Tae Hun Chung - Academia.edu (original) (raw)

Papers by Tae Hun Chung

Bulletin of the American Physical Society, Oct 3, 2013

PLOS ONE

Plasma activated medium (PAM) was prepared by a bipolar microsecond-pulsed atmospheric pressure p... more Plasma activated medium (PAM) was prepared by a bipolar microsecond-pulsed atmospheric pressure plasma jet (APPJ) array source and was utilized for cancer cell treatment. APPJ array-produced plasma were characterized. APPJ array treatment of three different solutions (deionized water (DW), HBSS (serum-free Hanks’ balanced salt solution), and DMEM (Dulbecco’s Modified Eagle Medium) + 10% FBS (fetal bovine serum)) were performed to induce the changes in the concentration of reactive oxygen and nitrogen species (RONS) as functions of the operating parameters. Human cervical cancer cells (HeLa) injected with plasma-treated media were investigated for changes in cell viability using MTT assay. It was observed that PAM-induced ROS can regulate the protein expression associated with mitochondria, and PAM causes apoptosis through Cyto C/JNK/p38 signaling on human cervical cancer cells.

Submitted for the GEC13 Meeting of The American Physical Society The interaction of atmospheric p... more Submitted for the GEC13 Meeting of The American Physical Society The interaction of atmospheric pressure plasma jets with cancer and normal cells: generation of intracellular reactive oxygen species and changes of the cell proliferation and cell cycle 1 TAE HUN CHUNG, HEA MIN JOH, SUN JA KIM, SUN HEE LEEM, Dong-A University-The possibility of atmospheric pressure plasmas is emerging as a candidate in cancer therapy. The primary role is played by reactive oxygen species (ROS), UV photons, charged particles and electric fields. Among them, intracellular ROS induced by plasma are considered to be the key constituents that induce cellular changes and apoptosis. In this study, the effects of atmospheric pressure plasma jet on cancer cells (human lung carcinoma cells) and normal cells (embryonic kidney cells and bronchial epithelial cells) were investigated. The plasma treatment was performed under different working gases, applied voltages, gas flow rates, and with and without additive oxygen flow. Using a detection dye, we observed that plasma exposure leads to the increase of the intracellular ROS and that the intracellular ROS production can be controlled by plasma parameters. A significant ROS generation was induced by plasma exposure on cancer cells and the overproduction of ROS contributes to the reduced cell proliferation. Normal cells were observed to be less affected by the plasma-mediated ROS and cell proliferation was less changed. The plasma treatment also resulted in the alteration of the cell cycle that contributes to the induction of apoptosis in cancer cells. The selective effect on cancer and normal cells provides a promising prospect of cold plasma as cancer therapy.

JOURNAL-KOREAN …, 2006

Ultra-large-scale integrated-circuit (ULSI) technology has developed rapidly, and the minimum tra... more Ultra-large-scale integrated-circuit (ULSI) technology has developed rapidly, and the minimum transistor gate length has reached the 100 nm level [1]. In contrast to the reduced dimension of ULSI device elements, the total length of the metal interconnections has ...

IEEE Transactions on Plasma Science, 2017

This paper explores the effects of tube shape and pin electrode diameter on the plume generation ... more This paper explores the effects of tube shape and pin electrode diameter on the plume generation and electrical characteristics in atmospheric pressure helium plasma jets generated from a centered-pin electrode inside a dielectric tube. The quartz-covered (or bare) pin electrode and different shapes of the dielectric tube (straight cylinder or conical shape) are employed and their effects are investigated. Optical emission spectra are obtained at different positions along the coaxial direction to determine the axial distributions of the electron excitation temperature for the straight cylinder and conical jets. The rotational temperatures for the both jets are also compared.

