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Nanomaterials have been extensively explored in developing sensors due to their unique properties, contributing to the development of reliable sensor designs with improved sensitivity and specificity. Herein, we propose the construction of a fluorescent/electrochemical dual-mode self-powered biosensor for advanced biosensing using DNA-templated silver nanoclusters (AgNCs@DNA). AgNC@DNA, due to its small size, exhibits advantageous characteristics as an optical probe. We investigated the sensing efficacy of AgNCs@DNA as a fluorescent probe for glucose detection. Fluorescence emitted by AgNCs@DNA served as the readout signal as a response to more H2O2 being generated by glucose oxidase for increasing glucose levels. The second readout signal of this dual-mode biosensor was utilized via the electrochemical route, where AgNCs served as charge mediators between the glucose oxidase (GOx) enzyme and carbon working electrode during the oxidation process of glucose catalyzed by GOx. The developed biosensor features low-level limits of detection (LODs), ~23 μM for optical and ~29 μM for electrochemical readout, which are much lower than the typical glucose concentrations found in body fluids, including blood, urine, tears, and sweat. The low LODs, simultaneous utilization of different readout strategies, and self-powered design demonstrated in this study open new prospects for developing next-generation biosensor devices. [ABSTRACT FROM AUTHOR]

Inkjet printing is a popular technique for depositing high-precision ink lines. This study reports the printing parameters' influence on the electrical properties of the sensing devices. The electrochemical sensors are fabricated with a commercial piezoelectric printer and silver ink. Different substrates are evaluated in the printing process, including paper, polyimide, and polyvinyl chloride (PVC) tapes. Ink depositions' temperature, ink drop spacing, length, and the number of the ink layer are also evaluated in this study. Higher temperatures (40 °C) make the substrate surface smoother, improving the printing quality. Controlling the ink drop spacing produces narrow continuous ink lines. The number of ink layers changes the film thickness, altering their electroactive surface area. The best printing parameters are PVC tape at 40 °C, 17 µm drop spacing, one layer, and 13 mm length. Under optimized conditions, three-electrode electrochemical systems are fully printed with silver ink, showing batch-to-batch reproducibility (RSD = 3%). Their analytical performance is evaluated for picric acid, hydrogen peroxide, and glucose quantification. The sensors are modified with glucose oxidase to quantify glucose in artificial saliva, confirming their analytical applicability. Therefore, this work reports fundamental aspects of inkjet printing, bringing valuable findings to guide new research involving inkjet-printed electrochemical biosensors/sensors ((bio)sensors). [ABSTRACT FROM AUTHOR]

Tumor microenvironment is characterized by the high concentration of reactive oxygen species (ROS), which is an effective key used to open the Pandora's Box against cancer. Herein, a tumor-targeted nanosystem HFNP@GOX@PFC composed of ROS-cleaved Fe-based metal–organic framework, hyaluronic acid (HA), glucose oxidase (GOX) and perfluorohexane (PFC) has been developed for tumor cascade amplified starvation and chemodynamic therapy (CDT). In response to the high concentration of hydrogen peroxide (H2O2) intratumorally, HFNP@GOX@PFC endocytosed by tumor cells can specially be disassembled and release GOX, PFC and Fe2+, which can collectively starve tumor and self-produce additional H2O2 via competitively glucose catalyzing, supply oxygen to continuous support GOX-mediated starvation therapy, initiate CDT and cascade amplify oxidative stress via Fe2+-mediated Fenton reaction, leading to the serious tumor damage with activated p53 signal pathway. Moreover, HFNP@GOX@PFC also significantly initiates antitumor immune response via re-educating tumor-associated macrophages (TAMs) by activating NF-κB and MAPK signal pathways. In vitro and in vivo results collectively demonstrate that nanosystem not only continuously initiates starvation therapy, but also pronouncedly cascade-amplify CDT and polarize TAMs, consequently efficiently inhibiting tumor growth with good biosafety. The functional nanosystem combined the cascade amplification of starvation and CDT provides a new nanoplatform for tumor therapy. [ABSTRACT FROM AUTHOR]

In this research a Hg2+ ion biosensor was developed by combining Prussian blue (PB) with glucose oxidase (GOx) – an enzyme that can be inhibited by Hg2+ ions. An application of PB in the design of Hg2+ ion biosensor enabled detecting changes in hydrogen peroxide reduction current at low operational potential of 0.2 vs Ag|AgCl,KClsat. The described Hg2+ ion biosensor exhibited wide linear range from 27 μM to 247 μM of Hg2+ and higher maximal detectable concentration of Hg2+ than other GOx inhibition‐based biosensors, making it convenient for the analysis of samples with high concentration of Hg2+ ions. [ABSTRACT FROM AUTHOR]

This study presents a glucose biosensor based on electrospun core–sheath nanofibers. Two types of film were fabricated using different electrospinning procedures. Film F1 was composed solely of core–sheath nanofibers fabricated using a modified coaxial electrospinning process. Film F2 was a double-layer hybrid film fabricated through a sequential electrospinning and blending process. The bottom layer of F2 comprised core–sheath nanofibers fabricated using a modified process, in which pure polymethacrylate type A (Eudragit L100) was used as the core section and water-soluble lignin (WSL) and phenol were loaded as the sheath section. The top layer of F2 contained glucose oxidase (GOx) and gold nanoparticles, which were distributed throughout the polyvinylpyrrolidone K90 (PVP K90) nanofibers through a single-fluid blending electrospinning process. The study investigated the sequential electrospinning process in detail. The experimental results demonstrated that the F2 hybrid film had a higher degradation efficiency of β-D-glucose than F1, reaching a maximum of over 70% after 12 h within the concentration range of 10–40 mmol/L. The hybrid film F2 is used for colorimetric sensing of β-D-glucose in the range of 1–15 mmol/L. The solution exhibited a color that deepened gradually with an increase in β-D-glucose concentration. Electrospinning is flexible in creating structures for bio-cascade reactions, and the double-layer hybrid film can provide a simple template for developing other sensing nanomaterials. [ABSTRACT FROM AUTHOR]

Aspergillus niger is a robust microbial cell factory for organic acid production. However, the regulation of many industrially important pathways is still poorly understood. The regulation of the glucose oxidase (Gox) expression system, involved in the biosynthesis of gluconic acid, has recently been uncovered. The results of that study show hydrogen peroxide, a by-product of the extracellular conversion of glucose to gluconate, has a pivotal role as a signaling molecule in the induction of this system. In this study, the facilitated diffusion of hydrogen peroxide via aquaporin water channels (AQPs) was studied. AQPs are transmembrane proteins of the major intrinsic proteins (MIPs) superfamily. In addition to water and glycerol, they may also transport small solutes such as hydrogen peroxide. The genome sequence of A. niger N402 was screened for putative AQPs. Seven AQPs were found and could be classified into three main groups. One protein (AQPA) belonged to orthodox AQP, three (AQPB, AQPD, and AQPE) were grouped in aquaglyceroporins (AQGP), two (AQPC and AQPF) were in X-intrinsic proteins (XIPs), and the other (AQPG) could not be classified. Their ability to facilitate diffusion of hydrogen peroxide was identified using yeast phenotypic growth assays and by studying AQP gene knock-outs in A. niger. The X-intrinsic protein AQPF appears to play roles in facilitating hydrogen peroxide transport across the cellular membrane in both Saccharomyces cerevisiae and A. niger experiments. [ABSTRACT FROM AUTHOR]

Background Psoriasis is a common, chronic, inflammatory condition of the skin. The incidence of metabolic syndrome is three times higher in psoriasis which has significant and serious implications on the health of patient overall health and life span. Objective To determine the frequency of metabolic syndrome in patients of chronic plaque psoriasis. Methods It was a Cross sectional study conducted in department of Dermatology, Services Hospital, Lahore on 150 patients were enrolled. All enrolled patients were tested for their fasting blood sugar, fasting lipid levels, postprandial blood sugar, serum cholesterol, and triglycerides levels. Plasma glucose was measured using glucose oxidase method and serum lipids with enzymatic assays. Waist circumference was measured. Blood pressure was recorded. Outcome variable i.e. metabolic syndrome was recorded. Results The mean age of the patients was 49.23±17.59 years, 114 (76%) patients were male and 117 (78%) patients were married. The familial dyslipidemia was detected in 15 (10%) patients and the metabolic syndrome was found in 49 (32.67%) patients. Conclusion This study concluded that in patients of chronic plaque psoriasis approximately one third of the patients are with metabolic syndrome. [ABSTRACT FROM AUTHOR]

