3,6-Carbazole Incorporatedinto Poly[9,9-dioctylfluorene-<i>alt</i>-(bisthienyl)benzothiadiazole]sImproving the Power ConversionEfficiency

Fu, Yuanhe,Cha, Hyojung,Lee, Gang-Young,Moon, Byung Joon,Park, Chan Eon,Park, Taiho American ChemicalSociety 2012 Macromolecules Vol.45 No.7

<P>A novel concept of D-A-type copolymers based on fluorene polymer incorporated with 3,6-carbazole unit enhances the device performance for organic photovoltaic cells. P(F45C5-DTBT), incorporating 5 mol % 3,6-carbazole into P(2,7F-DTBT), shows an almost 2-fold improvement (5.1%) in power conversion efficiency relative to P(2,7F-DTBT) (2.6%). This results is ascribed to the good balance between electron and hole mobilities in the devices (mu(e)/mu(h) similar to 1.8 for P(F45C5-DTBT) vs 152 for P(2,7F-DTBT)), and the formation of a nanoscale morphology in the blend of the copolymer and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM).</P>

Dynamic Behavior of WaterDroplets on Solid Surfaceswith Pillar-Type Nanostructures

Jeong, Woog-Jin,Ha, Man Yeong,Yoon, Hyun Sik,Ambrosia, Matthew American ChemicalSociety 2012 Langmuir Vol.28 No.12

<P>In the present study, we investigated the static and dynamic behavior of water droplets on solid surfaces featuring pillar-type nano-structures by using molecular dynamics simulations. We carried out the computation in two stages. As a result of the first computational stage, an initial water cube reached an equilibrium state at which the water droplet showed different shapes depending on the height and the lateral and gap dimensions of the pillars. In the second computational stage, we applied a constant body force to the static water droplet obtained from the first computational stage and evaluated the dynamic behavior of the water droplet as it slid along the pillar-type surface. The dynamic behavior of the water droplet, which could be classified into three different groups, depended on the static state of the water droplet, the pillar characteristics (e.g., height and the lateral and gap dimensions of the pillars), and the magnitude of the applied body force. We obtained the advancing and receding contact angles and the corresponding contact angle hysteresis of the water droplets, which helped classify the water droplets into the three different groups.</P>

Reverse Shape Selectivityin the Liquid-PhaseAdsorption of Xylene Isomers in Zirconium Terephthalate MOF UiO-66

Moreira, MarianaA.,Santos, Joã,o C.,Ferreira, Alexandre F. P.,Loureiro, José,M.,Ragon, Florence,Horcajada, Patricia,Shim, Kyu-E.,Hwang, Young-K.,Lee, U.-Hwang,Chang, Jong-S.,Serre, Christi American ChemicalSociety 2012 Langmuir Vol.28 No.13

<P>Powder, agglomerates, and tablets of the microporous zirconium(IV)terephthalate metal–organic framework UiO-66 were evaluatedfor the selective adsorption and separation of xylene isomers in theliquid phase using <I>n</I>-heptane as the eluent. Pulseexperiments, performed at 313 K in the presence of <I>n</I>-heptane, revealed the <I>o</I>-xylene preference of thismaterial, which was further confirmed by binary and multicomponentbreakthrough experiments in the presence of <I>m</I>- and <I>p</I>-xylene, resulting in selectivities at 313 K of 1.8 and2.4 with regards to <I>m</I>-xylene and <I>p</I>-xylene, respectively. Additionally, because <I>p</I>-xyleneis the less retained isomer, UiO-66 presents a selectivity patternthat is reverse of that of the xylenes' molecular dimension with respectto shape selectivity. The shaping of the material as tablets did notsignificantly change its selectivity toward the <I>o</I>-xylene isomer or toward <I>p</I>-xylene, which was theless retained isomer, despite a loss in capacity. Finally, the selectivitybehavior of UiO-66 in the liquid <I>n</I>-heptane phasemakes it a suitable material for <I>o</I>-xylene separationin the extract (heavy product) or <I>p</I>-xylene separationin the raffinate (light product) by simulated moving bed technology.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2012/langd5.2012.28.issue-13/la3004118/production/images/medium/la-2012-004118_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la3004118'>ACS Electronic Supporting Info</A></P>

Colorimetric and FluorescentSignaling of Au³⁺ by Desulfurization of Thiocoumarin

Park, Ji Eun,Choi, Myung Gil,Chang, Suk-Kyu American ChemicalSociety 2012 Inorganic chemistry Vol.51 No.5

