Changes in the gut microbiota mediate the differential regulatory effects of two glucose oxidases produced by Aspergillus niger and Penicillium amagasakiense on the meat quality and growth performance of broilers

Background: Glucose oxidase(GOD), an aerobic dehydrogenase, has been used as an antibiotic substitute in feed.A study was conducted to evaluate the differential effects of 2 different GODs fermented by Aspergillus niger or Penicillium amagasakiense on caecal microbiota and to further illuminate the potential roles of changes in the gut microbiota in regulating the growth performance and meat quality of broiler chickens.Results: A total of 420 one-day-old healthy Arbor Acres broilers were randomly assigned to 4 treatments: the control group,the antibiotic growth promoter(AGP) supplementation group, and the GOD-A and GOD-P(GODs produced by A. niger and P. amagasakiense, respectively) groups. As a result, supplementation with GOD produced by P. amagasakiense could significantly improve the average daily weight gain and average daily feed intake of broilers before 21 days of age by significantly increasing the enzymatic activities of jejunal amylase and those of ileal amylase, chymotrypsin, and lipase in21-day-old broilers and could increase the enzymatic activities of duodenal amylase, jejunal amylase and lipase, and ileal chymotrypsin and lipase in 42-day-old broilers. Meanwhile, compared with AGP treatment, supplementation with GOD produced by P. amagasakiense significantly decreased the L value of 21-day-old broilers and the Δp H and L* value of 42-day-old broilers, while supplementation with GOD produced by A. niger significantly increased the p H24 hvalue of 21-day-old and 42-day-old broilers by reducing plasma malondialdehyde content. By using 16 S r RNA sequencing, we found that the beneficial bacteria and microbiota in broilers were not disturbed but were improved by GOD supplementation compared with ADP treatment, including the genera Eubacterium and Christensenel a and the species uncultured_Eubacterium_sp,Clostridium_asparagiforme, and uncultured_Christensenel a_sp, which were positively related to the improved intestinal digestive enzymatic activities, growth performance, and meat quality of broilers.Conclusion: The altered gut microbiota induced by supplementation with glucose oxidase produced by P. amagasakiense mediate better regulatory effects on the meat quality and growth performance of broilers than that induced by supplementation with glucose oxidase produced by A. niger.

Predominating stable adsorption and direct electrochemistry of glucose oxidase on carbon nanotubes by oxygen-containing groups

Stable adsorption and direct electrochemistry of glucose oxidase （COx） occurred on nitric acid （HNO3）-treated multi-walled carbon nanotubcs （MWNTs） instead of as-received MWNTs, demonstrating the critical roles of oxygen-containing groups in stable adsorption and direct electrochemistry of GOx on carbon nanotubcs （CNTs）.

A Chemiluminescence Optical Fiber Glucose Biosensor Based on Co-immobilizing Glucose Oxidase and Horseradish Peroxidase in a Sol-gel Film

An optical fiber bienzyme sensor based on the luminol chemiluminescent reaction was developed and demonstrated to be sensitive to glucose. Glucose oxidase(GOD) and horseradish peroxidase(HRP) were co-immobilized by microencapsulation in a sol-gel film derived from tetraethyl orthosilicate(TEOS). The calibration plots for glucose were established by the optical fiber glucose sensor fabricated by attaching the bienzyme silica gel onto the glass window of the fiber bundle. The linear range was 0 2-2 mmol/L and the detection limit was approximately 0 12 mmol/L. The relative standard deviation was 5.3% ( n =6). The proposed biosensor was applied to glucose assay in ofloxacin injection successfully.

Immobilization of Glucose Oxidase on Cellulose/Cellulose Acetate Membrane and its Detection by Scanning Electrochemical Microscope (SECM)

s: Cellulose/cellulose acetate membranes were prepared and functionalized by introducing amino group on it, and then immobilized the glucose oxidase (Gox) on the functionalizd membrane. SECM was applied for the detection of enzyme activity immobilized on the membrane. Immobilized biomolecules on such membranes was combined with analysis apparatus and can be used in bioassays.

Direct Electron Communication Between Glucose Oxidase and Carbon Electrode Covered with Polypyrrole

Glucose oxidase can be effectively adsorbed onto the polypyrrole (PPy) thin film electrochemically formed on an anodized galssy carbon electrode (GCEa ). Direct electron communication between the redox of GOD and the modified electrode was successfully achieved, which was detected using cyclic voltammetry. GOD entrapped in PPy film still remained its biological activity and could catalyze the oxidation of glucose. As a third generation biosensor, GOD-PPy/GCEa responded linearly up to 20 mM glucose with a wider linear concentration range.

