Color Reaction Research Articles

Diversity, Chemical Constituents, and Biological Activities of Endophytic Fungi Isolated From Ligusticum chuanxiong Hort.

The objective of this study was to evaluate the diversity of endophytic fungi of different parts of Ligusticum chuanxiong Hort (CX) and further characterize their biological activities and identify chemical compounds produced by these endophytic fungi. A total of 21 endophytic fungi were isolated and identified from CX. Penicillium oxalicum, Simplicillium sp., and Colletotrichum sp. were identified as promising strains by the color reaction. Comparing different organic extracts of the three strains, it was observed that the ethyl acetate extract of Penicillium oxalicum and Simplicillium sp. and the n-butanol extract of Colletotrichum sp. showed significant antioxidant and antibacterial activities. The ethyl acetate extracts of Penicillium oxalicum had outstanding antioxidant and antibacterial effects, and its radical scavenging rates for ABTS and DPPH were 98.43 ± 0.006% and 90.11 ± 0.032%, respectively. At the same time, their IC50 values were only 0.18 ± 0.02 mg/mL and 0.04 ± 0.003 mg/mL. The ethyl acetate extract of Penicillium oxalicum showed MIC value of only 0.5 mg/mL against Escherichia coli and Staphylococcus aureus. By liquid chromatography-mass spectrometry (LC-MS), we found that Penicillium oxalicum could produce many high-value polyphenols, such as hesperidin (36.06 μmol/g), ferulic acid (1.17 μmol/g), and alternariol (12.64 μmol/g), which can be a potential resource for the pharmaceutical industry. In conclusion, these results increase the diversity of CX endophytic fungi and the antioxidant and antibacterial activities of their secondary metabolites.

DOPAMINE, AND ITS EFFECT ON THE HUMAN BRAIN

In this article, we look at how dopamine acts on our body, and what positive and negative can be seen behind dopamine. Of course, such an important hormone deserves much more careful consideration. Dopamine is responsible for motivation in our body. But do not think that "this is why I am so lazy - dopamine is not enough," no you are lazy simply, because lazy or there is no need to strain. Dopamine is produced behind the "motivation," and not in front of it. Because there is no desire - then there is no dopamine. There is a desire - here is dopamine to help, just act. Yes, people are different, someone can naturally have an overpriced background of dopamine, impulsive people who 5 minutes ago decided to buy a mobile phone and are already calling the store, even if they do not need it. But the vast majority live stably and smoothly and strain, there is no need to try. The association of a lack of dopamine with Parkinson's disease was established by Gornikevich using a fairly simple color reaction. However, the role of dopamine as a neurotransmitter was revealed by another scientist - Arvid Karlsson (Nobel Prize in Physiology or Medicine for 2000). Before him, dopamine was considered only a precursor to noradrenaline, and not a signalling substance. It was in Karlsson's experiments with reserpine that a direct connection was established between the level of dopamine and motor functions. With the development of biochemistry and molecular biology, it became possible to study in more detail the functions of this neurotransmitter. From his role in coordinating movements to explaining the actions of some antipsychotics and psychostimulants. Also, many researchers consider metabolic disorders of this neurotransmitter as one of the causes of schizophrenia, i.e., there is a "dopamine theory of schizophrenia."

