Azino-bis(3-ethylbenzthiazoline-6-sulfonic Acid) Diammonium Salt Research Articles

Vicenin-2 and vitexin participate in the in vitromodulation of the anti-inflammatory and antioxidant activities exerted by two Urtica circularis extracts

Urtica circularisis an Argentinean species traditionally used to treat inflammation symptoms and oxidative stress-related diseases. Considering the uses in folk medicine, the purpose of this work was to evaluate and compare the anti-inflammatory and antioxidant activities of two different U. circularisextracts. The contribution of vicenin-2 and vitexin, two compounds identified in the phytochemical analysis, in the biological activity of the extracts was evaluated. The anti-inflammatory activity of the extracts and the isolated compounds was tested on lipopolysaccharide (LPS)-stimulated macrophages, while the antioxidant activity was evaluated through the 2,2 ́ diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2 ́-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) scavenging activities. The popular uses of both extracts were validated, i.e., the use of U. circularisethanol extract for the treatment of inflammation, and the use of the aqueous extract to treat oxidative stress related-diseases. The differences in the biological activities observed between the extracts are probably due to qualitative and/or quantitative differences in the chemical composition and/or the occurrence of synergism between compounds.

Fungus-Based MnO/Porous Carbon Nanohybrid as Efficient Laccase Mimic for Oxygen Reduction Catalysis and Hydroquinone Detection.

Developing efficient laccase-mimicking nanozymes via a facile and sustainable strategy is intriguing in environmental sensing and fuel cells. In our work, a MnO/porous carbon (MnO/PC) nanohybrid based on fungus was synthesized via a facile carbonization route. The nanohybrid was found to possess excellent laccase-mimicking activity using 2,2′-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as the substrate. Compared with the natural laccase and reported nanozymes, the MnO/PC nanozyme had much lower Km value. Furthermore, the electrochemical results show that the MnO/PC nanozyme had high electrocatalytic activity toward the oxygen reduction reaction (ORR) when it was modified on the electrode. The hybrid nanozyme could catalyze the four-electron ORR, similar to natural laccase. Moreover, hydroquinone (HQ) induced the reduction of oxABTS and caused the green color to fade, which provided colorimetric detection of HQ. A desirable linear relationship (0–50 μM) and detection limit (0.5 μM) were obtained. Our work opens a simple and sustainable avenue to develop a carbon–metal hybrid nanozyme in environment and energy applications.

Solid‐state Synthesis of Cu doped CDs with Peroxidase‐mimicking Activity at Neutral pH and Sensing of Antioxidants

AbstractCarbon dots with peroxidase‐mimicking properties have attracted considerable attention for various sensing and biomedical applications. However, most peroxidase nanozymes do not show activity at neutral pH and only work in acidic conditions. In this work, crystalline Cu‐doped, Mn‐doped, and undoped carbon dots (CDs) are prepared via one‐step, solid‐state, microwave synthesis. Among them, Cu‐CDs demonstrate catalytic oxidation of 3,3′,5,5′‐tetramethylbenzidine (TMB) and 2,2′‐azino‐bis (3‐ethylbenzthiazoline‐6‐sulfonic acid) diammonium salt (ABTS) with H2O2 at pH 7 and pH 6 respectively. Our study shows that Mn‐doped and undoped CDs do not feature peroxidase‐like properties at pH=7. The mechanism and kinetics of the peroxidase‐mimicking reaction of Cu‐CDs were investigated by spectroscopic studies. Moreover, colorimetric sensing of different antioxidants was monitored based on the reduction of oxidized TMB, with selective detection of ascorbic acid in the range of ∼2–1000 μM with a limit of detection of 23.3 μM. This work introduces a facile strategy for synthesizing metal‐doped CDs with promising applications in biosensing and catalysis.

Novel green soybean shuidouchi fermented by Bacillus velezensis with multibioactivities.

