• Korean Chemical Engineering Research
• /
• v.53 no.6
• /
• pp.802-807
• /
• 2015

In this study, we synthesized a new biocatalyst consisting of glucose oxidase (GOx), polyethyleneimine (PEI) and carbon nanotube (CNT) with addition of terephthalaldehyde (TPA) (TPA/GOx/PEI/CNT) for fabrication of glucose sensor that shows improved sensing ability and stability compared with that using other biocatalysts. Main bonding of the new TPA/GOx/PEI/CNT catalyst is formed by Aldol condensation reaction of functional end groups between GOx/PEI and TPA. Such formed bonding structure promotes oxidation reaction of glucose. Catalytic activity of TPA/GOx/PEI/CNT is evaluated quantitatively by electrochemical measurements. As a result of that, large sensitivity value of $41{\mu}Acm^{-2}mM^{-1}$ is gained. Regarding biosensor stability of TPA/GOx/PEI/CNT catalyst, covalent bonding formed between GOx/PEI and TPA prevents GOx molecules from becoming leaching-out and contributes improvement in biosensor stability. With estimation of the biosensor stability, it is found that the TPA/GOx/PEI/CNT catalyst keeps 94.6% of its initial activity even after three weeks.

• Korean Journal of Optics and Photonics
• /
• v.19 no.6
• /
• pp.416-421
• /
• 2008

A scheme for predicting the concentration of a glucose solution based on its relative optical absorbance at multiple probe wavelengths was proposed and verified. The relative absorbance at each of the probe wavelength was obtained with respect to the absorbance at a reference wavelength. The single reference wavelength (1310 nm) and a group of four different probe wavelengths (1064, 1550, 1685, 1798 nm) were selected to exhibit the glucose absorbance with opposite signs, thereby enhancing the accuracy of the prediction. The final glucose concentration was estimated by taking the average of the predicted values provided by the four probe wavelengths. The absorbance of the glucose solution for the path length of 5 mm was $-1.42{\times}10^{-6}\;AU$/(mg/dL) at the reference wavelength of 1310 nm and peaked at $+8.12{\times}10^{-6}\;AU$/(mg/dL) at 1685 nm. The concentration of the glucose solution was decently predicted by means of the proposed scheme with the standard error of prediction of ${\sim}28\;mg/dL$. In addition, the influence of the ambient temperature and the fat thickness upon the prediction of the glucose concentration was examined. The absorption change with the temperature was $-9.1{\times}10^{-5}\;AU/^{\circ}C$ in the temperature range of $26{\sim}40^{\circ}C$ at the reference wavelength, and $-2.08{\times}10^{-2}\;AU/^{\circ}C$ at 1550 nm. And the absorption change with respect to the fat thickness was +1.093 AU/mm at the probe wavelength of 1685 nm.

• KSBB Journal
• /
• v.13 no.6
• /
• pp.681-686
• /
• 1998

Effect of glucose feeding strategy and initial concentration of glucose on Serratia marcescens ATCC 27117 in high cell density fed-batch fermentation was investigated. The final biomasses in batch, constant feeding, constant and exponentially feeding strategy at glucose starvation condition in fed-batch were 1.40, 5,07, 6,93 and 7.60 g/L at 40, 41, 24 and 40 hrs, respectively. Productivities of biomass were 0.035, 0.124, 0.289 and 0.190 g/L$.$h, respectively. As a result, constant feeding strategy at starvation condition was 1.5∼8.6 times higher than other strategies. The relationship between dissolved oxygen and glucose feeding times was good identified in exponential feeding strategy and constant feeding strategy at starvation condition. And high cell density cultivation was obtained when minimal media was used.

