Pohang University of Science and Technology (POSTECH) View Institution's Website 11 articles published in JoVE Biochemistry High-Speed Magnetic Tweezers for Nanomechanical Measurements on Force-Sensitive Elements Celine Park*1, Taehyun Yang*1, Sang-Hyun Rah1, Hyun Gyu Kim2,3, Tae-Young Yoon2,3, Min Ju Shon1,4 1Department of Physics, Pohang University of Science and Technology (POSTECH), 2School of Biological Sciences, Seoul National University, 3Institute for Molecular Biology and Genetics, Seoul National University, 4School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology (POSTECH) Here, we describe a high-speed magnetic tweezer setup that performs nanomechanical measurements on force-sensitive biomolecules at the maximum rate of 1.2 kHz. We introduce its application to DNA hairpins and SNARE complexes as model systems, but it will be also applicable to other molecules involved in mechanobiological events. Bioengineering 3D Cell-Printed Hypoxic Cancer-on-a-Chip for Recapitulating Pathologic Progression of Solid Cancer Wonbin Park*1, Mihyeon Bae*1, Minseon Hwang1, Jinah Jang2, Dong-Woo Cho1, Hee-Gyeong Yi1,3 1Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 2Department of Creative IT Engineering, Pohang University of Science and Technology (POSTECH), 3Department of Rural and Biosystems Engineering, College of Agriculture and Life Sciences, Chonnam National University Hypoxia is a hallmark of tumor microenvironment and plays a crucial role in cancer progression. This article describes the fabrication process of a hypoxic cancer-on-a-chip based on 3D cell-printing technology to recapitulate a hypoxia-related pathology of cancer. Engineering Demonstration of Spin-Multiplexed and Direction-Multiplexed All-Dielectric Visible Metaholograms Inki Kim1, Dasol Lee1, Junsuk Rho1,2 1Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 2Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH) We present a protocol for fabrication of spin- and direction-multiplexed visible metaholograms, then conduct an optical experiment to verify their function. These metaholograms can easily visualize encoded information, so they can be used for projective volumetric display and information encryption. Cancer Research Culture, Manipulation, and Orthotopic Transplantation of Mouse Bladder Tumor Organoids Yubin Kim*1, Juhee Lee*1, SungEun Kim*1, Kunyoo Shin1 1Department of Life Sciences, Pohang University of Science and Technology This protocol provides detailed experimental steps to establish a three-dimensional in vitro culture of bladder tumor organoids derived from carcinogen-induced murine bladder cancer. Culture methods including passaging, genetic engineering, and orthotopic transplantation of tumor organoids are described. Bioengineering Pancreatic Tissue-Derived Extracellular Matrix Bioink for Printing 3D Cell-Laden Pancreatic Tissue Constructs Jaewook Kim*1, Myungji Kim*2, Dong Gyu Hwang2, In Kyong Shim3, Song Cheol Kim3,4, Jinah Jang1,2,5 1Department of Mechanical Engineering, Pohang University of Science and Technology, 2School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 3Asan Institute for Life Science, University of Ulsan College of Medicine and Asan Medical Center, 4Division of Hepato-Biliary and Pancreatic Surgery, Department of Surgery, University of Ulsan College of Medicine and Asan Medical Center, 5Department of Creative IT Engineering, Pohang University of Science and Technology Decellularized extracellular matrix (dECM) can provide suitable microenvironmental cues to recapitulate the inherent functions of target tissues in an engineered construct. This article elucidates the protocols for the decellularization of pancreatic tissue, evaluation of pancreatic tissue-derived dECM bioink, and generation of 3D pancreatic tissue constructs using a bioprinting technique. Engineering Demonstration of Equal-Intensity Beam Generation by Dielectric Metasurfaces Gwanho Yoon1, Dasol Lee1, Junsuk Rho1,2,3 1Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 2Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), 3National Institute of Nanomaterials Technology (NINT) A protocol for the fabrication and optical characterization of dielectric metasurfaces is presented. This method can be applied to the fabrication of not only beam splitters, but also of general dielectric metasurfaces, such as lenses, holograms, and optical cloaks. Biochemistry Studying Protein Import into Chloroplasts Using Protoplasts Junho Lee1, Hyangju Kang1, Inhwan Hwang1,2 1Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, 2Department of Life Sciences, Pohang University of Science and Technology Here we describe a protocol to express proteins into protoplasts by using PEG-mediated transformation method. The method provides easy expression of proteins of interest, and efficient investigation of protein localization and the import process for various experimental conditions in vivo. Engineering Demonstration of a Hyperlens-integrated Microscope and Super-resolution Imaging Dasol Lee*1, Minkyung Kim*1, Sunae So*1, Inki Kim1, Gwanho Yoon1, Kyunghoon Kim2, Junsuk Rho1,3 1Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 2School of Mechanical Engineering, Sungkyunkwan University, 3Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH) The use of a hyperlens has been regarded as a novel super-resolution imaging technique due to its advantages in real-time imaging and its simple implementation with conventional optics. Here, we present a protocol describing the fabrication and imaging applications of a spherical hyperlens. Engineering Measurement of Outgassing Rates of Steels Chongdo Park1, Se-Hyun Kim1, Sanghoon Ki1, Taekyun Ha1, Boklae Cho2 1Accelerator Division, Pohang Accelerator Laboratory, POSTECH, 2Center for Advanced Instrumentation, Korea Research Institute of Standards and Science A protocol for the measurement of outgassing rates of hydrogen from ordinary steel vacuum chambers using the rate-of-pressure rise method is presented. Chemistry Synthesis of Poly(N-isopropylacrylamide) Janus Microhydrogels for Anisotropic Thermo-responsiveness and Organophilic/Hydrophilic Loading Capability Kyoung Duck Seo1, Andrew Choi1, Junsang Doh1,2, Dong Sung Kim1 1Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 2School of Interdisciplinary Bioscience and Bioengineering (I-Bio), Pohang University of Science and Technology (POSTECH) We present a protocol to synthesize Janus microhydrogels composed entirely of the same base material, poly(N-isopropylacrylamide) (PNIPAAm), with a clearly compartmentalized structure base on the phase separation of a supersaturated NIPAAm monomer solution. The synthesized Janus microhydrogels show unique properties such as anisotropic thermo-responsiveness and organophilic/hydrophilic loading capability. Bioengineering Photoacoustic Cystography Mansik Jeon1,2, Jeehyun Kim3, Chulhong Kim1,2 1Department of Biomedical Engineering, University at Buffalo, The State University of New York, 2Department of Creative IT Engineering, Pohang University of Science and Technology (POSTECH), 3School of Electrical Engineering and Computer Science, Kyungpook National University Photoacoustic cystography (PAC) has a great potential to map urinary bladders, a radiation sensitive internal organ in pediatric patients, without using any ionizing radiation or toxic contrast agent. Here we demonstrate the use of PAC for mapping urinary bladders with an injection of optical-opaque tracers in rats in vivo.
