Wide Range Of Glucose Research Articles

A bienzymatic amperometric glucose biosensor based on using a novel recombinant Mn peroxidase from corn and glucose oxidase with a Nafion membrane

• Representation of the a) SEM image of Modified gold electrode b) Glucose biosensor membrane on the gold electrode surface (yellow), the enzyme-based layer modified with PPMP, BSA, GOx and Nafion and c) Amperometric responses of the glucose biosensor. Using a recombinant enzyme derived from corn and a simple modification, we fabricated a facile, fast, and cost-beneficial novel biosensor to measure glucose. The Nafion/Plant Produced Mn Peroxidase (PPMP)–glucose oxidase (GOx)–Bovine serum albumin (BSA)/Au electrode showed an excellent amperometric response to detect glucose. This biosensor is capable of responding to a wide range of glucose, 20.0 µM–15.0 mM, and has a lower detection limit (LOD) of 2.9 µM. The reproducibility response using six electrodes is also very substantial and indicates high capability of this biosensor to detect glucose concentrations. Selectivity of this electrode was investigated in an optimized experimental solution containing 10% diet green tea with citrus containing ascorbic acid (AA), and citric acid (CA) in a wide concentration of glucose at 0.02–14.0 mM with an LOD of 3.1 µM. We also applied linear sweep voltammetry (LSV) and this technique shows a wide range of glucose detection. The performance and strength of this novel enzyme biosensor were the simplicity, wide linear ranges, sensitivities, selectivity, and low limits of detection. We expect that the modified biosensor has the potential for monitoring various biofluids.

Novel SWCNTs-mesoporous silicon nanocomposite as efficient non-enzymatic glucose biosensor

The development and designing of self-testing blood-glucose electrochemical biosensor is an effective approach for diabetic patients to overcome and control this high health concerning issue. Herein, we successfully designed novel single-walled carbon nanotubes-porous silicon nanocomposites framework (SWCNTs-PSi NCs) via simple stain etching and ultrasonication techniques. X-ray Diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Energy-Dispersive Spectroscopy (EDS), and X-ray Photoelectron Spectroscopy (XPS) were employed to study the porous morphology with ~30 nm pore size and overall structural characterization of the SWCNTs-PSi NCs. This newly fabricated SWCNTs-PSi modified glassy carbon electrode (GCE) biosensor can measure an extremely wide range of glucose (0.5–28.5 mM) in phosphate buffer solution (PBS) compared to the regular glucose concentration level in human blood serum (3.9–7.1 mM) with a sensitivity 0.0614 μAmM−1 cm−2 and detection limit 9.6 ± 0.1 μM. This non-enzymatic glucose biosensor demonstrated excellent selectivity during the investigation of the possible impact of common interfering substances that are present in human blood. This proposed non-enzymatic glucose biosensor has also been tested for real human blood serum analysis to determine blood glucose levels showing highly motivated results. The newly designed SWCNTs-PSi/GCE biosensor exhibits excellent reproducibility and repeatability, along with long-term stability.

A New Possibility for Fermentation Monitoring by Electrical Driven Sensing of Ultraviolet Light and Glucose.

Industrial fermentation generates products through microbial growth associated with the consumption of substrates. The efficiency of industrial production of high commercial value microbial products such as ethanol from glucose (GLU) is dependent on bacterial contamination. Controlling the sugar conversion into products as well as the sterility of the fermentation process are objectives to be considered here by studying GLU and ultraviolet light (UV) sensors. In this work, we present two different approaches of SnO2 nanowires grown by the Vapor–Liquid–Solid (VLS) method. In the GLU sensor, we use SnO2 nanowires as active electrodes, while for the UV sensor, a nanowire film was built for detection. The results showed a wide range of GLU sensing and as well as a significant influence of UV in the electrical signal. The effect of a wide range of GLU concentrations on the responsiveness of the sensor through current–voltage based on SnO2 nanowire films under different concentration conditions ranging was verified from 1 to 1000 mmol. UV sensors show a typical amperometric response of SnO2 nanowires under the excitation of UV and GLU in ten cycles of 300 s with 1.0 V observing a stable and reliable amperometric response. GLU and UV sensors proved to have a promising potential for detection and to control the conversion of a substrate into a product by GLU control and decontamination by UV control in industrial fermentation systems.

