Preparation of Fe₃O₄/SiO₂ Core/Shell Nanoparticles with Ultrathin Silica Layer

Jang, Eue-Soon Korean Chemical Society 2012 대한화학회지 Vol.56 No.4

We successfully synthesized $Fe_3O_4/SiO_2$ nanoparticles with ultrathin silica layer of $1.0{\pm}0.5$ nm that was fine controlled by changing concentration of $Fe_3O_4$. Among various reaction conditions for silica coating, increasing concentration of $Fe_3O_4$ was more effective approach to decrease silica thickness compared to water-to-surfactant ratio control. Moreover, we found that concentration of the 1-octanol is also important factor to produce the homogeneous $Fe_3O_4/SiO_2$ nanoparticles. The present approach could be available to apply on preparation of other core/shell nanoparticles with ultrathin silica layer.

Recent Progress in Synthesis of Plate-like ZnO and its Applications: A Review

Jang, Eue-Soon The Korean Ceramic Society 2017 한국세라믹학회지 Vol.54 No.3

Zinc oxide (ZnO) is one of the most versatile semiconductors, and one-dimensional (1D) ZnO nanostructures have attracted significant interest for use in ultraviolet (UV) lasers, photochemical sensors, and photocatalysts, among other applications. It is known that 1D ZnO nanowires can be fabricated readily owing to the anisotropic growth of ZnO along the [0001] direction. However, this type of growth results in a decrease in the surface area of the (0001) plane, which plays a vital role not only in UV lasing but also in the photocatalytic process. Thus, we attempted to synthesize ZnO crystals with an increased polar surface area by controlling the crystal growth process. The purpose of this review is to propose a simple route for the synthesis of plate-like ZnO crystals with highly enhanced polar surfaces and to explore their feasibility for use in UV lasers as well as as a photocatalyst and antibacterial agent. In addition, we highlight the recent progress made in the pilot-scale synthesis of plate-like ZnO crystals for industrial applications.

Lipofectamine-2000 Assisted Magnetofection to Fibroblast Cells Using Polyethyleneimine-Fe₃O₄@SiO₂ Nanoparticles

Jang, Eue-Soon,Park, Kyeong-Soon Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.8

We successfully synthesized $Fe_3O_4@SiO_2$ nanoparticles with ultrathin silica layer of $1.0{\pm}0.5$ nm that polyethyleneimine (PEI) with low molecular weight of 2.0-4.0 kDa was covalently conjugated with the resulting $Fe_3O_4@SiO_2$ nanoparticles by silane coupling reaction. The PEI-$Fe_3O_4@SiO_2$ nanoparticles were further used as gene delivery vector for a human fibroblast cell (IMR-90) line. Gene transfection efficiency of the PEI-$Fe_3O_4@SiO_2$ complexes did not increase remarkably after magnetofection; however, the addition of Lipofectamine 2000 significantly increased the transfection efficiency of the PEI-$Fe_3O_4@SiO_2$ complexes. We believe that the present approach could be utilized for magnetofection as alternative to $Fe_3O_4$ nanoparticles conjugated with the PEI of high molecular weight thanks to its relatively low cytotoxicity and high transfection efficiency.

Effect of Alcohol Chain Length on Formation of Cetyltrimethylammonium Bromide‐templated Mesoporous Silica Layer on Gold Nanorods

Jang Eue‐Soon 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.6

This is the first study that elucidates the effect of alcohol alkyl chain length on the formation of mesoporous silica (mSiO2) layers on cetyltrimethylammonium bromide (CTAB)-stabilized gold nanorods (CGNRs). The growth tendencies of the mSiO2 layers on the CGNRs (CGNR@mSiO2) in various alcohol solvents differed quite substantially from those observed for previously reported spherical silica particles. The formation of the mSiO2 layer was closely related to the interaction between the CTAB bilayer and alcohol.

바이오 물질 분석을 위한 금속 나노입자를 이용한 SERS 분석 연구동향

장의순(Eue-Soon Jang) 한국세라믹학회 2019 세라미스트 Vol.22 No.3

Surface enhanced Raman scattering (SERS) was first discovered in 1974 by an unexpected Raman signal increase from Pyridine adsorbed on rough Ag electrode surfaces by the M. Fleishmann group. 1) M. Moskovits group suggested that this phenomenon could be caused by surface plasmon resonance (SPR), which is a collective oscillation of free electrons at the surface of metal nanostructures by an external light source. 2-14) After about 40 years, the SERS study has attracted great attention as a biomolecule analysis technology, and more than 2500 new papers and 500 review papers related to SERS topic have been published each year in recently. 15) The advantages of biomaterials analysis using SERS are as follows; ① Molecular level analysis is possible based on unique fingerprint information of biomolecule, 16-20) ② There is no photo-bleaching effect of the Raman reporters, allowing long-term monitoring of biomaterials compared to fluorescence microscopy, ③ SERS peak bandwidth is approximately 10 to 100 times narrower than fluorescence emission from organic phosphor or quantum dot, resulting in higher analysis accuracy, 21), 22) ④ Single excitation wavelength allows analysis of various biomaterials, ⑤ By utilizing near-infrared (NIR) SERSactivated nanostructures and NIR excitation lasers, auto-fluorescence noise in the visible wavelength range can be avoided from in vivo experiment and light damage in living cells can be minimized compared to visible lasers, ⑥ The weak Raman signal of the water molecule makes it easy to analyze biomaterials in aqueous solutions. For this reason, SERS is attracting attention as a next-generation non-invasive medical diagnostic device as well as substance analysis. In this review, the principles of SERS and various biomaterial analysis principles using SERS analysis will be introduced through recent research papers.

