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Pohang University of Science and Technology (POSTECH)

7 ARTICLES PUBLISHED IN JoVE

Chemistry

Synthesis of Poly(N-isopropylacrylamide) Janus Microhydrogels for Anisotropic Thermo-responsiveness and Organophilic/Hydrophilic Loading Capability

Kyoung Duck Seo¹, Andrew Choi¹, Junsang Doh^1,2, 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.

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 Rho^1,3

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

Demonstration of Equal-Intensity Beam Generation by Dielectric Metasurfaces

Gwanho Yoon¹, Dasol Lee¹, Junsuk Rho^1,2,3

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.

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 Kim^3,4, Jinah Jang^1,2,5

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 Spin-Multiplexed and Direction-Multiplexed All-Dielectric Visible Metaholograms

Inki Kim¹, Dasol Lee¹, Junsuk Rho^1,2

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.

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 Yi^1,3

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.

Biochemistry

High-Speed Magnetic Tweezers for Nanomechanical Measurements on Force-Sensitive Elements

Celine Park^*1, Taehyun Yang^*1, Sang-Hyun Rah¹, Hyun Gyu Kim^2,3, Tae-Young Yoon^2,3, Min Ju Shon^1,4

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.