Search

AbstractAn optical biosensor was developed as a novel adsorbent to isolate glucose from saliva. A straightforward procedure was used to create the glucose-imprinted polymer coating on the surface of zeolitic imidazolate framework (ZIF-8) nanoparticles which served as the adsorbent. Glucose oxidase was immobilized. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis were used to characterize the novel adsorbent. The ZIF-8 nanoparticles were synthesized and coated with the MIP via precipitation polymerization on the surface of ZIF-8 nanoparticles with glucose acting as a template. To determine glucose, glucose oxidase catalyzed the conversion of adsorbed analyte on the polymer surface to gluconic acid. The resulting color change due to bromothymol blue was characterized using a colorimetric-based smartphone using the RGB profile. Key parameters such as pH, adsorbent mass, adsorption time, and indicator concentration were optimized and under these conditions this biosensor showed few interferences and good sensitivity with a 20 s response time. A linear range from 300 to 500 mg dL−1 was demonstrated by an exponentially growing calibration curve when saliva with pixel slopes (R + G + B) were used for calibration. This biosensor provides a low-cost and fast approach for glucose determination in biological samples. [ABSTRACT FROM AUTHOR]

Hydrolysable tannins are polyphenolic molecules contained in plant foodstuffs, potentially toxic for animals. Since tannins have been found in some bee products such as bee pollen, propolis, and honey, this work aimed to test the effects of tannins dietary assumption on bees' health. Results showed that supplementation of honey bees diets with 0.05% (w/w), as naturally amount reported in the honey, and 0.5% (w/w) of tannins significantly reduced bees' survival in a dose-dependent manner. In honey bees fed with a 0.5% tannins-enrichment diet a significantly decreased phenoloxidase activity than those fed with a 0.05% tannins-enrichment diet and with only syrup was recorded. Conversely, glucose oxidase activity significantly increased in honey bees fed with 0.5% tannins-enrichment diet than those with a 0.05% tannins-enrichment diet and only syrup. No differences were detected in glutathione S-transferase activity between honey bees fed with tannins-enrichment diets and syrup. Therefore, a naturally amount of hydrolysable tannins in foods can weakly affect bee wellness, whereas high levels of tannins can have a negative impact on honey bees' immunity and metabolism leading to a reduction of lifespan. [ABSTRACT FROM AUTHOR]

The anchoring of two-dimensional nanosheets (2D) with Prussian blue nanocubes has exhibited the advantage of high electron conductivity and better catalytic application. Herein, we reported the successful fabrication of molybdenum disulfide-supported Prussian blue nanocubes (MoS2@NiCo-PBANCs) and compared the bare MoS2 and NiCo-PBNCs for effective peroxidase, such as catalytic activity, which can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by the generation of H2O2, ensuring the appearance of blue colored solution. The MoS2@NiCo-PBANCs exhibited an excellent colorimetric sensing performance toward glucose in urine samples. Therefore, the present method demonstrates the high sensitivity, selectivity, simplicity, and fast colorimetric sensing ability for H2O2 and glucose detection. The synergistic effect of MoS2@NiCo-PBNCs reveals lower detection limits of 0.0075 µM and 0.01 µM for H2O2 and glucose, respectively. The exclusive structural morphology, excellent stability, large surface area, and high catalytic property have been utilized to achieve the closer interaction of glucose oxidase and TMB with MoS2@NiCo-PBANCs to oxidize glucose to gluconic acid. Overall, we utilized the MoS2@NiCo-PBNCs as a novel composite nanomaterial for the application of H2O2 and glucose peroxidase-like mimics in the urine sample. [ABSTRACT FROM AUTHOR]

Various studies have shown that the microbial proteins are often more stable than belongs to other sources like plant and animal origin. Hence, the interest in microbial enzymes has gained much attention due to many potential applications like bioenergy, biofuel production, biobleaching, bioconversion and so on. Additionally, recent trends revealed that the interest in isolating novel microbes from harsh environments have been the main focus of many scientists for various applications. Basically, industrially important enzymes can be categorized into mainly three groups: carbohydrases, proteases, and lipases. Among those, the enzymes especially carbohydrases involved in production of sugars. Carbohydrases include amylases, xylanases, pectinases, cellulases, chitinases, mannases, laccases, ligninases, lactase, glucanase, and glucose oxidase. Thus, here, an approach has been made to highlight five enzymes namely amylase, cellulase, laccase, pectinase, and xylanase from different sources with special emphasis on their properties, mechanism, applications, production optimization, purification, molecular approaches for its enhanced and stable production, and also biotechnological perspectives of its future development. Also, green and sustainable catalytic conversion strategies using nanoparticles of these enzymes have also been discussed. This review will provide insight into the carbohydrases importance and their usefulness that will help to the researchers working in this field. [ABSTRACT FROM AUTHOR]

The regulation and prohibition of antibiotics used as growth promoters (AGP) in the feed field are increasing because they cause antimicrobial resistance and drug residue issues and threaten community health. Recently, glucose oxidase (GOx) has attracted increasing interest in the feed industry as an alternative to antibiotics. GOx specifically catalyzes the production of gluconic acid (GA) and hydrogen peroxide (H2O2) by consuming molecular oxygen, and plays an important role in relieving oxidative stress, preserving health, and promoting animal growth. To expand the application of GOx in the feed field, considerable efforts have been made to mine new genetic resources. Efforts have also been made to heterologously overexpress relevant genes to reduce production costs and to engineer proteins by modifying enzyme properties, both of which are bottleneck problems that limit industrial feed applications. Herein, the: different sources, diverse biochemical properties, distinct structural features, and various strategies of GOx engineering and heterologous overexpression are summarized. The mechanism through which GOx promotes growth in animal production, including the improvement of antioxidant capacity, maintenance of intestinal microbiota homeostasis, and enhancement of gut function, are also systematically addressed. Finally, a new perspective is provided for the future development of GOx applications in the feed field. [ABSTRACT FROM AUTHOR]

Near-infrared luminescence glutathione-coated gold nanoparticles (NGS-AuNPs) were synthesized and employed as fluorescent probes for the selective determination of hydrogen peroxide and glucose. This approach was based upon the coordination-induced fluorescence quenching of tris(2-carboxyethyl)phosphine (TCEP) with the NGS-AuNPs and its reduction of H2O2. The NGS-AuNPs possessed a highly monodispersed spherical morphology with a uniform diameter of 2.1 ± 0.5 nm and a maximal fluorescence emission wavelength of 810 nm. The results of the H2O2 determination demonstrate the excellent selectivity of this strategy with a limit of detection of 5.4 μM. This system was also employed for the selective determination of glucose which generated H2O2 by the catalytic oxidation of glucose oxidase with a limit of detection of 0.42 μM. This strategy exhibited excellent performance for the test of H2O2 and glucose in urine with recoveries from 93% to 103%. This methodology may allow the analysis of biological samples and clinical diagnosis. [ABSTRACT FROM AUTHOR]