IMMOBILIZATION OF GLUCOSE OXIDASE AND CELLULASE BY CHITOSAN— POLYACRYLIC ACID COMPLEX

This study is concerned with chitosan-polyacrylic acid complex as a carrier to immobilize glucose oxidase (GOD)and cellulase. The optimum emperature of the immobilized GOD (IG) was determined to be 60℃ which is higher than that of the native GOD about 40℃. The optimum temperature of the immobilized cellulase (IC) was determined to be about 30℃ higher than that of native cellulase. Both of the optimum pH of IG and IC shifted one pH unit to acid. Immobilized enzyme may be used in more wide pH range. Their storage life are much longer compared with their native states. Both of them can be reused at least 12 times.

STUDIES ON IMMOBILIZED GLUCOSE OXIDASE BY DIETHYLAMINOETHYL CELLULOSE COMPLEXES

The properties of immobilized glucose oxidase (GOD) by the complexes of diethylaminoethyl cellulose(DEAEC) with different polymers, such as polymethylacrylic acid (PMAA), polyacrylic acid (PAA), polystyrene sulfonic acid (PSSA), polyvinylaleohol (PVA), polyethylene oxide (PEO) and styrene-maleic acid copolymer (PSMA) were investigated. The activity of immobilized GOD was obviously influenced by the component of the DEAEC complexes. The relative activity of the immobilized GOD reached to maximum and over 90% of the native GOD. when the DEAEC-PMAA DEAEC-PAA complexes were used as a carrier with the molar ratio of DEAEC and polyacid of about one. Michaelis constants (Km) of the immobilized enzymes of DEAEC-GOD-PMAA and DEAEC-GOD-PAA were determined to be 1.25 and 1.00, respectively. Moreover, the immobilized GOD has a good storage stability and cyclic life.

The Amperometric Glucose Enzyme Electrode by Immobilized Glucose Oxidase in Glucose Oxidase/N-ethyl-Poly (4-vinyl)pyridine Multilayer

Multilayers of glucose oxidase(GOD)/N-ethyl-poly (4-vinyl) pyridine (EPVP) have been assembled on thiol self-assembled monolayers on gold electrode.This electrode can be used as an amperometric enzyme elcctrode for glucose. Fe (CN)63-/4- incorporated in EPVP layer acts as the electron mediator, the linear range was 0.1 to 6 mmol/L when the number of GOD layers was 5.

Electrochemical Analysis of Single Glucose Oxidase with a Nanopipette

Nanopore-based electrochemical technique is a promising tool for detecting single proteins.However,detecting single proteins using a nanopipette in their native state without labeling is challenging due to the rapid translocation,which results in an inefficient signal identification.In our study,we finely tuned the driving force equilibrium between electrophoretic force(EPF)and electroosmotic flow(EOF)inside the nanopipette for efficient sensing of single glucose oxidase(GOD)molecules.The duration time of GOD within the nanopipette is extended to about 4 ms.This strategy provided clear ionic current signals with a signal-to-noise ratio of 3.3.As EPF increased in the direction opposite to the motion of GOD,we observed a nonlinear growth in GOD’s duration time.This extended the duration to about 4.4 times longer at−1000 mV compared to at−800 mV.Hence,nanopore-based electrochemical sensing could be used for single GOD molecule analysis as an ultrasensitive method.

Enhancing metformin-induced tumor metabolism destruction by glucose oxidase for triple-combination therapy

Despite decades of laboratory and clinical trials,breast cancer remains the main cause of cancer-related disease burden in women.Considering the metabolism destruction effect of metformin(Met)and cancer cell starvation induced by glucose oxidase(GOx),after their efficient delivery to tumor sites,GOx and Met may consume a large amount of glucose and produce sufficient hydrogen peroxide in situ.Herein,a pH-responsive epigallocatechin gallate(EGCG)-conjugated low-molecular-weight chitosan(LC-EGCG,LE)nanoparticle(Met–GOx/Fe@LE NPs)was constructed.The coordination between iron ions(Fe3+)and EGCG in this nanoplatform can enhance the efficacy of chemodynamic therapy via the Fenton reaction.Met–GOx/Fe@LE NPs allow GOx to retain its enzymatic activity while simultaneously improving its stability.Moreover,this pH-responsive nanoplatform presents controllable drug release behavior.An in vivo biodistribution study showed that the intracranial accumulation of GOx delivered by this nanoplatform was 3.6-fold higher than that of the free drug.The in vivo anticancer results indicated that this metabolism destruction/starvation/chemodynamic triple-combination therapy could induce increased apoptosis/death of tumor cells and reduce their proliferation.This triple-combination therapy approach is promising for efficient and targeted cancer treatment.