Soybeans are usually fermented by Bacillus subtilis to produce shuidouchi, which is a traditional fermentation soybean product in China. In the study, green soybeans were fermented by Bacillus velezensis to make a novel green soybean shuidouchi with multibioactivities. The processing conditions were optimized as follows: initial moisture content 75%, inoculum concentration 7 log CFU/g, and incubation time 24 h for prefermentation; water addition 50%, salt addition 6%, temperature 45°C, 3 days for postfermentation. The fermented green soybean shuidouchi (FGSS) showed 234.8 FU/g dry weight (DW) for the fibrinolytic activity and IC50 of 0.33 mg/ml for the anticoagulant activity. FGSS had higher contents of chemical components including 3.6 mg rutin (RE)/g DW of total flavonoids, 8.2 mg gallic acid (GAE)/g DW of total phenolics, 63.7 mg/g DW of reducing sugars, and 163.8 mg/g DW of peptides than the unfermented green soybean shuidouchi (UGSS). Moreover, it exhibited high antioxidant activities of 29.8, 85.1 μmol trolox equivalent (TE)/g DW, and 12.8 μmol Fe2+/g DW through 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2’‐azino‐bis (3‐ethylbenzthiazoline‐6‐sulfonic acid) diammonium salt (ABTS), and ferric reducing antioxidant power (FRAP) experiments. Thus, a novel green soybean shuidouchi fermented by B. velezensis owing to multibioactivities can provide a theoretical basis for the further development of functional shuidouchi.

Amphiphilic protein controlled synthesis of rice-shaped copper oxide and its substrate dependent enzyme-mimicking activity

Rice-shaped protein–copper oxide hybrid (RSPCO) was prepared by one-pot method in the presence of amphiphilic proteins. The enzyme-mimicking activity of RSPCO depends much on the substrate structure. RSPCO shows superior peroxidase-like activity with 3,3′,5,5′-tetramethylbenzidine (TMB) as a substrate. RSPCO exhibits both peroxidase- and oxidase-like activities with 1,2-diaminobenzene (OPD) as the substrate. RSPCO does not exhibit peroxidase-/oxidase-like activity when using 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonic acid)diammonium salt (ABTS) as the substrate. Furthermore, pyrogallol (PA)-induced activity switching effect is dependent on the type of enzyme-like activity of nanozyme and the substrate structure. The different effect of PA on the enzyme-like activity of RSPCO attributes mainly to the different affinity of substrates toward RSPCO. PA can significantly inhibit the peroxidase-like activity of RSPCO with TMB used as the substrate. Due to the efficient inhibiting effect, an excellent PA colorimetric sensor with low limit of detection being 15 nM (signal-to-noise ratio of 3) was developed based on RSPCO. With the features of simplification and low cost, protein–copper oxide hybrid nanozymes has the potential application in medial, environmental, and food areas. The present work provides new information about activity–structure relationship of copper oxide nanozyme, which is important for the applications of nanozymes in practice.

Characterization and Cytotoxicity Evaluation of Biologically Synthesized Silver Nanoparticles from Albuca setosa Aqueous Bulb Extract

Biologically synthesized nanoparticles are rapidly evolving because it is cost effective and eco-friendly, this also contributes to its preference over nanoparticles from other sources. In this study, silver nanoparticles were synthesized from Albuca setosa aqueous bulb (ASB) extracts and the biological activities evaluated. The silver nanoparticles were synthesized from ASB extracts using silver nitrate and characterized using UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The antioxidant activity was determined by evaluating the effect on 2,2-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, 2,2[Formula: see text]-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid diammonium salt (ABTS). The antibacterial potential was investigated on selected Gram positive and Gram negative bacteria while the cytotoxicity was evaluated on MDA-MB-231 breast cancer cells (ATCC HTB-26). Albuca setosa silver nanoparticles (AS-AgNPs) was formed within 60 min reaction time of UV–Vis absorption. The FTIR showed that acid anhydride, alkene, amine, aldehyde, ester, ketone and carbonyl groups contributed to the synthesis of the AS-AgNPs, while SEM and TEM showed stable irregular shaped monodispersed silver nanoparticles with average size of 7 nm. The XRD patterns revealed diffraction peaks at [Formula: see text] and 92.37∘ that was indexed to (1 1 0), (1 1 0), (1 0 0), (1 0 0) and (1 0 0) planes of face-centered cubic (fcc) crystalline structure respectively. The synthesized nanoparticles possess good antioxidant activity with IC50 of [Formula: see text] and [Formula: see text][Formula: see text][Formula: see text]g/ml for DPPH and ABTS, respectively, and inhibit the growth of Staphylococcus faecalis and Bacillus cereus with MIC of 25 and 15[Formula: see text][Formula: see text]g/ml respectively. AS-AgNPs also revealed higher cytotoxic efficacy against MDA-MB-231 breast cancer cells with IC50 of [Formula: see text][Formula: see text][Formula: see text]g/ml. AS-AgNPs showed acceptable size and shape of nanoparticles and could therefore be a potential source of antimicrobial and anticancer agents. It can be concluded that the synthesized AS-AgNPs is a good source of anticancer agent with broad spectrum of antibiotic activity.