In the present paper, symmetrical configuration of dual material double gate dielectric modulated junctionless TFET (DM DG JLTFET) for biosensor applications is explored. The JLTFET consists of Si material with an intensely doped n-type substrate. In this work, the JLTFET utilizes the dielectric modulation method which aids the bio-transistor to recognize neutral and charged analytes (biomolecules). A double metal gate structure is designed by employing two dissimilar metal gate electrodes to reduce short channel impact on device characteristics. The proposed device includes a nanogap region (cavity) which is framed for biomolecules to immobilize. Surface potential and their sensitivity are examined for neutral and charged-neutral analytes. The effects of structure parameters such as nanogap region length and fill-in factor have been analyzed through simulation. The paper examines the behavior of DM DG JLTFET for biological molecules sensing via change in relative permittivity and charge density. The proposed device shows noticeable sensitivity results for charged biomolecules (especially for positively charged analytes). The present work has analyzed the different parameters affecting the sensitivity of the biosensor which includes structural geometric variations like change in cavity length, cavity thickness and fill-in factor. The sensitivity of the neutral biomolecules having higher dielectric constant is observed higher; the surface potential sensitivity of the Gelatin (k = 12) is estimated as 3.75 × 10 3 which is 45%, 55%, and 135% higher than the sensitivity of Keratin (k = 7), Bacteriophage T7 (k = 6), and Glucose Oxidase (k = 3), respectively at the cavity length of 7 nm. [ABSTRACT FROM AUTHOR]

We conducted this experiment to establish a consistent result of dietary glucose oxidase (GOX) supplementation in broilers' growth performance, nutrient digestibility, gas emission, caecum bacterial count, and antoxidant status. A total of 792 broilers of 42.38 ± 0.72 g average body weight (BW) at one-day old were fractionated into four treatment groups (18 birds/pen; 11 pens/treatment) named as 0%, Basal diet; 0.01%, basal diet + 100 mg/kg GOX; 0.02%, basal diet + 200 mg/kg GOX; 0.03%, basal diet + 300 mg/kg GOX. For growth performance, this 35 days' experimental period was divided into three phases (d 1 to 7, d 7 to 21, d 22 to 35, overall). For the final phase, nutrient digestibility, gas emission, caecum bacterial count, and blood parameters were measured. GOX supplementation (0.02%, 0.03%) showed increased body weight gain (BWG) and reduced feed conversion ratio (FCR) during days 22 to 35 and in overall period. At the same time, linear increase of BWG and linear decrease of FCR were observed. Increasing doses of GOX showed linear improvement in dry matter digestibility and a tendency for a gradual increase in energy digestibility. On day 7, GOX supplementation (0.02%, 0.03%) reduced drip loss in meat with a gradual decrease. Blood antioxidant parameters of glutathione peroxidase (GSSG) and glutathione (GSH) were linearly increased by rising doses of GOX where 0.03% GOX had the highest value. In short, GOX supplementation brought improvements in digestibility and antioxidant capacity, which helped to increase body weight gain in broilers. Glucose oxidase enzyme supplementation could benefit growth performance in broilers Dietary addition of glucose oxidase could increase apparent nutrient digestibility in broilers As a health benefit, antioxidant status of broilers were improved with glucose oxidase supplementation [ABSTRACT FROM AUTHOR]

A chemiluminescence (CL) nanosensing platform was constructed by using reduced graphene oxide (rGO) as the carrier, which was loaded with N-(aminobutyl)-N-(ethylisoluminol) (ABEI) as the signaling molecule, hemin as the catalyst, and glucose oxidase (GOx) as the enzyme. The loading efficiency of GOx was determined to be 0.64 mg GOx/mg rGO. The nanosensing platform achieved one-step determination of glucose without pre-incubation steps. When glucose is added to the CL nanosensing platform, the GOx on the nanocomposite catalyzes the reaction between glucose and O2 to produce H2O2 which oxidizes ABEI to emit light with the catalysis of hemin. When glucose was mixed with the nanocomposite, a growth-type CL profile was observed and the maximum signal was obtained approximately 6 min after the addition of glucose to the nanocomposite. The CL nanosensing platform exhibited a linear enhanced response for glucose from 10 μM to 1 mM. The detection limit for glucose was 2.6 μM. The proposed glucose CL sensing platform also exhibited good selectivity and specificity. Furthermore, it was successfully applied in the determination of glucose in serum, and satisfactory recoveries were obtained, signifying its potential in clinical diagnosis. [ABSTRACT FROM AUTHOR]

A glucose-sensitive antibacterial and anti-inflammatory hydrogel film with controlled release of tannic acid (TA) was synthesized using chitosan (CS). Specifically, the photo-crosslinked CS hydrogel was first obtained and then immersed in TA solution to generate composite hydrogel film with enhanced mechanical properties. Subsequently, N-hydroxysuccinimide/1-ethyl-3-(3-dimethylaminopropyl) carbodiimide based coupling chemistry was used to covalently crosslink glucose oxidase (GOx) to CS to obtain glucose sensitivity. The physicochemical properties, including chemical composition, enzyme-related characteristics, glucose responsiveness, and mechanical strength, were thoroughly investigated, followed by the cytotoxicity, antibacterial and anti-inflammatory tests. The results showed that the GOx immobilized on the film surface by covalent bonding gave better stability than those that were physically adsorbed. In addition, it could quickly and correspondingly modify its inner pore structure in response to the glucose stimulus and then control the loaded TA release. Meanwhile, the TA addition could enhance the film's mechanical properties. The composite hydrogel film demonstrated adequate biocompatibility and can inhibit NO, IL-6, and TNF-α production in stimulated macrophages, as well as Porphyromonas gingivalis growth, demonstrating effective antibacterial and anti-inflammatory activity. [ABSTRACT FROM AUTHOR]

The nano-drug delivery system activated by the tumour microenvironment (TME) can effectively treat tumours with low toxicity. Based on a high level of reductive GSH in TME and the different coordination properties of Fe ions, this project intended to prepare a GSH-activated cascade catalytic nanoreactor for breast cancer treatment using Fe3+/Fe2+ as the molecular switch. In this study, the glucose oxidase (GOx) loaded iron alginate nano hydrogel (FeAlg/GOx) was prepared by the simple one-step titration method. Results showed that FeAlg/GOx could remain stable during in vivo circulation to avoid hypoglycaemia. When it reached the targeted tumour site, reductive GSH can reduce Fe3+ to Fe2+. Thereafter, FeAlg/GOx nanogel was broken and GOx was released to consume the essential nutrient glucose (Glu) to achieve tumour starvation therapy. Next, the substrate H2O2 generated by the reaction between GOx and Glu can be catalysed by Fe2+ to produce highly cytotoxic •OH in situ, which could further kill tumour cells. The in vivo pharmacodynamics results demonstrated that compared with the control group (V/V0 = 8.36 ± 1.73), FeAlg/GOx group showed the most significant anti-tumour effect with V/V0 of 3.08 ± 1.06. In conclusion, this "inactivated" FeAlg/GOx nanogel can be converted into "activated" therapeutic substances in situ to achieve starvation-chemodynamic combined treatment for breast cancer. [ABSTRACT FROM AUTHOR]

Ultrathin and vertical NiCo2O4 nanosheets were grown on nitrogen-doped reduced graphene oxide (NiCo2O4 NSs@N-rGO) through a simple one-step co-precipitation procedure. The NiCo2O4 NSs@N-rGO nanocomposites were investigated through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. And the performance of NiCo2O4NSs@N-rGO non-enzymatic glucose sensor was measured by cyclic voltammetry and amperometric method. The sensor exhibited two wide linear ranges of 0.01 mM-5.50 mM and 5.50 mM-15.50 mM with high sensitivity of 4372.9 μA·mM−1cm−2 and 1686.1 μA·mM−1cm−2, which is much better than other Co-based and Ni-based glucose sensors. In addition, the non-enzymatic glucose sensor also shows strong anti-interference and durability. Besides, it is found that this non-enzymatic glucose sensor can accurately measure the blood glucose concentration in human serum, which provides a great possibility for future application in medical treatment. [ABSTRACT FROM AUTHOR]