A glucose biosensor was layer-by-layer assembled on a modified glassy carbon electrode (GCE) from a nanocomposite of NAD(P)+-dependent glucose dehydrogenase, aminated polyethylene glycol (mPEG), carboxylic acid-functionalized multi-wall carbon nanotubes (fMWCNTs), and ionic liquid (IL) composite functional polymers. The electrochemical electrode was denoted as NF/IL/GDH/mPEG-fMWCNTs/GCE. The composite polymer membranes were characterized by cyclic voltammetry, ultraviolet-visible spectrophotometry, electrochemical impedance spectroscopy, scanning electron microscopy, and transmission electron microscopy. The cyclic voltammogram of the modified electrode had a pair of well-defined quasi-reversible redox peaks with a formal potential of −61 mV (vs. Ag/AgCl) at a scan rate of 0.05 V s−1. The heterogeneous electron transfer constant (ks) of GDH on the composite functional polymer-modified GCE was 6.5 s−1. The biosensor could sensitively recognize and detect glucose linearly from 0.8 to 100 µM with a detection limit down to 0.46 μM (S/N = 3) and a sensitivity of 29.1 nA μM−1. The apparent Michaelis–Menten constant ( K m app ) of the modified electrode was 0.21 mM. The constructed electrochemical sensor was compared with the high-performance liquid chromatography method for the determination of glucose in commercially available glucose injections. The results demonstrated that the sensor was highly accurate and could be used for the rapid and quantitative determination of glucose concentration. [ABSTRACT FROM AUTHOR]

Coculture and whole-cell immobilization have myriad industrial applications for enhancing enzyme production. Using pretreated wheat straw as the sole carbon source, improving glucose isomerase production and cell growth by synthetic bacterial consortia was investigated. Thirteen cocultures were constructed based on the performance and antagonistic activities of monocultures from six cellulolytic soil bacteria. The performance of monocultures immobilized with calcium alginate was also tested. Only five cocultures (A, B, C, G and J) exhibited cell growth and enzyme production synergies. The highest level of synergism (15.17 U/mL) was found in coculture J composed of Mycobacterium sp. MKAL3 (4.06 U/mL) and Stenotrophomonas sp. MKAL4 (3.37 U/mL) with a synergism degree of 2.04. The synergism was unique to growth on wheat straw as it was completely absent in xylose-grown cocultures. The wheat straw degradation synergism could rely on specific compounds released by the MKAL3 strain that promote the activity of the MKAL4 strain and vice versa. However, immobilized strains MKAL1, MKAL2, MKAL3, MKAL4 and MKAL5 improved glucose isomerase production in the wheat straw fermentation process at different sodium alginate concentrations. Immobilization studies of purified glucose isomerases for hydrolysis and saccharification of wheat straw are now being conducted. [ABSTRACT FROM AUTHOR]

Glucose oxidase (GOx) is a key enzyme used in many industries worldwide. To identify the GO x producer strain, Aspergillus niger was isolated from the Beehive and screened for its glucose oxidase-producing capability. Glucose oxidase was mass-produced by a submerged fermentation system. The activity of glucose oxidase was ascertained by the continuous spectrophotometric rate determination method. GOx was purified by (70%) ammonium sulphate precipitation, dialyzed, and gel filtration with 2.82, 3.54, and 3.69U/mg specific activity respectively. The enzyme exhibited an optimum pH range of 5.5 and a temperature optimum of 40°C. Ag2+ and Hg2+ had a remarkably inhibitory effect on the partially purified GOx, whereas Ca2+, Zn2+, and Mg2+ do not affect the enzyme activity. Cu2+ and Co2+ have a slight inhibitory effect on GOx. Kinetic characteristics of GOx from Aspergillus niger display Vmax as 40 U/ml, and Km as 0.12 mM. The findings on the properties of GOx exhibited optimum conditions for industrial applications [ABSTRACT FROM AUTHOR]

[Display omitted] Here, we report the preparation of a novel Janus nanoparticle with opposite Ir and mesoporous silica nanoparticles through a partial surface masking with toposelective modification method. This nanomaterial was employed to construct an enzyme-powered nanomachine with self-propulsion properties for on-command delivery. The cargo-loaded nanoparticle was provided with a pH-sensitive gate and unit control at the mesoporous face by first attaching boronic acid residues and further immobilization of glucose oxidase through reversible boronic acid esters with the carbohydrate residues of the glycoenzyme. Addition of glucose leads to the enzymatic production of H 2 O 2 and gluconic acid, being the first compound catalytically decomposed at the Ir nanoparticle face producing O 2 and causing the nanomachine propulsion. Gluconic acid leads to a pH reduction at the nanomachine microenvironment causing the disruption of the gating mechanism with the subsequent cargo release. This work demonstrates that enzyme-mediated self-propulsion improved release efficiency being this nanomotor successfully employed for the smart release of Doxorubicin in HeLa cancer cells. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrochemical responses of glucose oxidase loaded (via electrostatic immobilization) into a surface-attached pH- and temperature-sensitive copolymer microgel were examined. The observed temperature behavior of the immobilized enzyme provides evidence that such systems enable pH-dependent regulation of activity of glucose oxidase by a (repeated) temperature cycling, which reversibly transforms the polymeric (microgel) matrix from the swollen state to the collapsed one. [ABSTRACT FROM AUTHOR]

Highlights: Screen-printable functional nanocomposite inks are engineered for flexible, single-enzyme-based energy-harvesting, and self-powered biosensing devices. A BFC powered by the same biosubstrate (glucose) is developed to harvest energy in a biofluid model and act as a self-powered electrochemical glucose. Customized inks are advantageous in terms of integrating with flexible materials, which can be integrated with a wide range of wearables and soft bioelectronics. 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. [ABSTRACT FROM AUTHOR]

Bio-activity conservation of biomolecules after immobilizing in nanomaterials has been a tough challenge, especially in biomedical applications. Herein, we developed a novel freezing-assisted reverse microemulsion method to encapsulate water-soluble enzymes in hollow mesoporous silica nanospheres (HMSNs) for maximumly maintaining enzyme bio-activity. Firstly, a low-temperature and ethanol-free synthesis was carried out, and glucose oxidase (GOx) as a model enzyme was encapsulated into HMSNs to obtain GOx@HMSNs. The TEM and SEM images showed a uniform sphere morphology of GOx@HMSNs with a large hollow cavity for GOx loading. The element mapping, FTIR spectrum and TGA curve further confirmed the effective physical encapsulation of GOx in HMSNs, which can maintain stable bio-activity as verified by the enzyme activity assay. In addition to the facile synthesis for avoiding enzyme-denaturation, the N2 adsorption–desorption curves further demonstrated that small mesopores on HMSNs for blocking enzyme leakage may be another important factor for conserving GOx activity. Finally, GOx@HMSNs as a biosensor significantly possessed a wider linear range of 0.06 mM to 2.61 mM with a low detection limit of 0.01 mM, indicating high sensitivity. Therefore, our synthesis method provides a promising approach for biomolecule immobilization with potent bio-activity and biosensor applications with superior sensitivity. [ABSTRACT FROM AUTHOR]

Dynamic interactions of enzymes, including programmable configuration and cycling of enzymes, play important roles in the regulation of cellular metabolism. Here, we constructed a super DNA‐enzymes molecule (SDEM) that comprises at least two cascade enzymes and multiple linked DNA strands to control and detect metabolism. We found that the programmable SDEM, which comprises glucose oxidase (GOx) and horseradish peroxidase (HRP), has a 20‐fold lower detection limit and a 1.6‐fold higher reaction rate than free enzymes. An SDEM can be assembled and disassembled using a hairpin structure and a displacement DNA strand to complete multiple cycles. An entropically driven catalytic assembly (catassembly) enables different SDEMs to switch from an SDEM with GOx and HRP cascades to an SDEM with sarcosine oxidase (SOX) and HRP cascades in over six orders of magnitude less time than without the catassembly to detect different metabolisms (GO and sarcosine) on demand. [ABSTRACT FROM AUTHOR]

