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Printed cylindrical lens pair for application to the seam concealment in tiled displays
Lee, Seunghwan,Lee, Seungjae,Yoon, Hyungsoo,Lee, Chang-Kun,Yoo, Chanhyung,Park, Jongjang,Byun, Junghwan,Kim, Geonhee,Lee, Byeongmoon,Lee, Byoungho,Hong, Yongtaek The Optical Society 2018 Optics express Vol.26 No.2
Lee, Seon Sook,Choi, Go Eun,Lee, Hyun Jung,Kim, Yelin,Choy, Jin-Ho,Jeong, Byeongmoon American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.49
<P>Stem cell therapy for damaged cartilage suffers from low rates of retention, survival, and differentiation into chondrocytes at the target site. To solve these problems, here we propose a two-dimensional/three-dimensional (2D/3D) nanocomposite system. As a new two-dimensional (2D) material, hexagonal layered double hydroxides (LDHs) with a uniform lateral length of 23 pcm were prepared by a hydrothermal process. Then, tonsil-derived mesenchymal stem cells (TMSCs), arginylglycylaspartic acid-coated LDHs, and kartogenin (KGN) were incorporated into the gel through the thermal-energy driven gelation of the system. The cells exhibited a tendency to aggregate in the nanocomposite system. In particular, chondrogenic biomarkers of type II collagen and transcription factor SOX 9 significantly increased at both the mRNA and protein levels in the nanocomposite system, compared to the pure thermogel systems. The inorganic 2D materials increased the rigidity of the matrix, slowed down the release of a soluble factor (KGN), and improved cell material interactions in the gel. The current 2D/3D nanocomposite system of bioactive LDH/thermogel can be a new platform material overcoming drawbacks of hydrogel-based 3D cell culture systems and is eventually expected to be applied as an injectable stem cell therapy.</P>
F-number matching method in light field microscopy using an elastic micro lens array
Kim, Jonghyun,Jeong, Youngmo,Kim, Hyungjin,Lee, Chang-Kun,Lee, Byeongmoon,Hong, Jisoo,Kim, Youngmin,Hong, Yongtaek,Lee, Sin-Doo,Lee, Byoungho OPTICAL SOCIETY OF AMERICA 2016 Optics letters Vol.41 No.12
<P>In light field microscopy (LFM), the F-number of the micro lens array (MLA) should be matched with the image-side F-number of the objective lens to utilize full resolution of an image sensor. We propose a new F-number matching method that can be applied to multiple objective lenses by using an elastic MLA. We fabricate an elastic MLA with polydimethylsiloxane (PDMS) using a micro contact printing method and address the strain for the F-number variation. The strain response is analyzed, and the LFM system with the elastic MLA is demonstrated. Our proposed system can increase the F-number up to 27.3% and can be applied to multiple objective lenses. (C) 2016 Optical Society of America</P>
Temperature-Sensitive Biodegradable Poly(ethylene glycol)
Lee, Jisun,Joo, Min Kyung,Kim, Jinheung,Park, Jong Sang,Yoon, Moon-Young,Jeong, Byeongmoon Informa UK (TaylorFrancis) 2009 Journal of Biomaterials Science. Polymer Edition Vol. No.
<P>We report here that the incorporation of several disulfide bonds along poly(ethylene glycol) (PEG) gives temperature sensitivity, as well as biodegradability to PEG. To synthesize a PEG with temperature sensitivity in a physiologically important range (20-40 degrees C), PEGs with molecular masses of 400 and 600 Da were randomly coupled by disulfide bonds. As the mol ratio of PEG (400 Da) disulfide to PEG (600 Da) disulfide increased from 40:60 to 60:40, the cloud point of the polymer aqueous solution decreased from 35 degrees C to 27 degrees C. The disulfide bonds between PEGs were degraded in the presence of a thiol-containing biomolecule of glutathione in a thiol-concentration-dependent manner.</P>
Injectable thermogel for 3D culture of stem cells
Patel, Madhumita,Lee, Hyun Jung,Park, Sohee,Kim, Yelin,Jeong, Byeongmoon Elsevier 2018 Biomaterials Vol.159 No.-
<P><B>Abstract</B></P> <P>Thermogel is an aqueous polymer solution that undergoes sol-to-gel transition as the temperature increases. Cells, growth factors, and signaling molecules can be incorporated simultaneously during the sol-to-gel transition. The cytocompatible procedure makes the thermogel an excellent platform for 3D culture of stem cells. This review focuses on the crucial questions that need to be addressed to achieve effective differentiation of stem cells into target cells, comprising low modulus, cell adhesion, and controlled supply of the growth factors. Recent progress in the use of thermogel as a 3D culture system of stem cells is summarized, and our perspectives on designing a new thermogel for 3D culture and its eventual application to injectable tissue engineering of stem cells are presented.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Iron Ion-Releasing Polypeptide Thermogel for Neuronal Differentiation of Mesenchymal Stem Cells
