by closed-vessel acid digestion in PTFE cups. This was followed by complexation of aluminum in the sample solution using quercetin as a chelating agent. Sample solutions were transferred into a quartz ultraviolet/visible detection microcuvette for detection in a homemade colorimetric box designed for capturing images of the yellow complex with a smartphone camera. The pixel intensity of the images was converted to numbers for quantitation using ImageJ software for a personal computer. An independent study using high-performance liquid chromatography-diode-array detection was conducted to check the accuracy of the proposed method. RESULTS: Optimum SDIC conditions included a Samsung C9 smartphone as the detection camera, a cropped region of interest of 6400 px(2), and the side position of the colorimetric box were selected for capturing the images of the sample solutions placed 10.0 cm from the detection camera, whereas optimum complexation conditions were found to be as sample pH of 5.5, sample volume of 3.0 mL, complexation time of 1.0 min and a ligand concentration of 0.28 mmol L(-1). Analytical performance of the method included a limit of detection of 0.5 μmol L(-1) and a coefficient of determination (R(2)) of the calibration graph of 0.9981. CONCLUSION: The proposed method was successfully applied for the determination of aluminum in APPs with percentage recoveries ranging from 80.0 to 109.6%.

In this paper is reported the selective detection and quantification of levodopa in co-presence of carbidopa. The method took advantage of the spontaneous oxidation and color development of levodopa at basic pH here driven by alkaline earth cations and co-solvent in solution. We have shown for the first time the generation and stabilization of the purple melanochrome from levodopa, by using magnesium acetate and dimethyl sulfoxide, which was here exploited for the development of a quantitative colorimetric assay for the active principle ingredient in commercial drugs for the treatment of Parkinson’s disease. The calibration curves of levodopa in the two tablet formulations, containing carbidopa as decarboxylase inhibitor, showed a common linear trend between 10 mg L−1 and 40 mg L−1 with levodopa alone or in combination with carbidopa in standard solutions, with very good reproducibility (CVav%, 3.3% for both brand and generic drug) and very good sensitivity, with limit of quantification about 0.6 mg L−1 in any case. The colorimetric method here developed is very simple and effective, appearing as a rapid and low-cost alternative to other methodologies, involving large and expensive instrumentations, for drug estimation and quality control of pharmaceutical formulations.

Determining the authenticity of documents is an important task when conducting investigative measures. In practice, for the examination of documents to determine the prescription of their creation, a spectral method is used, in which it is necessary to make clippings from the document under study, which leads to damage to the document under study, and also requires the use of expensive equipment, which affects the price of the examination of the document. The article describes a method for determining the authenticity of a document based on computer colorimetry, which does not require expensive equipment for conducting an examination. This method for determining the authenticity of a document uses a change in the color of the strokes of a ballpoint pen over time, which is caused by the drying of the solvent in the ink of the pen, and also lacks the disadvantage of the need to damage the document under study.

Background: The tooth bleaching treatment can cause structural changes in the surfaces of the teeth; these changes can increase the absorption of staining agents. Purpose: This study assessed surface morphological changes and predisposition to staining in dental enamel bleached with different hydrogen peroxide (HP) concentrations, with or without the use of a light source (LS). Methods: 25 bovine incisor specimens were divided into five groups (n = 5): Control- no treatment; HP35 - hydrogen peroxide 35%; HP35+LED - hydrogen peroxide 35% + light emission; HP20 - hydrogen peroxide 20%; and HP7 - hydrogen peroxide 7,5%. Twenty days after bleaching, the specimens were immersed in staining solutions four hours a day for 28 days. The morphological alterations of the bovine enamel surface were evaluated by means of scanning electron microscopy, X-ray dispersive energy spectroscopy and predisposition to the staining of the brightened enamel by means of colorimetry. Results: ANOVA with Tukey's test (pp=0.176) (brightest), with a better lightening effect. The bleached groups exhibited morphological changes in the enamel. The groups did not exhibit significant changes in oxygen, calcium, and phosphorus values (p=0.020). The presence or absence of light was not significant (p=0.007) for the predisposition to staining in bleached teeth. Conclusion: The time of exposure to the staining solution was significant for staining bovine dental enamel. High concentrations of HP were not necessary for achieving effective bleaching. HP caused an increase in enamel porosity and depressions. The light source did not influence bleaching.

Water pollution has been one of the major issues of the present time. It is essential to educate students regarding this issue and its possible solutions. In this article, a demonstration of a typical adsorption-based water cleaning process is presented. The removal of methylene blue (MB) and detergent from a aqueous solution is demonstrated using rice husk as the adsorbent. Quantification of the MB removal was achieved with the help of a smartphone-based colorimetry process. This demonstration would be helpful to students for understanding the adsorption process, calibration curves, and waste management. The kinetic study of adsorption will help students learn various kinetic models and their applications.

A simple and fast method for determination of cephalexin using test papers with immobilized Fehling's reagent is reported. Color scales for the naked-eye determination of cephalexin were constructed. Based on RGB-analysis linear correlations between the intensities of the blue and green color channels, the concentration of cephalexin were obtained. Furthermore, the possibility of using radar charts for the analyte was investigated. For detection of antibiotic, the authors��� application for smartphone ��Digital colorimetric test�� was created. After loading a photo of the paper-based device, the application automatically displays the concentration of antibiotic on the screen. Moreover, for detection of the antibiotic, a small volume of sample (5 ��L) is required. The limits of detection for developed methods were from 0.13 to 0.4 mg/mL (Sr < 0.12).