This study features an enzyme-free amperometric determination of glucose with flow injection analysis (FIA) using pencil graphite electrodes (PGEs) modified with nickel oxide-cobalt (II,III) oxide (NiO-Co3O4/PGE) and nickel oxide-copper nanoparticle (NiO-CuNPs/PGE). Both modified PGEs exhibited excellent electrocatalytic activity toward oxidation of glucose in strong alkaline media since they enhanced the peak current compared with the bare PGE and single metal oxide- or metal nanoparticle-modified PGEs. Flow-injection (FI) amperometry showed the linear response range, the limit of detection and sensitivity for NiO-Co3O4/PGE and NiO-CuNPs/PGE were 1.0–1000 µM, 0.23 µM and 586 µA mM−1 cm−2, and 0.10–250 µM, 0.03 µM and 949 µA mM−1 cm−2, respectively. Glucose was determined in real samples with good accuracy and precision. [ABSTRACT FROM AUTHOR]

The physicochemical properties and chemical composition of bee's honey determine its nutritional and medicinal uses. The chemical constituents of honey include sugars, polyphenols, flavonoids, hydroxymethylfurfural, hydrogen peroxide, methylglyoxal, proteins, enzymes, vitamins, and minerals while the physical properties include color, aroma, taste, and conductivity. This review considers the factors that affect the physicochemical properties and chemical composition of bee's honey to help beekeepers produce high-quality bee's honey. [ABSTRACT FROM AUTHOR]

Biosensors are biological detection systems used for the analysis of chemicals with the help of biological species like enzymes, antibodies, etc. Nanoflowers for the detection of the glucose improve stability, strength and reduce mass transfer limitations. The main objective of the research work was to develop bioconjugated nanoflowers for effective and precise detection of the glucose in the saliva. Magnetic nanoparticles of iron oxide-chitosan-tripolyphosphate-calcium were used to develop hybrid scaffold like structure with proteins. The particle size of the nanoflowers were found to be range of 300-600 nm with zeta potential -15 to -24 mV. Spherical shape of nanoflowers were observed with scanning electron microscopy studies. The nanoflowers estimated glucose quickly and precisely in the concentration range of 0.2-300 mg/dl from saliva using fluorimeter. Bioconjugated nanoflowers hold futuristic approach for efficient, accurate and non-invasive technique for the detection of glucose. [ABSTRACT FROM AUTHOR]

Electrochemical biosensors have wider interest in the last decades than other analytical techniques such as chromatography, spectrophotometry, fluorescence, migration techniques and flow systems. Since they provide practicality, sensitivity, and fast response, these systems can be integrated with labs-on-chips to obtain excellent point of care analytical platforms. They are excellent devices for wide range of analytes such as drugs, proteins, markers, bacteria, and viruses etc. due to their unique features. Electrochemical methods are also successful at molecular recognition, user friendliness, sensitive responses, requirement of small volume reactive of reagents, low cost, and applicability to point of care tests. DNA, enzyme and immunosensor based biosensors are widely used as well. According to recent studies of electrochemical biosensors, nanomaterials and polymers have been used to increase the performance of biosensors. In this review, the recent studies of electrochemical biosensors have been presented with their applications at various fields. [ABSTRACT FROM AUTHOR]

1. The influence of glucose oxidase (GOD) supplementation on growth, gut inflammation and its compensatory effects in broilers was investigated before and after heat stress. 2. Before heat stress, one-day-old broilers were divided into two groups: the control (CON) and GOD (100 g/t complete feed) groups. On d 21, the CON group was equally divided into CON1 and CON2 groups, and heat stress (35°C) was applied to the CON2 and GOD groups for 8 h/day to the end of the study, d 27 of age. The chickens were either killed before heat stress and 2 d after heat stress for the determination of cytokines in the liver and ileum, serum antioxidant enzymes and ileal microbiota. Growth performance was determined before and 7 d after heat stress. 3. The GOD decreased Clostridiales and Enterobacteriaceae families of bacteria and increased ileal nuclear factor-κB, interleukin-1β, and interferon-γ (P < 0.05) before heat stress. The broilers exhibited compensatory effects, including increases in ileal sirtuin-1, heat shock protein 70 expression, liver nuclear factor erythroid 2-related factor 2 content, serum total antioxidant capacity and glutathione peroxidase level (P < 0.05). At 2 d after heat stress, inflammatory factors were increased in both the CON2 and GOD groups, but the levels were lower in the GOD than CON2 (P < 0.05). On d 7 after heat stress, GOS alleviated heat stress induced growth retardation (P < 0.05). 4. These data suggested that GOD supplementation in broiler diets before heat stress stimulated intestinal oxidative stress and produced a compensatory response, which prevented a rapid increase in intestinal inflammatory factors and helped to maintain growth performance under heat stress. [ABSTRACT FROM AUTHOR]

A nanocomposite, rGO/AuNPs, was synthesized simultaneously using one-pot approach with gold nanoparticles (AuNPs) and reduced graphene oxide (rGO) within gelatin which used as a reducing and stabilizing agent. Then, the fabricated nanocomposites were characterized by UV-Vis, transmission electron microscope (TEM) and field emission scanning electron microscope (FE-SEM). The optimal nanocomposite was determined using electrochemical approaches. After facile and eco-friendly synthesis of rGO/AuNPs nanocomposites, it was used to fabricate the bioanode of enzymatic glucose biosensors. After drop-casting the nanocomposites on a screen-printed electrode (SPE), the glucose oxidase (GOx) was immobilized on the pre-treated SPE through a protein cross-linking approach using glutaraldehyde (GA) as a crosslinking reagent and 2,5-dihydroxybenzaldehyde (DHB) as a mediator to improve the electrochemical performance. Then, electrochemical performance of enzyme immobilized nanocomposites was studied using the potentiostat. The results demonstrate that the enzymatic biosensor made of rGO/AuNPs nanocomposites showed enhanced the sensitivity of selectivity for detection of glucose. [ABSTRACT FROM AUTHOR]

Silver nanoparticles-decorated poly(m-aminophenol) nanofibers (PmAPNFs) was prepared through the initial synthesis of PmAPNFs via chemical polymerization of m-aminophenol with ammonium persulfate (APS) and NaOCl as oxidizing agents, followed by thermo-chemical reduction of Ag+ ions into Ag nanoparticles on the PmAPNFs. Different spectroscopic and morphological analyses confirmed the formation of Ag nanoparticles (AgNPs) on the surface of PmAPNFs. As-prepared PmAPNFs/AgNPs nanocomposite showed remarkable catalytic activity toward the electro-oxidation reaction of glucose in NaOH medium. The PmAPNFs/AgNPs based biosensor demonstrated a very low detection limit of 0.062 µM (S/N = 3) together with high sensitivity (17.45 µAmM−1 cm−2) and wide linear range (0.1 − 8 mM). It has short response time (∼7 s) even at lower concentration of glucose. It also exhibited strong tolerance against various electroactive interfering agents during glucose sensing process. The present PmAPNFs/AgNPs nanocomposite could be a promising material for the fabrication of highly sensitive, environment-friendly and low-cost enzyme-free glucose sensor devices. [ABSTRACT FROM AUTHOR]

