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Kwen, Hai-Doo,Yang, Hee-Soo,Lee, In-Ho,Choi, Seong-Ho American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.7
<P>A PtRu@TiO2-hollow nanocomposite for the detection of biomolecules was synthesized by chemical reduction. First, poly(styrene-co-vinylphenylboronic acid), PSB, was prepared as a template (approximately 250 nm) by surfactant-free emulsion polymerization. Second, PSB/TiO2 core-shell spheres were prepared by sol-gel reaction. Finally, TiO2 hollow spheres (TiO2-H) were then formed after removing the PSB template by calcination at 450 degrees C under air atmosphere. To prepare the electrocatalyst, PtRu nanoparticles (NPs) were deposited onto the TiO2-H surface by chemical reduction. The prepared PtRu@TiO2-H nanocomposite was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and elemental analysis. A non-enzymatic sensor was fabricated by depositing the as-prepared PtRu@TiO2-H nanocomposite on the surface of a glassy carbon electrode (GCE), which was prepared by a hand casting method with Nafion solution as a binder. The sensor was tested as a biomolecule sensor, especially for the detection of glucose and dopamine. The cyclic voltammograms (CV) obtained during the oxidation studies revealed that the PtRu@TiO2-H nanocomposite showed better catalytic function toward the oxidation of dopamine. The sensing range of the non-enzymatic sensor for glucose was 5.0-100 mM in a phosphate buffer. The results demonstrated the potential usefulness of this bimetallic@TiO2-H bifunctional catalyst for biosensor applications.</P>
Kwen, Hai-Doo,Oh, Sang-Hyub,Choi, Seong-Ho American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.7
<P>An ECL sensor was fabricated by immobilization of a tris(2,2'-bipyridyl)ruthenium (II) complex (Ru(bpy)3(2+)) to an amine group-modified GC electrode (NH2-GC electrode). Here, the NH2-GC electrode was prepared by electrochemical reduction of a nitro group-modified GC electrode in 0.1 M KCl ethanol solution under H2 gas, which was followed by electrochemical grafting of 4-nitrophenyl diazonium salts in 0.1 M NBu4BF4 acetonitrile solution onto the GC electrode. The prepared ECL sensor was successfully confirmed via cyclic voltammetry, contact angle, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and ECL spectrometry. The contact angle for the surface of the GC electrode, NO2-GC electrode, and NH2-GC electrod was 88.4 degrees, 67.4 degrees, and 52.4 degrees, respectively. The stability of the ECL sensor was investigated under continuous cyclic potential scanning for 55 cycles and the ECL intensity remained at 55%. The prepared ECL electrode can be expected to immobilize enzymes for preparation of the ECL biosensor to detect target molecules.</P>
Kim, Sang-Kyum,Kwen, Hai-Doo,Choi, Seong-Ho Pergamon 2012 Radiation physics and chemistry Vol.81 No.5