Dynamic interactions of enzymes, including programmable configuration and cycling of enzymes, play important roles in the regulation of cellular metabolism. Here, we constructed a super DNA‐enzymes molecule (SDEM) that comprises at least two cascade enzymes and multiple linked DNA strands to control and detect metabolism. We found that the programmable SDEM, which comprises glucose oxidase (GOx) and horseradish peroxidase (HRP), has a 20‐fold lower detection limit and a 1.6‐fold higher reaction rate than free enzymes. An SDEM can be assembled and disassembled using a hairpin structure and a displacement DNA strand to complete multiple cycles. An entropically driven catalytic assembly (catassembly) enables different SDEMs to switch from an SDEM with GOx and HRP cascades to an SDEM with sarcosine oxidase (SOX) and HRP cascades in over six orders of magnitude less time than without the catassembly to detect different metabolisms (GO and sarcosine) on demand. [ABSTRACT FROM AUTHOR]

A continuous glucose monitoring (CGM) system is an ideal monitoring system for the blood glucose control of diabetic patients. The development of flexible glucose sensors with good glucose-responsive ability and high linearity within a large detection range is still challenging in the field of continuous glucose detection. A silver-doped Concanavalin A (Con A)-based hydrogel sensor is proposed to address the above issues. The proposed flexible enzyme-free glucose sensor was prepared by combining Con-A-based glucose-responsive hydrogels with green-synthetic silver particles on laser direct-writing graphene electrodes. The experimental results showed that in a glucose concentration range of 0–30 mM, the proposed sensor is capable of measuring the glucose level in a repeatable and reversible manner, showing a sensitivity of 150.12 Ω/mM with high linearity of R2 = 0.97. Due to its high performance and simple manufacturing process, the proposed glucose sensor is excellent among existing enzyme-free glucose sensors. It has good potential in the development of CGM devices. [ABSTRACT FROM AUTHOR]

Glucose sensors based blood glucose detection are of great significance for the diagnosis and treatment of diabetes because diabetes has aroused wide concern in the world. In this study, bovine serum albumin (BSA) was used to cross-link glucose oxidase (GOD) on a glassy carbon electrode (GCE) modified by a composite of hydroxy fullerene (HFs) and multi-walled carbon nanotubes (MWCNTs) and protected with a glutaraldehyde (GLA)/Nafion (NF) composite membrane to prepare a novel glucose biosensor. The modified materials were analyzed by UV-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), and cyclic voltammetry (CV). The prepared MWCNTs-HFs composite has excellent conductivity, the addition of BSA regulates MWCNTs-HFs hydrophobicity and biocompatibility, and better immobilizes GOD on MWCNTs-HFs. MWCNTs-BSA-HFs plays a synergistic role in the electrochemical response to glucose. The biosensor shows high sensitivity (167 μA·mM−1·cm−2), wide calibration range (0.01–3.5 mM), and low detection limit (17 μM). The apparent Michaelis–Menten constant K m app is 119 μM. Additionally, the proposed biosensor has good selectivity and excellent storage stability (120 days). The practicability of the biosensor was evaluated in real plasma samples, and the recovery rate was satisfactory. [ABSTRACT FROM AUTHOR]

In this study, we developed a glucose fiber sensor incorporating heterodyne interferometry to measure the phase difference produced by the chemical reaction between glucose and glucose oxidase (GOx). Both theoretical and experimental results showed that the amount of phase variation is inversely proportional to glucose concentration. The proposed method provided a linear measurement range of the glucose concentration from 10 mg/dL to 550 mg/dL. The experimental results indicated that the sensitivity is proportional to the length of the enzymatic glucose sensor, and the optimum resolution can be obtained at a sensor length of 3 cm. The optimum resolution of the proposed method is better than 0.6 mg/dL. Moreover, the proposed sensor demonstrates good repeatability and reliability. The average relative standard deviation (RSD) is better than 10% and satisfied the minimum requirement for point-of-care devices. [ABSTRACT FROM AUTHOR]

Endometriosis is an estrogen-dependent chronic inflammatory disease. Hormonal and surgical treatments are the most commonly used clinical therapies, but they have many sides effects or are traumatic to the body. Therefore, specific drugs for endometriosis treatment are urgently needed to develop. In this study, we identified two features of endometriosis, namely the continuous recruitment of neutrophils into the ectopic lesions and the higher uptake of glucose by ectopic cells. For the above features, we designed a glucose oxidase-loaded bovine serum albumin nanoparticle (BSA-GOx-NPs) that is inexpensive and facilitates large-scale production. After injection, BSA-GOx-NPs were high specifically delivered to ectopic lesions in a neutrophil-dependent manner. Furthermore, BSA-GOx-NPs deplete glucose and induce apoptosis in the ectopic lesions. Whereupon BSA-GOx-NPs produced excellent anti-endometriosis effects when administrated in both acute and chronic inflammatory phases. These results reveal for the first time that the neutrophil hitchhiking strategy is effective in chronic inflammatory disease and provide a non-hormonal and easy-to-achieve approach for endometriosis treatment. [ABSTRACT FROM AUTHOR]

Diabetics often prick their fingertips to measure the glucose levels in their blood. However, this traditional method not only causes prolonged pain but also increases the risk of infection. Hence, in this study, a non-invasive flexible glucose biosensor with high sensitivity was fabricated. Specifically, NiCo metal–organic frameworks (NiCo-MOFs) served as the electrode material of a micro-supercapacitor and sensing material of a glucose sensor. The electrochemical tests verified that the prominent sensitivity of the NiCo bimetal product is 1422.2 μA mM−1 cm−2. The micro-supercapacitor based on the as-fabricated NiCo-MOFs showed a high energy density of 11.5 mW h cm−2 at the power density 0.26 mW cm−2. In addition, the as-designed glucose device exhibited an excellent sensitivity of 0.31 μA μM−1. Furthermore, a flexible energy storage and glucose detection system was successfully prepared by further integrating the micro-supercapacitor and glucose sensor. The smart detector could accurately and conveniently measure the glucose concentration in sweat in real-time. Therefore, the wearable real-time sensing device displays feasible application for non-invasive glucose monitoring and health management. [ABSTRACT FROM AUTHOR]

This research is aimed towards a facile one-step preparation of magnetic poly(styrene-glycidyl methacrylate)-Fe3O4 nanocomposite particles named as P(S-GMA)-Fe3O4. The nanocomposite particles are prepared by a simultaneous free-radical copolymerization and co-precipitation of Fe2+ and Fe3+ salts. Two variable w/w ratios of styrene to GMA (98/2 and 96/4) are used. But, the overall copolymer to iron oxide ratio is kept identical. The structural analyses and morphology revealed the uniform distribution of Fe3O4 nanoparticles and the nanocomposites showed paramagnetic property. The potentiality of nanocomposite particles as glucose bisenosors via adsorption of glucose oxidase (GOD) is investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A comparative analysis of the glucose concentration dependent current response suggested that the modified electrode fabricated from P(S-GMA)-Fe3O4(2) (w/w ratio, 98/2) possessed superior response to other electrodes made from PS, P(S-GMA), PS-Fe3O4 and P(S-GMA)-Fe3O4(4) (w/w ratio, 96/4), respectively. The P(S-GMA)-Fe3O4(2)/GOD/Pt biosensor could measure glucose in the range of 2.2 × 10− 4 to 6.0 × 10− 3 M with a sensitivity of 14.47 µA mM− 1 and exhibited a detection limit of 5.07 µM at a signal to noise ratio of 3. The value of Michaelis-Menten constant (Km) is calculated as 0.019 mM. Overall results indicate that P(S-GMA)-Fe3O4(2) nanocomposite prepared in one-step is suitable for use in glucose biosensors. [ABSTRACT FROM AUTHOR]