<P>We investigated the chemosignaling of Au<SUP>3+</SUP> by the selectivedesulfurization of thiocoumarin. In the presence of a heavy metalion chelator <I>N</I>,<I>N</I>,<I>N</I>′,<I>N</I>′-tetrakis-(2-pyridylmethyl)ethylenediamine,thiocoumarin was selectively converted to its oxo analogue by reactionwith Au<SUP>3+</SUP>, resulting in a pronounced chromogenic and fluorescentsignaling. Selective signaling of Au<SUP>3+</SUP> was possible inthe presence of common alkali, alkaline earth, and transition metalions, as well as Au<SUP>+</SUP> in a mixed aqueous environment. Thecolorimetric determination of Au<SUP>3+</SUP> was possible by thecolor change from pink to yellowish green of the designed probe. Thedetection limit for the determination of Au<SUP>3+</SUP> in 50% aqueousacetonitrile was 1.1 × 10<SUP>–7</SUP> M.</P><P>The selectivechemosignaling of Au<SUP>3+</SUP> by the desulfurizationof thiocoumarin in the presence of a heavy metal ion chelator TPENwas investigated. Pronounced chromogenic and fluorescent signalingof Au<SUP>3+</SUP> was possible in the presence of common metal ionsas well as Au<SUP>+</SUP> in 50% aqueous acetonitrile. The colorimetricdetermination of Au<SUP>3+</SUP> was possible by the prominent colorchange from pink to yellowish green of the designed probe.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/inocaj/2012/inocaj.2012.51.issue-5/ic202080v/production/images/medium/ic-2011-02080v_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ic202080v'>ACS Electronic Supporting Info</A></P>

Structural Basis for DifferentialInsertion Kineticsof dNMPs Opposite a Difluorotoluene Nucleotide Residue

Xia, Shuangluo,Eom, Soo Hyun,Konigsberg, William H.,Wang, Jimin American ChemicalSociety 2012 Biochemistry Vol.51 No.7

<P>We have recently challenged the widely held view that2,4-difluorotoluene(dF) is a nonpolar isosteric analogue of the nucleotide dT, incapableof forming hydrogen bonds (HBs). To gain a further understanding forthe kinetic preference that favors dAMP insertion opposite a templatingdF, a result that mirrors the base selectivity that favors dAMP insertionopposite dT by RB69 DNA polymerase (RB69pol), we determined presteady-statekinetic parameters for incorporation of four dNMPs opposite dF byRB69pol and solved the structures of corresponding ternary complexes.We observed that both the F2 and F4 substituent of dF in these structuresserve as HB acceptors forming HBs either directly with dTTP and dGTPor indirectly with dATP and dCTP via ordered water molecules. We havedefined the shape and chemical features of each dF/dNTP pair in theRB69pol active site without the corresponding phosphodiester-linkageconstraints of dF/dNs when they are embedded in isolated DNA duplexes.These features can explain the kinetic preferences exhibited by thetemplating dF when the nucleotide incorporation is catalyzed by wildtype RB69pol or its mutants. We further show that the shapes of thedNTP/dF nascent base pair differ markedly from the corresponding dNTP/dTin the pol active site and that these differences have a profoundeffect on their incorporation efficiencies.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bichaw/2012/bichaw.2012.51.issue-7/bi2016487/production/images/medium/bi-2011-016487_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/bi2016487'>ACS Electronic Supporting Info</A></P>

Enhanced Charge Transportin Enzyme-Wired Organometallic Block Copolymers for Bioenergy andBiosensors

Lee, Joungphil,Ahn, Hyungmin,Choi, Ilyoung,Boese, Markus,Park, Moon Jeong American ChemicalSociety 2012 Macromolecules Vol.45 No.7

<P>Wiring of glucose oxidase (GOx) onto electrode surfacewas successfully achieved by cross-linked networks of organometallicblock copolymers comprising electroactive ferrocene moieties and chemicallycross-linkable diene groups, poly(ferrocenyldimethylsilane-<I>b</I>-isoprene)s (PFS–PIs). Different nanoscale morphologiesof PFS–PIs, i.e., bicontinuous structure, nanowires, and nanoparticles,have been derived by varying molecular weights and casting solvents.Upon examining catalytic current responses of the GOx integrated PFS–PIsystems, notably, the morphology of PFS–PI is foundout to be a crucial parameter in determining the efficiency of electrontransfer. For example, the use of bicontinuous PFS–PI confirms2–50 times improved catalytic current densities, compared withthe values of other morphologies; the maximum catalytic current ofglucose oxidation was 0.7 mA/cm<SUP>2</SUP> at 70 mM glucose concentration.The biosensing ability of the fabricated electrode with structuraloptimization was also exploited, and good sensitivity is obtainedat the physiological concentration of glucose in blood.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2012/mamobx.2012.45.issue-7/ma300155u/production/images/medium/ma-2012-00155u_0006.gif'></P>

Synthesis and Characterizationsof In Situ Cross-LinkableGelatin and 4-Arm-PPO-PEO Hybrid Hydrogels via Enzymatic Reactionfor Tissue Regenerative Medicine

