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Choi, Jonghoon,Park, Hoyoung,Kim, Taeho,Jeong, Yoon,Oh, Myoung Hwan,Hyeon, Taeghwan,Gilad, Assaf A,Lee, Kwan Hyi Dove Medical Press 2014 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.9 No.-
<P>We present here the in vitro release profiles of either fluorescently labeled biomolecules or computed tomography contrast nanoagents from engineered collagen hydrogels under physiological conditions. The collagen constructs were designed as potential biocompatible inserts into wounded human gingiva. The collagen hydrogels were fabricated under a variety of conditions in order to optimize the release profile of biomolecules and nanoparticles for the desired duration and amount. The collagen constructs containing biomolecules/nanoconstructs were incubated under physiological conditions (ie, 37°C and 5% CO<SUB>2</SUB>) for 24 hours, and the release profile was tuned from 20% to 70% of initially loaded materials by varying the gelation conditions of the collagen constructs. The amounts of released biomolecules and nanoparticles were quantified respectively by measuring the intensity of fluorescence and X-ray scattering. The collagen hydrogel we fabricated may serve as an efficient platform for the controlled release of biomolecules and imaging agents in human gingiva to facilitate the regeneration of oral tissues.</P>
Choi, Jonghoon,Park, Sungwook,Stojanović,, Zoran,Han, Hyung-Seop,Lee, Jongwook,Seok, Hyun Kwang,Uskoković,, Dragan,Lee, Kwan Hyi American Chemical Society 2013 Langmuir Vol.29 No.50
<P>Herein, we report a quick and simple synthesis of water-soluble gold nanoparticles using a HAuCl<SUB>4</SUB> and oleylamine mixture. Oleylamine serves as a reduction agent as well as a stabilizer for nanoparticle surfaces. The particle sizes can be adjusted by modulating reaction temperature and time. Solvothermal reduction of HAuCl<SUB>4</SUB> with oleylamine can be confirmed by measuring the product in Fourier transform infrared (FTIR) spectroscopy. The plasmon band shifting from yellow to red confirms a nanosized particle formation. Amide bonds on the surface of the nanoparticles formed hydrogen bonds with one another, resulting in a hydrophobic monolayer. Particles dispersed well in nonpolar organic solvents, such as in hexane or toluene, by brief sonication. Next, we demonstrated the transfer of gold nanoparticles into water by lipid capsulation using 1-myristoyl-2-hydroxy-<I>sn</I>-glycero-3-phosphocholine (MHPC), 1,2-distearoyl-<I>sn</I>-glycero-3-phosphoethanolamine-<I>N</I>-(methoxy polyethylene glycol)-2000 (DPPE-PEG2k), and 1,2-dioleoyl-<I>sn</I>-glycero-3-<I>N</I>-{5-amino-1-carboxypentyl}iminodiacetic acid succinyl nickel salt [DGS-NTA(Ni)]. The particle concentration can be obtained using an absorbance in ultraviolet–visible (UV–vis) spectra (at 420 nm). Instrumental analyses using transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) analysis, dynamic light scattering (DLS), and FTIR confirmed successful production of gold nanoparticles and fair solubility in water. Prepared gold particles were selectively clustered via engineered ferritin nanocages that provide multiple conjugation moieties. A total of 5–6 gold nanoparticles were clustered on a single ferritin nanocage confirmed in TEM. Reported solvothermal synthesis and preparation of gold nanoclusters may serve as an efficient, alternate way of preparing water-soluble gold nanoparticles, which can be used in a wide variety of biomedical applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2013/langd5.2013.29.issue-50/la403888f/production/images/medium/la-2013-03888f_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la403888f'>ACS Electronic Supporting Info</A></P>
Choi, Jonghoon,Oh, Hana,Han, Sang-Wook,Ahn, Seokhoon,Noh, Jaegeun,Park, Joon B. ELSEVIER 2017 Current Applied Physics Vol.17 No.2
<P>A highly efficient synthetic route was successfully developed to prepare crystallized and well dispersed Cu, Cu2O, and CuO nanoparticles (NPs) on reduced graphene oxide (rGO) by controlling the impregnation condition of a copper-precursor (Cu(NO3)(2)center dot 3H(2)O) on graphene oxide (GO) and subsequent thermal treatments. The morphological and chemical structures of the nanocomposites were systemically evaluated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS), and transmission electron microscopy (TEM). The rGO based CuOx nanocomposites exhibited a much higher catalytic activity than bare CuOx NPs toward the decomposition reaction of dye molecules under visible light illumination. Among the CuOx/rGO nanocomposites, CuO/rGO showed excellent photocatalytic efficiency and recyclability without significant loss of activity. Based on the XPS, XRD, XAFS, and TEM results, the high photocatalytic efficiency of the CuO/rGO can be attributed to the synergistic combination of dye adsorptivity and electron acceptability of the rGO, the surface hydroxyl species in the CuO/rGO, and the narrow band gap and smaller size of the CuO NPs. This work could be applied to the removal and water treatment of waste dye. (C) 2016 Elsevier B.V. All rights reserved.</P>