Thermogravimetric analysis is an analytical technique used to determine a material's thermal stability and its fraction of volatile components by monitoring the weight change that occurs as a sample is heated at a constant rate. Differential scanning colorimetry analysis is used to measure melting temperature, the heat of fusion, latent heat of melting, reaction energy etc. Mass spectroscopy is a powerful analytical tool with many applications in pharmaceuticals and biomedical fields. The increase in sensitivity and resolution of the instrument as opened new dimensions in analysis of pharmaceuticals and complex metabolites of biological systems. Thermo gravimetry coupled with differential scanning colorimetry and Quadra pole mass spectrometry was applied to monitor the thermal stability and chemical properties of natural polymers isolated from chemically different soils. The TGA/DSC, when coupled with MS generic multiple ions from the sample under investigation, it then separates them according to a specific mass-to-charge ratio. The coupled instrument is used for simultaneous identification of organic compounds, used to evaluate the physical properties, degradation stability of powder coating.

Increasing the yield of juice and biologically active components from plant raw materials is an urgent task in the production of functional beverages. For this, fruit, berry and vegetable pulp was treated with enzymatic preparations of pectolytic action and the yield of juice was determined. Samples of pulp of each raw material were treated with enzyme preparations: Fructocyme P6-L, Fructocyme P, Fructocyme MA, in an amount of 0.03% of the pulp mass. Enzymatic hydrolysis was carried out at 50 °C for two hours, after which the amount of obtained juice was compared with the control sample. As a result, when adding Fructocyme MA to the pulp of apples and carrots, the juice yield increases by 8% and 17%, respectively. When Fructocyme P6-L is added to the pulp of kiwi, blueberries, grapes, the juice yield increases by 6%, 12 and 10%, respectively. To determine the effect of enzyme preparations on the yield of biologically active components, the previously selected enzyme preparations were added to all samples in an amount of 0.01; 0.03; 0.05; 0.07% of the pulp mass, and the total content of polyphenols was determined by colorimetry and anthocyanins. As a result of the experiment, it was found that in terms of the amount of polyphenolic substances extracted from the pulp, fruit and berry raw materials can be divided into three groups: raw materials with loose pulp, with pulp of medium density and raw materials with dense pulp. As a result, individual enzyme preparations and optimal modes of application were selected for each type of raw material. The dependence of the content of polyphenolic compounds on the dosage of the addition of enzyme preparations has been established.

The majority of chemical experiments conducted during educational programs are carried out in laboratories because they require instructors with special skills, in addition to large, expensive instruments. Recently, there has been an increasing demand for chemical experiments that can be carried out anywhere. Herein, we propose a novel type of paper-based analytical device (PAD) for enabling quantitative analysis without the requirement for a micropipette, since the PAD features a large sample loading zone and a waste zone, enabling accurate volume control of a liquid sample. We initially employed a micropipette to evaluate the PAD and demonstrate the quantitative analysis of ascorbic acid (AA) and pH using different loading volumes. Finally, we determined the AA concentrations and pH values of commercially available beverages using disposable plastic droppers, and the obtained results were in good agreement with those obtained through conventional methods. This PAD format can therefore be used as a novel educational tool for conducting certain chemical analyses in remote learning environments.

Purpose This contribution aims to introduce an effective low cost polymer-nanocomposite for possible application to achieve a super protection for highly damaged ancient Egyptian wall paintings. Design/methodology/approach SiO2 and Al2O3 nanoparticles were synthesized by the sol-gel method. Then, the polymer-nanocomposite was prepared by simple mixing and dispersing the nanoparticles into the tetraethoxysilane polymer solution, with the aid of an ultrasonic dismembrator. The application of the polymer-nanocomposite and other polymeric nanodispersions, on laboratory models, was performed by the brushing technique. Next, the materials stability was evaluated by means of digital optical microscope, colorimetry, FE-scanning electron microscope, measuring the static contact angle and water absorption rates. Findings The results were promising in creating a superhydrophobicity and the static contact angle (?S) measured for the polymer-nanocomposite reached 135o. An average of three measurements of the water absorption rate after polymer-nanocomposite treatment was 0.66 g/m2 s, compared to 2.60 g/m2 s for the control model (untreated). Further, an average of color difference (?E*) for the treated surface was 2.78, and after the accelerated thermal aging was 3.6. Observing the surface morphology, the polymer-nanocomposite enhanced the roughness of the treated surface and showed a high resistance to laboratory salt weathering. Practical implications Preparation of a polymer-nanocomposite by adding SiO2 and Al2O3 NPs to tetraethoxysilane polymer has been proposed. As a promising conservation material, the produced polymer-nanocomposite helped to form an efficient protective film. Originality/value This paper attains to develop an economic polymer-nanocomposite to maintain a high protection to damaged ancient Egyptian wall paintings and similar objects.

