• Macromolecular Research
• /
• v.14 no.3
• /
• pp.267-271
• /
• 2006

Polyelectrolyte complex films were prepared with two compounds, chitosan and poly(ethylene glycol)-monosuccinate, using a casting in order to synthesize a polyelectrolyte complex film with various mole ratios of chitosan and poly(ethylene glycol)-monosuccinate. The solution properties of isolated PEC were investigated for the effects of FTIR, pH value, Brookfield viscosity and cell viability assay using MTT staining. The PEC films were evaluated for mechanical properties by typical stress-strain curve, far thermal properties by DSC and TGA and for surface morphology Properties by SEM. Furthermore, the surface resistance, moisture regain and water content of the films were characterized. The solution properties were affected by several factors including the chitosan content in the PEC, the mixing ratio of PEG and chitosan, and pH. Several PEC in acidic conditions exhibited film formation under appropriate conditions of mixing ratio and chitosan concentration in the mixing process. These PEC films were found to have sufficiently flexible and stable properties due to their hydrophilic structure, which was farmed by the oppositely charged interaction between PEG-MS and chitosan matrix. The results showed the potential applicability of chitosan and poly(ethylene glycol)-monosuccinate films as a biocompatible polymer.

• Toxicological Research
• /
• v.20 no.2
• /
• pp.89-100
• /
• 2004

The comet assay (also called the single-cell gel electrophoresis assay) has been widely used for detecting DNA damage and repair in individual cells. Since the conventional methods of evaluating comet assay data using frequency statistics are unsatisfactory we developed a new quantitative measure of DNA damage/repair that is based on all information residing in the dose/time-response curves of a comet experiment. Blood samples were taken from 25 breast cancer patients before undergoing radiotherapy. The comet assay was performed under alkaline conditions using isolated lymphocytes. Tail DNA, tail length, tail moment and tail inertia of the comet were measured for each patient at four doses of $\gamma$-rays (0, 2, 4 and 8 Gy) and at four time points after irradiation (0, 10, 20 and 30 min) using 100 cells each. The resulting three-dimensional dose-time response surface was modeled by multiple regression, and the second derivative, termed 2D, on dose and time was determined. A software module was programmed in SAS/AF to compute 2D values. We applied the new method successfully to data obtained from cancer patients to be assessed for their radiation sensitivity. We computed the 2D values for the four damage measures, i.e., tail moment, tail length, tail DNA and tail inertia, and examined the pairwise correlation coefficients of 2D both on the log scale and the unlogged scale. 2D values based on tail moment and tail DNA showed a high correlation and, therefore, these two damage measures can be used interchangeably as far as DNA repair is concerned. 2D values based on tail inertia have a correlation profile different from the other 2D values which may reflect different facets of DNA damage/repair. Using the dose-time response surface, other statistical models, e.g., the proportional hazards model, become applicable for data analysis. The 2D approach can be applied to all DNA repair measures, Le., tail moment, tail length, tail DNA and tail inertia, and appears to be superior to conventional evaluation methods as it integrates all data of the dose/time-response curves of a comet assay.

• Polymer(Korea)
• /
• v.28 no.6
• /
• pp.502-508
• /
• 2004

Cationic liposomes for cancer treatment have been developed in the field of chemotharpy. It was well combined on the surface of anionic tumor cell membrane by electrostatic interaction. Thus, the object of this study was to prepare the cationic liposomes capable of forming an ionic complex with the anionic cell membrane. To prepare the cationic liposomes, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) as a cationic lipid material and polyethylenimine (PEI) as a cationic polymer were synthesized. Ionic property on the surface of liposomes was determined by the zeta potential. The adsorption characteristics of plasma protein for liposome in bovine serum were determined by the particle size and turbidity change. To estimate the stability of liposome in buffered solution, the change of particle size was measured at room temperature for seven days. The cationic liposomes were absorbed a large amount of plasma protein in bovine serum because plasma protein having anionic charge was fixed on the surface of cationic liposomes. This result indicate that the modification on the surface of liposomes using cationic polyethylenimine enhances the protein adsorption in bovine serum. Additionaly, cationic liposomes showed good stability in buffered solution for seven days.

• Food Science and Biotechnology
• /
• v.17 no.2
• /
• pp.219-227
• /
• 2008

Bacillus thuringiensis was isolated as a pathogen of the sotto disease of silkmoth larvae about a hundred years ago. Since then, this bacterium has attracted attentions of not only insect pathologists but also many other scientists who are interested in its strong and specific insecticidal activity. This has led to the recent worldwide development of B. thuringiensis-based microbial insecticides and insect-resistant transgenic plants, as well as a landmark discovery of par asp orin, a cancer cell-specific cytotoxin produced by B. thuringiensis. In this review, we describe examination of interaction between inclusion proteins of B. thuringiensis and brush border membrane of insects using a surface plasmon resonance-based biosensor, identification and characterization of parasporin-4, the latest parasporin produced by the B. thuringiensis A1470 strain, and an effective method for preparing the parasporin-4 from inclusion bodies expressed in the recombinant Escherichia coli cells.