Grape wine is the most widely consumed fruit wine in the world. With the increasing diversification of consumers' needs, the variety of fruit wines in the market is becoming more and more abundant. Whether it is the production of grape wine or other fruit wines these processes are inseparable from the participation of enzymes. The quality of these wines is closely related to the application of enzymes in the winemaking process. Enzymes are involved in pretreatment, fermentation, filtration, flavoring, aging and storage of fruit wines. This review systematically illustrated the role of pectinase, β-glucanase, β-glucosidase, glucose oxidase, lysozyme, protease, tannase and urease in the production of wines and their current production status and also provided a theoretical basis for better application of various enzymes in the production of various fruit wines. This knowledge could be great significance to improve the quality of fruit wines and reduce the production costs in the fruit wine industry. [ABSTRACT FROM AUTHOR]

This research work intended to prepare and characterize novel dendrimer-based biosensors with an improved response for the detection of glucose in saliva. The nanoparticles of Fe3O4, a core material, encapsulated in PAMAM dendrimers to immobilize glucose oxidase in the presence of cross-linking agent, glutaraldehyde. Fe3O4 nanoparticles were synthesized by oxidative reaction of ferrous chloride and potassium hydroxide. A solvent-free or green chemistry concept was used to prepare PAMAM dendrimers (G4) using Michael addition and amidation reactions where ethylene diamine and methyl methacrylate were used as reactants. The particle size of Fe3O4 nanoparticles and dendrimers were in the range of 20–30 nm and 30–40 nm, respectively. Glucose was detected by photofluorometer using Tris(1, 10-phenanthroline) ruthenium (II) chloride hydrate [TPR(II)CH] as an indicator. The biosensor showed a response in 4–6 min both in the presence and absence of artificial saliva. The behavior of biosensor showed an increase in fluorescence intensity for the concentrations of glucose (5, 10, 15, and 20 ppm). Fourier-transform infrared spectroscopy and differential scanning calorimetry studies confirmed the synthesis of Fe3O4 nanoparticle and acted as a core of PAMAM dendrimers. This potential approach is a simple, cost-effective, and reproducible for noninvasive glucose detection in saliva. [ABSTRACT FROM AUTHOR]

In recent years, diabetes is one of the diseases that cause the most death and disability. It is a global public health problem. Diabetes is mainly due to metabolic disorders caused by insufficient insulin or high blood sugar in the body. Concentration range (4.4–6.6 mM). Therefore, the development of fast and reliable blood glucose sensors has been receiving widespread attention in the diagnosis of diabetes. This article is based on the nano-conjugate electrochemical aptamer sensor, and its performance is studied by detecting dopamine, using the affinity of the nucleic acid aptamer and the target to be stronger than the principle of base force between the nucleic acid aptamer and the complementary strand, and Combined with blood glucose meter to detect dopamine. The results showed that the incubation time of dopamine and the catalytic time of invertase were 30 min and 120 min respectively; the linear detection range of dopamine was 0.45–10 mmol/L, the correlation coefficient was 0.997, and the detection limit was 0.45 mmol/L; The chemical aptamer sensor can maintain the bioelectrocatalytic activity of glucose oxidation, and the electrode detection of glucose shows good electrochemical performance, with high sensitivity, good stability, strong anti-interference ability and other advantages, which can meet the requirements of noninvasive blood glucose detection. Need, has great application prospects in the noninvasive detection of blood glucose. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of supplementing glucose oxidase (GOX; 1000 unit/g) to the diet of growing pigs on growth performance, apparent nutrient digestibility, faecal bacteria counts, and serum antioxidant enzyme parameters. A total of 200 growing pigs [(Yorkshire × Landrace) × Duroc] with an initial body weight of 23.3 ± 0.33 kg were used in a 42-day trial. Pigs were randomly allotted to four dietary treatments with 10 replicate pens per treatment and five pigs (mixed sex) per pen based on the initial body weight. The dietary treatments consisted of the basal diet (control), control + 0.01% GOX, control + 0.02% GOX, or control + 0.03% GOX. One unit of GOX concentration is defined as the amount of enzyme which oxidises 1 μmol β-D-glucose per minute to D-gluconic acid and hydrogen peroxide at 37 °C and pH5.5. Body weight on day 42 (p =.035), average daily gain during days 22–42 (p =.001) and 1-42 (p =.001), average daily feed intake during days 22–42 (p =.008) and 1–42 (p =.020), apparent nitrogen digestibility on day 42 (p =.029), apparent energy retention on day 42 (p =.032), and the concentrations of serum glutathione peroxidase (p =.044) and glutathione (p =.032) on day 42 increased linearly at graduated doses of GOX increased in the diet. Therefore, supplementing GOX to the diet of growing pigs could improve the apparent nutrient digestibility and serum antioxidant enzyme parameters in a dose-dependent manner, thus improving growth performance. In this study, the suitable dosage of GOX used in the diet of growing pigs was 0.03%. Feeding growing pigs with GOX containing diet has beneficial effects on the growth performance Dietary supplementation of GOX could improve the apparent nutrient digestibility in growing pigs The antioxidant status of growing pigs has improved by GOX supplementation. [ABSTRACT FROM AUTHOR]

This study investigated the accuracy of a flash glucose monitoring system (FGMS) in a postprandial setting. Ten fasted adults without diabetes wore the FGMS sensors then consumed a standard breakfast. Their glucose levels were subsequently recorded for 2 hours, both by the FGMS and by measuring capillary glucose levels using the glucose oxidase method. The accuracy of the FGMS data was assessed using the accuracy limits stated in ISO 15197:2013. FGMS measurements were mostly lower than glucose oxidase measurements (mean absolute relative difference ± SD: 25.4 ± 17.0%, p < 0.001). However, the maximum difference from baseline captured by the two methods was not significantly different (mean ± SD, glucose oxidase: 58.5 ± 18.9 mg/dl; FGMS, 54.4 ± 28.9 mg/dl, p = 0.366). FGMS could track the incremental glycaemic excursions after meals in adults without diabetes, yet further studies with greater sample sizes are needed to confirm this finding. [ABSTRACT FROM AUTHOR]

Oxidative stress-induced DNA cleavage and apoptosis in pancreatic acinar cells has been implicated in the pathogenesis of acute pancreatitis. Thus, an efficient DNA repair process is key to prevention of apoptotic pancreatic acinar cell death. Ataxia telangiectasia mutated (ATM), a sensor of DNA breaks, functions by recruiting DNA repair proteins to initiate the DNA repair process. In the present study, we investigated whether H2O2 produced by the action of glucose oxidase on α-D-glucose (G/GO) induces apoptosis in pancreatic acinar AR42J cells through an alteration of the level of ATM. As a result, G/GO induced apoptosis by promoting a loss of cell viability, increase in Bax, decrease in Bcl-2, cleavage of poly (ADP-ribose) polymerase (PARP) and fragmentation of DNA. In addition, ATM cleavage along with elevated levels of calpain and caspase-3 activity was induced by G/GO. By using ATM siRNA, we demonstrated that reduction in ATM levels enhanced G/GO-induced apoptosis. Moreover, inhibition of calpain activity by calpeptin or calpastatin, or by inhibition of caspase-3 with z-DEVD, suppressed G/GO-induced apoptosis and ATM cleavage. Collectively, these findings suggest that proteolysis of ATM is the underlying mechanism of apoptosis of pancreatic acinar cells caused by exposure to oxidative stress. [ABSTRACT FROM AUTHOR]