The aim of this study is to develop a universal, rapid and affordable method for the identification of dydrogesterone, troxerutin, and ademetionine in drugs by multisensor digital colorimetry using a unique two-dimensional code. The developed approach can be applied to rapid detection of counterfeit drugs at the preliminary stage of the analysis (before using more expensive specialized equipment). Materials and methods. To implement the proposed approach, the substances of dydrogesterone (“Abbott Biologicals B.V.”, Netherlands), troxerutin (JSC “Interfarma”, Prague, Czech Republic) and ademetionine (LLC “Farmamed”, Moscow, Russia) , troxerutin capsules 300 mg (LLC “Pranafarm”, Samara, Russia), lyophilisate for an intravenous solution and the intramuscular administration “Heptral” ® (ademetionine) 400 mg (“Abbott Laboratories”, GMBH, Germany), tablets “Duphaston” ® (dydrogesterone) 10 mg (“Abbott Healthcare Products B.V.”, Netherlands), were used. A multisensor colorimetry method has been implemented using the following set of 8 sensors (C 1 -C 8 ): an intact solution – a 96% (v/v) aqueous ethanol solution – C 1 ; 1 mM alcoholic solution of anthraquinone green (CAS#4403-90-1) – C 2 ; a 0.2% aqueous solution of 3-methylbenzothiazolinone hydrazone (CAS#1128-67-2) – C 3 ; a 0.2% methyl orange aqueous solution (CAS#547-58-0) – C 4 ; a 1 mM alcoholic solution of sulforhodamine B (CAS#3520-42-1) – C 5 ; a 1 mM alcoholic solution of 1-hydroxypyrene (CAS#5315-79-7) – C 6 ; 1 mM alcoholic solution of allura red AC (CAS#25956-17-6) – C 7 ; a 1 mM aqueous solution of iron (III) chloride – C 8 . Transparent flat-bottomed polypropylene plates with 96 cells, with a cell volume of 350 µl (Thermo Fischer Scientific, USA, cat. No. 430341) were used as a base for the chip. For obtaining raster images, an Epson Perfection 1670 office flatbed scanner (CCD-matrix) with a removable cover was used. The obtained digital images of the cells were processed using the ImageJ software (Wayne Rasband, National Institutes of Health, USA; http://imagej.nih.gov/ij) with a 24-bit RGB color model (8 bits per channel). Results. The adequacy of the developed approach was confirmed by the analysis of the above-listed drugs. It has been shown that the results obtained have no statistically significant differences from the values determined by the spectrophotometric method. Conclusion. The possibility of using multisensor digital colorimetry for pharmaceutical analysis has been shown. The developed methods for the identification of the active substances can serve as a good supplement to the more expensive traditional methods.

V6O13 nanobelts with good crystallinity and distinct facets were prepared by a facile one-pot hydrothermal method and were first found to possess the peroxidase-mimicking activity. A simple colorim...

Flap endonuclease 1 (FEN1) is a structure-specific nuclease that cleaves the 5' single-stranded protrusion (also known as 5' flap) during Okazaki fragment processing. It is overexpressed in various types of human cancer cells and has been considered as an important biomarker for cancer diagnosis. However, conventional methods for FEN1 assay usually suffer from complicated platform and laborious procedures with a limited sensitivity. Here, we developed a dual-signal method for sensitive detection of FEN1 on the basis of duplex-specific nuclease actuated cyclic enzymatic repairing-mediated signal amplification. Once the 5' flap of the double-flap DNA substrate was cleaved by target FEN1, the cleaved 5' flap initiated strand-displacement amplification to produce plenty of G-rich DNA (G) sequences. These G sequences that self-assembled into G-quadruplexes in the presence of hemin revealed horseradish-peroxidase-like catalytic activities as well as fluorescence enhancement of thioflavin T. The UV-vis signal showed a good linear relationship with the logarithm of FEN1 activity ranging from 0.03 to 1.5 U with a detection limit of 0.01 U. The fluorescence signal correlated linearly with the logarithm of FEN1 activity ranging from 0.001 to 1.5 U with a detection limit of 0.75 mU. In addition, FEN1 can be visualized not only by colorimetry but also by fluorescence (under ice-water mixture conditions). This reliable, accurate, and convenient method would be a potential powerful tool in point-of-care testing applications and therapeutic response assessment.

The measurement of aerosol acidity is important to have a comprehensive understanding of aerosol chemistry, the adverse health effects of particulate matter, and climate. The Colorimetry Integrated with CAMera (CICAM) method is demonstrated to detect the color change of a filter (impregnated with an acid indicator), after the application of an acidic aerosol, using digital images. The CICAM images were analyzed by a computer program that employs the Matplotlib Library in python to decouple the camera image to the Red-Green-Blue (RGB) scale. The calibration of the CICAM method for the detection of proton concentration ([H+], mol L−1) in aerosol was performed with regard to the change of the G color component. The Colorimetry integrated with Reflective UV spectrometry (C-RUV) method that has recently been developed to detect [H+] in aerosol collected on a dyed filter using a micro-UV spectrometer can provide a lower uncertainty and a limit of detection that is an order of magnitude lower than the CICAM method, but is significantly more expensive. The CICAM method allows for the online detection of aerosol acidity utilizing a commercialized camera and LED light. The relationship between CICAM and C-RUV was also demonstrated by translating C-RUV spectral data into RGB values. Remarkably, the Green values measured by CICAM were statistically similar to the Green values obtained from C-RUV data. Therefore, we conclude that the CICAM and C-RUV method are comparable in their use for the prediction of proton concentration. Copyright © 2021 American Association for Aerosol Research

Enriching the micronutrient content of staple crops via biofortification provides a sustainable solution to iron (Fe) and zinc (Zn) deficiency in food. Analytical techniques such as colorimetry, at...