A Novel Chromogenic Scheme for the Determination of Cu(II) in Water Samples

In the present study, a novel chromogenic scheme for the determination of copper(II) using thiocyanate and variamine blue has been proposed. The proposed spectrophotometric method is based on the reaction of copper(II) with potassium thiocyanate which leads to the formation of thiocyanogen. The thiocyanogen formed subsequently oxidizes variamine blue to violet coloured dye cation which gives maximum absorbance at 550 nm. Beer’s law was obeyed in the concentration range 0.05-7.0 µg mL-1. The detection limit and quantification limit were found to be 7.8×10-3 μg mL-1 and 2.3×10-2 μg mL-1 respectively, for the coloured system. The molar absorptivity and Sandell’s sensitivity were found to be 6.646×103 L mol-1cm-1 and 9.5×10-3 μg cm-2, respectively. The effect of reagent concentration, pH, time, temperature on the color reaction were investigated and the required conditions for the method were optimized. The effect of various interfering species were also studied, and it was found that most of the ions did not interfere. The method is simple, rapid, cost-effective, comparably sensitive, highly selective, non-extractive, does not involve any tedious synthetic step and the recommended procedure has good accuracy and precision. The method was successfully applied for the determination of copper in different water sample and recovery percentage was found to be between 97.0 % to 99.4 % for different environmental matrices.

Spectrophotometric determination of atenolol via oxidation and bleaching color reaction for methyl red dye

A selective and sensitive spectrophotometric method has been suggested for the quantitative assay of atenolol (ATNL) as pure and in its manufactural formulation(Tablet). The suggested procedure included oxidation of ATNL with an excess quantity of the oxidant N-bromosuccinimide (NBS), and then the excess of NBS was occupied in bleaching the color of methyl red dye(MRD), then measuring the absorbance of remaining MRD at 518 nm. The absorbance of the unbleached color of MRD corresponds to the ATNL concentration in the sample solution. Beer’s law was followed in the range of 0.1-2.0 μg.ml−1with molar absorptivity value equal to 8.8864x104 l.mol−1. cm−1. The suggested method was applied to the assay of ATNL in commercial tablets, with satisfactory results.

SYNTHESIS AND CHARACTERIZATION OF ACETYLATION OF SUPRA MOLECULAR DENDRIMERS

Supra molecular dendrimers have emerged as one of the most interesting themes for researchers work as a result of unique functional architecture and macromolecular characteristics. The main drawback of Supra Molecular dendrimers is, due to presence of –NH2 group at the surface, it causes hemolytic toxicity and hence toxic for the blood cells. In this article, we have systematically modified the surface groups of amine-terminated Supra Molecular dendrimers with acetyl groups. The reported methods of Acetylation are very time consuming and multistep which require large amounts of chemicals. In present work we have synthesized Acetylation Supra Molecular dendrimers using 1-ethyl 3- [3-(dimethylamino) propyl] carbodiimide (EDC) as a cross linking agent. The Acetylated dendrimers were evaluated by color reaction, UV, FT-IR, DSC, Size distribution, NMR and ESI Mass Spectra studies and compared with standard data. The absolute molecular weight and molecular weight distribution of 4.0 G and Acetylated Supra Molecular dendrimers were determined respectively by Size distribution and ESI Mass Spectra respectivel. The results revealed that our approach for Acetylation gives considerable amount of Acetylation, cheap, elimination for ganic solvent, requires less time duration and hence gives a better option for Acetylation of dendrimers.

A pH-responsive fluorometric and colorimetric system based on silicon quantum dots and 4-nitrophenol for urease activity detection

In this paper, we proposed a dual-signal fluorometric and colorimetric system based on silicon quantum dots (SiQDs) and 4-nitrophenol (4-NP) for pH and urease sensing. SiQDs with fluorescence emission of 460 nm were prepared via aqueous-phase synthesis. As the pH of the system gradually increased, the absorption band of 4-NP at 400 nm increased and a color reaction from colorless to yellow occurred. The absorption of 4-NP overlapped quiet well with the fluorescence excitation spectrum of SiQDs, which can effectively quench the fluorescence of SiQDs. Therefore, the change of fluorescence and absorption intensities could be used to quantify pH value. The fluorometric and colorimetric pH-sensing systems both exhibited a linear respond to pH ranging from 6.0 to 7.8 with an interval of 0.2 pH unit. Urease could specifically hydrolyze urea to generate carbon dioxide and ammonia, causing an obvious increase of the pH value. Thus, urease could also be detected quantitatively by the above dual-signal pH sensing system. The linear ranges of the fluorometric and colorimetric methods for urease detection were both 2–40 U L-1. The limits of detection were 1.67 and 1.07 U L-1, respectively. More importantly, this established dual-signal system has been successfully exploited in the detection of urease in real samples with satisfactory recoveries. Compared with other traditional single-signal assay strategies, the results obtained by dual-signal methods are more accurate and reliable.