Hemin-incorporated nanoflowers as enzyme mimics for colorimetric detection of foodborne pathogenic bacteria

Rapid, sensitive and point-of-care detection of foodborne pathogenic bacteria is essential for food safety. In this study, we found that hemin-concanavalin A hybrid nanoflowers (HCH nanoflowers), as solid mimic peroxidase, could catalyze oxidation of 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) in the presence of H2O2 to a green-colored product. HCH nanoflowers, integrating the essential functions of both biological recognition and signal amplification, meet the requirements of signal labels for colorimetric immunoassay of bacteria. In view of the excellent peroxidase mimetic catalytic activity of HCH nanoflowers, a colorimetric biosensing platform was newly constructed and applied for sensitive detection of foodborne Escherichia coli O157:H7 (E. coli O157:H7). The corresponding detection limits was as low as 4.1 CFU/mL with wide linear ranges (101–106 CFU/mL).

Identification of Antidiabetic Compounds from Polyphenolic-rich Fractions of Bulbine abyssinica A. Rich Leaves.

Background:Bulbine abyssinica has been reported to possess a variety of pharmacological activities traditionally. Previous work suggested its antidiabetic properties, but information on the antidiabetic compounds is still lacking.Objective:The present research exertion was aimed to isolate and identify biologically active polyphenols from B. abyssinica leaves and to evaluate their efficacy on carbohydrate digesting enzymes.Materials and Methods:Fractionation of the polyphenolic contents from the methanolic extract of B. abyssinica leaves was executed by the silica gel column chromatography to yield different fractions. The antioxidant activities of these fractions were carried out against 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS), 2,2-diphenyl-1-picrylhydrazyl radicals, and ferric ion-reducing antioxidant power (FRAP). In vitro antidiabetic experimentation was performed by evaluating the α-amylase and α-glucosidase inhibitory capacity. The isolated polyphenols were then identified using liquid chromatography and mass spectroscopy (LC/MS).Results:Out of the eight polyphenolic fractions (BAL 1–8), BAL-4 has the highest inhibitory activity against ABTS radicals whereas BAL-6 showed potent ferric ion-reducing capacity. BAL-5 was the most effective fraction with antidiabetic activity with IC50of 140.0 and 68.58 ± 3.2 μg/ml for α-amylase and α-glucosidase inhibitory activities, respectively. All the fractions competitively inhibited α-amylase, BAL-5 and BAL-6 also inhibited α-glucosidase competitively, while BAL-4 and BAL-1 exhibited noncompetitive and near competitive inhibitions against α-glucosidase, respectively. The LC/MS analysis revealed the presence of carvone in all the fractions.Conclusions:The present study demonstrates the antioxidant and antidiabetic activities of the isolated polyphenols from B. abyssinica.SUMMARY Polyphenols were successfully isolated and identified from Bulbine abyssinica leavesThe isolated polyphenols are biologically active with high antioxidant as well as inhibitor of carbohydrate-digesting enzymesB. abyssinica can be a good source of amylase and glucosidase inhibitorsB. abyssinica can be used as complementary or alternative therapeutic agents especially for the treatment of diabetesCarvone, quercetin, and psoralen could be the compounds responsible for the α-amylase and α-glucosidase inhibitory activities. Abbreviations Used: ABTS: 2,2'-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid), DPPH: 2,2-diphenyl-1-picrylhydrazyl, FRAP: Ferric ion-reducing antioxidant power, LC/MS: Liquid chromatography and mass spectroscopy, AGEs: Advanced glycation end products, TLC: Thin-layer chromatography, MeOH: Methanol, PNP-G: ρ-Nitrophenyl-α-D-Glucoside, R2: Coefficient of determination, mgQE: Milligram quercetin equivalent, mgTAE: Milligram tannic acid equivalent, mgCE: Milligram catechin equivalent, g: Gram