Patel, Madhumita,Lee, Hyun Jung,Son, Seungyi,Kim, Heeju,Kim, Jinheung,Jeong, Byeongmoon American Chemical Society 2020 Biomacromolecules Vol.21 No.1
<P>A poly(ethylene glycol)-based thermogel can capture an iron ion (Fe<SUP>3+</SUP>) through a crown ether-like coordination bond between the oxygen atom and metal ions, thus, providing a sustained Fe<SUP>3+</SUP>-releasing system. Poly(ethylene glycol)-<SMALL>L</SMALL>-poly(alanine) thermogel was used in this study. The polypeptide forms a rather robust gel, and the degradation products are a neutral amino acid, which provides cyto-compatible neutral pH environments during the cell culture. During the heat-induced sol-to-gel transition at 37 °C, tonsil-derived mesenchymal stem cells (TMSCs) and iron ions were incorporated, leading to the formation of a three-dimensional matrix toward neuronal differentiation of the incorporated TMSCs. The initial concentration of the iron ions was varied between 0, 15, 30, and 60 mM. About 10% of the loaded iron ions was released over 21 days, which continuously supplied iron ions to the cells. The incorporation of iron ions not only increased the gel modulus at 37 °C from 107 to 680 Pa, but also promoted cell aggregation with a significant secretion of the cell adhesion signal of FAK. Expression of biomarkers related to the neuronal differentiation of TMSCs, including NFM, MAP2, GFAP, NURR1, NSE, and TUBB3, increased 4-35-fold at the mRNA level in the Fe<SUP>3+</SUP>-containing system compared to that of the system without Fe<SUP>3+</SUP>. Immunofluorescence studies also confirmed pronounced cell aggregation and a significant increase in neuronal biomarkers at the protein level. This study suggests that an iron ion-releasing thermogelling system can be a promising injectable scaffold toward neuronal differentiation of stem cells.</P> [FIG OMISSION]</BR>
Surface-Imprinted, Thermosensitive, Core-Shell Nanosphere for Molecular Recognition
Ko, Du Young,Lee, Hwa Jeong,Jeong, Byeongmoon WILEY-VCH Verlag 2006 Macromolecular rapid communications Vol.27 No.16
<P>Summary: The D-glucose imprinted core-shell nanosphere with an average size of ≈60 to 80 nm showed a significant preference for the binding of D-glucose than the non-imprinted core-shell nanosphere. Depending on temperature, the binding site in the shell with N-isopropylacrylamide oligomer underwent a significant change in binding affinity. In addition, the D-glucose imprinted core-shell nanosphere showed a two times higher affinity for D-glucose than L-glucose, suggesting chiral recognition of the binding site. The core-shell nanosphere reported here is a good biomimetic model system with a well-defined morphology, high surface area, and variable binding affinity through a change in temperature.</P><P> <img src='wiley_img/10221336-2006-27-16-MARC200600259-gra001.gif' alt='wiley_img/10221336-2006-27-16-MARC200600259-gra001'> Graphic D-glucose imprinted core-shell nanospheres showed excellent binding over the non-imprinted core-shell nanosphere. </P>
Fast Degradable Polycaprolactone for Drug Delivery
Chang, Seo Hee,Lee, Hyun Jung,Park, Sohee,Kim, Yelin,Jeong, Byeongmoon American Chemical Society 2018 Biomacromolecules Vol.19 No.6
<P>Polycaprolactone (PCL) was reported a long time ago; however, its biomedical applications has not been extensively investigated in comparison with poly(lactide-<I>co</I>-glycolide) (PLGA) due to its too slow degradation profile. Here, we are reporting an oxalate-connected oligocaprolactone multiblock copolymer (PCL-OX) as a fast degradable PCL while maintaining its crystalline properties and low melting point of PCL. The in vivo application of the paclitaxel-loaded PCL-OX microspheres provided a steady plasma drug concentration of 6-9 μg/mL over 28 days, similar to that of the PLGA microspheres. Both PCL and PLGA microspheres were completely cleared two months after in vivo implantation. The PCL-OX microspheres showed a similar tissue compatibility to that of PLGA microspheres in the subcutaneous layer of rats. These findings suggest that PCL-OX is a useful biomaterial that solves the slow degradation problems of PCL and, thus, may find uses in other biomedical applications as an alternative to PLGA.</P> [FIG OMISSION]</BR>