A colorimetric and ratiometric photometric sequential assay for ascorbic acid and alkaline phosphatase in serum based on valence states modulation

The photometric method is widely used in real clinical tests due to its simple operation, low cost and convenient. Many of the reported colorimetric ALP assays so far are non- ratiometric because the detection was based on changes in absorbance at a single wavelength. The development of novel colorimetric and ratiometric assay is of importance for quantitatively measuring target with high accuracy. The challenge in the design of ratiometric photometric assay is that the chromophore must have a significant spectral shift before and after binding to the target. Here, we report a colorimetric and ratiometric photometric sequential assay of AA and ALP based on the complexation between ARS and Cu2+ and redox reaction between AA and Cu2+. The absorption band of ARS centered at 425 nm (yellow color), which could be shifted to 510 nm (red color) upon Cu2+ binding. However, as far as we know, this classic color reaction has not been used to develop a ratiometric photometric method to sequentially detect AA and ALP, although photometric methods based on the regulation of other color reagents with oxidizing metal ions have been reported. The proposed sensing system shows a limit of detection for ALP at 0.24 U L−1 and could be applied for detecting ALP in newborn calf serum. The established sensing system makes a useful contribution to the detection of ALP in complex clinical samples.

Novel colorimetric sensor array for Chinese rice wine evaluation based on color reactions of flavor compounds

AbstractIn this study, a 3 × 3 comprehensive colorimetric sensor array (CSA) was constructed for the quality evaluation of Chinese rice wine based on three different action principles (pH change principle, indicators displacement assay principle, and ethanol fading principle). First, China national standard was used to determine the total acid, reducing sugar, and alcoholic strength of six kinds of rice wine, which forms the basis for the selection of the CSA sensitive points. Then, CSA was combined with pattern recognition technologies to qualitatively distinguish rice wine. The results showed that the when PCs = 3, the linear discriminant analysis model can achieve a recognition rate of 100%, which shows strong prediction ability compared with K‐nearest neighbor and back‐propagation artificial neural network models. Finally, CSA was combined with partial least squares (PLS) and support vector regression (SVR) to quantitatively analyze the three components in rice wine. The correlation coefficients of the training set and predictions are more than 85% in the SVR model, which is superior to the PLS model. Based on these findings, it is possible to conclude that the CSA can be used to rapidly evaluate the quality of rice wine.Practical Applications Established the 3 × 3 colorimetric sensor array (CSA) for the quality evaluation of Chinese rice wine based on three different action principles (pH change principle, indicators displacement assay principle, and ethanol fading principle). The CSA was combined with pattern recognition technologies to qualitatively distinguish different kinds of rice wine. The performance of linear discriminant analysis shows strong prediction ability compared with K‐nearest neighbor and back‐propagation artificial neural network. The CSA was combined with partial least squares (PLS) and support vector regression (SVR) to quantitatively analyze the three components in rice wine. The correlation coefficients of the training set and predictions are more than 85% in the SVR model, which is superior to the PLS model.