Characterization of the Biological Activity and Phenolics in Achillea lycaonica

ABSTRACTThe purpose of this study was to comparatively evaluate for the first time the antioxidant, antimicrobial, and antiurease effects of A. lycaonica extracts obtained using three extraction methods and five solvents followed by identification of the phenolic compounds obtained by Soxhlet extraction with ethyl acetate and maceration with chloroform that showed the highest total phenolic and flavonoid contents with antioxidant and antiurease activity. The phenolic compounds were identified to be chlorogenic acid, caffeic acid, rutin, dicaffeoylquinic acid, salicylic acid, luteolin, quercetin, naringenin, apigenin, and 8-hydroxy-salvigenin. Among the solvent extraction procedures, Soxhlet approach was found to have higher recoveries than other approaches. The results of 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assays showed that the 1:1 ethanol–water Soxhlet, ethanol ultrasonic bath, and ethyl acetate Soxhlet extraction methods had the highest DPPH antioxidant activities. The ethyl acetate Soxhlet extraction method showed the highest 2, 2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) and ferric reducing antioxidant power (FRAP) antioxidant activity. In addition, the chloroform maceration extraction method exhibited the highest antiurease activity. Therefore, 1:1 Soxhlet ethanol–water, ultrasonic bath ethanol, and Soxhlet ethyl acetate extracts may be used in medicine and food production as natural antioxidant sources. In addition, maceration with chloroform may provide a potential antiurease agent.

Highly sensitive and rapid colorimetric sensing platform based on water-soluble WOx quantum dots with intrinsic peroxidase-like activity

This report outlines a rapid and highly sensitive colorimetric sensing platform based on a novel water-soluble WOx quantum dots (QDs) as enzymatic mimics. The WOx QDs, synthesized by a green hydrothermal method, were proven to possess excellent intrinsic peroxidase-like activity. The peroxidase substrate, 2, 2′-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) could be catalyzed oxidation by WOx QDs quickly in the present of H2O2 to form a green color. Due to its excellent properties such as excellent water-solublity, good biocompatibility, easy preparation, and high stability, the proposed system showed typical Michaelis-Menten kinetics and high affinity for ABTS and H2O2, indicating WOx QDs can be used as satisfactory peroxidase mimics. Together with the fast detection process, WOx QDs-based colorimetric sensing system provided a facile, sensitive, and accurate method for the determination of H2O2 and glucose. The real glucose samples in human serum samples were detected with satisfying results. The proposed sensing platform not only expands the applications of WOx and WOx QDs-based nanocomposites, but also provides an alternative technique for biological, biomedical and environmental sample assay.

Phytochemical analysis and anti-oxidant activities of Albuca bracteata Jacq. and Albuca setosa Jacq bulb extracts used for the management of diabetes in the Eastern Cape, South Africa

ObjectiveThe bulb of Albuca bracteata Jacq., and Albuca setosa commonly used in Eastern Cape Province of South Africa for the treatment of several types of disease conditions including diabetes, was investigated for their phytochemical contents and antioxidant activities. MethodsThe antioxidant activity was determined by evaluating the effect of various solvent extracts (acetone, methanol, ethanol and water) on 2,2 – diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, 2,2′ – azino-bis (3-ethylbenzthiazoline-6-sulfonic acid diammonium salt (ABTS), ferric reducing power, hydrogen peroxide and nitric oxide scavenging activity while the various extracts were also analysed for phytochemical their contents. ResultsThe results obtained indicate that polyphenols, proanthocyanidins, saponins and alkaloids are present in higher concentrations. The composition of phenols (117 mg/g), flavonols (26.28 mg/g), proanthocyanidins (84.85 mg/g) and flavonoids (5.36 mg/g) were significantly higher in the acetone extract while saponin and alkaloids contents were higher in the aqueous extract. Antioxidant studies of the extracts for nitric oxide, hydrogen peroxide, ABTS and DPPH showed high antioxidant potential in a concentration-dependent manner that was not significantly different from Vitamin C, BHT and Rutin used as standard references. The methanol extract showed higher ferric reducing potential compared to the aqueous extract but was significantly different from Vitamin C, BHT and Rutin. ConclusionThis implies that the bulb of Albuca bracteata may serve as a natural source of antioxidants, which together with the numerous phytochemicals present, could account for its folkloric use as a medicinal plant.