Physics of Plasmas, 2011

The properties of low-pressure inductively coupled nitrogen-argon plasmas were investigated by us... more The properties of low-pressure inductively coupled nitrogen-argon plasmas were investigated by using a Langmuir probe combined with optical emission spectroscopy (OES) under the conditions of pressures in the range of 1–30 mTorr and applied rf powers of 200–600 W. In the experiments, the argon was introduced as an actinometer and as an adding gas. The effect of the argon content in the gas mixture was examined in the range of 5%–80%. The electron energy probability function (EEPF), the electron density, and the electron temperature were obtained by using an rf-compensated Langmuir probe. The dissociation fractions were obtained from the OES actinometry. The electron temperature was also obtained by OES corona model and compared with that measured by the probe. The second positive and first negative systems of spectral bands from nitrogen molecules were analyzed to estimate the vibrational and rotational temperatures. The effects of the control parameters on the plasma parameters and...

Bulletin of the American Physical Society, 2010

Submitted for the GEC10 Meeting of The American Physical Society Plasma-cell interactions: apopto... more Submitted for the GEC10 Meeting of The American Physical Society Plasma-cell interactions: apoptosis in cultured human breast cancer cells by a pulsed atmospheric pressure plasma jet TAE HUN CHUNG, SUN JA KIM, Dong-A University, HEA MIN JOH, SE HWAN BAE, SUN HEE LEEM-Atmospheric pressure plasma jet sources driven by pulsed dc voltage with repetition rate of several tens of kilohertz were specially fabricated and characterized. Using this plasma jet, apoptotic effect on cultured human breast cancer cells (MCF-7) was explored. The effect of plasma-forming gases (helium and argon) and additive O 2 gas on the cell treatment was investigated. The apoptotic changes in cells with plasma treatment were detected by DAPI staining and fluorescence staining assay, and also by flow cytometry. A significant portion of these cells was observed to exhibit the apoptotic fragmentation. Apoptosis is mediated by a various range of cell signals, both extracellular and intracellular. These signals may positively or negatively induce apoptosis. With monospecific antibodies, immunoblotting, and immunohistochemical methods, the relative level of apoptosis-regulating proteins in cell lysates can be detected. Biochemical mechanism of the plasma-cell interaction using human antibody assay will be also addressed. This plasma jet can provide an effective mode of human breast cancer cell therapy.

Scientific reports, Jan 3, 2016

Cold atmospheric helium plasma jets were fabricated and utilized for plasma-cell interactions. Th... more Cold atmospheric helium plasma jets were fabricated and utilized for plasma-cell interactions. The effect of operating parameters and jet design on the generation of specific reactive oxygen and nitrogen species (RONS) within cells and cellular response were investigated. It was found that plasma treatment induced the overproduction of RONS in various cancer cell lines selectively. The plasma under a relatively low applied voltage induced the detachment of cells, a reduction in cell viability, and apoptosis, while the plasma under higher applied voltage led to cellular necrosis in our case. To determine whether plasma-induced reactive oxygen species (ROS) generation occurs through interfering with mitochondria-related cellular response, we examined the plasma effects on ROS generation in both parental A549 cells and A549 ρ(0) cells. It was observed that cancer cells were more susceptible to plasma-induced RONS (especially nitric oxide (NO) and nitrogen dioxide (NO2(-)) radicals) tha...

IEEE Conference Record - Abstracts. 1996 IEEE International Conference on Plasma Science

For radio-frequency discharges of electronegative gases, one-dimensional equilibrium equations fo... more For radio-frequency discharges of electronegative gases, one-dimensional equilibrium equations for plasma variables are formulated and the scaling formulae of the plasma variables are derived in terms of the control parameters. The control parameters consist of three parameters: p (pressure), lp (halfsystem length), and P (power) or ne (electron density). The classifications of the operating regions are performed according to the prevailing particle-loss mechanism (recombination-loss-dominated or ion-flux-loss-dominated) and according to the main heating mechanism (ohmic-heating-dominated or stochastic-heating-dominated). The variations of the charged particle densities with pressure and absorbed power are estimated and compared with the results of a particle-in-cell simulation.