La_2/3Ca_1/3MnO₃ Nanoparticles with Novel Magnetoresistance Property

Zhang, Jianwu,Jang, Eue-Soon,Chung, Il-Won,Choy, Jin-Ho Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.2

Fine $La_{2/3}Ca_{1/3}MnO_3$ nanocrystalline powders have been successfully prepared by modified citrate pyrolysis process. The obtained LCMO nanoscale grains have a mean particle size of about 30 nm under optimal treatment conditions. The particle size can be controlled by adjusting processing parameters, such as treatment temperature and calcination time. X-ray diffraction, SEM and magnetoresistance effect were employed to study the crystal structure, morphology and magnetic property of these nanosized powders. A novel MR effect (MR > 45% (0 K < T < 340 K)) at room temperature has been found.

Evidence of Two-Dimensional Superconductivity in the Single Crystalline Nanohybrid of Organic-Bismuth Cuprate

Chung, Il-Won,Kwon, Soon-Jae,Kim, Seung-Joo,Jang, Eue Soon,Hwang, Seong-Ju,Choy, Jin-Ho American Chemical Society 2006 The journal of physical chemistry. B, Condensed ma Vol.110 No.33

<P>A coordination compound of HgI(2)(pyridine)(2) can be successfully intercalated into a single crystalline Bi(2)Sr(2)CaCu(2)O(y)() high-T(c) superconductor through an interlayer complexation reaction between pyridine molecules and bismuth cuprate pre-intercalated with mercuric iodide. X-ray diffraction and X-ray absorption spectroscopic results clearly demonstrate that the single crystalline nature of the pristine bismuth cuprate remains unchanged even after the intercalation of organic complex as well as those of iodine and mercuric iodide. According to the angle-dependent dc magnetization measurements, the intercalation of bulky organic molecules completely blocks superconductive currents along the c-axis, whereas a superconducting transition along the in-plane direction still occurs in the organic intercalate. In the case of the iodine or mercuric iodide intercalates with smaller lattice expansions, an out-of-plane diamagnetic transition is not wholly quenched but significantly depressed by the intercalation, confirming the reduction of interlayer interaction. The present finding can provide straightforward evidence of the two-dimensionality of high temperature superconductivity in the present cuprate-based nanohybrid material.</P>

La2/3Ca1/3MnO3 Nanoparticles with Novel Magnetoresistance Property

Jianwu Zhang,1 Eue-Soon Jang,Il-Won Chung,최진호 대한화학회 2004 Bulletin of the Korean Chemical Society Vol.25 No.2

Development of an Al-load-cell-based wireless ringer’s solution monitoring and alarm system: insight into vibrational error correction

Hyun Seok Moon,Eue-Soon Jang 대한의용생체공학회 2019 Biomedical Engineering Letters (BMEL) Vol.9 No.2

In this study, we developed an aluminum-load-cell-based wireless Ringer’s solution monitoring and alarm (WRMA) system. The Al load cell was designed with a rectangular shape, and the load was concentrated in the lower beam part of the loadcell because of the anisotropic thickness. From the static analysis, we identifi ed the appropriate location for a Wheatstonebridge circuit consisting of four strain gauges. In addition, the modal and harmonic analyses showed that the vibrational frequenciesof the hospital environment do not seriously interfere with the output voltage of the Al load cell. However, randomvibrations generated by the movement of the WRMA system on various surfaces severely increase the standard deviation ofthe measured solution weight by ± 10 g or more. Such vibrational error is too large because the average weight of Ringer’ssolution is 30–40 g at the time of replacing Ringer’s solution. Thus, this error could be confusing for nurses and result inmistakes in the timely replacement of the Ringer’s solution. However, the standard deviation of the measured weight wasdramatically reduced to ± 3 g or less by using the vibration correction algorithm developed in the present study.

Graphene, charcoal, ZnO, and ZnS/BiOX (X=Cl, Br, and I) hybrid microspheres for photocatalytic simulated real mixed dye treatments

Yoon, Hee Jung,Choi, Young In,Jang, Eue-Soon,Sohn, Youngku Elsevier 2015 Journal of industrial and engineering chemistry Vol.32 No.-

<P><B>Abstract</B></P> <P>Graphene, charcoal, ZnO, and ZnS/BiOX (X=Cl, Br, and I) hybrid microspheres were synthesized for use in the photocatalytic treatment of a mixed dye of MO (methyl orange), RhB (rhodamine B), and MB (methylene blue) solution. The dye degradation rate was generally observed in the order of RhB<MB<MO. The order became MB<RhB<MO for ZnO/BiOI and ZnS/BiOI. The catalysts hybridized with BiOI generally showed superior adsorption capacity to those of the materials hybridized with BiOCl or BiOBr. The 10 mol% ZnO/BiOI and ZnS/BiOI showed selectivity for MB adsorption in the mixed dye.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Graphene/BiOX, charcoal/BiOX, ZnO/BiOX, and ZnS/BiOX hybrid microspheres were synthesized by a solvothermal method. </LI> <LI> Physicochemical properties of the hybrid materials were fully examined. </LI> <LI> Adsorption and photocatalytic dye degradation were fully tested for mixed dye (MO+RhB+MB) under visible light. </LI> <LI> Adsorption and photocatalytic properties in a complicated dye system were discussed. </LI> </UL> </P>