Markovich I, Mandler D. Disorganized self-assembled monolayers (SAMs): the incorporation of amphiphilic molecules. Analyst (Cambridge, U. K.)Analyst (Cambridge, United Kingdom). 2001;126 (11) :1850 - 1856.Abstract
A new approach for designing a voltammetric selective electrode is presented. The approach is based on the formation of a disorganized inert self-assembled monolayer (SAM), in which an amphiphilic mol. is incorporated. The latter serves as the selectivity factor, which exts. the analyte. The purpose of these expts. is to study the parameters that affect the capability of a monolayer to host amphiphiles. As model systems the authors focused on the incorporation of simple amphiphilic mols. (quaternary alkyl ammonium salts), electroactive amphiphiles (dialkylviologens) and a macrocycle ligand (tetramethylcyclam) into octadecyl silane monolayers formed on In Sn oxide (ITO) and purposely made disorganized alkanethiols on Au. Basically, the incorporation of amphiphiles into a hydrophobic inert SAM resembles a reversed stationary phase in liq. chromatog. and this configuration can be used for designing selective electrodes. [on SciFinder(R)]
Tenenboum M, Mandler D, Tal R, Meir Y.; 2001. Disposable heating unit for food containers.Abstract
A disposable heating unit for use for heating the contents of a container, includes a first region contg. a combination of at least two solid substances which undergo an exothermic chem. reaction which is not spontaneous at room temp. Adjacent to the first region is a second region contg. at least a first reagent. A storage cell is configured for releasing the liq. contg. a second reagent into the second region. The first and second reagents undergo a spontaneous exothermic chem. reaction when brought into contact, thereby initiating the exothermic chem. reaction of the solid substances. [on SciFinder(R)]
Gluch G, Mandler D. Kitchen in a can for people on the go. Chem. InnovationChemical Innovation. 2001;31 (9) :24 - 28.Abstract
A review with refs. of self-heating beverage containers. [on SciFinder(R)]
Ammann E, Mandler D. Local deposition of gold on silicon by the scanning electrochemical microscope. J. Electrochem. Soc.Journal of the Electrochemical Society. 2001;148 (8) :C533-C539.Abstract
The scanning electrochem. microscope was applied in the feedback mode to deposit Au microstructures on n-Si(111) and indium-tin oxide. This was accomplished by the anodic dissoln. of Au at the microelectrode followed by the subsequent redeposition of the Au on the substrate. The influence of pH, substrate potential, and deposition time on the cryst. nanometer structure of the micrometer Au deposits was studied. The effect of these parameters on deposition could be explained by the band structure of the silicon. Also, understanding the role played by the different parameters allows depositing predefined nanocryst. structures. [on SciFinder(R)]
Turyan I, Erichsen T, Schuhmann W, Mandler D. On-line analysis of mercury by sequential injection stripping analysis (SISA) using a chemically modified electrode. ElectroanalysisElectroanalysis. 2001;13 (1) :79 - 82.Abstract
A highly flexible, automatic sequential-injection stripping anal. (SISA) system was developed and applied for monitoring the levels of Hg in aq. solns. using a chem. modified electrode. The prepn. of the modified electrode comprises spin coating of an EtOH soln. of poly(4-vinylpyridine) and Kryptofix-222 onto a glassy C electrode (GCE) followed by crosslinking the polymer. The anal. is based on the anodic stripping voltammetry of Hg using differential pulse voltammetry. A sequence of 36 operations was needed to complete a full cycle of cleaning, calibration and anal. [on SciFinder(R)]
Sfez R, Liu D-Z, Turyan I, Mandler D, Yitzchaik S. Polyaniline Monolayer Self-Assembled on Hydroxyl-Terminated Surfaces. LangmuirLangmuir. 2001;17 (9) :2556 - 2559.Abstract
A monolayer of conducting polymer, polyaniline (PAN), was assembled on hydroxyl-terminated surfaces, such as quartz, glass, indium-tin oxide, and native oxide on Si. The approach for assembling two-dimensional monolayers of PAN is based on a chem. or electrochem. surface polymn. of electrostatically bound anilinium. The latter was bound to the neg. charged sulfonate group of mercaptoethanesulfonate that was previously coupled by an SN2 reaction to an iodopropyl self-assembled monolayer. The consecutive assembling steps were followed by XPS, UV-vis-NIR spectroscopy, variable angle spectroscopic ellipsometry, contact angle, and at. force microscopy measurements. The characteristic electronic properties of the PAN monolayers were studied by UV-vis-NIR spectroscopy and cyclic voltammetry. [on SciFinder(R)]