Estimating the degree of hydrolysis (DH) of commercial protein hydrolysates from their molecular weight (MW) median values generated by high performance size exclusion chromatography with UV detection (HPSEC/UV) was evaluated. DH is defined as the proportion (%) of cleaved peptide bonds in a protein hydrolysate. Several methods for DH determination are available, and protein hydrolysates are often tested both for DH by one of these methods and for MW profile by an HPSEC/UV method. We describe a means of estimating the DH of a protein hydrolysate from its MW profile, thereby eliminating the need for the performance of a second, separate test. In this study, a plot of average DH (%) vs. MW median (Da) was constructed from pancreatin digestion time data for seven protein substrates, determined by an HPSEC/UV system with a peptide gel filtration column. A general formula obtained from the plot enables DH estimation for a protein hydrolysate from its MW median value. By using this approach, the DH values for a total of thirteen commercial protein hydrolysates derived from whey, casein, and soy were estimated. Method accuracy was assessed by comparing the MW median-estimated DH to the DH determined by TNBS colorimetry, which generally agreed well, with R2 > 0.95. This study demonstrated that a reliable estimate of protein hydrolysate DH may be obtained from its MW median so that the performance of a separate DH test may not be necessary.

Since multicolor switch was involved in both Sr2+-related flame and precipitation reactions, these reactions can be thus utilized for constructing a complementary atomic flame/molecular colorimetry dual-mode sensing platform for a sensitive and wide-range analysis of cancer cells by virtue of the gas generation from platinum nanozyme-mediated hydrogen peroxide decomposition.

A simple and affordable method is developed for the simultaneous determination of high concentrations of copper(II) and nickel(II) in an aqueous solution in the form of colored aqua complexes by digital colorimetry using an office flatbed photo scanner. The validity of the proposed approach is proved by the analysis of the standard nickel silver sample. The accuracy of the results of determining copper and nickel in a metal alloy by digital colorimetry and spectrophotometry differs insignificantly.

The relevance of the research lies in the use of conventional software products distributed under the GNU license to assess staining of histological material based on the analysis of photomicrographs. The purpose of the study is to demonstrate the opportunities of conventional software distributed under the GNU license, designed for color analysis of photos in histology to identify differences in tinctorial properties of tissues. The authors evaluated the opportunities of the Color Analysis program launched in the Android Nox Player 6.6.1.0 emulator (GNU license) under Windows 10 for color analysis of photomicrographs of various tissues histological sections. Photomicrographs of paraffin sections of 5 microns thick were obtained using a micro-microscope Mikmed-5 using a Levenhuk C800 NG 8M video eyepiece, USB 2.0. A white light lamp Feron G4 4000 K was used as an illuminator. In color analysis of photomicrographs stained with hematoxylin and eosin, or hematoxylin and Congo red, or by Unna, or by the designer three-color amyloid staining in the Color Analysis program, color separation patterns were obtained that reflect the relative area (%) of the field of view staining with shades characteristic for this method of staining. The authors formulate the standard conditions for the preparation of histological specimen and conditions for photographing micro-preparations to obtain comparable results in an experiment with the control-experience design. It is concluded that the program color analysis provides a significant amount of additional information about the histological material, which can be formalized and studied as statistical values.

Рассмотрены преимущества и недостатки метода количественной цветометрии для оценки устой-чивости полимерных и композиционных материалов на основе поливинилхлорида и полифениленсульфида при воздействии высоких температур и света. Проанализированы кинетические закономерности и особенности изменения цветового различия и цветовых характеристик при термо-, фото- и фототермической деструкции. Оценены энергии активации процессов. Показана перспективность кинетического подхода для оценки характеристик деструкции и прогнозирования устойчивости.

Introduction: Electrolyte abnormalities are known to cause significant morbidity and mortality, when it is not detected. Dyselectrolytemias are usually treatable. Hyponatremia is a common manifestation encountered in the elderly. The rural health care facilities may not have well equipped laboratories. Therefore, this study intended to look for the possibility of establishing a screening technique that can help detect hyponatremia in such centres. Materials and Methods: Serum sodium levels were estimated in 120 samples using direct, indirect ISE and colorimeter. Statistical analysis was done using SPSS version 17, NCSS 11 and MINITAB 18 software. A p value Results: A simple linear regression analysis was done and a regression equation was derived for sodium levels while comparing between the instruments. The Bland Altman analysis gave an agreement limit of 95% between the instruments which is well within the CLIA suggested target value of ±4 mmol/L in the hyponatremic and normonatremic range. Conclusion: The derived regression equation calculates a predicted value for direct and Indirect ISE using the values obtained on the colorimeter making it comparable on all the three instruments in the hyponatremic and normonatremic ranges. The colorimetric method can be used as a cost effective screening technique to identify the hyponatremic elderly for whom a tertiary hospital may not be accessible, thus facilitating early intervention. Keywords: Serum sodium, Direct ISE, Indirect ISE, Colorimetry, Hyponatremia.