Chitosan-Graphene Oxide-Based Ultra-Thin and Flexible Sensor for Diabetic Wound Monitoring

This paper presents a Chitosan-Graphene Oxide (CS-GO)-based array of ultra-thin biosensors with gold (Au)-based microgap (60 μm) electrode. The cross-linked GO is shown to improve the stability of chitosan substrate in aqueous medium and compatibility with microfabrication steps. The sensor patch has been evaluated for label-free monitoring by immobilizing the CS-GO surface with human dermal fibroblast (HDF) cells. The cyclic voltammetry (CV) of HDF cell immobilized CS-GO surface show quasi-reversible nature with a characteristic cathodic peak at +300 mV and anodic peak at -300 mV. Both peaks are stable and repeatable up to 50-scan cycle without any potential shift. The device shows a steady-state peak enhancement (1.923-11.195nA) during the DHF cell growth period (0-96h). The redox peak enhancement correlates with the cell proliferation rates over time, indicating that it could be employed for investigation of the cyto-physiological state against any endo and exogenous stimulation. In addition, the developed sensor-patch was used to detect a wide range of glucose from 1 μM to 20mM in vitro with a sensitivity of 0.17 μA/mM. Considering these, the presented sensor-patch has a great potential for the detection of glucose level, cell-health proliferation rate at the wound site, and diabetic wound monitoring applications.

Metabolic engineering of Escherichia coli for 2,3-butanediol production from cellulosic biomass by using glucose-inducible gene expression system

A glucose-inducible gene expression system has been developed using HexR-Pzwf1 of Pseudomonas putida to induce the metabolic pathways. Since the system is controlled by an Entner–Doudoroff pathway (EDP) intermediate, the EDP of Escherichia coli was activated by deleting pfkA and gntR genes. Growth experiment with green fluorescent protein as a reporter indicated that the induction of this system was tightly controlled over a wide range of glucose in E. coli without adding any inducer. 2,3-butanediol (BDO) synthetic pathway genes were expressed by this system in the pfkA-gntR-deleted strain. The resultant engineered strain harbouring this system efficiently produced BDO with a 71% increased titer than the control strain. The strain was also able to produce BDO from a mixture of glucose and xylose which is comparable to glucose alone. Further, the strain produced 11 g/L of BDO at a yield of 0.48 g/g from the hydrolysate of empty palm fruit bunches. This system can also be applied in many other bio-production processes from lignocellulosic biomass.

Patient and Health-care Professional Satisfaction with a New, Simple, High Accuracy Blood Glucose Meter with Color Range Indicator.

Background:Accurate self-monitoring of blood glucose (BG) is a key component of effective self-management of glycemic control.Methods:The OneTouch Select Plus Simple™ (OTSPS) BG monitoring system (BGMS) was evaluated for accuracy in a clinical setting.Results:OTSPS was accurate over a wide glucose range and met lay user and system accuracy BG standards described in ISO 15197:2013. Patients also used OTSPS for a 1-week trial period and reported their level of satisfaction with meter features. In a separate study, health-care professionals (HCPs) in India naïve to OTSPS experienced OTSPS online using a variety of interactive demonstrations of the BGMS and answered questions about its potential utility to their patients.Summary:Patients and HCPs felt the features of OTSPS, including a color range indicator, could provide significant benefits to them and their patients.