Markovich I, Mandler D. Preparation and characterization of octadecylsilane monolayers on indium-tin oxide (ITO) surfaces. J. Electroanal. Chem.Journal of Electroanalytical Chemistry. 2001;500 (1-2) :453 - 460.Abstract
The prepn. and characterization of octadecylsilane, C18, monolayers on indium-tin oxide (ITO) were studied carefully. A reproducible procedure was developed for the formation of C18/ITO employing octadecyltrimethoxysilane (OTMS) as a monomer. The films were studied by electrochem., wettability, IR and at. force microscopy. All these measurements provide evidence for the formation of a disorganized, 'brush-type' monolayer with a max. surface fractional coverage of 0.90 ± 0.04. The surface coverage can be controlled through the silanization time. The applications and implications of such disorganized monolayers in electroanal. chem. are discussed. [on SciFinder(R)]
Turyan I, Zeltser C, Lewinstein I, Schuhmann W, Mandler D. Comparing different approaches for assembling selective electrode for mercury ions. Proc. - Electrochem. Soc.Proceedings - Electrochemical Society. 2001;2001-18 (Chemical and Biological Sensors and Analytical Methods II) :284 - 292.Abstract
Different approaches for increasing the sensitivity, selectivity and stability of a voltammetric probe for mercury ions were probed. These involve the application of adsorbed monolayers of a host mol., i.e., 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (Kryptofix-222) and thin polymeric films. The stability, reproducibility and durability of the sensors in the anal. of Hg2+ from different sources were examd. and compared. A monolayer of the macrocyclic ligand, which is capable of forming a strong and selective complex with the mercury, is superior to polymeric films in terms of sensitivity and ease of regeneration. However, the stability and durability of polymeric films, in which Kryptofix-222 is incorporated, will eventually dictate their use as preferred interfaces for repetitive analyses esp. in flow anal. systems. An application of a polymer-Kryptofix-222 modified electrode for monitoring mercury in a bioremediation pilot was examd. using an automatic sequential-injection stripping anal. (SISA) system. [on SciFinder(R)]
Mandler D. Micro- and nanopatterning using the scanning electrochemical microscope., in Scanning Electrochem. Microsc. Marcel Dekker, Inc. ; 2001 :593 - 627.Abstract
A review is given on scanning electrochem. microscopy (SECM) as a tool for surface modification. It is distinguished between the direct mode and the feedback mode of the SECM. In the direct mode, the substrate serves as the auxiliary electrode, while, in the feedback mode, the substrate is unibiased, and a mediator is used that shuttles between the ultramicroelectrode and the surface. The etching of semiconductors, the metal deposition and etching, the deposition of conducting polymers, and the patterning of org. and biomols. are treated for both the direct- and the feedback mode technique of the SECM. The achievable resoln. and the patterning rate are addressed. [on SciFinder(R)]
Turyan I, Matsue T, Mandler D. Patterning and characterization of surfaces with organic and biological molecules by the scanning electrochemical microscope. Anal ChemAnalytical chemistry. 2000;72 (15) :3431 - 5.Abstract
A novel approach for micropatterning of surfaces with organic and biological microstructures using the scanning electrochemical microscope (SECM) is described. The approach is based on the introduction of the spatial resolution by local deposition of gold particles followed by monolayer formation and functionalization. Specifically, gold patterns were deposited locally on silicon wafers with the SECM as a result of the controlled anodic dissolution of a gold microelectrode. The gold patterns were further used as microsubstrates for assembling cystamine monolayers to which either fluoresceine isothiocyanate (FIT) or glucose oxidase (GOD) were covalently attached. Characterization of the organic monolayers, as well as the biological activity of the enzyme patterns, was carried out by fluorescence microscopy and the SECM, respectively.[on SciFinder (R)]
Markovich I, Mandler D. The effect of an alkylsilane monolayer on an indium-tin oxide surface on the electrochemistry of hexacyanoferrate. J. Electroanal. Chem.Journal of Electroanalytical Chemistry. 2000;484 (2) :194 - 202.Abstract