Immobilization and Characterization of Glucose Oxidase on Single-Walled Carbon Nanotubes and Its Application to Sensing Glucose

The negatively charged （at pH 8.2） glucose oxidase （GOx, pI ca. 4.2） was assembled onto the surface of single-walled carbon nanotubes （SWNT）, which was covered （or wrapped） by a layer of positively charged polyelectrolyte poly（dimethyldiallylammonium chloride） （PDDA）, via the electrostatic interaction forming GOx-PDDASWNT nanocomposites. Fourier transform infrared （FTIR）, UV-Vis and electrochemical impedance spectroscopy （EIS） were used to characterize the growth processes of the nanocomposites. The results indicated that GOx retained its native secondary conformational structure after it was immobilized on the surface of PDDA-SWNT. A biosensor （Nafion-GOx-PDDA-SWNT/GC） was developed by immobilization of GOx-PDDA-SWNT nanocomposites on the surface of glassy carbon （GC） electrode using Nafion （5%） as a binder. The biosensor showed the electrocatalytic activity toward the oxidation of glucose under the presence of ferrocene monocarboxylic acid （FcM） as an electroactive mediator with a good stability, reproducibility and higher biological affinity. Under an optimal condition, the biosensor could be used to detection of glucose, presenting a typical characteristic of Michaelis-Menten kinetics with the apparent Michaelis-Menten constant of KM^app ca. 4.5 mmol/L, with a linear range of the concentration of glucose from 0.5 to 5.5 mmol/L （with correlation coefficient of 0.999） and the detection limit of ca. 83 μmol/L （at a signal-to-noise ratio of 3）. Thus the biosensor was useful in sensing the glucose concentration in serum since the normal glucose concentration in blood serum was around 4.6 mmol/L. The facile procedure of immobilizing GOx used in present work would promote the developments of electrochemical research for enzymes （proteins）, biosensors, biofuel cells and other bioelectrochemical devices.

Direct Electron Transfer between Glucose Oxidase and Multi-walled Carbon Nanotubes

The direct electrochemical behavior between the glucose oxidase (GOD) and the multi walled carbon nanotubes (MWNTs) has been studied. Two pairs of cyclic voltammetric peaks corresponding to the two different processes, i.e. mass transport and surface reaction of GOD are observed on this MWNTs. The formal potentials with E o′=-0.45 V and E o′=-0.55 V were obtained respectively. The GOD film was observed on the carbon nanotube by the TEM.

Regulation of Glucose Oxidase Activity through Interaction with Fullerene Derivatives

The 2-（hydroxymethyl）pyridine modified C60 （PY-C60） and methoxydiglycol modified C60 （MDG-C60） are synthesized using Bingel-Hirsch reaction and characterized by nuclear magnetic resonance （NMR） and mass spectra. PY-C60 and MDG-C60 can bind to glucose oxidase （GOx） and quench the fluorescence of tryptophan （Trp） residue in GOx through static mechanism. The conformation of GOx is disturbed after formation of complex with these fullerene derivatives. Kinetic analysis indicates that PY-C60 and MDG-C60 may affect the catalytic activity of GOx with a partial mixed-type inhibition mechanism. In the plasma glucose concentration range （3.6--5.2 mmol·L-1）, PY-C60 may significantly accelerate the catalytic velocity of GOx, however, MDG-C60 exerts almost no obvious change to the initial velocity of GOx, suggesting that elaborate design of molecular structure of fullerene derivative is very important for regulating the biological activity of fullerene-enzyme complex.

Immobilization of Glucose Oxidase on Ordered Macroporous Silicas Functionalized with Amino Group

A novel glucose oxidase immobilized on three-dimensionally ordered macroporous （3DOM） material has been prepared by firstly preparation of hybrid 3DOM SiO2-NH2 materials using colloidal crystal method, and following covalent immobilization of glucose oxidase on the pore walls of the 3DOM materials. The materials were characterized by SEM, FTIR, DSC and BET techniques. SEM observation shows that the macropores are highly ordered and are interconnected by small windows. FTIR measurement shows that there are amino and organic groups in the pore walls. The surface area of the 3DOM SiO2-NH2 material is about 10.2 m2/g. The loaded amount of enzyme is increased with amino content in the materials. The immobilized enzyme has high activity, thermal stability and can be reused.