A new amperometric biosensor was fabricated by means of electropolymerization of L-aspartic acid on a carbon-paste electrode (CPE) for the bioelectrochemical determination of glucose. The electropolymerization process was conducted via cyclic voltammetry (CV). The modified CPE with poly (L-aspartic acid) (PAA) provided free carboxyl groups so as to immobilize the glucose oxidase (GOx), and further, enhanced the electrocatalytic activity of the hydrogen peroxide (H2O2). The biosensor displayed both good stability and good bioactivity. The sensitivity of the prepared biosensor was 5.3 µA cm−2 mM−1. Its linear range extended from 0.05 mM to 1.0 mM, with the low limit of detection (LOD) being 69.2 µM. The Michaelis–Menten constant was found to be 1.17 mM. Furthermore, the biosensor showed good anti-interference ability in relation to dopamine, uric acid, and ascorbic acid. Taken together, these results demonstrate that PAA/CPE is a promising material for the fabrication of glucose biosensor. [ABSTRACT FROM AUTHOR]

In this work, a novel flexible photoelectrochemical immunosensor is developed to determine cardiac troponin I (cTnI) in serum. The flower-like ZnIn2S4 nanospheres (ZIS), as signal amplification material, were successfully synthesized by a solvothermal method. The ZIS and Bi2Se3 were modified on the indium tin oxide- polyethylene terephthalate (ITO-PET) electrode, which effectively accelerates the electronic transition and improved the photocurrent conversion efficiency (signal on). However, the binding of antigen–antibody proteins blocks the electron transfer, resulting in a greatly reduced photocurrent (signal off). By adding the second antibody modified by CdSe quantum dots (CdSe QDs-Ab2), the photocurrent is increased (signal on). The constructed immunosensor has a linear range from 0.08 to 40 ng/mL with a detection limit of 0.026 ng/mL, which shows excellent selectivity, high sensitivity, and good stability. The photoelectrochemical immunosensor has broad application prospects for the clinical examination of myocardial infarction. [ABSTRACT FROM AUTHOR]

In this study, the different mole ratios of glucose oxidase/chitosan/dextran–aldehyde and glucose oxidase/chitosan/dextran–sulfate complexes were synthesized. The modification of glucose oxidase by non-covalent complexation with dextran and chitosan in different molar ratios was studied in order to increase the enzyme activity. The enzyme/polymer complexes obtained were investigated by UV spectrophotometer and dynamic light scattering. Activity determination of synthesized complexes and free enzyme were performed at a temperature range. The best results were obtained by Cchitosan/Cdextran–aldehyde = 10/1 ratio and Cchitosan/Cdextran–sulfate = 1/5 ratio that were used in thermal stability, shelf life, salt stress, and ethanol effect experiments. The results demonstrated that both complexes were thermally stable at 60 °C and had superior storage stability compared to the free glucose oxidase. Complexes showed higher enzymatic activity than free enzyme in the organic solvent environment using 10% ethanol. The complexes were resistant to salt stress containing 0.1 M NaCl or CaCl2. The particle size distribution results of the triple complex evaluated the complexation of the chitosan, dextran derivative, and glucose oxidase. The average size of the triple complex in diameter was found to be 325.8 ± 9.3 nm. Overall findings suggest that the complexes of glucose oxidase, chitosan, and dextran showed significant enhancement in the enzyme activity. [ABSTRACT FROM AUTHOR]

A label free electrochemiluminescence (ECL) immunosensor for the determination of cardiac troponin I was developed using CdS-MoS2 composites as the electrochemiluminescence emitters. The CdS-MoS2 composites were synthesized by a hydrothermal method and used for the construction of the electrochemiluminescence biosensing platform. For the fabrication of the immunosensor, CdS-MoS2 composites, chitosan, cardiac troponin I antibodies, and bovine serum albumin were consecutively assembled on the glass carbon electrode. Under the optimum conditions, the label free electrochemiluminescence determination of cardiac troponin I was obtained. Due to the excellent electrochemiluminescence performance of CdS-MoS2 composites and high specificity of the immunoreactions, the sensor shows satisfactory selectivity and high sensitivity for cardiac troponin I determination. The detection limit was 1.0 pg mL−1 and the linear range was from 5.0 pg mL−1 to 100.0 ng mL−1. Moreover, the method was successfully used to determine cardiac troponin I in human serum samples with recoveries between 85.4 and 111.0%. This label-free immunosensor possesses many merits, including a simple sensing process, good electrochemiluminescence performance of the CdS-MoS2 composites, and high flexibility for extending the strategy for the determination of other biomarkers. [ABSTRACT FROM AUTHOR]

High catalytic activities of enzymes are necessary for the enzyme immobilizing technology for the development of better biocatalysts and biosensors. Basic polypeptide (poly-L-lysine)-templated precipitation of silica synthesized by sol-gel chemistry produced a composite material that allows high enzyme activity. This study investigates the structural properties of the composite material that allow retaining the glucose oxidase (GOx) activity. Scanning (SEM) and transmission (TEM) electron microscopies reveal that the composite has plate- or sheet-type morphologies composed of hexagonal structures that are 0.2–2 µm in diameter. After the encapsulation in a sol-gel silica matrix, encapsulated GOx retained high activity (over 85% of oxidation activity compared with that of free GOx). The relative activity of GOx-encapsulated in SiO2@pLys remained approximately at 50–60% after eight cycles; in addition, the catalytic stability of encapsulated GOx improved under high temperature (60°C) and in several solvents (e.g., HCl, urea, and acetone). Moreover, D-glucose detection was performed in the linear range of 1–400 µM using SiO2@pLys-GOx composites. The obtained results show that SiO2@pLys-GOx composites can be used for enzyme encapsulation with high activity and stability and as biosensor materials with high sensitivity. [ABSTRACT FROM AUTHOR]

Nowadays, breast cancer is one of the riskiest and common cancer types. The early diagnosis of breast cancer is very important just as in other cancer types. Recent investigations demonstrate the biomarkers can be useful for the disease phase. These biomarkers are the very important materials to determine the good or bad diagnostic of the patient. Vascular endothelial growth factor is considered the most powerful mitogen for endothelial cells and also is an important regulator of vascular permeability and angiogenesis. In the frame of this study, it is purposed to design an electrochemical immunosensor system based on indium-tin oxide covered polyethylene terephthalate electrode. Electrochemical impedance spectroscopy, which is a quick and sensitive method, was used for vascular endothelial growth factor determination. Electrochemical impedance spectroscopy and cyclic voltammetry techniques were used in all optimisation processes of the produced biosensor. Scanning electron microscopy images, energy-dispersive X-ray spectra and mapping, atomic force microscopy and infrared spectra were examined to support the optimisation studies and to reveal surface morphology and chemical components. In the electrochemical characterisation studies, repeatability, reproducibility, storage, regeneration, single frequency impedance, square wave voltammetry and Kramer's-Kronig transform studies were performed. The measurements were taken in human serum. [ABSTRACT FROM AUTHOR]