Atmospheric pressure microplasma jet sources driven by radio-frequency wave and by low frequency ... more Atmospheric pressure microplasma jet sources driven by radio-frequency wave and by low frequency pulsed wave of several kilohertz were specially fabricated and characterized. Two different types of jet were developed. The first one consists of a sharpened metal pin which is covered with a cone type Teflon layer confined in an acrylic tube. This structure allows an efficient ignition since

Journal of the …, 2004

Since the first discovery of light emission from porous silicon [1], the interest toward Si-based... more Since the first discovery of light emission from porous silicon [1], the interest toward Si-based optoelectronics has rapidly increased. Due to better compatibility with standard ultra-large scale integrated circuit (ULSI) processes, Si nanocrystals in a dielectric matrix have ...

Electrostatic probe measurements for low-pressure inductively coupled SF6 and O2 plasmas are perf... more Electrostatic probe measurements for low-pressure inductively coupled SF6 and O2 plasmas are performed. From the probe I-V curves, we measure the electron saturation current, the positive ion saturation current, and the electron temperature. By using the ratios of these parameters at three adjacent pressure points, we calculate the electronegativity of the discharges at those pressures. By using the electronegativity and the electron density measured from probe I-V curve, we estimate the negative ion density. The positive ion density is calculated either by the Laframboise OML theory or by the sum of the electron density and the negative ion density. The validity of this approach is discussed and compared to other methods in estimating the negative ion density. The variations of the charged species density with pressure and power are investigated. In addition, mass spectra of SF6 and O2 plasmas are obtained to determine the various species in the discharge and the effective mass of ...

Plasma Sources Science and Technology, 2000

The equilibrium of electronegative discharges is studied in the plane-parallel approximation over... more The equilibrium of electronegative discharges is studied in the plane-parallel approximation over a wide range of pressures and electron densities, encompassing a number of regimes that have previously been modeled analytically. The transitions between the various regimes (models) have been determined in the input parameter space. It is shown that for a given feedstock gas, these transitions can be found in terms of the two input parameters p p and n e0 p , where p is the pressure, n e0 the electron density, and p the system half-length. Here n e0 is used as a convenient input related to the power, and the conversion from electron power to n e0 is given. The input parameter space is partitioned by whether ion flux to the wall or positive-negative ion recombination is the dominant positive ion loss mechanism. For each of the principal regimes, scaling laws are developed for the most important plasma parameters in terms of the input parameters.

IEEE Transactions on Plasma Science, 1990

A free-electron laser with an ac electric wiggler is analyzed using linear fluid theory. The disp... more A free-electron laser with an ac electric wiggler is analyzed using linear fluid theory. The dispersion relation, the growth rate of the instability, and the efficiency of the laser are formulated, and the operating regimes are then investigated by a study of the parameters. Gain calculation according to the Madey theorem is also performed.

Current Applied Physics, 2010

Plasma enhanced chemical vapor deposition of nitrogen-incorporated silicon oxycarbide thin films ... more Plasma enhanced chemical vapor deposition of nitrogen-incorporated silicon oxycarbide thin films obtained from the gas mixture of TMOS (tetramethoxysilane), N 2 , and NH 3 is studied. The effects of the TMOS to N 2 pressure ratio on the properties of the film and the plasma are investigated. The deposited films are analyzed by in situ ellipsometry, ex situ Fourier transform infrared spectroscopy (FTIR), and by X-ray photoelectron spectroscopy (XPS). The plasma is characterized by using optical emission spectroscopy (OES). The mass spectra of the constituents in the plasma are obtained by quadrupole mass spectroscopy. The correlation between the film properties and the plasma characteristics is explained wherever possible. As the partial pressure of N 2 is decreased, the refractive index begins to decrease, reaches a minimum, and then saturates. The FTIR absorption bands are observed from about 850 to 1000 cm À1 and from 1000 to 1250 cm À1 , and can be attributed to the formation of a nitrogen-incorporated silicon oxycarbide thin film. The variation of the refractive index is discussed in relationship with the deposition rate, the OES spectra, the mass spectra of the plasma, the film composition obtained by XPS, and FTIR spectra.