Enhanced thermostability and catalytic efciency of glucose oxidase in Pichia Pastoris

Glucose oxidase(GOD)has many practical applications,but its poor thermostability limits its broader use.In this research,three primary mutants of wild-type GOD were designed using rational mutagenesis,and the GODm mutant was constructed by combinatorial design.The expression,purifcation,and enzymatic properties of the mutants were studied.The specifc enzyme activity of GODm was 2.10-fold higher than that of wild type,and the(k_(cat)/K_(m))value was increased by 1.45-fold.After treatment at 55℃for 3 h,GODm retained 37.5%of its enzymatic activity,and the half-life(t_(1/2))of GODm at 55℃and 65℃was 2.28-fold and 3.36-fold higher than that of wild type,respectively.By analyzing the three-dimensional structure of wild type and the GODm mutant,it was found that T30V formed a new hydrogen bond with FAD and strengthened the hydrophobic interaction,D315K optimized the surface electrostatic interaction,and A162T improved the efciency of the electron pathway.Thus,a novel mutant with improved thermostability and catalytic efciency was obtained in this research.

Direct Electron Transfer Reactions of Glucose Oxidase and D-Amino Acid Oxidase at a Glassy Carbon Electrode in Organic Media

Cyclic voltammetry is employed to demonstrate feasibility of direct electron transfer of glucose oxidase and D amino acid oxidase at a glassy carbon electrode in organic media. The reversible slight conformational change of glucose oxidase is observed by changing 0.1 mol/L phosphate buffer to acetonitrile containing 10% v/v of water and 0.05 mol/L tetrabutyalammonium perchlorate, and vice versa.

Glucose Biosensor Based on Carbon/PVC-COOH/Ferrocene Composite with Covalently Immobilized Enzyme

A carbon/PVC-COOH/ferrocene composite electrode used for the determination of glucose has been prepared. The ferrocene acted as mediator was incorporated into the PVC-COOH polymer and the leakage could be prevented. The presence of carboxyl groups on the electrode surface allowed immobilizing enzyme via EDC and NHS. The ratio of PVC-COOH to graphite powder （w/w） has been studied. Amperometric determination of glucose has been performed at potential of 0.30 V vs SCE. The response time was 〈 15 s. The linear response range was of 0.1-20 mmol/L with a detection limit of 48μmol/L.

Study on the Amperometric Glucose Biosensor Based on Tin Oxide Electrode

An amperometric glucose biosensor based on a tin oxide (SnO_2) electrode has been developed.The SnO_2 electrode is prepared by depositing the SnO_2 thin film onto a carbon electrode.To fabricate the SnO_2 amperometric glucose biosensor,the glucose oxidase and electron transfer mediator (ferrocenecarboxylic acid,FcA) are coimmobilized on the SnO_2 electrode using polyacrylamide.The detection range is up to glucose concentration of 520mg/dl as the applied potential is set at 300mV. Moreover,the most merit for the SnO_2 electrode as the base electrode of the SnO_2 amperometric glucose biosensor is that it can be operated at 150mV constant applied potential.The interference reduction,detection range,sensitivity and linearity are improved as the SnO_2 thin film is deposited onto a carbon electrode.Furthermore,due to the low cost substrate and simple fabrication characteristics,a disposable amperometric glucose biosensor based on the SnO_2 electrode has been realized in this study.

A New Amperometric Glucose Biosensor with Naphthol Green B as Mediator

Naphthol green B was used, for the first time, as a new mediator in an amperometric glucose biosensor. It is a good mediator, promoting electron transfer from glucose oxidase to graphite electrode. The biosensor shows high sensitivity to glucose at low potential with response time of 30 seconds. The linear range is from 1.5 to 18 靘ol/L glucose with detection limit of 0.5 靘ol/L glucose.

Screen-Printable Functional Nanomaterials for Flexible and Wearable Single-Enzyme-Based Energy-Harvesting and Self-Powered Biosensing Devices

Developing flexible bioelectronics is essential to the realization of artificial intelligence devices and biomedical applications, such as wearables, but their potential is limited by sustainable energy supply. An enzymatic biofuel cell(BFC) is promising for power supply, but its use is limited by the challenges of incorporating multiple enzymes and rigid platforms. This paper shows the first example of screen-printable nanocomposite inks engineered for a single-enzyme-based energy-harvesting device and a self-powered biosensor driven by glucose on bioanode and biocathode. The anode ink is modified with naphthoquinone and multiwalled carbon nanotubes(MWCNTs), whereas the cathode ink is modified with Prussian blue/MWCNT hybrid before immobilizing with glucose oxidase. The flexible bioanode and the biocathode consume glucose. This BFC yields an open circuit voltage of 0.45 V and a maximum power density of 266 μW cm-2. The wearable device coupled with a wireless portable system can convert chemical energy into electric energy and detect glucose in artificial sweat. The self-powered sensor can detect glucose concentrations up to 10 mM. Common interfering substances,including lactate, uric acid, ascorbic acid, and creatinine, have no effect on this self-powered biosensor. Additionally, the device can endure multiple mechanical deformations. New advances in ink development and flexible platforms enable a wide range of applications, including on-body electronics, self-sustainable applications, and smart fabrics.