Background: Sonodynamic therapy (SDT) has emerged as an alternative to the traditional treatments of cancer. However, the oxygen consumption induced by SDT and glucose oxidase (GOx) mediated starvation therapy would worsen the hypoxic tumor environment, which further impeded therapeutic efficacy. Purpose: To develop a nanoplatform and investigate its anti-cancer mechanism for enhanced starvation and SDT. Methods: We constructed a cascade catalytic nanoplatform based on GOx modified the mesoporous MnO2 NPs loaded with hematoporphyrin monomethyl ether (HMME), which were designated as GOx-MnO2/HMME. We characterized them for their catalytic activity, and investigate the magnetic resonance imaging and anti-tumor efficiency in vitro and in vivo. Results: MnO2 NPs with catalase-like activity could oxidize H2O2 under acid condition to produce O2, which not only in turn was supplied to the glucose-depletion reaction for an efficient starvation therapy, but also enhanced the 1O2 generation for HMME mediated SDT effect. In addition, the released Mn2+ ions in the system were able to enhance the MRI signal. Both in vitro and in vivo experiments suggested the cascade catalytic-therapeutic effect between GOx, MnO2 NPs and HMME, demonstrating the enhanced starvation and SDT. [ABSTRACT FROM AUTHOR]

Glucose oxidase (GOx)-based amperometric enzyme electrodes have been the target of substantial research. In this study, new amperometric biosensor for determination of glucose was developed. GOx enzyme was immobilized at bovine serum albumin via entrapment method. For this reason, the optimum conditions of Pd–Au NPs/GOx/C-modified glassy carbon electrode were determined. The electron is directly transferred from glucose to the electrode via the active site of the enzyme. The absence of mediators is the main advantage of such third-generation biosensors. The resulting materials were characterized employing scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. In addition, the effects of glucose concentration, scan rate, temperature, electroactive interference, stability, reusability of the biosensors were discussed. The applicability to blood analysis was also evaluated. The biosensor has a limit of detection for the determination of glucose 0.0014 mM. [ABSTRACT FROM AUTHOR]

An improved amperometric creatinine biosensor was fabricated that dependent on covalent immobilisation of nanoparticles of creatininase (CANPs), creatinase (CINPs) and sarcosine oxidase (SOxNPs) onto gold electrode (AuE). The CANPs/CINPs/SOxNPs/AuE was characterised by scanning electron microscopy and cyclic voltammetry at various stages. The working electrode exhibited optimal response within 2 s at a potential of 0.6 V, against Ag/AgCl, pH 6.5 and 30 °C. A linear relationship was observed between creatinine concentration range, 0.1–200μM and biosensor response i.e. current in mA, under optimum conditions. Biosensor offered a low detection limit of 0.1 μM with long storage stability. Analytical recoveries of added creatinine in blood sera at 0.5 mM and at 1.0 mM concentrations, were 92.0% and 79.20% respectively. The precision i.e. within and between-batch coefficients of variation were 2.04% and 3.06% respectively. There was a good correlation (R2 = 0.99) between level of creatinine in sera, as calculated by the colorimetric method and present electrode. The CANPs/CINPs/SOxNPs/Au electrode was reused 200 times during the period of 180 days, with just 10% loss in its initial activity, while being stored at 4 °C, when not in use. Prepared and characterised creatininase (CA), creatinase (CI) sarcosine oxidase (SOx) nanoparticles and immobilised them onto gold electrode (AuE) for fabrication of an improved amperometric creatinine biosensor. The biosensor displayed a limit of detection (LOD) of 0.1 μM with a linear working range of 0.1 μM–200 μM. The biosensor was evaluated and applied to measure elevated creatinine levels in sera from whom suffering from kidney and muscular disorders. The working electrode retained 90% of its initial activity, while being stored dry at 4 ˚C for 180 days. [ABSTRACT FROM AUTHOR]

Enzymes are powerful versatile biocatalysts, however, industrial application of enzymes is usually hampered by their susceptibility. Bio-inspired Eudragit-α-amylase conjugate (E-AC) was proposed as a biocatalyst for various pharmaceutical and industrial applications. In this study, α -Amylase (E.C. 3.2.1.1) was immobilized by covalent conjugation to Eudragit L-100 under mild conditions. The effect of polymer, carbodiimide and enzyme concentrations on optimization of (E-AC) was investigated. In addition, characterization of the free α -Amylase and E-AC with regard to pH, temperature, kinetic parameters, reusability and operational and storage conditions was carried out. Results showed a shift of the optimum pH of E-AC towards the alkaline side whereas, E-AC exhibited higher thermal stability at all tested temperatures. The kinetic parameters, Km values were 2.87 mg/ml and 3.15 mg/ml and Vmax values were 8.35 mg/ml/min and 8.98 mg/ml/min for free and E-AC, respectively. E-AC retained 85% of the initial activity after five consecutive amylolytic cycles, thus emphasizing its powerful potentials. Operational storage and thermal stability were highly improved as well for E-AC conjugate with an 11.6 stabilization factor in comparison to the free α-amylase. In this study, Eudragit L-100 polymer was successfully used as smart immobilization support to create a reversibly soluble-insoluble enzyme biocatalyst to enforce and extend biotechnological applications of α-amylase in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

The fabrication of amperometric biosensors based on whole cell Gluconobacter oxydans DSMZ 2343 (G. oxydans) and glucose oxidase (GOx) was performed for the detection of glucose. Glassy carbon electrodes (GCE) were coated with a 10-(4H-dithiyeno [3,2-b:2',3'-d]pyroll-4-il)decan-1-amine (DTP-alkyl-NH2) polymer using an electropolymerization method and the formed interface was used to connect the bacteria and the enzyme to the electrode. The transfer of electrons from enzyme to electrode was successfully demonstrated by the biocatalytic activity and unique morphology of the conducting polymer. Characterization of the biosensors was assessed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) analyses. The detection limits of the enzyme and microbial based biosensors for glucose were 0.022 and 0.081 mM, respectively. The broad linear dynamic ranges of the GOx and G. oxydans biosensors were observed to be 0.045-50.0 and 0.19-50.0 mM, respectively. The analytical performances of biosensors were compared according to the following figures of merit: detection limits, limits of quantification, pH and current response time. In addition, to demonstrate the applicability of the biosensors, real-time measurements and recovery studies were evaluated. [ABSTRACT FROM AUTHOR]

The sized cotton fabric was enzymatically desized, scoured and bleached with an enzyme mixture of starch degrading enzymes, pectinases and glucose oxidases (GOxs) was added to generate hydrogen peroxide (HP). In this study, enzyme selection and process optimisation was made in order to increase the glucose content of the desizing liquor of a starch-sized cotton fabric. The highest glucose concentration of 4175 mg/L was measured in one-bath containing mixture of α-amylase, amyloglucosidase and pectinase and GOx produced 758 mg/L peroxide. This combination was used in further bleaching processes. For bleaching, hydrogen peroxide was converted into peracetic acid (PAA) by incorporating the bleach activator tetraacetylethylenediamine (TAED). Whiteness values, water absorbency, polymerization degree and tenacity at maximum load were measured on pre-treated samples. The total organic carbon (TOC), chemical oxygen demand (COD), biological oxygen demand (BOD5), the biological degradability (BOD5/COD) and the final pH values were measured on residual pre-treatment baths. [ABSTRACT FROM AUTHOR]