MVDI25K: A large-scale dataset of microscopic vaginal discharge images

With the widespread application of artificial intelligence technology in the field of biomedical images, the deep learning-based detection of vaginal discharge, an important but challenging topic in medical image processing, has drawn an increasing amount of research interest. Although the past few decades have witnessed major advances in object detection of natural scenes, such successes have been slow to medical images, not only because of the complex background and diverse cell morphology in the microscope images, but also due to the scarcity of well-annotated datasets of objects in medical images. Until now, in most hospitals in China, the vaginal diseases are often checked by observation of cell morphology using the microscope manually, or observation of the color reaction experiment by inspectors, which are time-consuming, inefficient and easily interfered by subjective factors. To this end, we elaborately construct the first large-scale dataset of microscopic vaginal discharge images, named MVDI25K, which consists of 25,708 images covering 10 cell categories related to vaginal discharge detection. All the images in MVDI25K dataset are carefully annotated by experts with bounding-box and object-level labels. In addition, we conduct a systematical benchmark experiments on MVDI25K dataset with 10 representative state-of-the-art (SOTA) deep models focusing on two key tasks, i.e., object detection and object segmentation. Our research offers the community an opportunity to explore more in this new field.

AIM2 Inflammasome in Tumor Cells as a Biomarker for Predicting the Treatment Response to Antiangiogenic Therapy in Epithelial Ovarian Cancer Patients.

Antiangiogenic therapy, such as bevacizumab (BEV), has improved progression-free survival (PFS) and overall survival (OS) in high-risk patients with epithelial ovarian cancer (EOC) according to several clinical trials. Clinically, no reliable molecular biomarker is available to predict the treatment response to antiangiogenic therapy. Immune-related proteins can indirectly contribute to angiogenesis by regulating stromal cells in the tumor microenvironment. This study was performed to search biomarkers for prediction of the BEV treatment response in EOC patients. We conducted a hospital-based retrospective study from March 2013 to May 2020. Tissues from 78 Taiwanese patients who were newly diagnosed with EOC and peritoneal serous papillary carcinoma (PSPC) and received BEV therapy were collected. We used immunohistochemistry (IHC) staining and analyzed the expression of these putative biomarkers (complement component 3 (C3), complement component 5 (C5), and absent in melanoma 2 (AIM2)) based on the staining area and intensity of the color reaction to predict BEV efficacy in EOC patients. The immunostaining scores of AIM2 were significantly higher in the BEV-resistant group (RG) than in the BEV-sensitive group (SG) (355.5 vs. 297.1, p < 0.001). A high level of AIM2 (mean value > 310) conferred worse PFS after treatment with BEV than a low level of AIM2 (13.58 vs. 19.36 months, adjusted hazard ratio (HR) = 4.44, 95% confidence interval (CI) = 2.01–9.80, p < 0.001). There were no significant differences in C3 (p = 0.077) or C5 (p = 0.326) regarding BEV efficacy. AIM2 inflammasome expression can be a histopathological biomarker to predict the antiangiogenic therapy benefit in EOC patients. The molecular mechanism requires further investigation.

Colorimetric quantification of sodium benzoate in food by using d-amino acid oxidase and 2D metal organic framework nanosheets mediated cascade enzyme reactions

A rapid colorimetric method for detecting sodium benzoate in food products was established based on the d-amino acid oxidase (DAAO) and 2D metal organic framework (2D MOF) nanosheets mediated cascade enzyme reactions. Firstly, the synthesized 2D MOF nanosheets served as high efficient nanozyme with outstanding peroxidase-like catalytic activity and catalyzed the color reaction between H2O2 and 3, 3’, 5, 5′- tetramethylbenzidine. Secondly, sodium benzoate as a competitive inhibitor of DAAO, could influence the production of H2O2 in DAAO mediated oxidation reaction. After a combination of those two reactions, this colorimetric quantitative method was constructed and validated for sodium benzoate determination with wide linear range (2.0–200.0 μM), low limit of detection (2.0 μM), high accuracy (recovery rate in 95.80–108.00%) and satisfied selectivity. Lastly, this method was utilized to analyze sodium benzoate concentration in juice, wine and vinegar by naked eyes.