여주 분말 함유 쌀누룩을 이용하여 제조된 막걸리의 품질 특성 및 항산화 활성

Bitter melon powder (BMP) was used in the preparation of rice nuruk (RN) and makgeolli as one of raw materials.RN containing BMP (BMP-RN) was prepared by adding 0~2.0% (w/w) BMP into rice. Fermentative microbial, and antioxidant characteristics of makgeolli were determined during the fermentation process. pH during fermentation decreased from 4.52 (0% BMP-RN), 4.93 (0.5%), 4.80 (1.0%), and 4.88 (2.0%) on the initial fermentation day (day 0) to 4.15, 4.30, 4.57, and 4.59, respectively, corresponding to increases in acidity from 0.64~0.70% to 1.17~1.28%, respectively. Soluble solid contents increased from an initial 2.2~4.4 g/L (day 0) to 9.0~9.3 g/L, and alcohol level increased up to 13.0% by the end of fermentation (day 7). Soluble phenolic contents increased from 0.92, 1.01, 1.32, and 1.41 mg/mL on day 0, to 1.85, 2.03, 2.24, and 2.48 mg/mL on day 7, respectively, while the levels of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activities and ferric reducing/antioxidant power (FRAP) assay increased from 46.95~70.04%, 55.33~74.13%, and 0.629~1.243 on day 0, respectively, to 54.98~83.4%, 70.34~92.39%, and 0.964~1.455 on day 7, respectively. Makgeolli made with BMP-RN had higher soluble phenolic contents and antioxidant activity than those of makgeolli made without BMP-RN. These results suggested that BNP-RN made a functional makgeolli.

Optimization of thermal processing conditions for brown rice noodles

Based on the current thermal processing conditions for rice noodles (80–85 °C for 20–30 min), we used response surface methodology to find brown rice (BR) noodle processing conditions that maximize the noodles antioxidant activity, digestibility, and gelatinization. The experiments were designed according to the central composite design, including two independent variables (temperature and time) and six dependent variables [total phenolic contents (TPC), total flavonoid contents (TFC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activities, digestibility, and gelatinization]. Antioxidant activities decreased but digestibility and gelatinization increased with increasing temperature and time. All dependent variables suggested a quadratic model except TFC, but the probability of TPC was not applicable (0.1505), and DPPH radical scavenging activity showed a relatively low R 2 (0.6750). Therefore, we applied the other three dependent variables (ABTS radical scavenging activity, digestibility, and gelatinization) to the 3D response surface and proposed three optimum conditions: (1) for antioxidant activity (70 °C, 22.95 min), (2) for digestibility and gelatinization (88.18 °C, 34.89 min), and (3) for all three variables (88.5 °C, 40 min). In a validation test, all dependent variables showed values within a 5 % error range except TFC. These results show the optimum processing conditions for BR noodles to maximize antioxidant activity and provide sustainability in BR noodle processing.

Assessment of the Bioactive Capacity of Mixed Juice Scum Extracts from Sugarcane Mills

AbstractThe scum is a semisolid by‐product in canesugar mills where flotation technology is used for mixed juice clarification. To evaluate its potential bioactive properties, an aqueous extract, a 70% ethanol extract and a 100% ethanol extract from the scum were obtained and used for antioxidant activity assessment. Chemical assays of 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulfonic acid) diammonium salt (ABTS) were used to determine the total antioxidant activity, and a chemiluminescence assay was conducted to assess the hydroxyl (•OH) and superoxide anion ( ) radicals’ scavenging activity. Results showed that all extracts had high antioxidant activity, of which the 100% ethanol extract was more powerful in DPPH, ABTS and •OH assays. Potential antioxidants in ethanol extracts could be associated with sugarcane wax, polyphenols and flavonoids, while in the aqueous extract, it could be water‐soluble vitamins and proteins which resulted in the highest ( ) scavenging activity. This study suggested that the scum has potential bioactive application.Practical ApplicationsComprehensive utilization of sugarcane mixed juice scum plays an important role in extending the application of flotation clarification technology in canesugar industry. General composition analysis of the scum in the study suggested the possibility of using scum as a raw resource of animal feeds, as it contains a high percentage of protein, cellulose and sucrose. High antioxidant activity of scum extracts implicated its potential utilizations in producing antioxidant related products in food industry.

