Changyoon Baek
Chung-Ang University
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Publication
Featured researches published by Changyoon Baek.
Biosensors and Bioelectronics | 2015
Sung Hee Chung; Changyoon Baek; Vu Tan Cong; Junhong Min
Sample preparation has recently been an issue in the detection of food poisoning pathogens, particularly viruses such as norovirus (NoV), in food because of the complexity of foods and raw fresh materials. Here, we demonstrate a total analytical microfluidic chip module to automatically perform a series of essential processes (cell concentration, lysis (RNA extraction), nucleic acid amplification, and detection) for the fast but sensitive detection of norovirus in oysters. The murine NoV spiked oyster was stomached using a standard method. The supernatant was first loaded into a shape switchable sample preparation chamber consisting of charge switchable micro-beads. Murine NoV, which was adsorbed on microbeads by electrostatic physisorption, was lysed using bead beating. The extracted RNA was transferred to the detection chamber to be amplified using Nucleic Acid Sequence Based Amplification (NASBA). The optimal surface functionality, size, and number of microbeads were achieved for the virus concentration and the stable RNA extraction in the shape-switchable micro-channel. As a result, murine NoV in a single oyster was successfully detected within 4h by the microfluidic chip developed here, and could be directly applied to the large volume environmental sample as well as the food sample.
PLOS ONE | 2016
Trong Binh Tran; Changyoon Baek; Junhong Min
The tumor microenvironment, including stromal cells, surrounding blood vessels and extracellular matrix components, has been defined as a crucial factor that influences the proliferation, drug-resistance, invasion and metastasis of malignant epithelial cells. Among other factors, the communications and interaction between cancer cells and stromal cells have been reported to play pivotal roles in cancer promotion and progression. To investigate these relationships, an on-chip co-culture model was developed to study the cellular interaction between A549—human lung carcinoma cells and MRC-5—human lung epithelial cells in both normal proliferation and treatment conditions. In brief, a co-culture device consisting of 2 individual fluidic chambers in parallel, which were separated by a 100 μm fence was utilized for cell patterning. Microelectrodes arrays were installed within each chamber including electrodes at various distances away from the confrontation line for the electrochemical impedimetric sensing assessment of cell-to-cell influence. After the fence was removed and cell-to-cell contact occurred, by evaluating the impedance signal responses representing cell condition and behavior, both direct and indirect cell-to-cell interactions through conditioned media were investigated. The impact of specific distances that lead to different influences of fibroblast cells on cancer cells in the co-culture environment was also defined.
Biosensors and Bioelectronics | 2016
Trong Binh Tran; Phuong Diem Nguyen; Changyoon Baek; Junhong Min
MMP-9 (92 kDa gelatinease), which is member of matrix metalloproteinases (MMPs) family, plays a crucial role in the breakdown of extracellular matrix (ECM) by degrading the major components of ECM that lead to tumor cell invasion and metastasis through the basement membrane. Our study presents the on-chip dual-sensing device for rapid detection of cell-secreted MMP-9 and corresponding cell morphology changes in real-time domain. The device consists of 2 sensing platforms (both are interdigitated array microelectrodes - IDAMs) within 1 common fluidic chamber: one detects the cell morphology responses via Electric Cell-substrate Impedance Sensing (ECIS) technique, meanwhile the other records the cleavage effect between cell-secreted MMP-9 and the surface immobilized peptide via the capacitance-based sensing method. Thanks to the selectivity of designed peptide, this approach allows the rapid and specific detection of MMP-9. In comparison with gold standard ELISA assay, the detection time was significantly reduced from over 4h to within 30 min with the wide detection range from 10 pM to 10nM. Finally, this study provides the novel model for MMP-9 protease direct detection from living cell and new insights in multi-purpose detection of cancer associated enzyme and cell migration behavior.
Sensors | 2018
Ajay Kumar Yagati; Sachin Ganpat Chavan; Changyoon Baek; Min-Ho Lee; Junhong Min
Aflatoxin B1 (AFB1) is produced by the Aspergillus flavus and Aspergillus parasiticus group of fungi which is most hepatotoxic and hepatocarcinogenic and occurs as a contaminant in a variety of foods. AFB1 is mutagenic, teratogenic, and causes immunosuppression in animals and is mostly found in peanuts, corn, and food grains. Therefore, novel methodologies of sensitive and expedient strategy are often required to detect mycotoxins at the lowest level. Herein, we report an electrochemical impedance sensor that selectively detects AFB1 at the lowest level by utilizing polyaniline nanofibers (PANI) coated with gold (Au) nanoparticles composite based indium tin oxide (ITO) disk electrodes. The Au-PANI nanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) spectroscopy, and electrochemical impedance spectroscopy (EIS). The composite electrode exhibited a 14-fold decrement in |Z|1 Hz in comparison with the bare electrode. The Au-PANI acted as an effective sensing platform having high surface area, electrochemical conductivity, and biocompatibility which enabled greater loading deposits of capture antibodies. As a result, the presence of AFB1 was screened with high sensitivity and stability by monitoring the changes in impedance magnitude (|Z|) in the presence of a standard iron probe which was target specific and proportional to logarithmic AFB1 concentrations (CAFB1). The sensor exhibits a linear range 0.1 to 100 ng/mL with a detection limit (3σ) of 0.05 ng/mL and possesses good reproducibility and high selectivity against another fungal mycotoxin, Ochratoxin A (OTA). With regard to the practicability, the proposed sensor was successfully applied to spiked corn samples and proved excellent potential for AFB1 detection and development of point-of-care (POC) disease sensing applications.