Sensor surface via inspiration from Nature: The specific case of electron trapping in TiO2/WO3(∙0.33H2O) and reaction center/WO3(∙0.33H2O) systems

In this work, reaction center protein (RC) isolated from Rhodobacter sphaeroides purple bacteria was coupled with WO3(∙0.33H2O) via physical adsorption, where vectorial electron transfer (from RCs towards the inorganic carrier) was demonstrated using flash kinetics and photoluminescence measurements. The efficiency of the interaction between RCs and WO3(∙0.33H2O) was correlated to the components’ surface charge at the working pH and the structural/morphological and surface properties of the inorganic carrier (e.g., anchoring capacity assured by HO, WO bonds). The role of WO3(∙0.33H2O) as final electron trap and charge separator was proven not only in RCs/WO3(∙0.33H2O) biohybrid systems but also in TiO2/WO3(∙0.33H2O) composites. The charge transfer in the inorganic composites was evaluated by monitoring the reverse process of the color reaction (W5+ → W6+) via diffuse reflectance spectroscopy (DRS) after a previous UV-A (320–400 nm) exposure. The efficiency of the charge transfer process in inorganic systems was correlated to the initial W5+ content of WO3(∙0.33H2O), followed by the photocatalytic efficiency evaluation of these inorganic composites under UV-A irradiation.

A nanoenzyme linked immunochromatographic sensor for rapid and quantitative detection of SARS-CoV-2 nucleocapsid protein in human blood

The establishment of a simple, low-cost, high-sensitive and rapid immunoassay for detecting SARS-CoV-2 antigen in human blood is an effective mean of discovering early SARS-CoV-2 infection and controlling the pandemic of COVID-19. Herein, a smartphone based nanozyme linked immunochromatographic sensor (NLICS) for the detection of SARS-CoV-2 nucleocapsid protein (NP) has been developed on demand. The system is integrated by disposable immunochromatography assay (ICA) and optical sensor devices. Immunoreaction and enzyme-catalyzed substrate color reaction were carried out on the chromatographic strip in a device, of which the light signal was read by a photometer through a biosensor channel, and the data was synchronously transmitted via the Bluetooth to the app in-stored smartphone for reporting the result. With a limit of detection (LOD) of 0.026 ng/mL NP, NLICS had the linear detection range (LDR) between 0.05 and 1.6 ng/mL NP, which was more sensitive than conventional ICA. NLICS took 25 min for reporting results. For detection of NP antigen in clinical serum samples from 21 COVID-19 patients and 80 healthy blood donor controls, NLICS and commercial enzyme linked immunosorbent assay (ELISA) had 76.2% or 47.6% positivity, and 100% specificity, respectively (P = 0.057), while a good correlation coefficient (r = 0.99) for quantification of NP between two assays was obtained. In conclusion, the NLICS was a rapid, simple, cheap, sensitive and specific immunochromatographic sensing assay for early diagnosis of SARS-CoV-2 infection.

Isolation and Identification of the Plant Endophyte R-13 and Its Effect on Cadmium Accumulation in Solanum nigrum L.

The combination of endophytes and hyperaccumulator plants can significantly improve the efficiency of heavy metal phytoremediation in contaminated soil. A plant endophyte named Herbaspirillum R-13 was isolated from rice roots in a cadmium (Cd) contaminated paddy field. This strain exhibited a strong tolerance to Cd2+ and could grow on a solid medium with a Cd2+ concentration of 300 mg·kg-1. The R-13 strain was able to produce siderophores and Indole acetic acid (IAA), through color reactions. In addition, Pikovskaya's and Ashby's solid medium tests showed that the R-13 strain had a lower capacity for dissolving phosphorus but a higher capacity for fixing nitrogen. In the pot experiment, high-throughput sequencing technology was used to track the colonization of the R-13 strain in Solanum nigrum L. roots. Three days after inoculation, the relative abundance of Herbaspirillum in the root of Solanum nigrum L. had increased by 201.88% compared to the blank control (CK) and after two inoculations, the relative abundance of Herbaspirillum in the root of Solanum nigrum L. had increased by 1182.44% compared to CK. The relative abundance of Herbaspirillum in the root of Solanum nigrum L. began to decrease significantly from 5 days after inoculation. Inoculation with 20 mL·pot-1 of R-13 fermentation broth resulted in no significant effects on the Cd content of roots, stems, leaves, or fruits of S. nigrum L. With 40 mL·pot-1 of fermentation broth, the Cd content of vegetative organs and fruits was significantly increased. When it reached 200 mL·pot-1, the Cd content of vegetative organs was the highest, with Cd concentrations in the roots, stems, leaves, and fruits increasing by 84.42%, 43.67%, 64.06%, and 20.29%, respectively. In conclusion, root inoculation with endophytic Herbaspirillum R-13 can significantly increase the relative content of Herbaspirillum in the root system and enhance Cd absorption of S. nigrum L. Therefore, this strain has excellent prospects for application in the phytoremediation of soil contaminated with Cd.

