• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.47-51
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• 2019

Sweat-based glucose sensors are being widely investigated and researched as they facilitate painless and continuous measurement. However, because the concentration of sweat glucose is almost a hundred times lower than that of blood glucose, it is important to develop electrochemical sensing electrode materials that are highly sensitive to glucose molecules for the detection of low concentrations of glucose. The preparation of a flexible and ultra-sensitive sensor for detection of sweat glucose is presented in this study. Oxygen and nitrogen are removed from the surface of a polyimide film by exposure to a CO2 laser; hence, laser-induced graphene (LIG) is formed. The fabricated LIG electrode showed favorable properties of high roughness and good stability, flexibility, and conductivity. After the laser scanning, Pt nanoparticles (PtNP) with good catalytic behavior were electrodeposited and the glucose sensor thus developed, with a LIG/PtNP hybrid electrode, exhibited a high order of sensitivity and detection limit for sweat glucose.

• Journal of Nutrition and Health
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• v.56 no.4
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• pp.349-360
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• 2023

Purpose: Ketogenic diets (KDs) have anti-obesity effects that may be related to glucose control and the gut microbiota. This paper hypothesizes that KD reduces body weight and changes the insulin sensitivity and gut microbiota composition in a mouse model of diet-induced obesity. Methods: In this study, C57BL/6 male mice were assigned randomly to 3 groups. The assigned diets were provided to the control and high-fat (HF) diet groups for 14 weeks. The KD group was given a HF diet for 8 weeks to induce obesity, followed by feeding the KD for the next 6 weeks. Results: After the treatment period, the KD group exhibited a 35.82% decrease in body weight gain compared to the HF group. In addition, the KD group demonstrated enhanced glucose control, as shown by the lower levels of serum fasting glucose, serum fasting insulin, and the homeostatic model assessment of insulin resistance, compared to the HF group. An analysis of the gut microbiota using 16S ribosomal RNA sequencing revealed a significant decrease in the proportion of Firmicutes when the KD was administered. In addition, feeding the KD reduced the overall alpha-diversity measures and caused a notable separation of microbial composition compared to the HF diet group. The KD also led to a decrease in the relative abundance of specific species, such as Acetatifactor_muris, Ligilactobacillus_apodemi, and Muribaculum_intestinale, compared with the HF group. These species were positively correlated with the body weight, whereas the abundant species in the KD group (Kineothrix_alysoides and Saccharofermentans_acetigenes) showed a negative correlation with body weight. Conclusion: The current study presents supporting evidence that KD reduced the body weight and altered the insulin sensitivity and gut microbiota composition in a mouse model of diet-induced obesity.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.86-87
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• 2007

An amperometric glucose biosensor has been developed using viologen derivatives as electron mediator of glucose oxidase (GOD) at Au electrode. Highly stable self assembled monolayer (SAM) of thiol-based viologen is immobilized onto the Au electrode followed byGOD is immobilized onto the viologen modified electrode. This biosensor response to glucose was evaluated amperometrically in the potential of -300 mV. Upon immobilization of glucose oxidase onto the viologen modified-electrode, the biosensor showed rapid response towards glucose. Experimental conditions influencing the biosensor performance such as, pH, potential were optimized and assessed. This biosensor offered an excellent electrochemical response for glucose concentration below ${\mu}mol$ level with high sensitivity and selectivity and short response time. The levels of the RSD's (< 5 %) for the entire analyses reflected the highly reproducible sensor performance. Using the optimized a linear relationship between current and glucose concentration was obtained up to $4.5{\times}10^{-4}$ M. In addition, this biosensor showed well reproducibility and stability.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.340-346
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• 2009

Lithium has only a minimal effect on basal glucose transport activity, instead that lithium markedly increased the sensitivity of glucose transport to insulin by increasing in insulin induced glucose transport activity. And Lithium increases in insulin responsiveness as well. Previous studies has reported this enhancement of lithium to stimulate the glucose transport process is not only limited to insulin, it also induce the increases in the sensitivity of glucose transport by submaximal contractile activity. The preliminary study, however, leads that Lithium possibly improves the responsiveness of glucose transport with maximal muscle contraction. In this study, we investigated the effect of Lithium on contraction for the maximal glucose transport. For the purpose of this study, Epitrochlearis muscles of SD rat were isolated and treated Lithium with electric contraction and/or insulin to activate the maximal glucose transport. The results support that Lithium improves the responsiveness of glucose transport through potentiates contraction and/or insulin induced-glucose uptake in muscle. Consequently Lithium treated with muscle contraction and insulin has the important potential to improve the insulin resistance and diabetes.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.179-183
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• 2015