Nanotechnology | 2016
Phuong-Diem Nguyen; Vu Thanh Cong; Changyoon Baek; Junhong Min
Upcoversion nanoparticles are an emerging luminescent nanomaterial with excellent photophysical properties that have great benefits in biological sensing. In this study, a luminescent turn-on biosensor for cell-secreted protease activity assay is established based on resonance energy transfer in an upconversion nanoparticle-graphene oxide nano-assembly. The proposed biosensor consists of a blue-emitting upconversion nanoparticle covered with a quenching complex, comprising gelatin as the proteinase substrate and graphene oxide nanosheets as luminescence acceptors. After enzymatic digestion, the upconversion nanoparticles lose the gelatin cover due to the disassembly of the quenching complex, thus the upconverting luminescence in the blue region is restored (a turn-on response). The recovered upconverting luminescence is proportional to the protease concentration; the limit of detection was 12 ng ml(-1). Finally, the upconversion-graphene oxide nanocomplex was successfully applied in the detection of cell-secreted protease-metalloproteinase in MCF-7 cancer cells with high sensitivity and specificity.
Journal of Nanoscience and Nanotechnology | 2018
Hyun Jin Yoo; Changyoon Baek; Donghyun Lee; Junhong Min
Nucleic acid preparation (concentration and purification of various nucleic acid targets) from biological samples is essential for personalized and precision medicine. The adsorption of short-length DNA on graphene oxide (GO) layers was investigated and compared with that on silica surfaces. GO was efficiently coated on glass beads to be used more easily and spatially. Surface of the GO bead was confirmed by field-emission scanning electron microscopy. GO-coated beads were packed and the adsorption conditions of short-length DNA were optimized under various pH and flow rate conditions. The amount of adsorbed DNA was confirmed by real-time polymerase chain reaction and visualized using fluorescence microscopy.
Journal of Nanoscience and Nanotechnology | 2018
Changyoon Baek; Hyun Jin Yoo; Won-Nyoung Lee; Minho Lee; Junhong Min
Natural organic matter (NOM) is known to cause major problems with drinking water quality management, such as sedimentation of disinfectants during the purification process, microbial growth of water pipes, and corrosion of pipes. For efficient and continuous removal of NOM from drinking water, a packed bed-type platform containing microbeads based on nanostructured zinc oxide (ZnO) was developed. ZnO was synthesized on graphene oxide (GO)-coated microbeads by optimizing the ZnO concentration and reaction time. The morphology of the synthesized ZnO-coated microbeads was confirmed by scanning electron microscopy, and an adsorption test was conducted using a cationic dye. The ZnO/GO microbeads were packed in a microtube. A humic acid contaminated aqueous solution was allowed to flow through the microbeads, and its removal rate was measured by UV-vis spectroscopy. This study confirmed that the purification platform containing ZnO removed more than 90% of humic acid of about 1,000 ppm.
Biochip Journal | 2018
Ju Hun Yeon; Sung Hee Chung; Changyoon Baek; Hyundoo Hwang; Junhong Min
Here, we present a simple pipetting-based approach for generating multi-layered core-shell hydrogel droplets composed of alginate for outer shell and collagen for culturing cells inside. By using a multi-hole plastic substrate and by pipetting, multi-layered hydrogel droplets were generated in a simple and rapid manner. HEK293 cells, which are human embryonic kidney cells, were cultured for 14 days in double-layered hydrogel droplet with high viability. Cancer cells were co-cultured with epithelial cells in multi-layered hydrogel droplets and applied for drug tests with curcumin. As epithelial cells protect cancer cells from anti-cancer drugs, co-cultured cells showed lower sensitivity to curcumin. We developed a simple and easy method for creating complex hydrogel particles for 3D multicellular co-culture and developed an alternative method for drug testing in vivo.
Biochip Journal | 2017
YeJi Kim; Won-Nyoung Lee; Hyun Jin Yoo; Changyoon Baek; Junhong Min
Recently, a variety of methods, so called “direct buffer”, have been developed to utilize nucleic acid in the blood for the measurement of infectious bacteria and virus without any equipment in the field. In here, we first investigated the individual and combinatory effects of candidate chemicals which might be composed of the direct buffer on the PCR inhibition reduction of main compositions in whole blood. The long and short PEGs, Na2SO4 and GuSCN were selected as representative kosmotropic and chaotropic salts, respectively. MgCl2 were chosen as divalent cation source and NaOH was used to control blood pH. The effect of common non-ionic biological detergent was tested with Triton X-100 and SDS (Sodium Dodecyl sulfate) was chosen as anionic detergent. These results could provide a foundation for the development of sample preparation solution in nucleic acid based diagnostic field. As a result, the direct buffer developed in this study was able to detect viruses with a concentration of 102 pfu/100 μL of whole blood by a very simple method.
Biochip Journal | 2015
Changyoon Baek; Junhong Min
Microfluidic chips are versatile tools for automatic nucleic acid extraction and are very important for nucleic acid-based detection of pathogens in aqueous samples because polymerase chain reaction can amplify nucleic acids outside of the cell. In this study, we developed a simple and effective microfluidic chip platform for selectively extracting nucleic acid from bacteria and viruses by physical adsorption and bead beating. The sample was spiked with bacteria and virus, which were pseudo-selectively adsorbed onto the microbead in the first microchamber, whereas viruses in the output solution from the first chamber were adsorbed onto the surface of microbeads in second chamber. The bacteria and viruses were efficiently lysed in each chamber by microvalve-assisted bead beating following optimization of lysis conditions. The nucleic acids of viruses were well-separated in the first chamber and those of bacteria were isolated in the second chamber.