Highly sensitive solid-phase colorimetry for nickel ion was demonstrated using an improved reflection colorimeter equipped with a coaxial optical-fiber cable. The nickel complex with α-furil dioxime was collected on a small-size membrane filter embedded in a disposable syringe filter unit. The leading edge of the optical-fiber cable was connected to the syringe filter unit via a Luer-lock fitting, and the color intensity of the sample on the filter was evaluated accurately. The detection limit was 0.8 ng in 2.5 mL of the complex solution (0.3 μg L−1). This improved configuration is applicable to highly sensitive on-site analysis without expensive instruments nor high laboratory skills.

Plasmonic nanoparticles functionalized by organic molecules appear to be a promising approach for developing detection systems for effective, simple, sensitive, selective, and cost-effective colori...

A novel sensitive, selective, and reversible tin(IV) ion optical sensor was prepared depends on the incorporation of amino-4-(3-nitrophenylazo)pyridine-3-ol, (ANPAP) and sodium tetraphenylborate (N...

The damage to blood coagulation factor XIII (FXIII) at different stages of its enzymatic activation under the action of various physiological amounts of hypochlorite ion was studied. The results obtained by HPLC-MS/MS, SDS-PAGE, and colorimetry showed that, during the conversion of FXIII to FXIIIa, the vulnerability of FXIII to hypochlorite-induced oxidation increased. FXIII oxidized with 150 μM hypochlorite completely retained its enzymatic activity inherent to the intact protein, whereas FXIIIa treated with 50 μM hypochlorite showed sharply reduced enzymatic activity. It was shown that a number of methionine and cysteine residues on the catalytic subunit can perform antioxidant function; additionally, the regulatory subunits of FXIII-B contribute to the antioxidant protection of the catalytic center of the FXIII-A subunit, which, together with the tight packing of the tetrameric structure of the FXIII proenzyme, are the three factors that provide high protein resistance to the oxidizing agent.

Background Rapid, reliable, and widespread testing is required to curtail the ongoing COVID-19 pandemic. Current gold-standard nucleic acid tests are hampered by supply shortages in critical reagents including nasal swabs, RNA extraction kits, personal protective equipment, instrumentation, and labor. Methods To overcome these challenges, we developed a rapid colorimetric assay using reverse-transcription loop-mediated isothermal amplification (RT-LAMP) optimized on human saliva samples without an RNA purification step. We describe the optimization of saliva pretreatment protocols to enable analytically sensitive viral detection by RT-LAMP. We optimized the RT-LAMP reaction conditions and implemented high-throughput unbiased methods for assay interpretation. We tested whether saliva pretreatment could also enable viral detection by conventional reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Finally, we validated these assays on clinical samples. Results The optimized saliva pretreatment protocol enabled analytically sensitive extraction-free detection of SARS-CoV-2 from saliva by colorimetric RT-LAMP or RT-qPCR. In simulated samples, the optimized RT-LAMP assay had a limit of detection of 59 (95% confidence interval: 44–104) particle copies per reaction. We highlighted the flexibility of LAMP assay implementation using 3 readouts: naked-eye colorimetry, spectrophotometry, and real-time fluorescence. In a set of 30 clinical saliva samples, colorimetric RT-LAMP and RT-qPCR assays performed directly on pretreated saliva samples without RNA extraction had accuracies greater than 90%. Conclusions Rapid and extraction-free detection of SARS-CoV-2 from saliva by colorimetric RT-LAMP is a simple, sensitive, and cost-effective approach with broad potential to expand diagnostic testing for the virus causing COVID-19.

Introduction. One of the urgent problems of medicine and biology is the use of plant objects as industrial producers of target metabolites in vitro. In vitro cells can be used as pharmaceutical preparations. Study objects and methods. The present research featured medicinal plants that grow in the Siberian Federal district and are a popular source of medicinal raw materials. The physicochemical properties, e.g. total ash content in extracts, the content of heavy metals, the content of organic solvents in the extracts, and the mass loss upon drying was determined by standard methods. The antimicrobial properties of in vitro extracts were determined by the diffusion method and the method based on optical density measurement. The list of opportunistic and pathogenic test strains included the following microorganisms: E. coli ATCC 25922, S. aureus ATCC 25923, P. vulgaris ATCC 63, P. aeruginosa ATCC 9027, and C. albicans EMTC 34. The number of viable cancer cells was determined using the MTT colorimetric method. Results and discussion. The paper describes the physicochemical properties, safety indicators, antioxidant activity, antimicrobial activity, and antitumor properties of extracts of a complex of biologically active substances obtained in vitro from the dried biomass of callus and suspension cell cultures and root cultures. The root extracts proved to have the maximum antimicrobial and cytotoxic properties. They could reduce the survival rate of cancer cells to 24.8–36.8 %. Conclusion. The research featured extracts obtained from the dried biomass of callus and suspension cell cultures and root cultures in vitro of safflower leuzea (Leuzea carthamoides L.), Rhodiola rosea (Rhodiola rosea L.), various sorts of skullcap (Scutellaria baicalensis L., Scutellaria andrachnoides L., Scutellaria galericulata L.), Potentilla alba (Potentilla alba L.) and ginseng (Panax L.). The results showed that the extracts can be used for the production of pharmaceuticals and biologically active additives with antitumor, antimicrobial, and antioxidant properties.