The current petroleum chemical methods for fumaric acid production can cause heavy pollution and global warming. In this study, the engineered strains of A. pullulans var. aubasidani were found to be suitable for green fumaric acid producer. Removal and complementation of the relevant genes showed only the ornithine-urea cycle (OUC) was involved in high level fumarate biosynthesis which was controlled by the Ca2+ signaling pathway. Removal of both the GOX gene encoding glucose oxidase and the PKS1 gene encoding the polyketide synthase for 3,5-dihydroxydecanoic acid biosynthesis and overexpression of the PYC gene encoding pyruvate carboxylase made the strain e-PYC produce 88.1 ± 4.3 g/L of fumarate at flask level and 93.9 ± 0.8 g/L of fumarate during the fed-batch fermentation. As a yeast-like fungal strain, it was very easy to cultivate A. pullulans var. aubasidani DH177 and their mutants in the bioreactor and to edit its genomic DNAs to enhance fumarate production. It was found that 2 mol of CO2 could be fixed during a maximal theoretical yield of 2 mol of fumarate per mole of glucose consumed in the OUC. Therefore, the OUC-mediated fumarate biosynthesis pathway in A. pullulans var. aubasidani was a green and eco-friendly process for the global sustainable development and carbon neutrality. [ABSTRACT FROM AUTHOR]

Glucose oxidase is an enzyme that is widely used in biosensors, especially kits for measuring blood sugar. Many diabetics use this type of kit to determine their blood sugar level. Aspergillus niger is the most important source of glucose oxidase for use in biosensors. Diabetes causes secondary diseases in patients for which medications are prescribed to improve them. Dexamethasone, a corticosteroid, is one of the drugs prescribed to diabetics to cure some secondary diseases. In this study, the effect of this drug on glucose oxidase was investigated from a kinetic and molecular point of view. In this study, the kinetics of drug binding to the enzyme was measured and the type of inhibition was determined by Lineweaver-Burk plot. The Ki value of the drug was determined by drawing the secondary curve. Using fluorescence spectrophotometry and molecular docking, the binding of the drug to the enzyme was confirmed. The results showed that the drug inhibits the enzyme non-competitively. Determining the kinetics parameters of the drug-enzyme interaction showed that the drug acts as a potent inhibitor. Study at the molecular level by fluorescence spectrophotometer showed that the drug attachment alters the enzyme conformation to more compaction. In silico results showed that the drug is placed between two helices that are outside the active site and binds to the enzyme by three hydrogen bonds. The result of this study is useful because it suggests that in diabetic patients taking dexamethasone, the amount of glucose declared by the kit may not be real due to the inhibition of glucose oxidase. [ABSTRACT FROM AUTHOR]

Glucose oxidase (GOx)-based electrodes are important for bioelectronics, such as glucose sensors. It is challenging to effectively link GOx with nanomaterial-modified electrodes while preserving enzyme activity in a biocompatible environment. To date, no reports have used biocompatible food-based materials, such as egg white proteins, combined with GOx, redox molecules, and nanoparticles to create the biorecognition layer for biosensors and biofuel cells. This article demonstrates the interface of GOx integrated with egg white proteins on a 5 nm gold nanoparticle (AuNP) functionalized with a 1,4-naphthoquinone (NQ) and conjugated with a screen-printed flexible conductive carbon nanotube (CNT)-modified electrode. Egg white proteins containing ovalbumin can form three-dimensional scaffolds to accommodate immobilized enzymes and adjust the analytical performance. The structure of this biointerface prevents the escape of enzymes and provides a suitable microenvironment for the effective reaction. The bioelectrode's performance and kinetics were evaluated. Using redox-mediated molecules with the AuNPs and the three-dimensional matrix made of egg white proteins improves the transfer of electrons between the electrode and the redox center. By engineering the layer of egg white proteins on the GOx-NQ-AuNPs-mediated CNT-functionalized electrodes, we can modulate analytical performances such as sensitivity and linear range. The bioelectrodes demonstrate high sensitivity and can prolong the stability by more than 85% after 6 h of continuous operation. The use of food-based proteins with redox molecule-modified AuNPs and printed electrodes demonstrates advantages for biosensors and energy devices due to their small size, large surface area, and ease of modification. This concept holds a promise for creating biocompatible electrodes for biosensors and self-sustaining energy devices. [ABSTRACT FROM AUTHOR]

Enzymatic cascade reactions are essential for metabolic pathway and biological signal transduction in living cells. More and more attention has been paid to artificial microreactors, which mimic these efficient, methodical, and selective biological cascade catalytic systems in cells. Natural hydrogels such as alginate and chitosan are thought of as suitable materials for matching the chemical, physical, and mechanical properties with extracellular matrix. Inspired by the structures of eukaryotic cells, alginate/chitosan multicompartment microcapsules for enzymatic cascade reaction are developed using an oil‐free gas‐shearing method. Multiple enzymes as biocatalysts are encapsulated in the particles to resemble complex physiological reactions. Biocatalysts, including glucose oxidase and peroxidase in alginate Janus core as a model, sense the external hyperglycemic environment, resulting in insulin release following chitosan shell protonation. The microcapsules show an excellent recyclability, room‐temperature long‐term and anti‐proteolysis stability. The microreactor approach leads to the development of a multi‐enzymatic cascade reaction system and provides an ideal carbohydrate platform to further understand the biomimetic metabolic function of organelles and organs. [ABSTRACT FROM AUTHOR]

A Co(II)‐organic framework (Co‐MOF), [Co3(3,5‐bimpy)2(5‐cpia)2(H2O)2], was constructed via the hydrothermal reaction of 3,5‐bis(1‐imidazoly)pyridine (3,5‐bimpy) and 5‐(2′‐carboxylphenoxy)isophthalic acid (5‐H3cpia). The Co‐MOF possessed a three‐dimensional (3D) porous architecture with the porosity of 22.4% per unit volume. The Co‐MOF@Hemin composite was further constructed via the encapsulation of Hemin into the Co‐MOF material. The constructed Co‐MOF@Hemin exhibited satisfactory peroxidase‐like activity through catalytic oxidation of the colorless peroxidase substrate 3,3,5,5‐tetramethylbenzidine (TMB) to a blue‐colored oxTMB in the presence of H2O2. Hence, the detection of H2O2 was achieved with a wide linear range from 0.005 to 0.5 mM (R2 = 0.992) and a low detection limit of 1.26 μM. More importantly, the peroxidase‐like Co‐MOF@Hemin was suitable for the sensitive and selective detection of glucose under the presence of glucose oxidase (GOx), which reduced O2 to H2O2. This analytical procedure for the detection of glucose had a linear range from 0.3 to 3 mM (R2 = 0.997), with a detection limit of 49 μM. The experimental results display the broad application prospects of the enzyme‐based MOFs in green and selective targets analyses. [ABSTRACT FROM AUTHOR]