Patient and healthcare professional satisfaction with a new, high accuracy blood glucose meter with color range indicator and wireless connectivity

ABSTRACTAccurate self-monitoring of blood glucose is a key component of effective self-management of glycemic control. The OneTouch VerioFlex™ (OTVF) blood glucose monitoring system (BGMS) was evaluated for accuracy in a clinical setting. Patients also used OTVF for a 1-wk trial period and reported their level of satisfaction with meter features. In a separate study, healthcare professionals used an on-line simulator of the BGMS and answered questions about its potential utility to their patients. OTVF was accurate over a wide glucose range and met lay user and system accuracy blood glucose standards described in ISO15197:2013 as well as the accuracy requirements to fulfill US FDA expectations for 510(k) clearance of BGMS. Patients and healthcare professionals felt the features of OTVF, which has the capability to connect wirelessly to mobile devices and interact wirelessly with diabetes management software, could provide significant benefits to them or their patients.

Glucose Sensing Properties of Electrospinning-Synthesized ZnO Nanofibers

The development of glucose biosensors has been attracting much attention because of their importance in monitoring glucose in the human body; such sensors are used to diagnose diabetes and related human diseases. Thanks to the high selectivity, sensitivity to glucose detection, and relatively low-cost fabrication of enzyme-immobilized electrochemical glucose sensors, these devices are recognized as one of the most intensively investigated glucose sensor types. In this work, ZnO nanofibers were synthesized using an electrospinning method with polyvinyl alcohol zinc acetate as precursor material. Using the synthesized ZnO nanofibers, we fabricated glucose biosensors in which glucose oxidase was immobilized on the ZnO nanofibers. The sensors were used to detect a wide range of glucose from 10 to 700 M with a sensitivity of 10.01 nA/cm2- μM, indicating that the ZnO nanofiber-based glucose sensor can be used for the detection of glucose in the human body. The control of nanograins in terms of the size and crystalline quality of the individual nanofibers is required for improving the glucose-sensing abilities of the nanofibers.

Association of β-cell function and insulin sensitivity with fasting and 2-h plasma glucose in a large Chinese population

Our aim was to provide a quantitative analysis of the changes in the principal determinants of insulin sensitivity and secretion in relation to fasting plasma glucose (FPG) or 2-h plasma glucose (2h PG) in a Chinese population with a wide range of glucose tolerance. A total of 5728 adults spanning the entire range of glucose tolerance were included. Insulin sensitivity was measured by Matsuda insulin sensitivity index (ISI(M)) and homeostasis model assessment of 1/homeostasis model assessment of insulin resistance (HOMA-IR). β-Cell function adjusted by insulin sensitivity was assessed from disposition index (DI) at early-phase DI(30) and total DI(120). The exponential curve was established as the best fit for the relationship between insulin sensitivity or β-cell function and FPG or 2h PG. Relative to the trend classified as increasing 2h PG, hepatic insulin sensitivity and insulin secretion showed a decreasing trend to a substantial degree as FPG increased. A 1 mmol/l increase in FPG and 2h PG concentration was associated with a -22 and -21% decline in ISI(M), -16 and -4% in 1/HOMA-IR, -38 and -35% in DI(30) and -36 and -26% in DI(120). The decay constant of ISI(M) and DI(30) in IFG or ISI(M), 1/HOMA-IR, DI(30) and DI(120) in IGT was lower than that in normal glucose tolerance. Significant interactions between sex and glucose levels determining DI were found. We conclude that impairment of insulin sensitivity and insulin secretion contributes to both FPG or 2h PG hyperglycaemia in a Chinese population, but that the decline in insulin secretion is more pronounced with increasing fasting than 2h PG.