Desugarization of duck albumen using glucose oxidase/catalase was optimized before drying. Optimum condition for desugarization using response surface methodology was as follows: glucose oxidase 31.24 units and catalase 781 units/mL albumen and incubation time of 6.55 h at 30 °C. Foaming capacity (FC) and foam stability (FS) were enhanced, while the solubility decreased after desugarization. This coincided with the increase in surface hydrophobicity (p < 0.05). Higher trypsin inhibitory activity was found in freeze-dried albumen powder than spray-dried counterpart. Trypsin inhibitory activity was continuously decreased as the inlet temperature for spray-drying increased (p < 0.05). Desugarization could increase FC and FS, but slightly decreased solubility of powders. No marked differences in protein patterns were observed in all the powders, regardless of desugarization and drying methods. L* of albumen powder decreased but ΔE, a*-, b*-values and browning index increased as spray-drying temperatures increased (p < 0.05). Therefore, prior desugarization could lower browning and increased foaming property of duck albumen, particularly when spray-dried with inlet temperature of 160 °C. [ABSTRACT FROM AUTHOR]

Glucose oxidase (GOx) catalyses oxidation of glucose accompanied with the generation of hydrogen peroxide. With the addition of Fe2+, hydroxyl radical produced by Fenton reaction between hydrogen peroxide and Fe2+ may quench the fluorescence of gold nanoclusters. In this work, a fluorescent enzyme-linked immunosorbent assay with gold nanoclusters was designed with a straightforward signal output, in which the fluorescence of gold nanoclusters was quenched by GOx-triggered Fenton reaction. Olaquindox was selected as a target analyte. Gold nanoclusters capped with bovine serum albumin and GOx-linked olaquindox conjugates were successfully prepared. Olaquindox in samples directly competed with the GOx-linked olaquindox conjugates for binding immobilized antibody. Consequently, the fluorescence signal increased with the amount of olaquindox. Under optimal conditions, the fluorescent enzyme-linked immunosorbent assay exhibited a favorable performance to detect olaquindox in swine feeds, demonstrating a good linear range from 1.0 μg kg-1 to 150 μg kg-1 with a reliable correlation coefficient (R2 = 0.9918); the limit of detection was 0.68 μg kg-1. Average recoveries in spiked samples were 85.3% to 113.5%. The proposed strategy is a promising approach for the detection of olaquindox and other harmful small molecules. [ABSTRACT FROM AUTHOR]

This study demonstrates a miniaturized integrated glucose biosensor based on a carbon microbeads entrapped by glucose oxidase (GOx) immobilized on poly (N-isopropylacrylamide) (pNIPAm) microgels. Determined by the Lowry protein assay, the pNIPAm microgel possesses a high enzyme loading capacity of 31 mg/g. The pNIPAm GOx loaded on the microgel was found to maintain a high activity of approximately 0.140 U determined using the 4-aminoantipyrine colorimetric method. The integrated microelectrochemical cell was constructed using a microcentrifuge vial housing packed with (1:1, w/w) carbon entrapped by pNIPAm GOx microgels, which played the dual role of the microbioreactor and the working electrode. The microcentrifuge vial cover was used as a miniaturized reference electrode and an auxiliary electrode holder. The device can work as biosensor, effectively converting glucose to H2O2, with subsequent amperometric detection at an applied potential of −0.4 V. The microelectrochemical biosensor was used to detect glucose in wide linear range from 30 µM to 8.0 mM, a low detection limit of 10 µM, a good linear regression coefficient (R2) of 0.994, and a calibration sensitivity of 0.0388 µA/mM. The surface coverage of active GOx, electron transfer rate constant (ks), and Michaelis-Menten constant (KMapp) of the immobilized GOx were 4.0 × 10−11 mol/cm2, 5.4 s−1, and 0.086 mM, respectively. To demonstrate the applicability and robustness of the biosensor for analysis of high sample matrix environment, glucose was analyzed in root beer. The microelectrochemical device was demonstrated for analysis of small sample (<50 µL), while affording high precision and fast signal measurement (≤5 s). [ABSTRACT FROM AUTHOR]

A self-assembled functionalized metal-organic framework, Zn4O(NH2BDC)3 microcrystalline (IRMOF3) could be prepared by washing complex with DMF and CH2Cl2. Via modification with sodium alginate (AA), IRMOF3-AA samples could be obtained. IR and TEM were used for structural confirmation of IRMOF3-AA samples. PEG-GOD could be obtained via PEGylation of glucose oxidase (GOD), which could be confirmed by X-ray photoelectron spectroscopy (XPS) and used for further application. IRMOF3-AA@PEG-GOD samples could be obtained by the immobilization of PEG-GOD to IRMOF3-AA, and the best immobilization condition was achieved by adjusting the amount of GOD. From the view point of enzyme mimics, combined with peroxidase-like properties of the IRMOFS-AA samples, the determination of glucose was demonstrated with a linear range from 5 × 10−5 mol/L to 1.6 × 10−3 mol L−1 using tetramethylbenzidine (TMB) as chromogenic substrate. The prepared IRMOF3-AA@PEG-GOD samples exhibited dual functional enzyme-like (peroxidase and GOD-like) activities, with simple experimental steps. [ABSTRACT FROM AUTHOR]

Worldwide legislation is driving the development of novel and highly efficient analytical tools for assessing the composition of every material that interacts with Consumers or Nature. The biosensor technology is one of the most active R&D domains of Analytical Sciences focused on the challenge of taking analytical chemistry to the field. Electrochemical biosensors based on redox enzymes, in particular, are highly appealing due to their usual quick response, high selectivity and sensitivity, low cost and portable dimensions. This review paper aims to provide an overview of the most important advances made in the field since the proposal of the first biosensor, the well-known hand-held glucose meter. The first section addresses the current needs and challenges for novel analytical tools, followed by a brief description of the different components and configurations of biosensing devices, and the fundamentals of enzyme kinetics and amperometry. The following sections emphasize on enzyme-based amperometric biosensors and the different stages of their development. [ABSTRACT FROM AUTHOR]

To develop a convenient promoter analysis system for fungi, a null-pigment mutant (NPG) of Aspergillus nidulans was used with the 4'-phosphopantetheinyl transferase (PPTase) gene, npgA, which restores the normal pigmentation in A. nidulans, as a new reporter gene. The functional organization of serially deleted promoter regions of the A. nidulans trpC gene and the Cryphonectria parasitica crp gene in filamentous fungi was representatively investigated to establish a novel fungal promoter assay system that depends on color complementation of the NPG mutant with the PPTase npgA gene. Several promoter regions of the trpC and crp genes were fused to the npgA gene containing the 1,034-bp open reading frame and the 966-bp 3' downstream region from the TAA, and the constructed fusions were introduced into the NPG mutant in A. nidulans to evaluate color recovery due to the transcriptional activity of the sequence elements. Serial deletion of the trpC and crp promoter regions in this PPTase reporter assay system reaffirmed results in previous reports by using the fungal transformation step without a laborious verification process. This approach suggests a more rapid and convenient system than conventional analyses for fungal gene expression studies. [ABSTRACT FROM AUTHOR]