Glucose sensors as a tool for diabetics to monitor blood glucose are of great significance in the diagnosis and treatment of diabetes. With the rapid development of flexible smart wearable devices the development of glucose sensors based on flexible substrate has also gradually become a research hotspot. Silk has good biocompatibility degradability and flexibility its surface is rich in chemical bonds such as carboxyl hydroxyl and amide bonds which can interact with active substances and it is a good conductive substrate material. The flexible glucose sensor developed by using silk and silk fibroin as the substrate and by being compounded with conductive active materials has excellent sensing performance and good long-term stability. This article aims to review the research progress of silk-based glucose sensors developed based on silk fibroin silk fiber and silk fabric analyze their characteristics and mechanism and prospect their development tendency. In order to fully understand the application of silk in the field of glucose sensors this paper starts with the development of glucose sensors and focuses on the research progress of silk-based glucose sensors on basis of two main kinds of silk and silk fibroin. We first introduced the characteristics and properties of silk and discussed the application of silk yarns silk fabrics and carbonized silk fabrics in the field of glucose sensors. Then we summarized the application of fibroin films and spun fibers based on silk fibroin in the field of glucose sensors. By reviewing the preparation methods and sensing performance of various silk-based glucose sensors we analyzed the role of silk in them and summarized the effect of the silk substrate on the glucose sensing performance. It is hoped that this paper can provide a reference for the design and development of high-performance silk-based flexible glucose sensors. Glucose sensors based on silk fabrics have better mechanical properties higher conductivity and sensitivity while those made of silk fibroin have better biocompatibility and degradability. Finally we compared and analyzed the sensitivity response time detection limit advantages and disadvantages of the silk-based glucose sensors. In sum in virtue of its good characteristics silk has the excellent application value in the field of flexible glucose sensors and the developed glucose sensors show good sensing performance which can also keep the original flexibility and biocompatibility of silk and show good conductivity and ultrahigh response to glucose molecules. However the problems such as the poor fixation rate of silk fibroin to glucose oxidase the poor mechanical properties of silk fibroin films and the weak binding between silk fabric and conductive materials still need to be solved urgently. In addition the cost and maintenance of silk-based glucose sensors are also the factors that cannot be ignored. At present the development of silk-based glucose sensors is mainly based on the silk fibroin membrane and the carbonized silk fabric and there are relatively few studies and applications based on the silk fiber and the silk fabric. The functionalized silk produced by the silkworm feeding method and spinning technology can be applied to the research and development of sensors which would possibly become one of the important research directions of silk-based glucose sensors in the future. Overall although the development of silk-based glucose sensors is still in its infancy its application prospects are very broad and it is worth looking forward to future development. [ABSTRACT FROM AUTHOR]

A flexible photoelectrochemical (PEC) biosensor is proposed for the sensitive detection of ochratoxin A (OTA) based on glucose oxidase (GOx)-encapsulated target-responsive hydrogel, using Fenton reaction-mediated in situ formation of polyaniline (PANI) as signal amplified strategy. The target-responsive DNA hydrogels with high loading capacity can carry a large amount of GOx, which not only avoids laborious labeling process but also enhances the analytical performance. Upon introduction of target molecules, the hydrogel can be opened, and multiple GOx was released, thus producing lots of H2O2 via catalytic reduction of glucose. As a component of the Fenton reagent, H2O2 can react with the Fe2+ on the graphene oxidase-PAMAM-Fe2+ (GO-PAMAM-Fe2+) to generate Fe3+ and ·OH. This in turn can oxidize aniline and generate polyaniline (PANI), resulting in the enhancement of the photocurrent signal of GO-MoS2-CdS photoelectrode. The GO-PAMAM-Fe2+ as the neighborhood component of GO-MoS2-CdS-based photoactive material not only can increase the loading amount of Fe2+, but also can inhibit the decrease of photocurrent of GO-MoS2-CdS by direct modification of Fe2+ on the photoactive material. Moreover, the high loading capacity of DNA hydrogel can efficiently promote the performance of the PEC biosensor. The PEC biosensor exhibited satisfactory analytical performance for OTA with a linear range of 0.0001–0.1 ng/mL and a low detection limit of 0.05 pg/mL. It presents recommendable specificity, stability, and practical applications. Importantly, the PEC biosensor provides a new concept for construction of PEC biosensing platform. [ABSTRACT FROM AUTHOR]

An aminated Fe–Ni bimetallic metal–organic framework (Fe3Ni-MOF-NH2) with both peroxidase-like activity and fluorescence properties was developed. Fe3Ni-MOF-NH2 possessed the enhanced peroxidase-like activity through the enhanced electron transfer process and hydroxyl radical (·OH) generation. It was found that the amino group endowed the material with fluorescent property and the metal site Ni in Fe3Ni-MOF-NH2 could also enhance the fluorescence emission intensity (Ex = 345 nm, Em = 452 nm). Based on the dual excellent performance of Fe3Ni-MOF-NH2, a novel sensitive fluorescence detection strategy for H2O2 and glucose was designed and achieved. First, Fe3Ni-MOF-NH2 converted H2O2 to ·OH by exerting peroxidase-like activity, and ·OH converts catechol to o-benzoquinone. Then, the amino group in Fe3Ni-MOF-NH2 connected to o-benzoquinone, which resulted in its fluorescence quenching. The detection limit of H2O2 was as low as 5 nM. Combined with glucose oxidase which can oxidize glucose and produce H2O2 the glucose could be indirectly determined with a detection limit of 40 nM. The method was applied to the detection of low-level glucose in human urine samples with good recoveries and reproducibilities. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of silent information regulator 2 (SIRT2)on the aerobic glycolysis, growth and proliferation of the colorectal cancer cells, and to clarify its related mechanism. Methods The HCT116 cells and SW480 cells were cultured, and Western blotting method was used to detect the expression levels of SIRT2 protein in two kinds of cells.The HCT116 cells with high expression of SIRT2 protein were selected for the following RNA interference experiment. Negative control group, SIRT2-siRNA#1 group, SIRT2-siRNA#2 group, and SIRT2-siRNA#3 group were established； the SW480 cells with low expression of SIRT2 protein were selected for the following SIRT2 overexpression experiment.The SIRT2 recombinant plasmids were constructed, and the SW480 cells at logarithmic growth phase were selected； blank group, empty vector plasmid transfection group, and SIRT2 plasmid transfection group were established；the recovery experiment was carried out in the HCT116 cells；control group, SIRT2-siRNA+glucose-6-phosphate dehydrogense (G6PD) plasmid co-transfection group and SIRT2-siRNA#3 group were established.The plasmid and siRNA were transfected into the SW480 cells and HCT116 cells by Lipofectamine 2000, respectively, the conterts of glucose in the culture medium in various groups were measured by glucose oxidase method after silencing SIRT2 and over-expression of SIRT2；the levels of lactic acid in the culture medium in various groups were measured by colorimetry after silencing SIRT2 and over-expression of SIRT2；the clone formation rates of the cells in various groups were determined by clonal formation assay； the proliferation activities of the cells in various groups were determined by CCK-8 assay；the expression levels of G6PD mRNA in the cells after silencing SIRT2 and over-expression of SIRT2 were determined by reverse transcriptionPCR (RT-PCR) method；the expression levels of G6PD protein in the cells in various groups after silencing SIRT2 and over-expression of SIRT2 were detected by Western blotting method；the expression levels of SIRT2 and G6PD proteins in colorectal cancer tissue were determined by immunohistochemistry.After co-transfection of SIRT2-siRNA and G6PD plasmids, the glucose levels, lactic acid levels, survival rates, and proliferation abilities of the cells were detected. Results Compared with negative control group, the level of glucose in the culture medium in SIRT2-siRNA#3 group was increased significantly (P<0.05), the level of lactic acid was significantly decreased (P<0.05), the survival rate and proliferation ability of the cells were significantly decreased (P<0.05), the expression levels of G6PD mRNA and protein were decreased (P<0.05)；compared with empty vector plasmid transfection group, the level of glucose in the culture medium in SIRT2 plasmid transfection group was decreased significantly (P<0.05), the level of lactic acid was significantly increased (P<0.05), the proliferation ability and clone formation rate of the cells were significantly increased (P<0.05).The expression levels of SIRT2 and G6PD proteins in colorectal cancer tissue were significantly higher than that in paracancerous tissue (P<0.05). Compared with SIRT2-siRNA#3 group, the level of glucose in the culture medium in SIRT2-siRNA+G6PD plasmid co-transfection group was significantly decreased (P<0.05), the level of lactic acid in the culture medium was significantly increased (P<0.05), and the proliferation ability and clone formation rate of the cells were significantly increased (P<0.05). Conclusion SIRT2 promotes the aerobic glycolysis and growth and proliferation of the colorectal cancer cells, and its mechanism may be related to the expression of G6PD regulated by SIRT2. [ABSTRACT FROM AUTHOR]

This paper presents three devices of biosensors for glucose concentrations. A resonator based on the defected ground structure (DGS) was designed and the optimizations for the single square and both squares of the DGS via adaptive genetic algorithm were applied to enhance the performance of the sensors including the Q‐factor and the electric field distribution. The fabricated devices of the best optimized one exhibited an enhanced Q‐factor of 442 and a sensitivity of 142.2 MHz/mgml−1, which is more than 2.37 times than the basic structure. [ABSTRACT FROM AUTHOR]