Introducing N-glycans into natural products through a chemoenzymatic approach

The present study describes an efficient chemoenzymatic method for introducing a core N-glycan of glycoprotein origin into various lipophilic natural products. It was found that the endo-β- N-acetylglucosaminidase from Arthrobactor protophormiae (Endo-A) had broad substrate specificity and can accommodate a wide range of glucose (Glc)- or N-acetylglucosamine (GlcNAc)-containing natural products as acceptors for transglycosylation, when an N-glycan oxazoline was used as a donor substrate. Using lithocholic acid as a model compound, we have shown that introduction of an N-glycan could be achieved by a two-step approach: chemical glycosylation to introduce a monosaccharide (Glc or GlcNAc) as a handle, and then Endo-A catalyzed transglycosylation to accomplish the site-specific N-glycan attachment. For those natural products that already carry terminal Glc or GlcNAc residues, direct enzymatic transglycosylation using sugar oxazoline as the donor substrate was achievable to introduce an N-glycan. It was also demonstrated that simultaneous double glycosylation could be fulfilled when the natural product contains two Glc residues. This chemoenzymatic method is concise, site-specific, and highly convergent. Because N-glycans of glycoprotein origin can serve as ligands for diverse lectins and cell-surface receptors, introduction of a defined N-glycan into biologically significant natural products may bestow novel properties onto these natural products for drug discovery and development.

Performance Evaluation of a New Blood Glucose Monitor That Requires No Coding: The OneTouch® Vita™ System

Improvements to blood glucose monitoring systems aim to simplify the testing process, reduce or eliminate errors, and provide additional information for patients with diabetes. New systems must continue to demonstrate high-quality analytical performance. The new OneTouch Vita System (LifeScan, Inc., Milpitas, CA) offers a no-code testing process and proven technology found in the OneTouch Ultra System. Comparative studies were conducted with the new and established systems to evaluate their precision and accuracy. Within-run precision in blood, total precision with controls, and system accuracy were evaluated using three lots of OneTouch Vita Test Strips and one lot of OneTouch Ultra Test Strips. Accuracy was tested across a wide glucose range (38-520 mg/dl, 2.1-28.9 mmol/liter) using fingertip blood samples from 139 subjects. Reference plasma glucose values were obtained using the YSI 2300 STAT Plus Glucose & Lactate Analyzer (YSI Inc., Yellow Springs, OH). All studies were designed in accordance with requirements published by the International Organization for Standardization (ISO 15197). Precision testing (within-run and total) with both systems produced coefficients of variation (CVs) of <5% for all sample types and glucose levels. Within-run precision testing with blood showed CVs of <3.1% and <4.7% for the OneTouch Vita and OneTouch Ultra Systems respectively. Total precision with control samples gave CVs of <3.0% and <3.6% for the two systems. Consensus error grid analysis showed equivalent clinical accuracy with 98.4% (821/834) and 98.2% (273/278) of results within zone A. Both systems met the ISO acceptability requirements for system accuracy. The OneTouch Vita System provides a simple no-code testing process with performance comparable to the OneTouch Ultra and OneTouch Ultra2 Systems.

Identification of key patterns in the metabolism of hybridoma cells in culture

In transformed cell lines, glucose and glutamine transport into cells as well as glycolysis and glutaminolysis pathways occur at high rates. As a consequence, cells in culture show a poor exploitation of these resources and produce excessive amounts of lactic acid and ammonium. In this work, a murine hybridoma cell line (KB-26.5) was cultivated in batch cultures with different concentrations of oxamate, an specific inhibitor of lactate dehydrogenase. The results show that the conversion of pyruvate into lactate is absolutely necessary for cell survival as a way to reoxidize the large amounts of NADH produced in the rapid glycolysis; moreover, this metabolic analysis was completed with a continuous culture at changing inlet concentrations of glucose and glutamine. Steady-state viable cell, total cell, glucose, lactate, ammonium glutamine, and other amino acids were measured over a wide range of glucose and glutamine feed concentrations. The results show the metabolic deregulation existing in hybridoma cells and make it possible to calculate the minimal specific requirements for glucose (76.8 nmol 10 6 cells −1 h −1) and glutamine (30.72 nmol 10 6 cells −1 h −1) to maintain a cell population with minimal excretion of partly oxidized undesirable end products and a minimal increase in osmolarity. An explanation of these metabolic patterns is discussed in terms of NADH regeneration.