• Journal of Korean Society on Water Environment
• /
• v.32 no.2
• /
• pp.197-204
• /
• 2016

The growth of the algae strain Chlorella vulgaris under mixotrophic conditions in the presence of saccharified acorn-starch (acorn-glucose) was evaluated with the objective of increasing biomass growth and triacylglycerols (TAGs) content. The results indicated that 81.3% of starch was converted to glucose in acorns. C.vulgaris algal strains grown with acorn-glucose produced higher biomass and TAGs content than with autotrophic growth. The highest biomass production and TAGs content with 3 g/L acorn-glucose were 12.44 g/L and 32.9%, respectively. Biomass production with 3 g/L acorn-glucose was 16.4 fold higher than under autotrophic growth condition. These findings suggested that 3 g/L acorn-glucose is economic and efficient for biomass production/productivity and TAGs content of microalgae. This study provides a feasible way to reduce the cost of bioenergy production from microalgae.

• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.2
• /
• pp.179-183
• /
• 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 Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.435-437
• /
• 2005

This research proposes the methods to measure glucose with signals from the OCT system and verifies accuracy by the way numerical analysis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.343-345
• /
• 2005

This research proposes the methods to measure glucose with signals from the OCT system and verifies accuracy by the way numerical analysis.

• Korean Chemical Engineering Research
• /
• v.54 no.5
• /
• pp.693-697
• /
• 2016

In this study, we fabricated the catalysts for enzymatic biofuel cell anode with carbon nanotube (CNT), glucose oxidase (GOx) and various molecular weights branched poly(ethyleneimine)(bPEI) and terephthalaldehyde (TPA) as cross-linker. In case of GOx/bPEI/CNT using only physical entrapments for immobilization, the molecular weights of bPEI didn't affect to electrochemical performances and long term stability. but that of the catalysts cross linked via TPA (TPA[GOx/bPEI/CNT]) improved and the mass transfer of glucose to FAD was interrupted as increasing of the bPEI's molecular weights. Furthermore, it was confirmed that the optimum molecular weight of PEI for TPA [GOx/bPEI/CNT]) structure is 750k that showed marvelous high performance (maximum power density of $0.995mW{\cdot}cm^{-2}$).

• Applied Chemistry for Engineering
• /
• v.24 no.1
• /
• pp.99-103
• /
• 2013

An emzymatic bioanode for a glucose/oxygen biofuel cell was prepared by the sequential coating of carbon nanotube (CNT), charge transfer complex (CTC) based on tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF), glucose oxidase (GOx), and polyion complex (mixture of poly-L-lysine hydrobromide and poly (sodium 4-styrenesulfonate)) on a glassy carbon electrode. A biocathode was also prepared by the sequential coating of CNT, bilirubin oxidase (BOD), 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and polyion complex. The effect of CNT and CTC on the electrochemical performance was investigated. The biofuel cell exhibited a promising performance with maximum power densities of 3.6, 10.1, and $46.5{\mu}W/cm^2$ at 5, 20, and 200 mM of glucose concentration, respectively. The result indicates that the biofuel cell architecture prepared in this study can be used in the development of biofuel cells and biosensors.

• Analytical Science and Technology
• /
• v.23 no.2
• /
• pp.165-171
• /
• 2010

Glucose oxidase ($GOD_{ox}$) immobilized biosensor was fabricated by two methods. In one of the methods, gold nanoparticles (Au-NPs) prepared by ${\gamma}$-irradiation were loaded into the poly(maleic anhydride)-grafted multi-walled carbon nanotube, PMAn-g-MWCNT electrode via physical entrapment. In the other method, the Au-NPs were prepared by electrochemical reduction of Au ions on the surface of PMAn-g-MWCNT electrode and then GODox was immobilized into the Au-NPs. The $GOD_{ox}$ immobilized biosensors were tested for electrocatalytic activities to sense glucose. The sensing range of the biosensor based on the Au-NPs physically modified PMAn-g-MWCNT electrode was from $30\;{\mu}M$ to $100\;{\mu}M$ for the glucose concentration, and the detection limit was $15\;{\mu}M$. Interferences of ascorbic acid and uric acid were below 7.6%. The physically Au deposited PMAn-g-MWCNT paste electrodes appear to be good sensor in detecting glucose.