Trichoderma reesei (T. reesei) is well-known for its excellent ability to secret a large quantity of cellulase. However, unlike the endogenous proteins, little is known about the molecular mechanisms governing heterologous protein production. Herein, we focused on the integration loci and the secretory pathway, and investigated their combinatorial effects on heterologous gene expression in T. reesei using a glucose oxidase from Aspergillus niger as a model protein. Integration in the cel3c locus was more efficient than the cbh1 locus in expressing the AnGOx by increasing the transcription of AnGOx in the early stage. In addition, we discovered that interruption of the cel3c locus has an additional effect by increasing the expression of the secretory pathway component genes. Accordingly, overexpressing three secretory pathway component genes, that were snc1, sso2, and rho3, increased AnGOx expression in the cbh1 transformant but not in the cel3c transformant. [ABSTRACT FROM AUTHOR]

Chemodynamic therapy of cancer is limited by insufficient endogenous H2O2 generation and acidity in the tumor microenvironment (TME). Herein, we developed a biodegradable theranostic platform (pLMOFePt-TGO) involving composite of dendritic organosilica and FePt alloy, loaded with tamoxifen (TAM) and glucose oxidase (GOx), and encapsulated by platelet-derived growth factor-B (PDGFB)-labeled liposomes, that effectively uses the synergy among chemotherapy, enhanced chemodynamic therapy (CDT), and anti-angiogenesis. The increased concentration of glutathione (GSH) present in the cancer cells induces the disintegration of pLMOFePt-TGO, releasing FePt, GOx, and TAM. The synergistic action of GOx and TAM significantly enhanced the acidity and H2O2 level in the TME by aerobiotic glucose consumption and hypoxic glycolysis pathways, respectively. The combined effect of GSH depletion, acidity enhancement, and H2O2 supplementation dramatically promotes the Fenton-catalytic behavior of FePt alloys, which, in combination with tumor starvation caused by GOx and TAM-mediated chemotherapy, significantly increases the anticancer efficacy of this treatment. In addition, T2-shortening caused by FePt alloys released in TME significantly enhances contrast in the MRI signal of tumor, enabling a more accurate diagnosis. Results of in vitro and in vivo experiments suggest that pLMOFePt-TGO can effectively suppress tumor growth and angiogenesis, thus providing an exciting potential strategy for developing satisfactory tumor theranostics. [ABSTRACT FROM AUTHOR]

The non-enzymatic glucose sensing response of pure and Ag-decorated vertically aligned ZnO nanorods grown on Si substrates was investigated. The simple low-temperature hydrothermal method was employed to synthesize the ZnO NRs on the Si substrates, and then Ag decoration was achieved by sputtering. The crystal structure and surface morphologies were characterized by X-ray diffraction, field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The Ag incorporation on the ZnO NR surfaces was confirmed using EDS mapping and spectra. Furthermore, the chemical states, the variation in oxygen vacancies, and the surface modifications of Ag@ZnO were investigated by XPS analysis. Both the glucose/ZnO/Si and glucose/Ag@ZnO/Si device structures were investigated for their non-enzymatic glucose sensing performances with different glucose concentrations. Based on EIS measurements and amperometric analysis, the Ag@ZnO-NR-based glucose sensor device exhibited a better sensing ability with excellent stability over time than pure ZnO NRs. The Ag@ZnO NR glucose sensor device recorded 2792 µA/(mM·cm2) sensitivity with a lowest detection limit of 1.29 µM. [ABSTRACT FROM AUTHOR]

In this work, a new glucose oxidase-N-succinyl chitosan (GOD-NSCS) nanospheres was prepared through the immobilization of glucose oxidase (GOD) on N-succinyl chitosan (NSCS) nanospheres. Compared to the free GOD, GOD-NSCS nanospheres demonstrated the excellent anti- Colletotrichum gloeosporioides activity with the EC 50 values of 211.2 and 10.7 μg/mL against mycelial growth and spores germination. The computational biology analysis demonstrated that the substrate presented the similar binding free energy with GOD-NSCS nanospheres (−27.64 kcal/mol) compared with the free GOD (−24.04 kcal/mol), indicating that GOD-NSCS nanospheres had the same oxidation efficiency and produced more H 2 O 2. Moreover, the enzyme activity stability of GOD-NSCS nanospheres could be prolonged to 10 d. The cell membrane was destructed by the treatment of H 2 O 2 produced by GOD, leading to the cell death. In vivo test, GOD-NSCS nanospheres treatment significantly prolonged the preservation period of mangoes 2-fold. Collectively, these results suggested that GOD-NSCS nanospheres suppresses anthracnose in postharvest mangoes by inhibiting the growth of C. gloeosporioides and might become a potential natural preservative for fruits and vegetables. • GOD-NSCS nanospheres was prepared. • The nanospheres had the better oxidation efficiency and produced more H 2 O 2. • GOD-NSCS nanospheres presented the excellent anti- C. gloeosporioides activity. • The shelf life of mangoes could be significantly prolonged by GOD-NSCS nanospheres. [ABSTRACT FROM AUTHOR]

Fluorescent silver coordination polymer nanoparticles (Ag-TPA CPNs) were synthesized using a combination of terephthalic acid (TPA) and silver nitrate via an ultrarapid microwave-assisted strategy within 15 min. The Ag-TPA CPNs displayed a high fluorescent quantum yield (QY = 20.19%) and large Stokes shift (~200 nm), with two emission peaks at 490 nm and 520 nm under an excitation wavelength of 320 nm. A fluorescent "turn-off" method using fluorescent Ag-TPA CPNs was applied to detect the alkaline phosphatase (ALP) activity on the basis of the ALP-catalyzed hydrolysis of ascorbic acid 2-phosphate (AA2P) to ascorbic acid (AA), and the AA product triggered the reduction of Ag+ ions into silver nanoparticles. The fluorescent lifetime of Ag-TPA CPNs decreased from 3.93 ms to 3.80 ms after the addition of ALP, which suggests that this fluorescent "turn-off" detection of ALP activity is a dynamic quenching process. The fluorescent intensity had a linear relationship with the concentration of ALP in the range of 0.2–12 mU/mL (r = 0.991) and with a limit of detection (LOD) of 0.07 mU/mL. It showed high selectivity in ALP detection towards metal ions and amino acids, as well as other enzymes such as horseradish peroxidase, glucose oxidase, tyrosinase, trypsin, lysozyme, and superoxides. When it was applied for the fluorescent "turn-off" detection of ALP activity in serum samples, mean recovery levels ranging from 99.5% to 101.2% were obtained, with relative standard deviations (RSDs) lower than 4% accuracy. Therefore, it is an efficient and accurate tool for analyzing ALP levels in biosamples. [ABSTRACT FROM AUTHOR]

Currently, the co-immobilization of multi-enzymes on a solid carrier and their applications in cascade catalytic reactions are primarily studied. In this study, a MOF/polymer porous membrane composed of DUT-5 incorporated polyvinylidene fluoride (PVDF) is constructed and employed in the co-immobilization of porcine pancreatic lipase (PPL) and glucose oxidase (GOx) for the first time. The loading amounts of DUT-5 nanoparticles were varied to optimize the subsequent immobilization efficiency for the two enzymes. The adsorption conditions, isotherms and kinetics for both PPL and GOx were investigated systematically, and the optimum adsorption conditions were determined and used in the co-immobilization of the two enzymes step by step. It is interesting that the maximum adsorption amounts for the two enzymes in the co-immobilization process are similar to the results obtained in the single enzyme immobilization, which indicates the better compatibility of PPL and GOx in the hybrid membranes. The catalytic activities of the co-immobilized enzymes were evaluated using a cascade oxidation reaction, in which H2O2 produced in the GOx-catalyzed oxidation of glucose worked as the oxidant in the subsequent oxidation of styrene. Further, the catalytic efficiency of the co-immobilized enzymes is compared to that of the mixed free PPL and GOx. The improved catalytic rates and better reusability of the co-immobilized enzymes highlight the broader applications of MOF-based membranes in the co-immobilization of two or more enzymes and the catalytic applicabality in the cascade organic reactions. [ABSTRACT FROM AUTHOR]