In this article, aldehyde derivative of poly(ethylene glycol) (PEG) was synthesized directly with sodium periodate agent. To obtain a conjugate which possesses better stability, PEG aldehyde was bonded to native enzyme with different molar ratios. The conjugation reaction turned out to be efficient and mild. Colorimetric method was applied to evaluate the enzymatic activity of native GOD and its derivatives by introducing another enzyme, horseradish peroxidase. The GOD-PEG aldehyde conjugate with polymeric chains exhibited reduced enzymatic activity towards the catalytical oxidation of glucose, but with significantly increased thermal stability and elongated lifetime. When GOD was modified with PEG aldehyde the enzymatic activity was decreased 40% at 30 °C. However, when incubated at 60 °C the GOD-PEG aldehyde conjugate still retained the enzyme bioactivity of 40% bioactivity left after 4 h, whereas the native GOD lost almost all the activity in 4 h. The polymer chain attached, the more reduction of the enzymatic activity resulted, however, the longer the lifetime and higher thermal stability of the enzyme obtained. [ABSTRACT FROM AUTHOR]

Carbon nanomaterials have emerged as suitable supports for enzyme immobilization and stabilization due to their inherently large surface area, high electrical conductivity, chemical stability, and mechanical strength. In this paper, carbon nano-onions (CNOs) were used as supports to immobilize alkaline phosphatase, horseradish peroxidase, and glucose oxidase. CNOs were first functionalized by oxidation to generate carboxylic groups on the surface followed by the covalent linking of using a soluble carbodiimide as coupling agent. The CNO-enzyme conjugates were characterized by transmission electron microscopy and Raman spectroscopy. Thermogravimetric analysis revealed a specific enzyme load of ∼0.5 mg of protein per milligram of CNO. The immobilized enzymes showed enhanced storage stability without altering the optimum pH and temperatures. These properties make the prepared nanobiocatalyst of potential interest in biosensing and other biotechnological applications. [ABSTRACT FROM AUTHOR]

An enzymatic reaction using glucose oxidase (GOx) was applied for continues production of hydrogen peroxide and organic acid inPhanerochaete chrysosporiumcultures for use simultaneously in catalytic cycle of peroxidases. Decolorization efficiency of crystal violet (CV) as a model pollutant was investigated in 16 d old cultures which overproduced manganese peroxidase (MnP) in response to daily GOx addition and control cultures (i.e. no GOxwas added). However, the ability of overproduced cultures in decolorization of CV was not increased significantly, through addition of GOx(300 U/L) + glucose (10 Mm) to the culture medium at the start of decolorization, the time needed to obtain 87 ± 0.5% removal of CV was reduced 10.7-fold in compared with the control culture. The best GOxconcentration in culture medium for more efficient decolorization was obtained to be 300 U/L. These findings indicated that GOx in the presence of glucose could increase the degradation of CV not only by inducing ligninolytic activity in cultures but also as a subsidiary source forin situH2O2and organic acid production for catalytic activity of peroxidases inP. chrysosporiumcultures. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a highly sensitive and biocompatible glucose sensor using a semiconductor-based field effect transistor (FET) with a functionalized hydrogel. The principle of the FET device contributes to the easy detection of ionic charges with high sensitivity, and the hydrogel coated on the electrode enables the specific detection of glucose with biocompatibility. The copolymerized hydrogel on the Au gate electrode of the FET device is optimized by controlling the mixture ratio of biocompatible 2-hydroxyethylmethacrylate (HEMA) as the main monomer and vinylphenylboronic acid (VPBA) as a glucose-responsive monomer. The gate surface potential of the hydrogel FETs shifts in the negative direction with increasing glucose concentration from 10 μM to 40 mM, which results from the increase in the negative charges on the basis of the diol-binding of PBA derivatives with glucose molecules in the hydrogel. Moreover, the hydrogel coated on the gate suppresses the signal noise caused by the nonspecific adsorption of proteins such as albumin. The hydrogel FET can serve as a highly sensitive and biocompatible glucose sensor inin vivoorex vivoapplications such as eye contact lenses and sheets adhering to the skin. [ABSTRACT FROM AUTHOR]

To understand the circadian rhythms of the glucose metabolism and related hormones in desert reptiles, we studied the daily changes in plasma leptin, insulin, and glucose in the toad-headed lizard,Phrynocephalus versicolor, in the semi-desert of the Alashan Plateau. Blood samples were obtained from groups of 20 lizards (about equal sex ratio for each group) at 4-h intervals throughout a 24-h period. Leptin, insulin, and glucose levels were determined using ELISA, RIA, and the glucose oxidase method, respectively. Ambient temperature and humidity were also measured when the blood samples were taken. We found that: (1) there was a significant difference in plasma leptin concentrations at different times of day; (2) no significant circadian rhythm could be measured for plasma insulin and glucose; (3) ambient temperature, humidity, and body condition had no significant effect on plasma leptin, insulin, and glucose levels; and (4) there were significant correlations between plasma glucose concentrations and leptin concentrations 8 h later, and between insulin concentrations and leptin concentration 8–12 h later. These results suggested that the secretions of leptin and insulin played an important role in glucose metabolism in reptiles in an arid environment. [ABSTRACT FROM PUBLISHER]

This study presents the corrosion behavior of the copper–nickel (Cu–Ni) alloy in the presence ofAcidithiobacillus ferrooxidans(A. ferrooxidans) and glucose oxidase (GOx) enzyme. In both the cases ferric ions played an important role in weight loss and thereby to carry out the corrosion of the Cu–Ni alloy. A corrosion rate of 0.6 (±0.008), 2.11 (±0.05), 3.69 (±0.26), 0.7 (±0.006) and 0.08 (±0.002) mm/year was obtained in 72 h using 9K medium with ferrous sulfate,A. ferrooxidansculture supernatant,A. ferrooxidanscells, GOx enzyme and hydrogen peroxide (H2O2) solution respectively. The scanning electron microscopy (SEM) micrographs showed that a variable extent of corrosion was caused by 9K medium with ferrous sulfate, GOx andA. ferrooxidanscells. An arithmetic average surface roughness (Ra) of 174.78 nm was observed for the control work-piece using optical profilometer. The change in Ra was observed with the treatment of the Cu–Ni alloy using various systems. The Ra for 9K medium with ferrous sulfate, GOx andA. ferrooxidanscells was 374.54, 607.32 and 799.48 nm, respectively, after 24 h. These results suggest thatA. ferrooxidanscells were responsible for more corrosion of the Cu–Ni alloy than other systems used. [ABSTRACT FROM PUBLISHER]

Glucose-responsive monoolein (MO) cubic phase was prepared by immobilizing proteinoid composed of Asp and Leu (PAL) and hydrophobically modified glucose oxidase (HmGOD) onto the MO bilayers. The hydrodynamic mean diameter of PAL aggregate in aqueous solution decreased with increasing the pH value. The number of pamitic acid residue per one molecule of HmGOD was determined to be 6.3 by a calorimetric method. HmGOD could acidify glucose solution in a few hours, possibly because it converted glucose to gluconic acid. PAL- and HmGOD-immobilized MO cubic phase was prepared by hydrating MO melt with the mixture aqueous solution of PAL and HmGOD. The cubic phase exhibited its phase transition around 62.5°C, determined by polarizing microscopy. The release of carboxylic fluorescein (CF) from the cubic phase was suppressed when the pH value of release medium decreased, possibly because PAL can aggregate more at a lower pH value. The release was suppressed when glucose concentration increased, possibly because the release medium can be more acidified and PAL will be more aggregated at a higher glucose concentration. The cubic phase could be used as a drug carrier which releases its content in a sustained manner when the glucose concentration is abnormally high. [ABSTRACT FROM PUBLISHER]