Inter- and intra-plant variation in phenol content in grains of rice (Oriza sativa varieties using phenol colour reaction

Different stages of phenol colour reaction showed induction of phenol colour reaction occur post anthesis, i.e. stage 2. In the later stages, i.e. stage 3 (dough) and 4 (harvest maturity) seeds showed similar phenol reaction with less intensity. Phenol content estimated at different stages of growth and maturity showed the highest at post fertilization stage, i.e. stage 2 and it decreased in stage third and fourth. Inter-panicle phenol content was not significantly different whereas intra-panicle difference in phenol content was observed.

Antioxidant identification using a colorimetric sensor array based on Co-N-C nanozyme

Here we develop a simple and effective nose/tongue sensor array based on Co-N-C single-atom nanozymes-3,3′,5,5′-tetramethylbenzidine (TMB)-H2O2 for colorimetric discrimination of antioxidants, which makes use of the color reaction of TMB oxidation by H2O2 in two different pH (3.8 and 4.6) environments under the catalysis of Co-N-C nanoenzyme with peroxidase-like activity. Different antioxidants have varying reducing ability to the oxidation products of TMB (oxTMB), thus resulting in differential absorbance and color changes. Linear discriminant analysis (LDA) results indicate that the sensor array successfully identified 7 antioxidants, i.e., glutathione (GSH), ascorbic acid (AA), cysteine (Cys), tannin (TA), Catechin (C), dopamine (DA), and uric acid (UA) in both buffer and even serum samples. Additionally, the performance of the sensor array was validated with antioxidant mixtures, individual antioxidants with different concentrations, and target antioxidants and interfering substances. In general, the versatile sensor array based on Co-N-C single-atom nanozymes provides an excellent strategy for identifying a variety of antioxidants, which exhibits a broad application prospect in medical diagnosis.

Optimization of acquisition parameters of slurry coating characteristics based on multiple yarn simultaneous detection

A simultaneous detection method was proposed to detect slurry coating characteristics based on the same spatial resolution of starch-based sized and raw yarns. A dynamic image acquisition device was improved to capture the apparent images of multiple yarns simultaneously after the starch–iodine color reaction. The slurry coating characteristics were calculated utilizing image-processing technology. For the sake of effective and stable detection, the effects of illumination conditions on the concentration of I2-KI solution were studied through the absorbance value test. The effects of image-processing parameters on the experimental results were analyzed respectively by measuring six kinds of yarn of different counts and size pick-up. The results showed that the illumination conditions within an illumination time of 0–60 min, illumination intensity of 0–80,000 lux and illumination distance of 0.01–0.20 m had no significant effects on the concentration of I2-KI solution. Eight rows of pixels in the central axis areas of the yarn were determined as the effective statistical areas. It was determined that the sample size can meet the needs of stability test in 200 pieces. A dynamic threshold method, which served the intersection of the gray histogram of sized and raw yarn under the same spatial resolution as the threshold, can effectively segment the slurry coating areas. On the above basis, the optimization acquisition parameters of the detection method were obtained. The proposed method can meet the requirements of the efficiency test, common applicability and ease of operation.