• Journal of Photoscience
• /
• v.10 no.3
• /
• pp.237-240
• /
• 2003

The tetradecameric peptide (K47-K60) near the NH$_2$-terminal region of epithelial-cell adhesion molecule (Ep-CAM) was chosen as antigenic site and a polyclonal antibody was generated, which could recognize Ep-CAM from the mouse colon tissue or the colon cancer cell, CT-26, in Western blot analysis. Then, the fluorescein isothiocyanate (FITC), a fluorescence dye, was conjugated with the affinity purified Ep-CAM antibody using thiocyanate and the amino groups of FITC and antibody, respectively. The molar ratio of FITC to antibody was estimated approximately 1.86 to 1.00 by measuring the optical densities at 492 nm and 280 nm. Ep-CAM antibody-FITC conjugate was then used for immunohistochemistry of the CT-26 cells. Judging from the shapes formed by fluorescence, the Ep-CAM antibody could delivered FITC to the surface of cells in which Ep-CAM was expressed. This result implies that Ep-CAM antibody could be also used for the tissue-specific delivery of the photosensitizer to the target protein via antigen-antibody interaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.11a
• /
• pp.198-201
• /
• 1997

We investigated the generation of pretilt angle for nematic liquid crystal (NLC) in a cell with slanted non-polarized ultraviolet (UV) light irradiation on mixtured polyimide (PI) surfaces. It was found that the monodomain alignment of NLC is obtained in a cell with an angle of incidence of 75∼85 degrees on PI surface. We consider that the monodomain alignment of NLC is attributed to anisotropic dispersion force effect due to photo-depolymerization of polymer on Pl surfaces. We successfully observed that the pretilt angle of NLC is generated above 5 degree with an angle of incidence of 75∼85 degree. It is considered that the pretilt angle generation in NLC is attributed to interaction between the LC molecules and the Polymer surfaces.

• Korean Journal of Environmental Biology
• /
• v.26 no.4
• /
• pp.377-384
• /
• 2008

A cell is the product of a long period of evolution and can be represented as an optimized system (homeostasis). Stimuli from the outside environment are received by sensory apparatus on the surface of the cell and transferred through complicated pathways and eventually regulate gene expression. These signals affect cell physiology, growth, and development, and the interaction among genes in the signal transduction pathway is a critical part of the regulation. In this study, the interactions of deletion mutants and overexpression of the extracopies of the genes were used to understand their relationships to each other. Also, green fluorescent protein (GFP reporter gene) was fused to the regulatory genes to elucidate their interactions. Cooverexpression of the two genes in extracopy plasmids suggested that patS acts at the downstream of hetR in the regulatory network. The experiments using gfp fusion in different genetic background cells also indicated the epistasis relationships between the two genes. A model describing the regulatory network that controls cell development is presented.

• Molecules and Cells
• /
• v.25 no.1
• /
• pp.99-104
• /
• 2008

Gangliosides, sialic acid-containing glycosphingolipids, are implicated in many neuronal diseases, but the precise molecular mechanisms underlying their pathological activities are poorly understood. Here we report that TLR2 participates in the initiation of ganglioside-triggered inflammatory signaling responses. Using FACS analysis and immunofluorescence microscopy, we found that gangliosides rapidly enhanced the cell surface expression of TLR2 in microglia, while reducing that of TLR4. The ganglioside-dependent increase of TLR2 expression was also observed at the messenger and protein levels. We also showed that gangliosides stimulate the interaction of TLR2 with Myd88, an adaptor for TLRs, and obtained evidence that lipid raft formation is closely associated with the ganglioside-induced activation of TLR2 and subsequent inflammatory signaling. These results collectively suggest that TLR2 contributes to the ability of gangliosides to cause inflammatory conditions in the brain.

• Transactions on Electrical and Electronic Materials
• /
• v.10 no.5
• /
• pp.177-181
• /
• 2009

Employing statistical design of experiments, we have performed studies on the characterization of electrodes using $TiO_2$ and process variables in the fabrication process of nanocrystalline dye sensitized solar cell. Systematic experiment to identify the effects of process variables on cell's efficiency has based on broad-band absorption of light by tailor made organometallic dye molecules dispersed on a high surface of $TiO_2$. Employing statistical design of experiment on $TiO_2$ photoelectrode forming process, structural characterization of electrodes and process variable have been investigated. Through the statistical analysis we have found that the particle size of $TiO_2$ and the amount of PEG/PEO are significantly affecting on the cell efficiency. In addition, a significant amount of interaction exists between the particle size and the amount of PEG/PEO.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2003.11a
• /
• pp.438-446
• /
• 2003

This paper presents the development of the remotely operated decontamination systems for use in a highly radioactive zone of the DUPIC Fuel Development facility of the Irradiated Material Examination Facility at the Korea Atomic Energy Research Institute. The remotely operated decontamination systems were designed to completely eliminate human interaction with hazardous radioactive contaminants. These decontamination systems are mainly classified into three systems depending on the task environment - a fabrication equipment decontamination system, a hot-cell floor decontamination system, and an isolation room floor decontamination system. A decontamination system for contaminated fabrication equipment utilizes dry ice pellet blasting method to decontaminate contaminated surface of the equipment. The decontamination systems for the hot-cell floor and isolation room floor employ a vacuum cleaning method to decontaminate the contaminated floor and collect loose dry spent nuclear fuel debris and other radioactive waste placed on the floor. The human operator from the out-of-cell performs a series of decontamination tasks remotely by manipulating decontamination systems located in-cell via a handcontroller with the aid of vision feedback information. The environmental, functional and mechanical design considerations, control system and capabilities of the remotely operated decontamination systems at a high radioactive environment are also described.