Understanding “insulin resistance”: Both glucose resistance and insulin resistance are required to model human diabetes

A methematical model of normal glucose/insulin homoeostasis has been based on the known, experimentally determined responses of the liver and periphery to different glucose/insulin concentrations. Different defects of glucose resistance and insulin resistance have been applied to the model to investigate the degree to which these abnormalities could successfully predict the range of fasting glucose and insulin values found in normal, obese, and diabetic subjects. Modeling glucose resistance or insulin resistance at the liver or the periphery alone did not increase the plasma glucose to levels observed in diabetes, even when associated with marked deficiency of β-cell function. A defect of either glucose resistance or insulin resistance affecting both periphery and liver allowed a wider range of basal glucose and insulin concentration values, but resulted in unphysiologically low hepatic glucose output: with modeling insulin resistance, hyperglycemia suppressed glucose output, whereas with glucose resistance, raised insulin levels suppressed hepatic glucose output. A wide range of glucose and insulin values, with appropriate basal hepatic glucose output, could only be modeled by insulin resistance at both the liver and periphery with additional glucose resistance at the liver. The modeling results are in accord with investigative studies that suggest secondary hepatic and peripheral glucose resistance in response to hyperglycemia. Modeling provides a systematic means of examining the likely effect of different putative defects in a complex physiological system.

The glucose stimulus-response curve of the β-cell in physically trained humans, assessed by hyperglycemic clamps

In order to examine the effect of habitual exercise on β-cell responses over a wide range of plasma glucose levels, plasma insulin and C-peptide responses to 2 1 2 - hour hyperglycemic clamps at 7.5, 10, and 15 mmol/L glucose were assessed in six trained athletes and six age- and weight-matched sedentary controls. Athletes were significantly fitter than controls (estimated maximal oxygen uptake [VO 2 max] mean 44 v 30 mL · kg −1 · min −1, P < .05) and were more sensitive to insulin as assessed by dividing the mean glucose infusion rate over the last 20 minutes of the clamp by the steady-state plasma insulin (mean 0.44 v 0.19 mg · min −1 · kg −1 · nmol −1 · L, respectively, P < .01). Plasma C-peptide responses were lower in the athletes, both fasting (geometric mean 0.28 v 0.62 nmol/L, P < .05), and at the end of all clamps (at 7.5, 10, and 15 mmol/L plasma glucose, respectively, 0.65 v 1.43, 1.25 v 2.85, and 2.40 v 4.46 nmol/L each, P < .05). First-phase plasma C-peptide responses were lower in the athletes at the 10 and 15 mmol clamp levels. The slope of the glucose-C-peptide stimulus-response curve was approximately linear over the range examined, the slope being significantly shallower in athletes than controls for both first phase ( P < .01) and second phase ( P < .01). Plasma insulin responses were similar to C-peptide responses. The attenuation of β-cell responsiveness over a wide glucose range may be an adaptation to the enhanced peripheral insulin sensitivity seen in athletes.

Initial-rate studies of a thermophilic glucokinase from Bacillus stearothermophilus.

The initial rates of phosphorylation of glucose catalysed by glucokinase from Bacillus stearothermophilus were measured over a wide range of glucose, MgATP2-, MgADP- and glucose 6-phosphate concentrations. The results of the effects of the inhibitors on the initial rates suggest that the reaction mechanism is essentially the ordered Bi Bi, in which glucose adds to the enzyme before MgATP2- and glucose 6-phosphate is released from the enzyme after the dissociation of MgADP-, and also suggest that the final step in which glucose 6-phosphate is released is irreversible. For many reaction schemes, the rate equations were derived on the basis of the pseudo-steady-state assumption and were used to correlate the experimental rate data. From this result, we concluded that the reaction obeys the ordered mechanism accompanied by the formation of a non-productive ternary complex, glucose-MgADP--enzyme. By using the experimental Dalziel coefficients phi i, some kinetic parameters were evaluated. The enzyme was characterized by the thermal stability and the low Michaelis constant, the values of which were 54 microM for glucose and 32 microM for MgATP2-.