Facile in Situ Synthesis of Silver Nanoparticles on the Surface of Metal-Organic Framework for Ultrasensitive Surface-Enhanced Raman Scattering Detection of Dopamine.

Surface-enhanced Raman scattering (SERS) signals are intensively dominated by the Raman hot spots and distance between analyte molecules and metallic nanostructures. Herein, an efficient SERS substrate was developed by in situ synthesis of silver nanoparticles (AgNPs) on the surface of MIL-101 (Fe), a typical metal-organic framework (MOF). The as-prepared SERS substrate combines the numerous Raman hot spots between the high-density Ag NPs and the excellent adsorption performance of MOFs, making it an excellent SERS substrate for highly sensitive SERS detection by effectively concentrating analytes in close proximity to the Raman hot spots domains between the adjacent AgNPs. The resulting hybrid material was used for ultrasensitive SERS detection of dopamine based on the peroxidase-like activity of MIL-101 (Fe) by utilizing the enzyme-linked immunosorbent assay (ELISA) colorimetric substrate, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as a SERS marker. This new developed method showed good linearity in the range from 1.054 pM to 210.8 nM for dopamine with the correlation coefficient of 0.992, detection limit of approximately 0.32 pM [signal-to-noise ratio (S/N) = 3], and acceptable recoveries ranging from 99.8% to 108.0% in human urine. These results predict that the proposed SERS system may open up a new opportunity for chemical and biological assay applications.

Au@Ag Heterogeneous Nanorods as Nanozyme Interfaces with Peroxidase-Like Activity and Their Application for One-Pot Analysis of Glucose at Nearly Neutral pH.

As substitutes for natural peroxidases, most nanomaterial-based enzyme mimetics (nanozymes) have unique properties such as high stability, low-cost, large surface area, and high catalytic activity. However, they usually work in acidic conditions and thus impede their real applications. In this work, by modulating the nanostructure, composition, and surface property of the bimetallic materials, the positively charged poly(diallyldimethylammonium)-stabilized Au@Ag heterogeneous nanorods (NRs) were developed as synergistic peroxidase-like interfaces, which exhibited high activity over a wide pH range (pH 4.0-6.5) using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as the chromogenic substrate. At pH 6.5, the peroxidase-like activity for the Au@Ag heterogeneous NRs was stable and optimal within 20-40 °C. Moreover, the Au@Ag heterogeneous NRs showed excellent temperature stability and long-term storage stability. Given these characters, the detection of H2O2 at pH 6.5 was proposed on the basis of the Au@Ag heterogeneous NRs catalyzing the colorimetric reaction of H2O2 and ABTS, where the oxidized ABTS showed a typical absorption peak at 414 nm. The absorbance at 414 nm was linear with H2O2 concentration from 0.01 to 10 mM. Further, considering that Au@Ag heterogeneous NRs and glucose oxidase (GOx) have similar optimal pH for catalytic activities, a novel one-pot method for the detection of glucose was developed by the coupled catalytic reaction using GOx, Au@Ag heterogeneous NRs, and ABTS at nearly neutral pH (pH 6.5) and 37 °C. This proposed method had simple and rapid processes, wide linear range (0.05-20 mM), and reliability for the successful analysis of real samples. On the basis of these attractive and unique characteristics, Au@Ag heterogeneous NRs can become promising substitutes for peroxidase in analytical chemistry and environmental science.

ChemInform Abstract: Syntheses of Aromatic Aldehydes by Laccase of Pleurotus ostreatus MTCC‐1801.