<P><B>Abstract</B></P><P>Vinyl copolymer–clay nanocomposites were prepared by γ-irradiation-initiated radical polymerization using a mixture of styrene (St) and divinyl benzene (DVB) in the presence of reactive organic montmorillonite clay (OMMT) in methanol at room temperature. Reactive OMMT was synthesized by a cation exchange reaction of Na<SUP>+</SUP>-MMT and 1-[(4-ethylphenyl)methyl]-3-butyl-imidazolium chloride as a reactive organic modifier in an aqueous solution. The microstructures of the nanocomposites were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal stability was examined by thermo gravimetric analysis (TGA). As a result, the reactive OMMT was a good additive material for preparing vinyl copolymer–clay nanocomposites.</P> <P><B>Highlights</B></P><P>► Vinyl copolymer–clay nanocomposites were prepared by γ-irradiation. ► Different St/DVB monomer ratios used to alter the crosslinking of the polymers. ► TEM revealed well exfoliated clay sheets dispersed in the ST/DVB copolymer matrix. ► More highly crosslinked copolymers formed as increasing DVB content.</P>
Kwon, Sun-Young,Kwen, Hai-Doo,Choi, Seong-Ho Hindawi Limited 2012 Journal of sensors Vol.2012 No.-
<P>Nonenzymatic glucose sensors employing multiwalled carbon nanotubes (MWNTs) with highly dispersed Pt-M (M = Ru and Sn) nanoparticles (Pt-M@PVP-MWNTs) were fabricated by radiolytic deposition. The Pt-M nanoparticles on the MWNTs were characterized by transmittance electron microscopy, elemental analysis, and X-ray diffraction. They were found to be well dispersed and to exhibit alloy properties on the MWNT support. Electrochemical testing showed that these nonenzymatic sensors had larger currents (mA) than that of a bare glassy carbon (GC) electrode and one modified with MWNTs. The sensitivity (A mM<SUP>−1</SUP>), linear range (mM), and detection limit (mM) (S/N = 3) of the glucose sensor with the Pt-Ru catalyst in NaOH electrolyte were determined as 18.0, 1.0–2.5, 0.7, respectively. The corresponding data of the sensor with Pt-Sn catalyst were 889.0, 1.00–3.00, and 0.3, respectively. In addition, these non-enzymatic sensors can effectively avoid interference arising from the oxidation of the common interfering species ascorbic acid and uric acid in NaOH electrolyte. The experimental results show that such sensors can be applied in the detection of glucose in commercial red wine samples.</P>
방사선 그래프트법에 의해 제조된 탄소나노튜브 지지체를 기반으로 한 전기화학 미생물 바이오센서의 제작
신수란(Shin Soo Ran),권해두(Hai Doo Kwen),최성호(Seong Ho Choi) 한국고분자학회 2011 폴리머 Vol.35 No.3
4급 아민에 의한 이온성 및 3급 아민에 의한 비공유전자쌍의 이중 특성을 갖은 다중벽 탄소나노튜브 지지체를 글리시딜 메타크릴레이트의 방사선 그래프트법을 수행한 후, 아민화 반응을 수행하여 제조하였다. 제조된 이중 다중벽 탄소나노튜브 지지체와 나피온 용액을 혼합 후, 이 코팅용액을 GC 전극 표면에 코팅시킨 후, 여기에 미생물인 Alkaligenes spp.를 고정화하여 미생물 바이오센서를 제작하였다. 이 미생물 센서의 페놀에 대한 검출범위는 0.005∼7.0 mM이었다. 이 미생물 바이오센서를 이용하여 상용의 적포도주에서 페놀함량을 측정하였다. A multi-walled carbon nanotube (MWNT) support with dual properties, an ionic property via tetra-amine and unpaired electrons via tri-amine, was prepared by radiation-induced graft polymerization of glycidyl methacrylate (GMA) and the subsequent amination of its epoxy group. The electrochemical microbial biosensor (EMB) was then fabricated by immobilization of a microbe (Alkaligenes spp.) onto the dual property-modified electrode, which was prepared with the mixture of the MWNT support and a Nafion(R) solution on a glass carbon (GC) electrode surface by a hand-casting method. The sensing range of the prepared EMB for phenol in a phosphate buffer solution was 0.005∼7.0 mM. The total concentration of phenolic compounds in a commercial red wine was also determined using the EMB.