Physics of Plasmas, 2014

In low-pressure inductively coupled argon and oxygen discharges, the plasma density and electron ... more In low-pressure inductively coupled argon and oxygen discharges, the plasma density and electron temperature and the electron energy distribution function (EEDF) were obtained by using a cylindrical electric probe. The plasma densities were determined by various methods to interpret the probe current-voltage characteristic curve: the EEDF integration, the electron saturation current, the ion current at the floating potential, and the orbital-motion-limited (OML) ion current. Quite a good agreement exists between the plasma densities determined by various classical methods. Although the probe technique has some limitation in electronegative plasmas, the plasma densities determined from OML theory compare well with those measured by the ion saturation current at the floating potential in the oxygen discharges. In addition, the EEDFs of inductively coupled Ar and oxygen plasmas are observed to be nearly Maxwellian at the pressure range of 1-40 mTorr.

International Journal of Molecular Sciences

Despite continuous progress in therapy, melanoma is one of the most aggressive and malignant huma... more Despite continuous progress in therapy, melanoma is one of the most aggressive and malignant human tumors, often relapsing and metastasizing to almost all organs. Cold atmospheric plasma (CAP) is a novel anticancer tool that utilizes abundant reactive oxygen and nitrogen species (RONS) being deposited on the target cells and tissues. CAP-induced differential effects between non-cancerous and cancer cells were comparatively examined. Melanoma and non-cancerous skin fibroblast cells (counterparts; both cell types were isolated from the same patient) were used for plasma–cell interactions. The production of intracellular RONS, such as nitric oxide (NO), hydroxyl radical (•OH), and hydrogen peroxide (H2O2), increased remarkably only in melanoma cancer cells. It was observed that cancer cells morphed from spread to round cell shapes after plasma exposure, suggesting that they were more affected than non-cancerous cells in the same plasma condition. Immediately after both cell types were ...

Cell Death & Disease, 2022

Cold atmospheric plasma (CAP) that generates reactive oxygen species (ROS) has received considera... more Cold atmospheric plasma (CAP) that generates reactive oxygen species (ROS) has received considerable scientific attentions as a new type of anticancer. In particular, an indirect treatment method of inducing cancer cell death through plasma-activated medium (PAM), rather than direct plasma treatment has been well established. Although various cell death pathways such as apoptosis, necroptosis, and autophagy have been suggested to be involved in PAM-induced cell death, the involvement of ferroptosis, another type of cell death regulated by lipid ROS is largely unknown. This study reports, that PAM promotes cell death via ferroptosis in human lung cancer cells, and PAM increases intracellular and lipid ROS, thereby resulting in mitochondrial dysfunction. The treatment of cells with N-acetylcysteine, an ROS scavenging agent, or ferrostatin-1, a ferroptosis inhibitor, protects cells against PAM-induced cell death. Interestingly, ferroptosis suppressor protein 1 (FSP1) is downregulated u...

Journal of Applied Physics, 1971

Localized photonic modes are studied in a non-ideal chain of coupled microcavities with the use o... more Localized photonic modes are studied in a non-ideal chain of coupled microcavities with the use of the virtual crystal approximation. The approach proves sufficient to elucidate the effects of varying composition and nearest-neighbor distances on the spectrum. It permits to obtain the density of states of the studied quasiparticles as well as the dispersion dependence of collective excitation frequencies on defect concentration. Based upon the developed description of ideal photonic structures we proceed to study a non-ideal polaritonic crystal constituted by an array of spatially ordered cavities containing atomic clusters. Frequency, effective mass and group velocity of polaritons are analytically derived as functions of vacancy concentration.

Applied Physics Letters, 2015