Although much progress has been made by multifunctional nanoplatforms in the treatment of cancer, several defects of existing nanoplatforms, such as tedious preparation, poor biocompatibility, and failure to activate the immune system, have limited their clinical applications. Herein, a versatile nanosystem of folic acid‐modified metal‐phenolic networks (MPNs) loaded with GOx and CHA (F‐MGC) is fabricated by the easy self‐assembly of MPNs, during which glucose oxidase (GOx) and chlorogenic acid (CHA) are concurrently loaded. The resulting nanosystem, having a folic acid‐modified surface and inherent acid sensitivity, shows versatility in being able to target tumors and release active ingredients in the weakly acidic tumor microenvironment (TME). Based on the catalysis of GOx and Fe3+, the cascade reaction aroused by F‐MGC efficiently consumes glucose in the TME and produces abundant cytotoxic hydroxyl radicals, thereby causing the starving and chemodynamic death of cancer cells. In addition, CHA can reshape M2 tumor‐associated macrophages (TAMs) into the M1 type, so as to change the immunosuppressive state of TME. The immunogenic cell death (ICD) that occurs from the starvation and chemodynamic therapy, in conjunction with the CHA‐induced TAMs polarization, further activates the immune system. Overall, the easily prepared nanoplatform has excellent biocompatibility and effectively inhibits tumor growth and metastasis. [ABSTRACT FROM AUTHOR]

This paper describes a simple electrochemical sensing platform based on single-walled carbon nanotube (SWCNT) electrodes for glucose detection. The device fabrication using O2-plasma treatment allows precision and uniformity for the construction of three SWCNT electrodes on the flexible plastic substrate. Glucose assay can be simply accomplished by introducing a glucose sample into the fabricated biosensor. The marked electrocatalytic and biocompatible properties of biosensors based on SWCNT electrodes with the incorporation of ferrocenecarboxylic acid and polyethylene glycol enable effective amperometric measurement of glucose at a low oxidation potential (0.3 V) with low interferences from coexisting species. The device shows efficient electroanalytical performances with high sensitivity (5.5 μA·mM−1·cm−2), good reproducibility (CV less than 3%), and long-term stability (over a month). A linear range of response was found from 0 to 10 mM of glucose with a fast response time of 10 s. This attractive electroanalytical device based on GOx/FCA/PEG/SWCNT electrodes offers a promising system to facilitate a new approach for diverse biosensors and electrochemical devices. [ABSTRACT FROM AUTHOR]

Diabetes is a chronic disease affecting 10% of the population globally, and can lead to serious damage in the heart, kidneys, eyes, blood vessels or nerves. Commercial artificial closed-loop feedback systems can significantly improve diabetes management and save lives. However, they are large and expensive for users. Here, we demonstrate for the first time a wearable, minimally-invasive, fully electrochemically-controlled feedback minisystem for diabetes management. Both the working principles of the sensor and pump in the feedback system are based on electrochemical reactions. The smart minisystem was constructed based on integrating the thermoplastic polyurethane hollow microneedles with an electrochemical biosensing device on its outer layer and an electrochemical micropump facing the inner layer of the microneedles. The sensing device was constructed based on sputtering thin metal films through a shadow mask and electroplating Prussian blue on the surface of the microneedles, followed by the immobilization of glucose oxidase on the working electrode. The electrochemical micropump was constructed by sputtering the interdigital electrodes, followed by sealing with a thin elastic film, which was further integrated with the inner channels of the microneedles. Both the sensor and the pump were electrically powered. Via being controlled by a printed circuit board, the biosensing device monitored the levels of interstitial glucose continuously to drive the electrochemical pump to deliver insulin intelligently, in order to control blood glucose within the normal range. The closed-loop feedback system was studied for its capability in maintaining the blood glucose levels of diabetic rats under various physiological conditions. The utility of the intelligent feedback system was successfully demonstrated on diabetic rats for controlling the blood glucose levels within the normal range. The minisystem is wearable, small, cost-effective, precise, stable and painless. It is anticipated that this approach opens a new paradigm for the development of closed-loop diabetes minisystems and may lead to a compelling future for diabetes management. [ABSTRACT FROM AUTHOR]

This work addresses a novel biosensor design and its surface potential sensitivity analysis to identify various biomolecules. The designed structure integrates the attributes of linear graded work function gate electrode of binary metal alloy and N + pocket of low bandgap SiGe material in double gate-gate stack charge plasma vertical TFET with a single cavity. The dielectric constant modulation corresponding to distinct biomolecules is performed in the cavity to estimate their sensitivity. The dielectric constant modulation leads to variation in energy bands, electric field, and hence in the surface potential of the TFET, the surface potential variation is judged to be resolute sensitivity. Results show that 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 607 which is 5%, 10%, and 48% higher than the sensitivity of Keratin (k = 8), Bacteriophage T7 (k = 6.3), and Glucose Oxidase (k = 3.46) respectively at the cavity length of 43 nm. [ABSTRACT FROM AUTHOR]

Accurate monitoring of blood glucose levels is crucial for the diagnosis of diabetes patients. In this paper, we proposed a simple "mixed-catalyzer layer" modified silicon nanowire field-effect transistor biosensor that enabled direct detection of glucose with low-charge in high ionic strength solutions. A stable screening system was established to overcome Debye screening effect by forming a porous biopolymer layer with polyethylene glycol (PEG) modified on the surface of SiNW. The experimental results show that when the optimal ratio (APTMS:silane-PEG = 2:1) modified the surface of silicon nanowires, glucose oxidase can detect glucose in the concentration range of 10 nM to 10 mM. The sensitivity of the biosensor is calculated to be 0.47 μAcm−2mM−1, its fast response time not exceeding 8 s, and the detection limit is up to 10 nM. This glucose sensor has the advantages of high sensitivity, strong specificity and fast real-time response. Therefore, it has a potential clinical application prospect in disease diagnosis. [ABSTRACT FROM AUTHOR]

This study aimed to conjugate glucose oxidase (GOX) with carbon-encapsulated iron nanoparticles (Fe@C) which were functionalized with carboxylic groups and decorated with branched polyethyleneimine (PEI), in order to yield Fe@C-NH-PEI-GOX and Fe@C-(CH2)2-CONH-PEI-GOX derivatives. The process of electrostatic attachment of the GOX enzyme on the Fe@C-NH-PEI and Fe@C-(CH2)2CONH-PEI constructs was optimized, and the amount of enzyme attached on the constructs was also estimated. The steady-state kinetics of β-D-glucose oxidation by molecular oxygen, a reaction catalyzed by GOX, were compared using a native GOX enzyme obtained from Aspergillus niger and nanoparticles-conjugated GOX. The Fe@C-NH-PEI-GOX and Fe@C-(CH2)2-CONH-PEI-GOX constructs were formed by electrostatic interaction between positively charged Fe@C-NH-PEI and Fe@C-(CH2)2-CONH-PEI and negatively charged GOX in water media at pH 6. The activity of the immobilized enzyme on Fe@C-NH-PEI-GOX and Fe@C-(CH2)2-CONH-PEI-GOX derivatives was preserved, with Km values of 3271 and 1605 µM, respectively. However, the catalytic activity of Fe@C-NH-PEI-GOX and Fe@C-(CH2)2-CONH-PEI-GOX was reduced up to 20- and tenfold in comparison to that of the free GOX enzyme. The results of the study suggest that PEI is a promising cationic polymer with a high loading capacity and that the use of a simple adsorption process for preparing Fe@C-NH-PEI-GOX and Fe@C-(CH2)2-CONH-PEI-GOX conjugates is a highly efficient approach for stable immobilization of GOX enzyme on carbon-encapsulated iron nanoparticles. [ABSTRACT FROM AUTHOR]