We developed a dual-modal colorimetric and photothermal assay for glutathione (GSH) using MnO2 nanosheets prepared with environmentally friendly materials. The nanosheets were synthesized by using ascorbic acid present abundantly in lemon and orange juices to reduce KMnO4. The as-prepared MnO2 nanosheets display oxidase-like activity and can catalyze the oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB), yielding a blue oxidative product (oxTMB) that exhibits a UV–Vis absorption peak at 652 nm. In the presence of GSH, the MnO2 nanosheets are reduced and decomposed, resulting in a decrease in the peak intensity. The colorimetric assay offers a wide dynamic range (0.1–100 μM) and a detection limit of 100 nM. The MnO2 nanosheets are also efficient in converting photoenergy to thermal energy, with a photothermal conversion efficiency of 23.3%. The temperature change, after near-infrared (NIR) irradiation at 808 nm, can be easily measured by an inexpensive pen-type thermometer. This effect can also be used for GSH quantification and expands the GSH concentration detection to the range from 6.0 to 200 μM. The viability of our dual-modal assay for clinical applications was demonstrated with successful analyses of GSH in human serum samples.

Objective: This study aimed to determine the effects of dimer captosuccinic acid-coated Fe3O4 (super paramagnetic) nanoparticles (NP) on 2-deoxy-d-glucose in targeted cancer cells with high rates of glucose metabolism. Methods: We prepared Fe3O4@DMSA NP and 2-DG-conjugated Fe3O4@DMSA NP, γ-FE, O, and @DMSA-DG NP. Glucose consumption in MDA-MB-231 and MCF-7 breast cancer cells was determined using γ-Fe2O3@DMSA NP or Fe3O4@DMSA-DG NP, and absorption was tested using Prussian blue staining, ultraviolet colorimetry, and magnetic resonance imaging. Results: Glucose consumption was the highest in MDA-MB-231, and the lowest in human mammary epithelial cells (HMEPiC). The significant uptake of Fe2O3@DMSA-DG NP by MDA-MB-231 and MCF-7 cells within two hours was inhibited by glucose. The uptake of Fe3O4@DMSA-DG NP was significantly higher in MDA-MB-231 than in MCF-7 cells, whereas Fe3O4@DMSA NP was not obviously uptaken by either cell line. Absorption was also not evident in HMEPiC incubated with Fe3O4@DMSA-DG NP and Fe3O4@DMSA NP. Conclusions: The tumor targeting efficacy of 2-DG coated Fe3O4@DMSA NP was improved over Fe3O4,@DMSA NP in cancer cells with high rates of glucose metabolism.

The success of pancreas islet isolation largely depends on donor characteristics, including extracellular matrix composition of which collagen is the main element. We hypothesized that isolation yields are proportional to collagen digestion percentage, and aimed to determine a threshold that predicts isolation success. The amount of pancreas collagen (I-V) was determined using colorimetry prior to and after the digestion process in 52 human islet isolations. Collagen I-V and VI were also assessed histologically. We identified a collagen digestion threshold of ≥ 60% as an independent factor beyond which an islet preparation has a ninefold increased odds of yielding ≥ 250 000 islet equivalents (IEQ) (P = 0.009) and a sixfold increased odds of being transplanted (P = 0.015). Preparations with ≥ 60% collagen digestion (n = 35) yielded 283 017 ± 164 214 IEQ versus 180 142 ± 85 397 in the < 60% collagen digestion group (n = 17) (P = 0.016); respectively 62.9% versus 29.4% of those were transplanted (P = 0.024). Common donor characteristics, initial collagen content, enzyme blend, and digestion times were not associated with collagen digestion percentage variations. Donor age positively correlated with the amount of collagen VI (P = 0.013). There was no difference in islet graft survival between high and low digestion groups. We determined that a 60% pancreas collagen digestion is the threshold beyond which an islet isolation is likely to be successful and transplanted.