In this study, we propose a catalyst structure including enzyme and metal nano rod for glucose sensing. In the catalyst structure, glucose oxidase (GOx) and gold nano rod (GNR) are alternatingly immobilized on the surface of carbon nanotube (CNT), while poly(ethyleneimine) (PEI) is inserted in between the GOx and GNR to fortify their bonding and give them opposite polarization ($[GOx/GNR]_nPEI/CNT$). To investigate the impact of $[GOx/GNR]_nPEI/CNT$ on glucose sensing, some electrochemical measurements are carried out. Initially, their optimal layer is determined by using cyclic voltammogram and as a result of that, it is proved that $[GOx/GNR/PEI]_2/CNT$ is the best layer. Its glucose sensitivity is $13.315{\mu}AmM^{-1}cm^{-2}$. When it comes to the redox reaction mechanism of flavin adenine dinucleotide (FAD) within $[GOx/GNR/PEI]_2/CNT$, (i) oxygen plays a mediator role in moving electrons and protons generated by glucose oxidation reaction to those for the reduction reaction of FAD and (ii) glucose does not affect the redox reaction of FAD. It is also recognized that the $[GOx/GNR/PEI]_3/CNT$ is limited to the surface reaction and the reaction is quasi-reversible.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.451-454
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• 2001

In this study, a micro-glucose sensor was fabricated by micromachining technology and its sensing characteristics were investigated. The 7740 pyrex glass was used as the bottom substrate and anisotropically etched silicon wafer was used as the top substrate. The size of the fabricated microchip is 1.58${\times}$1.58mm$^2$. It is shown that output current exhibits a linear change according to glucose concentration (100 mM ∼ 300 mM). It is also shown that the response time for glucose was within 240 sec. It was followed by a saturation trend within 50 sec. The g1ucose sensor with Fc$\^$+/ exhibits relatively higher sensitivity than that without Fc$\sub$+/ for output current.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.975-980
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• 1994

The preparation procedure and optimal composition of polyurethane diagnostic membranes were described to measure the glucose concentration in a urine. Vessel size, blade size and the ratio of solvent mixtures were found to be critical factors to get the better sensitivity and the stability of the color which appeared on polyurethane membranes after the reaction with the urine glucose. These urine strips made of polyurethane membranes made it possible to measure the urine glucose quantitatively because they showed a good color separation at glucose concentration from 30mg/dL to 500mg/dL.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.107-115
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• 1990

New insulin-releasing system on the basis of the redox reaction of glucose was synthesized by immobilizing insulin through a disulfide bond(5, 5'-dithiobis(2-nitrobenzoic acid) to polymer membrane(poly(methyl methacrylate)) and enzyme(glucose oxidase). The disulfide bonds were cleaved upon oxidation of glucose with glucose dehydrogenase and glucose oxidase, releasing insulin from the membrane and enzyme. Sensitivity to glucose concentration was enhanced by coimmobilization of enzyme cofactors(nicotinamide adenin dinucleotide and flavin adenin dinucleotide) acting as electron mediator(for the membrane device), and further enhanced by direct immobilization of insulin on glucose oxidase(for the protein device). Both systems were specific to glucose, and the released insulin was indistinguishable from native insulin. The biological activity of released insulin was 81% of native insulin.

• Journal of Sensor Science and Technology
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• v.23 no.5
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• pp.295-298
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• 2014

A novel approach to fabricating high-performance glucose sensors is reported, which is based on the process of self-assembled monolayers (SAMs). In this study, we have particularly used ${\alpha}$-lipoic acid (LA) SAMs for the glucose sensors. To our best knowledge, this study is the first one to use LA as SAMs for this purpose. N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) were deliberately attached at the same time on the LA SAM. Then, glucose oxidase ($GO_X$) and horseradish peroxidase (HRP) were sequentially immobilized. Thus, the HRP/$GO_X$/NHS-EDC/LA-SAM/Au/Cr/glass working electrode was developed. The glucose-sensing capability of the fabricated sensor was systematically measured by the use of cyclic voltammetry in the range of 1-30 mM glucose in phosphate-buffered saline. The result showed a good sensitivity, that is, as high as $27.5{\mu}A/(mM{\cdot}cm^2)$. This result conspicuously demonstrates that LA can be one of promising substances for use as SAMs for accurately monitoring trace levels of glucose concentration in human blood.

• YAKHAK HOEJI
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• v.47 no.6
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• pp.461-468
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• 2003

A method is described for measuring clinically relevant levels of glucose in a pH 7.4 phosphate buffer by nearinfrared (NIR) absorption spectroscopy. Three types of NIR spectrometer, dispersive type, photo-diode array (PDA) type, and fourier transform (FT) type spectrometer were used and the performance was compared. Spectra were collected with a cuvette cell or quartz liquid fiber of 1 mm or 2 mm optical pathlength as transmittance method. Glucose absorption band appeared at second overtone, first overtone, and combination region for all systems. By use of the multivariate technigue of partial least squares (PLS) regression, glucose concentrations can be determined with a 16, 44, and 9.1 mg/d l standard error of prediction for dispersive type, photo-diode array type, and fourier transform type system, respectively. Sensitivity of spectrometer was evaluated by absorbance for the difference of 10 mg/d l glucose. Three absorption bands, second overtone, first overtone, and combination region were suited to three types systems, dispersive type, photo-diode array type, and fourier transform type systems, respectively. This investigation showed that three types NIR spectrometer were proper method for identification and quantitative analysis of glucose and possible for noninvasive blood glucose monitoring.