Abstract Selective bioconversion of the aromatic methyl group to its aldehyde group is one of the best applications of the laccases. In the present communication, crude laccase, obtained from the liquid culture medium of the fungal strain Pleurotus ostreatus MTCC-1801, has been used for the selective bioconversion of toluene, 3-nitrotoluene, 4-nitrotoluene, 2-fluorotoluene, 4-fluorotoluene, 2-chlorotoluene, 3-chlorotoluene, 4-chlorotoluene, and 3,4-dimethoxytoluene to benzaldehyde, 3-nitrobenzaldehyde, 4-nitrobenzaldehyde, 2-fluorobenzaldehyde, 4-fluorobenzaldehyde, 2-chlorobenzaldehyde, 3-chlorobenzaldehyde, 4-chlorobenzaldehyde, and 3,4-dimethoxybenzaldehyde, respectively, in the presence of 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as a mediator molecule. Time taken by these conversions was 1–2 h, and average yield of products was more than 93%.

Syntheses of Aromatic Aldehydes by Laccase of Pleurotus ostreatus MTCC-1801

Selective bioconversion of the aromatic methyl group to its aldehyde group is one of the best applications of the laccases. In the present communication, crude laccase, obtained from the liquid culture medium of the fungal strain Pleurotus ostreatus MTCC-1801, has been used for the selective bioconversion of toluene, 3-nitrotoluene, 4-nitrotoluene, 2-fluorotoluene, 4-fluorotoluene, 2-chlorotoluene, 3-chlorotoluene, 4-chlorotoluene, and 3,4-dimethoxytoluene to benzaldehyde, 3-nitrobenzaldehyde, 4-nitrobenzaldehyde, 2-fluorobenzaldehyde, 4-fluorobenzaldehyde, 2-chlorobenzaldehyde, 3-chlorobenzaldehyde, 4-chlorobenzaldehyde, and 3,4-dimethoxybenzaldehyde, respectively, in the presence of 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as a mediator molecule. Time taken by these conversions was 1–2 h, and average yield of products was more than 93%.

Microfluidic device on a nonwoven fabric: A potential biosensor for lactate detection

In the present study, a novel, wearable textile based microfluidic device was developed that provides a non-invasive, rapid, semi-quantitative detection of the lactate level in simulated sweat solution. The potential application was envisioned to be a biosensor that can monitor an athlete’s physical status during exercise. A photolithography technique was used for the fabrication of hydrophilic micro channels and reservoirs surrounded by hydrophobic barriers made from SU-8 negative photoresist. The reservoirs were functionalized by co-immobilization of lactate oxidase (LOX) and horseradish peroxidase (POX) enzymes. LOX uses L-(+)-Lactic acid as substrate and produces H2O2 which is a POX substrate. Then, POX oxidases H2O2 in the presence of 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) and results in color formation. The studies showed that excess amount of analyte presence resulted in analyte inhibition. It was also shown that analyte pH and temperature were effective on the color formation. For effective results, analyte pH and temperature should be ≥5℃ and 25–30℃, respectively. Lower pH and higher temperature values resulted in a decrease in the enzyme activity. The textile based biosensor system could make a semi-quantitative visual detection to differentiate between the normal (<5 mM) and high (≥5 mM) lactate level: while a high lactate level led to a denser purple color formation, normal levels led to a light purple formation and a green color started to be observed.

A novel biofuel cell based on electrospun collagen-carbon nanotube nanofibres

The paper demonstrates a novel glucose/O2 biofuel cell (BFC) based on the electrospun collagen-SWNTs nanofibres with the glucose oxidase (GOD) as the anodic biocatalysts and the laccase as the cathodic biocatalysts. With an average diameter of about (260±95) nm, the electrospun collagen-SWNTs nanofibres exhibited smooth surfaces. The collagen-SWNTs nanofibres modified electrode showed good electron transfer behavior, because of the properties of SWNTs and the three-dimensional reticular structure of the electrospun nanofibers. The GOD and laccase, immobilized in the collagen-SWNTs nanofibres, exhibited good catalytic activity towards glucose oxidation and oxygen reduction through mediators of ferrocene monocarboxylic acid (FMCA) and 2,2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS), respectively. The maximum power density of the assembled glucose/O2 BFC based on the electrospun collagen-SWNTs nanofibres was ca. 14.3 μW/cm2. Moreover, more than 50% of the initial value remained after continuous operation of 100 h. The results indicated the potential to apply the electrospun collagen-SWNTs nanofibres for novel BFC device.