Copper pollution poses a serious threat to the aquatic environment; however, in situ analytical methods for copper monitoring are still scarce. In the current study, Escherichia coli Rosetta was genetically modified to express OprF and ribB with promoter Pt7 and PcusC, respectively, which could synthesize porin and senses Cu2+ to produce riboflavin. The cell membrane permeability of this engineered strain was increased and its riboflavin production (1.45–3.56 μM) was positively correlated to Cu2+ (0–0.5 mM). The biosynthetic strain was then employed in microbial fuel cell (MFC) based biosensor. Under optimal operating parameters of pH 7.1 and 37°C, the maximum voltage (248, 295, 333, 352, and 407 mV) of the constructed MFC biosensor showed a linear correlation with Cu2+ concentration (0.1, 0.2, 0.3, 0.4, 0.5 mM, respectively; R2 = 0.977). The continuous mode testing demonstrated that the MFC biosensor specifically senses Cu2+ with calculated detection limit of 28 μM, which conforms to the common Cu2+ safety standard (32 μM). The results obtained with the developed biosensor system were consistent with the existing analytical methods such as colorimetry, flame atomic absorption spectrometry, and inductively coupled plasma optical emission spectrometry. In conclusion, this MFC-based biosensor overcomes the signal conversion and transmission problems of conventional approaches, providing a fast and economic analytical alternative for in situ monitoring of Cu2+ in water. © 2020 Wiley Periodicals LLC

The effects of calcium hydrogen phosphate on lead (Pb) uptake by cowpea (Vigna unguiculata) were investigated in a growth chamber experiment coupled with atomic absorption spectrophotometry (AAS) and colorimetry analyses. Cowpea seeds were planted and harvested in soil samples treated with Pb+2 added as lead nitrate at the rates of 0, 1000 and 3000 mg/kg followed by calcium hydrogen phosphate (CaHPO4) at 0, 10, 50 and 250 mg/kg. Increases in shoot yield brought about by phosphate fertilization were observed to oppress the shoot lead concentration as a result of growth dilution, where the actual amount of lead in shoots was unaffected by phosphate treatment. This work revealed that there is no substantial effect on lead uptake by cowpea, as a result of phosphate fertilization. Therefore, phosphate fertilization is a good means of cowpea production with minimal lead uptake and hence safe for human consumption

Sanitizing solutions against bacterial and viral pathogens are of utmost importance in general and, in particular, in these times of pandemic due to Sars-Cov2. They frequently consist of chlorine-based solutions, or in the direct input of a certain amount of chlorine in water supply systems and swimming pools. Colorimetry is one of the techniques used to measure the crucial persistence of chlorine in water, including household chlorine test kits commonly based on colorimetric indicators. Here, we show a simple and cheap colorimetric method based on 3,3′,5,5′-tetramethylbenzidine (TMB), commonly used as chromogenic reagent for enzyme-linked immunosorbent assays. TMB is converted by chlorine to a colored molecule through a pH-dependent multi-step oxidation process where the chromaticity of TMB is directly proportional to chlorine content. This molecule offers several advantages over other commonly used reagents in terms of safety, sensitivity, and, peculiarly, hue modulation, giving rise to the detection of chlorine in water with a multi-color change of the indicator solution (transparent/blue/green/yellow). Moreover, through the appropriate setting of reaction conditions, such coloration is finely tunable to cover the range of chlorine concentration recommended by international health agencies for treatment of drinking water and swimming pools and to test homemade solutions prepared by dilution of household bleach during health emergency events such as during the current pandemic. Graphical abstract Electronic supplementary material The online version of this article (10.1007/s00216-020-02918-9) contains supplementary material, which is available to authorized users.

Satureja montana L. has several biological properties related to its diverse composition of secondary metabolites. Nevertheless, it has been mainly studied for its essential oil, with only a few studies on the profile and bioactivities of the bioactive compounds from its leaf extracts being reported. This work aimed to study the antioxidant activity (by oxygen radical absorbance capacity (ORAC) assay), antimicrobial minimum inhibitory and bactericidal concentrations (MIC and MBC) determination, antibiofilm (by colorimetry), impact upon DNA (anti- and pro-oxidant assay), and cytotoxicity (by cell metabolism viability assays) of S. montana extracts obtained by high-pressure-assisted extraction (HPE). The extract obtained at 348 MPa, 35% (v/v) ethanol presented the highest concentration of individual phenolic compounds, and a minimum bactericidal concentration of 20 mg/mL against Listeria monocytogenes. HPE extracts showed antioxidant activity not only in ORAC but they were also able to prevent/attenuate peroxide-induced damage upon DNA. Moreover, on its own, HPE extract induced less oxidative damage than the control extract. Concerning the cytotoxicity, HPE extracts (at 0.5 and 1.0 mg/mL) were not harmful to HT29 cell lines, while control extracts (obtained at atmospheric pressure) at higher concentrations (&gt, 1.0 mg/mL) slightly reduced the metabolism of the cells. Finally, all extracts showed inhibition of the viability of 3 cancerous cell lines (&gt, 2.0 mg/mL for Caco-2, HeLa, and TR146) to below 15%.

In the restoration field and the cultural heritage, the treatment of colour is very important, being an important factor for the decisions and interventions in historic buildings. However, some of these have not the same recognition and protection by authorities, being really vulnerable, especially against natural phenomena like the earthquakes. After the 2017 Puebla Earthquake, the remainders of the earthen architecture of Jojutla de Juarez were collected to be analysed. Natural clays of the quarries near the town were compared by colorimetry tests with the traditional adobe samples which were collected in the locality. There also were conducted particle size analysis and the Unified Soil Classification System, USCS, to obtain the composition and properties of the soils and the adobe bricks, as well as the additives used, mainly straw as fibre reinforcements of the adobe masonry. One of the factors observed which contributed to change the colorimetric values of the clays was the use of stabilizers like lime, on the other hand, these stabilizers also helped to change the USCS classification of the soils and their cohesive properties.