이인호,권해두,최성호,Lee, In-Ho,Kwen, Hai-Doo,Choi, Seong-Ho The Korean Society of Analytical Science 2013 분석과학 Vol.26 No.1
이 논문은 센서 및 연료전지에 사용할 수 있는 $Pt-Ru@TiO_2-H$ 나노구조체촉매의 제조 및 전기화학적 촉매의 특성에 대한 것이다. 이 $Pt-Ru@TiO_2-H$ 나노구조체촉매는 주형제인 폴리스틸렌볼(PSB)을 제조하고, 이 주형제의 표면에 졸-겔 반응을 통해 $TiO_2$를 코팅한 후, $Pt^{4+}$와 $Ru^{3+}$의 환원에 의해 제조하였다. 제조된, $Pt-Ru@TiO_2-H$ 나노구조체촉매는 전자투과현미경(TEM), X-선 회절(XRD)와 원소분석에 의해 특성평가 하였고, $Pt-Ru@TiO_2-H$의 전기화학적 촉매특성은 에탄올, 메탄올, 도파민, 아스크로브 산, 프로말린과 글루코오즈의 산화-환원 능력에 의해 평가 하였다. 이 $Pt-Ru@TiO_2-H$ 나노구조체촉매는 바이오분자에 대해 전기화학적촉매 특성을 나타내어, 연료전지 전극 또는 비효소바이오센서에 사용 될 것으로 기대된다. This paper describes the electrocatalytic activity for the oxidation of small biomolecules on the surface of Pt-Ru nanoparticles supported by $TiO_2$-hollow sphere prepared for use in sensor applications or fuel cells. The $TiO_2$-hollow sphere supports were first prepared by sol-gel reaction of titanium tetraisopropoxide with poly(styrene-co-vinylphenylboronic acid), PSB used as a template. Pt-Ru nanoparticles were then deposited by chemical reduction of the $Pt^{4+}$ and $Ru^{3+}$ ions onto $TiO_2$-hollow sphere ($Pt-Ru@TiO_2-H$). The prepared $Pt-Ru@TiO_2-H$ nanocomposites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and elemental analysis. The electrocatalytic efficiency of Pt-Ru nanoparticles was evaluated via ethanol, methanol, dopamine, ascorbic acid, formalin, and glucose oxidation. The cyclic voltammograms (CV) obtained during the oxidation studies revealed that the $Pt-Ru@TiO_2-H$ nanocomposites showed high electrocatalytic activity for the oxidation of biomolecules. As a result, the prepared Pt-Ru catalysts doped onto $TiO_2$-H sphere nanocomposites supports can be used for non-enzymatic biosensor or fuel cell anode electrode.
Sim, Kwang-Sik,Lim, Sin-Mook,Kwen, Hai-Doo,Choi, Seong-Ho Hindawi Limited 2011 Journal of nanomaterials Vol.2011 No.-
<P>This paper describes the electrocatalytic activity for CO, MeOH, and EtOH oxidation on the surface of Pt-Ru nanoparticles supported by metal oxide (Nb-<SUB>TiO2</SUB>-H) prepared for use in a fuel cell. To prepare Nb-<SUB>TiO2</SUB>-supported Pt-Ru nanoparticles, first, the Nb-<SUB>TiO2</SUB>supports were prepared by sol-gel reaction of titanium tetraisopropoxide with a small amount of the niobium ethoxide in polystyrene (PS) colloids. Second, Pt-Ru nanoparticles were then deposited by chemical reduction of the Pt<SUP>4+</SUP>and Ru<SUP>3+</SUP>ions onto Nb-<SUB>TiO2</SUB>supports (Pt-Ru@Nb-<SUB>TiO2</SUB>-CS). Nb element was used to reduce electrical resistance to facilitate electron transport during the electrochemical reactions on a fuel cell electrode. Finally, the Pt-Ru@Nb-<SUB>TiO2</SUB>-H catalysts were formed by the removal of core-polystyrene ball from Pt-Ru@<SUB>TiO2</SUB>-CS at<SUP>500∘</SUP>C. The successfully prepared Pt-Ru electrocatalysts were confirmed via TEM, XPS, and ICP analysis. The electrocatalytic efficiency of Pt-Ru nanoparticles was evaluated via CO, MeOH, and EtOH oxidation for use in a direct methanol fuel cell (DMFC). As a result, the Pt-Ru@Nb-<SUB>TiO2</SUB>-H electrodes showed high electrocatalytic activity for the electrooxidation of CO, MeOH, and EtOH.</P>