Jin Young Lee

Improvement of electrical properties via glucose oxidase-immobilization by actively turning over glucose for an enzyme-based biofuel cell modified with DNA-wrapped single walled nanotubes

One of the major areas of study associated with enzyme fuel cells (EFCs) has been identification of redox enzymes with high electron transfer rates that lead to a high power output. The effects of a method of enzyme immobilization by actively turning over glucose on the electrical properties of a fuel cell were evaluated under ambient conditions in attempt to increase the power of an EFC modified with DNA-wrapped single walled carbon nanotubes (SWNTs). The anode cyclic voltammetry (CV cycle) electrical properties increased as a result of glucose oxidase (GOD) immobilization by actively turning over glucose. Furthermore, an EFC that employed DNA-wrapped SWNTs and GOD immobilization in conjunction with protection of the active site increased the stability of the cell, which enabled maintenance of a high level of power production (ca. 730-760 μW cm(-2)) for 1 week.

Quantitative Detection of Glyphosate by Simultaneous Analysis of UV Spectroscopy and Fluorescence Using DNA-Labeled Gold Nanoparticles

A sandwich-type immunosensor composed of antigen-double target/probe DNA-coated gold nanoparticles (NPs) was developed for the measurement of fluorescence intensity and quantitative analysis of single-stranded DNA based on the concentration of free glyphosate. The reaction between the antigen-double DNA-gold NPs and immobilized antibody on the substrate was carried out for 2 h. The results of the antigen-antibody reaction were measured on the basis of the fluorescence intensity obtained from comparison with the free antigens at concentrations of 0.01-100 μg mL(-1) for the detection of immobilized antigen-double DNA-gold NPs. For the quantitative analysis based on the concentration of glyphosate(0.01-100 μg mL(-1)), the immunosensor response also revealed the same detection range of glyphosate using DNA detection.

Application of an enzyme-based biofuel cell containing a bioelectrode modified with deoxyribonucleic acid-wrapped single-walled carbon nanotubes to serum.

Enzyme-based biofuel cells (EFCs) are a form of biofuel cells (BFCs) that can utilize redox enzymes as biocatalysts. Applications of an EFC to an implantable system are evaluated under mild conditions, such as ambient temperature or neutral pH. In the present study, an EFC containing a bioelectrode modified with deoxyribonucleic acid (DNA)-wrapped single-walled carbon nanotubes (SWNTs) was applied to a serum system. The protection of immobilized glucose oxidase (GOD) using DNA-wrapped SWNTs was investigated in a trypsin environment, which can exist in a serum. GOD is immobilized by masking the active site onto the anode electrode. The anode/cathode system in the cell was composed of GOD/laccase as the biocatalysts and glucose/oxygen as the substrates in serum. The electrical properties of the anode in serum according to cyclic voltammetry (CV cycle) were improved using the DNA-wrapped SWNTs. Overall, an EFC that employed DNA-wrapped SWNTs and GOD immobilization in conjunction with protection of the active site increased the stability of GOD in serum, which enabled a high level of power production (ca. 190 μW/cm(2)) for up to 1 week.

Verticillium lecanii Spore Formulation Using UV Protectant and Wetting Agent and the Biocontrol of Cotton Aphids

Verticillium lecanii spores (108xa0spores ml−1) suspended in 1% (w/v) montmorillonite SCPX-1374 and 1% (w/v) of the wetting agent, EM-APW#2, which is a polyoxyethylene, had approx. 80% survival after exposure to UV-C for 30xa0min and about 93% after exposure to UV-B for 6xa0h. In greenhouse testing, cotton aphid densities increased 14-fold over their initial density in 15xa0d without spore application. However, initial cotton aphid densities were decreased by 60% of the initial level when plants were treated with the spore formulation.

Stimulation of cephalosporin C production in Acremonium chrysogenum M35 by glycerol.

In this study, the effects of glycerol on cephalosporin C production by Acremonium chrysogenum M35 were evaluated. The addition of glycerol increased cephalosporin production by up to 12-fold. Glycerol caused the upregulation of the transcription of the isopenicillin synthase (pcbC) and transporter (cefT) genes in early exponential phase, and affected the cell morphology since hyphal fragments differentiated into arthrospores. These results indicate that glycerol effectively enhances cephalosporin C production via stimulation of cell differentiation.

Production of cephalosporin C using crude glycerol in fed-batch culture of Acremonium chrysogenum M35.

In this study, cephalosporin C production by Acremonium chrysogenum M35 cultured with crude glycerol instead of rice oil and methionine was investigated. The addition of crude glycerol increased cephalosporin C production by 6-fold in shake-flask culture, and also the amount of cysteine. In fed-batch culture without methionine, crude glycerol resulted only in overall improvement in cephalosporin C production (about 700%). In addition, A. chrysogenum M35 became highly differentiated in fed-batch culture with crude glycerol, compared with the differentiation in batch culture. The results presented here suggest that crude glycerol can replace methionine and plant oil as cysteine and carbon sources during cephalosporin C production by A. chrysogenum M35.

Utilization of glycerol as cysteine and carbon sources for cephalosporin C production by Acremonium chrysogenum M35 in methionine-unsupplemented culture

In this study, the role of glycerol in cephalosporin C production was evaluated in Acremonium chrysogenum M35. Methionine-unsupplemented culture with glycerol stimulated cephalosporin C production in A. chrysogenum M35 by up to 10-fold while increasing the amount of cysteine. Glycerol caused the upregulation of isopenicillin N-CoA epimerase (cefD2) and δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine synthase (pcbAB) transcription in exponential phase. These results indicate that glycerol without methionine effectively enhanced cephalosporin C production via stimulation of cysteine and valine in A. chrysogemun M35.

Rapid quantification of lipids in Acremonium chrysogenum using Oil red O.

A method based on staining condition and volume of culture broth for the rapid estimation of the level of intracellular lipids in Acremonium chrysogenum using Oil red O was developed. Lipids in A. chrysogenum were strongly stained by the modified Oil red O after treatment for 10xa0min at 75°C. The results of the study indicated that the Oil red O staining method developed here is useful for the quantification of 0.1–5xa0mgxa0ml−1 of lipids in A. chrysogenum.