The reported fluorescent dye–based artificial light–responsive oxidase mimics are suffering from their low catalytic efficiency. To overcome the limitation, we report the photooxidase-mimicking activity of Eosin Y which can catalyze the oxidation of various chromogenic substrates such as 3,3′,5,5′-tetramethylbenzydine (TMB), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 3,3′-diaminobenzidine (DAB), and o-phenylenediamine (OPD) by dissolved oxygen. The photooxidase-like activity of Eosin Y is highly efficient for TMB substrate, and its catalytic efficiency is higher than that of the reported fluorescein (130 fold) and 9-mesityl-10-methylacridinium ion (7.7-fold) mimetic photooxidase. Moreover, the photosensitized Eosin Y-TMB chromogenic system is utilized for colorimetric detection of highly toxic and explosive sodium azide (NaN3) in a linear range from 5 to 500 μM with a limit of detection of 3.5 μM. The resulting colorimetric assay is selective and applied to determine NaN3 in real lake water samples.

Hydrogen peroxide (H2O2) is widely involved in various physiological or pathological processes such as cell differentiation, proliferation, tumorigenesis, and immune responses. The accurate detection of H2O2 is highly required in many situations ranging from chemical sensing to biomedical diagnosis. However, it is exceedingly challenging to develop a single sensor that can respond to H2O2 in different conditions. Herein, a three-in-one stimulus-responsive nanoplatform (Au@MnO2@Raman reporter) was designed for colorimetry/SERS/MR tri-channel H2O2 detection which satisfied different applications. The MnO2 shell acted as a distance mediator between the gold nanoparticle (Au NP) core and the Raman reporter layer. In the presence of H2O2, the MnO2 shell is degraded, thus releasing the Mn2+ and Au NP core, which act as magnetic resonance (MR) and colorimetry signals, respectively. Simultaneously, the Raman reporters adsorb on the exposed Au NPs, resulting in the surface-enhanced Raman scattering (SERS) effect. The Au NP-based colorimetric assay was employed as H2O2 sensors for glucose detection while the turn-on signals of SERS and MR were used for H2O2 sensing and imaging in live cells and tumors, showing great versatility and flexibility of the multichannel probes in diverse situations.

To eliminate the occurrence of false positives and improve the accuracy of measurement results in the process of environmental detection, a single-switch dual-mode nanosensing method should be deve...

Background: Ethanol is considered as a toxic compound when used in excess amounts. The toxic concentration for ethanol was reported to be 1000 – 2000 μg.mL-1 in plasma and serum samples. The aim of the current study was to develop a rapid and catalyst free colorimetric method for determination of ethanol in exhaled breath condensate (EBC) sample. Methods: A redox reaction with dichromate-based colorimetric method was used for determination of ethanol in EBC. Results: The proposed method shows a good sensitivity and selectivity for ethanol in compared with other compounds and biomarkers existing in EBC. The color change can be easily observed by the naked eye in the presence of ethanol in the range of 300 - 8000 μg.mL-1. The quantitative detection of ethanol was fully validated and used for determination of ethanol in EBC of alcohol administrated individuals. Conclusion: This catalyst free colorimetric method has great potential for ethanol determination owing to many desirable properties such as high reliability, high sensitivity, and fast response time.

In view of the fact that a large amount of formaldehyde was involved in the production of urea–formaldehyde fertilizer, and the residual and decomposed formaldehyde has never been paid attention to. In this paper, the determination method of free formaldehyde content in urea–formaldehyde fertilizer was studied. A simple and accurate method for the determination of formaldehyde in urea–formaldehyde fertilizer was established based on the screening of traditional iodometry titration and acetylacetone colorimetry. The recovery rate of titration method and colorimetric method were 73.9–94.5% and 96.5–103.9%, which indicated that colorimetric method was more accurate. The optimized test conditions are as follows: fertilizer/water extraction ratio 1/20, developer acetylacetone 6 mL, the condition of reacting at 60 °C for 30 min. The linear range of formaldehyde content in urea–formaldehyde fertilizer determined by optimized method is 0.21–3.26 g/mL.

A DNA aptamer screening method for human immunoglobulin G (IgG) Fc fragments was established based on capillary electrophoresis- systematic evolution of ligands by exponential enrichment (CE-SELEX). The purity, charged properties and non-adsorptivity of the samples of IgG, Fc and Fab were analyzed by capillary zone electrophoresis (CZE), and their affinity with ssDNA libraries was compared. The results showed that IgG formed significant complex with the ssDNA libraries, while Fc and Fab fragments exhibited weak affinity with the ssDNA libraries. Therefore, the use of the Fab fragment as the reverse screening target had no significant effect on the sequence except for the specific binding of Fc. The aptamer screening strategy for Fc fragments was designed. Aptamers (Seq Fc1–3) were obtained under optimized incubation conditions (10 mmol/L Na2HPO4-KH2PO4 (pH 7.17), 0.05 mmol/L Mg2+, incubated at 37 °C for 25 min) by three rounds of CE-SELEX, with KD values of 0.071–0.321 μmol/L, and their affinity and specificity were verified by AuNPs colorimetry assay.