Electrochemical Synthesis of Red Fluorescent Silicon Nanoparticles
Choi, Jonghoon,Kim, Kyobum,Han, Hyung-Seop,Hwang, Mintai P.,Lee, Kwan Hyi Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.1
Herein, we report on the preparation of red fluorescent Si nanoparticles stabilized with styrene. Nano-sized Si particles emit fluorescence under UV excitation, which could be used to open up new applications in the fields of optics and semi-conductor research. Unfortunately, conventional methods for the preparation of red fluorescent Si nanoparticles suffer from the lack of a fully-established standard synthesis protocol. A common initial approach during the preparation of semi-conductors is the etching of crystalline Si wafers in a HF/ethanol/$H_2O$ bath, which provides a uniformly-etched surface of nanopores amenable for further nano-sized modifications via tuning of various parameters. Subsequent sonication of the etched surface crumbles the pores on the wafer, resulting in the dispersion of particles into the solution. In this study, we use styrene to occupy these platforms to stabilize the surface. We determine that the liberated silicon particles in ethanol solution interact with styrene, resulting in the substitution of Si-H bonds with those of Si-C as determined via UV photo-catalysis. The synthesized styrene-coated Si nanoparticles exhibit a stable, bright, red fluorescence under excitation with a 365 nm UV light, and yield approximately 100 mg per wafer with a synthesis time of 2 h. We believe this protocol could be further expanded as a cost-effective and high-throughput standard method in the preparation of red fluorescent Si nanoparticles.
Choi, Jonghoon,Hwang, Mintai P,Lee, Jong-Wook,Lee, Kwan Hyi Dove Medical Press 2014 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.9 No.1
<P>Mesenchymal stem cells (MSCs) have been thought to hold potential as a mode of therapy for immuno-related pathologies, particularly for autoimmune diseases. Despite their potential, the interaction between MSCs and T cells, key players in the pathophysiology of autoimmune diseases, is not yet well understood, thereby preventing further clinical progress. A major obstacle is the highly heterogeneous nature of MSCs in vitro. Unfortunately, bulk assays do not provide information with regard to cell–cell contributions that may play a critical role in the overall cellular response. To address these issues, we investigated the interaction between smaller subsets of MSCs and CD4 T cells in a microwell array. We demonstrate that MSCs appear capable of modulating the T cell proliferation rate in response to persistent cell–cell interactions, and we anticipate the use of our microwell array in the classification of subpopulations within MSCs, ultimately leading to specific therapeutic interventions.</P>
Microdevices for examining immunological responses of single cells to HIV
Choi, Jonghoon,Jeong, Yoon,Han, Hyung-Seop,Lee, Kwan ,Hyi Portland Press Ltd. 2014 Bioscience reports Vol.34 No.4
<P>More than 60 million people in the world have been diagnosed with HIV infections since the virus was recognized as the causative agent of AIDS in the 1980s. Even though more than half of the infected patients have died, effective disease treatment and prevention measures have not been established. ART (antiretroviral therapy) is the only proven HIV treatment that sustains the suppression of patient viraemia. Current routine approaches to treat HIV infections are targeted at developing vaccines that will induce humoral or cell memory immune responses. However, developing an effective vaccine has been challenging because the HIV mutates rapidly, which allows the virus to evade immune surveillances established against the previous strain. In addition, the virus is able to quickly establish a reservoir and treatment is difficult because of the general lack of knowledge about HIV immune response mechanisms. This review introduces common disease symptoms and the progression of HIV infection with a brief summary of the current treatment approaches. Different cellular immune responses against HIV are also discussed, with emphasis on a nanotechnology research that has focused on probing T-cell response to HIV infection. Furthermore, we discuss recent noteworthy nanotechnology updates on T-cell response screening that is focused on HIV infection. Finally, we review potential future treatment strategies based on the correlations between T-cell response and HIV infection.</P>