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Hyeonjun Hong,Seongsu Eom,Seong Jin Lee,Jaeseung Youn,Dohui Kim,Hyeon Beom Chong,Dong Sung Kim 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.2
Life-like 3D in vitro barrier models, which recapitulate complex tissue compartments bridging the outside environments with the internal tissue, have garnered great attention because they provide tools for a better understanding of in vivo tissue physiology and pathology as well as more realistic drug and toxicity tests. Recent advancements in collagen hydrogel fabrication techniques offer immense possibilities in reproducing such 3D in vitro barrier models by providing well-defined extracellular matrix (ECM) analogs with physiological biochemical and biophysical microenvironments. This review focuses on multiscale fabrication techniques of collagen hydrogels to generate various geometries to reproduce structural microenvironments of the in vivo organ containing an epithelial barrier. The engineered collagen hydrogel created by the multiscale fabrication techniques enables the construction of in vivo-like tissue compartments (epithelium, connective tissue, and blood vessel) and their surrounding ECM, leading to the development of physiologically relevant in vitro barrier models. An overview of the state-of-the-art in vitro barrier models is presented based on the collagen hydrogels, which reproduce the epithelial barrier, epithelium–connective tissue interface, and epithelium–blood vessel barrier.
( Hyeonjun Kim ),( Xiaomeng Tong ),( Sungyoung Choi ),( Jeong K. Lee ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.12
The intracytoplasmic membrane of Rhodobacter sphaeroides readily vesiculates when cells are lysed. The resulting chromatophore membrane vesicle (CMV) contains the photosynthetic machineries to synthesize ATP by ATPase. The light-dependent ATPase activity of CMV was lowered in the presence of O<sub>2</sub>, but the activity increased to the level observed under anaerobic condition when the reaction mixture was supplemented with ascorbic acid (≥0.5 mM). Cell lysis in the presence of biotinyl cap phospholipid (bcp) resulted in the incorporation of bcp into the membrane to form biotinylated CMV (bCMV), which binds to streptavidin resin at a ratio of approximately 24 μg bacteriochlorophyll a/ml resin. The ATPase activity of CMV was not affected by biotinylation, but approximately 30% of the activity was lost by immobilization to resin. Interestingly, the remaining 70% of ATPase activity stayed constant during 7-day storage at 4℃. On the contrary, the ATPase activity of bCMV without immobilization gradually decreased to approximately 40% of the initial level in the same comparison. Thus, the ATPase activity of CMV is sustainable after immobilization, and the immobilized bCMV can be used repeatedly as an ATP generator.
Kim, Whi Dong,Kim, Dahin,Yoon, Da-Eun,Lee, Hyeonjun,Lim, Jaehoon,Bae, Wan Ki,Lee, Doh C. American Chemical Society 2019 Chemistry of materials Vol.31 No.9
<P>Colloidal semiconductor nanocrystals hold great promise in display technologies, as the tunable energy levels and narrow emission bandwidth allow for wide gamut in color space. Impetus for energy-efficient, high-color-quality display has driven the surge of interest in electrically driven quantum dot-based light-emitting diodes (QD-LEDs). While extensive efforts have led to synthesis of QDs with near-unity photoluminescence quantum yield and fabrication of QD-LEDs with external quantum efficiency reaching to the theoretical limit (∼20%), low out-coupling factor poses a challenge in the way of improving the device performance when spherical QDs are used. Geometrically anisotropic nanocrystals (NCs) such as nanorods or nanoplatelets represent a unique possible solution to enhancing light extraction efficiency. In this Perspective, we highlight important design principles of individual anisotropic NCs and their assembly in the context of LED applications.</P> [FIG OMISSION]</BR>
Thickness Dependence on the Magnetism in Mo-Capped Epitaxial Fe Films
Hyeonjun Kong,Eun-Young Ahn,Gowoon Kim,Sangkyun Ryu,Sungkyun Park,Hyoungjeen Jeen,Tae-Yeol Jeon,Younghak Kim,Jin Hyung Cho 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.5
When magnetic metal films are oxidized, in many cases, their saturation magnetization values decrease. The importance of high magnetization is well-known because it is directly related to the maximum energy product. Thus, prevention of oxidation in magnetic metal films via capping is important not only for studying the magnetism in magnetic metal films but also for developing new packaging technology for such films. In this research, we successfully grow epitaxial (110) Fe lms on (0001) Al2O3 substrates by using radio-frequency (RF) magnetron sputtering. We capped 10-nm-thick Mo layers on the Fe films to prevent oxidation. By varying the thickness of the films, we systematically observed the changes in both the coercivity and the saturation magnetization. Especially, when the film's thickness was below 8.5 nm, the coercivity of the film started to decrease. We believe the drastic change in the coercivity appeared in the Fe films when the film's thickness approached the critical domain size for a magnetic domain transition.