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Han, Sewoon,Yang, Kisuk,Shin, Yoojin,Lee, Jung Seung,Kamm, Roger D,Chung, Seok,Cho, Seung-Woo Royal Society of Chemistry 2012 Lab on a chip Vol.12 No.13
<P>Here, we report a unique method to quantify the effects of in vivo-like extracellular matrix (ECM) for guiding differentiation of neural stem cells (NSCs) in three-dimensional (3D) microenvironments using quantitative real-time polymerase chain reaction (qRT-PCR). We successfully monitored and quantified differentiation of NSCs in small volume ECMs and found that differentiation of NSCs, especially those differentiating towards neuronal and oligodendrocytic lineages, is significantly enhanced by 3D microenvironments reconstituted in the microfluidic channels.</P>
A versatile assay for monitoring in vivo-like transendothelial migration of neutrophils.
Han, Sewoon,Yan, Ji-Jing,Shin, Yoojin,Jeon, Jessie J,Won, Jihee,Jeong, Hyo Eun,Kamm, Roger D,Kim, Young-Joon,Chung, Seok Royal Society of Chemistry 2012 Lab on a chip Vol.12 No.20
<P>Spatiotemporal analysis of the inflammatory response has been limited by the difficulties of in vivo imaging and reconstitution of inflammation in vitro. Here, we present a novel method for establishing in vivo-like inflammatory models in a microfluidic device and quantitatively measuring the three-dimensional transmigration of neutrophils during the inflammatory process. This enabled us to concurrently characterize transendothelial migration behaviors of neutrophils under the influence of various inflammatory stimuli.</P>
은 나노입자 박막 소결 및 나노초 레이저 어블레이션 특성
한세운(Sewoon Han),임태웅(Taewoong Lim),정재원(Jaewon Chung),김동조(Dongjo Kim),문주호(Jooho Moon) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Conventional integrated circuit fabrication processes are multi-step, involve high sintering temperature, toxic waste, and are therefore expensive. Therefore, employment of cost-effective drop on demand inkjet printing process is expected to give new opportunities in flexible electronics and other applications. However, the typical resolution of inkjet printing (=50~100㎛), which is mainly governed by the nozzle diameter, is an issue. In this work, sintering characteristics and ablation of Ag nanoparticles using frequency doubled Nd:YAG nanosecond laser were studied to apply for trimming electrical micro-conductor printed by inkjet. Ag nano particles dissolved in ethylene glycol was used and polyvinylpyrrolidone was added to prevent agglomeration. Here, nanoparticles are used to exploit the melting temperature depression compared to bulk material, so that printed metal nanoparticle film could be sintered at a reduced temperature compatible to polymer.
Han, Jonghun,Jun, Byung-Moon,Heo, Jiyong,Kim, Sewoon,Yoon, Yeomin,Park, Chang Min Elsevier 2019 Ecotoxicology and environmental safety Vol.182 No.-
<P><B>Abstract</B></P> <P>We report herein the sonochemical synthesis of a lanthanum dioxide carbonate (La<SUB>2</SUB>O<SUB>2</SUB>CO<SUB>3</SUB>) and zinc ferrite (ZnFe<SUB>2</SUB>O<SUB>4</SUB>)-loaded reduced graphene oxide (LZF-rGO) nanoheterostructure for ultrasound (US)-assisted degradation of methyl orange (MO) from water. The MO was chosen as a model organic dye due to its toxicological and biodegradable-resistant properties. The LZF-rGO catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results of characterizations confirmed successful synthesis of sonocatalyst. Among different removal systems, US/LZF-rGO displayed outstanding sonodegradation performance for degradation of MO. The maximum removal efficiency of 75.9% was achieved using 0.2 g/L sonocatalyst, 20 mg/L MO, and 0.71 W/cm<SUP>2</SUP> US power intensity for 65 min. MO can be partially adsorbed on LZF-rGO but mostly sonodegraded by reactive radical species. The reaction conditions were optimized by investigating the effect of key operating parameters, including the sonocatalyst dosage, initial MO concentration, US power intensity, presence of inorganic salts, and use of an enhancer, on the decolorization of MO. The degradation intermediates produced from MO during the sonocatalytic process were identified by UPLC<SUP>®</SUP>/MS-MS, and possible mechanism and pathway for the degradation of MO in the US/LZF-rGO system were also proposed. Reusability experiments with this sonocatalyst revealed a less than 10% drop in the degradation efficiency after four adsorption–desorption cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel LZF-rGO was synthesized via a simple precipitation-hydrothermal process. </LI> <LI> US-assisted catalytic process was used to degrade MO in the presence of LZF-rGO. </LI> <LI> Key operating parameters for MO removal were optimized in the US/LZF-rGO system. </LI> <LI> The degradation pathway of MO in the US/LZF-rGO system was proposed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Intratumoral phenotypic heterogeneity as an encourager of cancer invasion
Shin, Yoojin,Han, Sewoon,Chung, Euiheon,Chung, Seok Oxford University Press 2014 Integrative biology Vol.6 No.7
<P>We present a novel <I>in vitro</I> breast tumor model to mimic intratumoral phenotypic heterogeneity based on a microfluidic system incorporating ECM scaffolds capable of providing a physiologically relevant tumor microenvironment. To study the regulation of invasive potentials by intratumoral subpopulation conditions, we developed heterogeneous cancer cell subpopulations by co-culturing two breast cancer cell types with distinct phenotypes, specifically, highly invasive and epithelial-like cancer cells. Our results indicate that intratumoral phenotypic heterogeneity acts as an encourager of cancer cell invasion through a 3D matrix depending on the neighboring ECM, with highly invasive cancer cells acting as the ‘leader’ and epithelial-like cancer cells as the ‘follower’, therefore enhancing the metastatic potential.</P>