Sulfoxaflor (SULF), a well-known alternative for the banned neonicotinoids, is not environmentally persistent, yet numerous studies using field-realistic levels have demonstrated its detrimental impact on honey bee colonies. Despite this, even just a limited number of studies have addressed its residue-level effects on the physiological and immunological biomarkers of foraging honey bees in semi-field conditions. In the present study, we determined the LT50 of sulfoxaflor (Closer™ 24% SC) on forager bees in the laboratory at concentrations that were 12 to 300,000-fold lower than the field-recommended concentration. Following that, we exposed bee colonies in a semi-field in-hive experiment for 21 days to a concentration that is 600,000-fold lower than the field-recommended concentration to assess potential effects on the physiological state of honey bee foragers. To do that, a total of six colonies were treated with Closer™ (0.3 µg a.i./L) or control treatment, and the activities of acetylcholinesterase (AChE), glucose oxidase (GOX), and carboxylesterase (CaEs) in head tissues and invertase (IV), alkaline phosphatase (ALP), and glutathione-S-transferase (GST) in the midgut tissues of forager bees were assessed at 5-, 10-, 15-, and 20-day post-exposure. The LT50 results for the least and greatest concentrations of Closer™ were 0.37 and 74.3 h, respectively. Furthermore, all measured physiological and immunological biomarkers were negatively impacted in the chronic exposure to 0.3 µg a.i./L concentration of Closer™. This data demonstrated the importance of reviewing the risk assessment of various sulfoxaflor formulations on bees and rephrasing the legislation that governs how beekeepers deal with sulfoxaflor-sprayed fields. [ABSTRACT FROM AUTHOR]

Immobilizing enzymes with nanozymes to catalyze cascade reactions overcomes many of the shortcomings of biological enzymes in industrial manufacturing. In the study, glucose oxidases were covalently bound to FeS2 nanozymes as immobilization carriers while chitosan encapsulation increased the activity and stability of the immobilized enzymes. The immobilized enzymes exhibited a 10% greater increase in catalytic efficiency than the free enzymes while also being more stable and catalytically active in environments with an alkaline pH of 9.0 and a high temperature of 100 °C. Additionally, the FeS2 nanozyme-driven double-enzyme cascade reaction showed high glucose selectivity, even in the presence of lactose, dopamine, and uric acid, with a limit of detection (LOD) (S/N = 3) as low as 1.9 × 10−6 M. This research demonstrates that nanozymes may be employed as ideal carriers for biological enzymes and that the nanozymes can catalyze cascade reactions together with natural enzymes, offering new insights into interactions between natural and synthetic biosystems. [ABSTRACT FROM AUTHOR]

Conversion of the redox probe hydroethidine (HE) to 2-chloroethidium (2-Cl-E+) by myeloperoxidase (MPO)-derived hypochlorous acid (HOCl) provides comparable specificity and superior sensitivity to measurement of 3-chlorotyrosine (3-Cl-Tyr), the gold standard biomarker for MPO chlorinating activity in biological systems. However, a limitation of the former method is the complex mixture of products formed by the reaction of HE with reagent HOCl, coupled with the difficult purification of 2-Cl-E+ from this mixture for analytical purposes. This limitation prompted us to test whether 2-Cl-E+ could be formed by reaction of HE with the strong and widely used chlorinating agent, N -chlorosuccinimide (NCS). Unexpectedly, such reaction yielded 2-chlorohydroethidine (2-Cl-HE) as the major product in addition to 2-Cl-E+, as assessed by high performance liquid chromatography (HPLC), mass spectrometry (MS), and nuclear magnetic resonance (NMR). 2-Cl-HE was also observed to be the major chlorination product formed from HE with both reagent and enzymatically generated HOCl, just as it was formed ex vivo in different healthy and diseased mouse and human tissues upon incubation with glucose/glucose oxidase to generate a flux of hydrogen peroxide (H 2 O 2). Quantification of 2-Cl-HE plus 2-Cl-E+ improved the sensitivity of the HE-based method compared with measurement of only 2-Cl-E+. Moreover, 2-chlorodimidium (2-Cl-D+) was developed as a practical internal standard instead of the previously used internal standard, deuterated 2-Cl-E+ (d 5 -2-Cl-E+). Overall, the present study describes an improved method for the detection of MPO/chlorinating activity in biological systems of health and disease. [Display omitted] • Hydroethidine (HE) is useful to measure MPO activity in biological samples. • 2-Chlorohydroethidine (2-Cl-HE) is the primary chlorination product. • 2-Cl-HE is a major chlorination product formed in vivo. • Improved method for the detection of MPO/chlorinating activity in biological systems. [ABSTRACT FROM AUTHOR]

A pH‐responsive charge‐convertible drug delivery nanocarrier (MSN‐TPZ‐GOx@ZnO@PAH‐PEG‐DMMA, abbreviated as MTGZ@PPD) was prepared, which could specifically release hypoxia‐activated chemotherapeutic Tirapazamine (TPZ) and glucose oxidase (GOx) in the tumor site for precise starvation and chemo synergistic oncotherapy. Acid‐responsive Schiff base structure modified mesoporous silica nanoparticles (MSN) co‐load with GOx and TPZ, then link with ZnO quantum dots (QDs). PAH‐PEG‐DMMA (PPD) polymer makes MTGZ@PPD with biocompatibility and charge‐convertible feature. MTGZ@PPD is negatively charged at physiological pH, and the charge reversal of PPD and acidolysis of the Schiff base structure under the acidic tumor microenvironment (TME) induce a positively charged surface, which could potentiate the cell internalization. ZnO QDs could decompose at acidic TME, achieving controllable drug release. GOx could starve the tumor cells and enhance hypoxia level, thus initiates the activation of TPZ to realize synergistic starvation therapy and chemotherapy. This intelligent MTGZ@PPD has shown great potential for starvation and chemo synergistic oncotherapy. [ABSTRACT FROM AUTHOR]

Gas pressure biosensing is a promising portable analysis method. The gas-generation reaction is crucial to its sensitivity, speed, repeatability, and usability. However, very few gas-generation reactions are available for sensitive, safe, and diverse biosensing. Herein, acid-accelerated hydrolysis of sodium borohydride (NaBH4) was explored for the first time to achieve portable and diverse gas pressure biosensing. The slow hydrolysis and hydrogen generation of NaBH4 in alkaline medium is accelerated with increasing acidity, which increased the gas pressure in a small and sealed tube within 10 min. Thus, a label-free bioassay is easily and specifically achieved once analytes can in-situ generate acid to accelerate the hydrolysis rate of NaBH4, such as glucose, acetylcholine (ACh), adenosine triphosphate (ATP) and others. More importantly, analytes without acid generation could be quantitatively and selectively detected by combining target recognition with acid-generated biochemical reactions for enzyme-linked gas pressure biosensing. Inspired by this, aflatoxin B1 (AFB1)-aptamer interaction-triggered strand displacement reaction was combined with glucose oxidation by glucose oxidase (GOD) to detect AFB1 as low as 7.1 pM. Therefore, acid-accelerated hydrolysis of NaBH4 is powerful for developing portable, cheap, and diverse gas pressure biosensing. It opens up a new way for cheap, universal, and portable biosensing. [ABSTRACT FROM AUTHOR]

Monitoring exocellular adenosine-5′-triphosphate (ATP) is a demanding task but the biosensor development is limited by the low concentration and rapid degradation of ATP. Herein, we developed a simple yet effective biosensor based on ZIF-67 loaded with bi-enzymes of glucose (GOx) and hexokinase (HEX) for effective detection of ATP. In the confined space of the porous matrix, the bi-enzymes competed for the glucose substrate in the presence of ATP, facilitating the biosensor to detect low ATP concentrations down to the micromole level (3.75 μM) at working potential of 0.55 V (vs. Ag/AgCl). Furthermore, ZIF-67 with cobalt served as a porous matrix to specifically adsorb ATP molecules, allowing it to differentiate isomers with sensitivity of 0.53 nA/μM, RSD of 5.4%, and recovery rate of 93.3%. We successfully applied the fabricated biosensor to measure ATP secreted from rat PC12 cells in the pericellular space thus realizing time-resolving measurement. This work paved the path for real-time monitoring of ATP released by cells, which will aid in understanding tumor cell glycolysis and immune responses. [ABSTRACT FROM AUTHOR]