Park, KyungMin,Lee, Yunki,Son, Joo Young,Oh, Dong Hwan,Lee, Jung Seok,Park, Ki Dong American ChemicalSociety 2012 Biomacromolecules Vol.13 No.3

<P>In situ cross-linkable hybrid hydrogels composed of gelatin and 4-arm-polypropylene oxide polyethylene oxide (Tetronic) was developed as an injectable scaffold for tissue regeneration. The gelatin was modified by hydroxyphenyl propionic acid (HPA) and the Tetronic was conjugated with tyramines (Tet-TA). The hydrogels were rapidly formed by mixing the polymer solutions containing horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). The gelation time and mechanical properties of the hydrogels could be controlled by varying the HRP and H2O2 concentrations. In vitro degradation study of the hybrid hydrogels was carried out using collagenase and the prolonged proteolytic degradation was obtained due to the presence of the Tetronic. Human dermal fibroblast (hDFB) was cultured in the hydrogel matrices to evaluate the cyto-compatibility. The encapsulated cells were shown to be highly viable and spread over the gel matrices, suggesting that the hybrid hydrogels have an excellent cyto-compatibility. The hydrogels were also subcutaneously injected in the back of mice and the results demonstrated that the hydrogels were rapidly formed at the injected site. From these results, we demonstrate that the in situ cross-linkable hydrogels formed by hybridization of gelatin and Tetronic via enzyme-mediated reactions hold great promise for use as injectable matrices for tissue regenerative medicine due to their tunable physico-chemical properties and excellent bioactivity.</P>

Acremostrictin, a HighlyOxygenated Metabolite fromthe Marine Fungus <i>Acremonium strictum</i>

Julianti, Elin,Oh, Hana,Jang, Kyoung Hwa,Lee, Jae Kyun,Lee, Sang Kook,Oh, Dong-Chan,Oh, Ki-Bong,Shin, Jongheon American ChemicalSociety and AmericanSociety of Ph 2011 Journal of natural products Vol.74 No.12

<P>The novel natural product acremostrictin (1) was isolated from the culture broth of Acremonium strictum, a marine fungus collected from a Choristida sponge off the coast of Korea. Structurally, acremostrictin is a tricyclic lactone of an unprecedented skeletal class based on combined spectroscopic and X-ray crystallographic analyses. The new compound exhibited weak antibacterial and moderate antioxidant activities.</P>

Triterpene Galactosidesof the Pouoside Class andCorresponding Aglycones from the Sponge <i>Lipastrotethya</i> sp.

Lee, Jung-Ho,Jang, KyoungHwa,Lee, Yeon-Ju,Lee, Hyi-Seung,Sim, Chung J.,Oh, Ki-Bong,Shin, Jongheon American ChemicalSociety and AmericanSociety of Ph 2011 Journal of natural products Vol.74 No.12

<P>Nine new triterpene galactosides and aglycones, along with three known compounds from the rare pouoside class, were isolated from the tropical sponge Lipastrotethya sp. collected from Micronesia. The structures of these new compounds were determined by combined spectroscopic methods and designated as pouosides F-I (4, 8, 10, and 12) and pouogenins A-E (5-7, 9, and 11). The absolute configurations of the asymmetric centers and the cyclohexenone moiety, which had been previously undetermined, were assigned by NOESY analyses and Mosher's methods. Several of these compounds exhibited weak cytotoxicity against the K562 cell line.</P>

Full Surface Embeddingof Gold Clusters on Silicon Nanowires for Efficient Capture and PhotothermalTherapy of Circulating Tumor Cells

Park, Gyeong-Su,Kwon, Hyuksang,Kwak, Dong Wook,Park, Seong Yong,Kim, Minseok,Lee, Jun-Ho,Han, Hyouksoo,Heo, Sung,Li, Xiang Shu,Lee, Jae Hak,Kim, Young Hwan,Lee, Jeong-Gun,Yang, Woochul,Cho, Hoon Young American ChemicalSociety 2012 Nano letters Vol.12 No.3

<P>We report on rapid thermal chemical vapor depositiongrowth of silicon nanowires (Si NWs) that contain a high density ofgold nanoclusters (Au NCs) with a uniform coverage over the entirelength of the nanowire sidewalls. The Au NC-coated Si NWs with anantibody-coated surface obtain the unique capability to capture breastcancer cells at twice the highest efficiency currently achievable(∼88% at 40 min cell incubation time) from a nanostructuredsubstrate. We also found that irradiation of breast cancer cells capturedon Au NC-coated Si NWs with a near-infrared light resulted in a highmortality rate of these cancer cells, raising a fine prospect forsimultaneous capture and plasmonic photothermal therapy for circulatingtumor cells.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-3/nl2045759/production/images/medium/nl-2011-045759_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl2045759'>ACS Electronic Supporting Info</A></P>