02127nas a2200253 4500008004100000022001400041245011800055210006900173260009500242300001200337490000800349520114900357653002301506653001401529653002301543653003501566653001801601653003501619100002101654700002801675700002201703700001901725856012901744 2006 eng d a0021-979700aSuppression of electron-transfer characteristics of ferrocene by OTS monolayer on a silicon/electrolyte interface0 aSuppression of electrontransfer characteristics of ferrocene by  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcJUL a777-7840 v2993 a

The passivating behavior of self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS) on an n-type Si(100) electrode with and without a redox species like ferrocene in a polar non-aqueous medium has been investigated using techniques like contact angle measurements, Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to understand the role of the monolayer. The electron-transfer behavior of ferrocene is found to be drastically affected by the presence of monolayer and the reasons for these are analyzed as a function of the change in resistance, dielectric thickness and coverage of the monolayer. Electrochemical impedance analysis in the presence of ferrocene gives the monolayer coverage as 0.998 and the apparent rate constant calculated from this gives 4.85 x 10(-12) cm s(-1) in comparison with 4.4 x 10(-8) cm s(-1) for a similar electrode without any monolayer. A positive shift of 200 mV in the flat-band potential after monolayer formation also suggests the covalent coupling of the silane nionolayer offering a protective barrier. (c) 2006 Elsevier Inc. All rights reserved.

10acyclic voltammetry10aferrocene10aimpedance analysis10aoctadecyltrichlorosilane (OTS)10arate constant10aself-assembled monolayer (SAM)1 aKulkarni, S., A.1 aKakade, Bhalchandra, A.1 aMulla, Imtiaz, S.1 aPillai, V., K. uhttp://library.ncl.res.in/content/suppression-electron-transfer-characteristics-ferrocene-ots-monolayer-siliconelectrolyte-002378nas a2200265 4500008004100000022001400041245008500055210006900140260009500209300001000304490000800314520144900322653002001771653002301791653001501814653001401829653001101843653001901854100002501873700003001898700002201928700002101950700002601971856011501997 2007 eng d a0006-291X00aAll-solid-state' electrochemistry of a protein-confined polymer electrolyte film0 aAllsolidstate electrochemistry of a proteinconfined polymer elec a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcDEC a86-910 v3643 a

Interfacial redox behavior of a heme protein (hemoglobin) confined in a solid polymer electrolyte membrane, Nafion (a perfluoro sulfonic acid ionomer) is investigated using a unique `all-solid-state' electrochemical methodology. The supple phase-separated structure of the polymer electrolyte membrane, with hydrophilic pools containing solvated protons and water molecules, is found to preserve the incorporated protein in its active form even in the solid-state, using UV-visible, Fluorescence (of Tryptophan and Tyrosine residues) and DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy. More specifically, solid-state cyclic voltammetry and electrochemical impedance of the protein-incorporated polymer films reveal that the Fe2+-form of the entrapped protein is found to bind molecular oxygen more strongly than the native protein. In the `all-solid-state' methodology, as there is no need to dip the protein-modified electrode in a liquid electrolyte (like the conventional electrochemical methods), it offers an easier means to study a number of proteins in a variety of polymer matrices (even biomimetic assemblies). In addition, the results of the present investigation could find interesting application in a variety of research disciplines, in addition to its fundamental scientific interest, including protein biotechnology, pharmaceutical and biomimetic chemistry. (C) 2007 Elsevier Inc. All rights reserved.

10aall-solid-state10acyclic voltammetry10ahemoglobin10aImpedance10aNafion10aredox behavior1 aParthasarathy, Meera1 aPillai, Vijayamohanan, K.1 aMulla, Imtiaz, S.1 aShabab, Mohammed1 aKhan, Mohammad, Islam uhttp://library.ncl.res.in/content/all-solid-state-electrochemistry-protein-confined-polymer-electrolyte-film-002298nas a2200241 4500008004100000022001400041245011800055210006900173260009200242300001400334490000600348520130800354653002301662653004401685653005201729653001501781653003201796100002301828700002301851700002201874700003001896856013001926 2008 eng d a1533-488000aElectrochemical sensing of sulphur dioxide: a comparison using dodecanethiol and citrate capped gold nanoclusters0 aElectrochemical sensing of sulphur dioxide a comparison using do a26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USAbAMER SCIENTIFIC PUBLISHERScJUN a3184-31900 v83 a

A comparison of cyclic voltammograms of dodecanethiol (DDT) capped Au nanoclusters (5.0 +/- 0.5 nm) and trisodium citrate (Cit) capped Au nanoclusters (similar to 10-15 nm) modified glassy carbon electrode shows a dramatic variation in the current when exposed to a small amount of sulphur dioxide. This is explained using the electrocatalytic properties of Au nanoclusters towards the oxidation of SO2, thus facilitating the fabrication of electrochemical sensors for the detection of SO2. The intrinsic redox changes observed for gold nanocluster-modified glassy carbon electrodes disappear on passing SO2, despite a dramatic current increase, which indeed scales up with the amount of dissolved SO2. Interestingly, a complete rejuvenation of the redox behavior of gold is also observed on subsequent removal of SO2 from the solution by passing pure nitrogen for 15 minutes. Further, these nanoclusters when characterized with X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) after SO2 passage reveal a variety of SO2 adsorption modes on gold surface. XP spectra also show a shift of 1.03 eV towards higher binding energy indicating a strong adsorption of SO2 gas, while FTIR gives conclusive evidence for the interaction of SO2 with gold nanoparticles.

10acyclic voltammetry10aFourier transform infrared spectroscopy10amonolayer protected gold nanoclusters (Au-MPCs)10aSO2 sensor10aX-ray photoelectron spectra1 aSathe, Bhaskar, R.1 aRisbud, Mandar, S.1 aMulla, Imtiaz, S.1 aPillai, Vijayamohanan, K. uhttp://library.ncl.res.in/content/electrochemical-sensing-sulphur-dioxide-comparison-using-dodecanethiol-and-citrate-capped-0