Preparation of pH‐indicator films based on soy protein isolate/bromothymol blue and methyl red for monitoring fresh‐cut apple freshness

Intelligent pH-indicator films based on soy protein isolate (SPI) were prepared using pH-sensitive dyes (bromothymol blue and methyl red). The addition of mixed indicators imparts pH-indicator films with an appreciable microstructure, acceptable water resistance, and favorable optical properties. The incorporation of the mixed indicators did not lead to significant improvement in the mechanical properties of films due to weak ionic cross-linking by hydrogen bonding between the SPI macromolecules and low-molecular-weight indicators. Fourier-transform infrared spectroscopy indicated hydrogen bond-mediated intermolecular interactions, and scanning electron microscopy showed that BB/MR were well dispersed in the SPI film. The indicator addition hindered the sorption and passage of water molecules. The water vapor permeability, moisture sorption, moisture content, and total soluble matter were 4.32 to 6.12 ×10-12 g·cm/cm2 ·s·Pa, 36.70% to 73.33%, 25.28% to 44.11%, and 8.21% to 25.56%, respectively. Also, the addition of indicators reduced UV light transmittance with minimal effect on the transparency of the film. The presence of indicators enhanced the pH sensitivity, seen as a visible color reaction at different pHs (total color difference, ΔE>5). When the pH-indicator film containing 8ml/100ml final film emulsions was used to monitor the fresh-cut apple freshness, a green color for fresh status was observed, which turned blue after 60h. Collectively, our findings suggested that indicator-containing SPI films have the potential for monitoring the freshness of fruits. PRACTICAL APPLICATION: pH-indicator films can help consumers to identify the freshness of packaged food by a change in the color of the packaging material, which is easily visible to the unaided eye without the need for opening the packaging. This protects consumers' interests.

Co-MOF-74 based Co3O4/cellulose derivative membrane as dual-functional catalyst for colorimetric detection and degradation of phenol

Smart nanomaterials that can simultaneously detect and eliminate contaminants in water environment are significant for health protection. To achieve such goal, Co-MOF-74 was in-situ assembled on regenerated cellulose membranes followed by calcination process, thus achieving dual-functional Co3O4/cellulose derivative membrane (Co3O4/CDM) catalyst. The Co3O4 morphology was readily controlled by further recrystallization of the deposited MOF precursor. Combining the high enrichment ability of cellulose membrane and outstanding peroxidase-active of Co3O4, the fast color reaction for phenol was accomplished within 10 min by Co3O4/CDM with the assistance of H2O2 and 4-aminoantipyrine (4-AAP). Moreover, the Co3O4/CDM also portrayed an excellent degradation property for phenol elimination via sulfate radical-advanced oxidation processes (SR-AOPs). The degradation efficiency of phenol reached 93% in 20 min, and the possible mineralization mechanism was proposed based on the XPS and LC-MS analysis. Thus, Co-MOF-74 derived Co3O4/CDM shows excellent properties in aiding the colorimetric detection and degradation of phenol in aqueous solutions.

Paper-Based Analytical Device for the On-Site Detection of Nerve Agents.

We report a colorimetric paper-based microfluidic device based on an enzyme inhibition assay that allows the on-site detection of nerve agents by sampling and wicking. The sample and reagents are automatically transported through the channel where an enzyme inhibition reaction is conducted, followed by an enzyme-substrate reaction and a color reaction. This device can detect 0.1 μg/mL of the nerve agent VX in a 2.5 μL drop and is nerve agent selective and robust against temperature, pH, and several liquids. We confirmed that sampling procedures (dilution and wiping) are applicable to this device. Furthermore, the fabrication procedure is easy, and the cost is at most a few tens of cents. Thus, the present device provides a practical method for the urgent detection of nerve agents in suspected chemical terrorism incidents.