The presence of a disorganized octadecylsilane, C18, monolayer on an indium-tin oxide (ITO) electrode has a profound effect on the electrochem. of hexacyanoferrate, Fe(CN)63-/4-. The alkylsilane monolayer forms a hydrophobic matrix, which affects the heterogeneous rate of electron transfer of the metallic complex, depending on the nature of the counter cation presence in the soln. A model is suggested which accounts for these effects as well as for the changes in the formal redox potential that are obsd. [on SciFinder(R)]
Batz V, Schneeweiss MA, Kramer D, Hagenstrom H, Kolb DM, Mandler D. Electrochemistry and structure of the isomers of aminothiophenol adsorbed on gold. J. Electroanal. Chem.Journal of Electroanalytical Chemistry. 2000;491 (1,2) :55 - 68.Abstract
The self-assembled monolayers (SAMs) of the three isomers of aminothiophenol, ATP, have been studied by means of electrochem., in-situ STM and XPS. We find that the isomers are organized differently. The organization is presumably governed by their intermol. and surface interactions. Moreover, the chem. and phys. characteristics of the interface are significantly and differently affected by the isomers comprising the SAMs. The electrochem. of the modified surface as well as the bare gold surface in contact with the thiol-contg. electrolyte, copper deposition and palladium(II) extn. have been studied for the 2-, 3- and 4-ATP monolayers. The organization of the layers has been investigated by STM. In essence, we find that the different isomers are likely to adopt an orientation that is perpendicular to the surface. While 4-ATP forms the densest monolayer, 2-ATP probably interacts with the gold surface with both the amino and the mercapto groups. Moreover, STM images indicate the partial formation of more than a monolayer. This is supported by XPS measurements and electrochem. and can be attributed to the SAM modification soln., i.e. sulfuric acid, which allows the formation of sulfate-bridged ATP bilayers. The chem. and phys. characteristics of the interfaces are governed by the different organization as well as by the individual chem. properties of each isomer. [on SciFinder(R)]
Yasukawa T, Kanaya N, Mandler D, Matsue T. Imaging of diaphorase micropatterned at gold arrays with scanning electrochemical microscopy. Chem. Lett.Chemistry Letters. 2000;(5) :458 - 459.Abstract
Diaphorase was hydrophobically immobilized onto a self-assembled monolayer of alkanethiol at an interdigitated Au microarray. The diaphorase activity at the array substrates was imaged with the scanning electrochem. microscopy (SECM) in the presence of NADH and ferrocenemethanol as a redox mediator. The images demonstrate that diaphorase was immobilized onto the SAM layer to form a line-and-space micropattern which reflected the pattern of the Au microarray. [on SciFinder(R)]
Turyan I, Matsue T, Mandler D. Patterning and Characterization of Surfaces with Organic and Biological Molecules by the Scanning Electrochemical Microscope. Anal. Chem.Analytical Chemistry. 2000;72 (15) :3431 - 3435.Abstract
A novel approach for micropatterning of surfaces with org. and biol. microstructures using the scanning electrochem. microscope (SECM) is described. The approach is based on the introduction of the spatial resoln. by local deposition of Au particles followed by monolayer formation and functionalization. Specifically, Au patterns were deposited locally on Si wafers with the SECM as a result of the controlled anodic dissoln. of a Au microelectrode. The Au patterns were further used as microsubstrates for assembling cystamine monolayers to which either fluoresceine isothiocyanate (FIT) or glucose oxidase (GOD) were covalently attached. Characterization of the org. monolayers, as well as the biol. activity of the enzyme patterns, was carried out by fluorescence microscopy and the SECM, resp. [on SciFinder(R)]
Selzer Y, Mandler D. Probing the coupling of charge-transfer processes across liquid/liquid interfaces by the scanning electrochemical microscope. J. Phys. Chem. BJournal of Physical Chemistry B. 2000;104 (20) :4903 - 4910.Abstract
The feedback mode of the scanning electrochem. microscope (SECM) was used to induce and measure charge-transfer coupling (CTC) between two ion-transfer (IT) processes across liq./liq. interfaces. Results are interpreted using a general model for coupling processes under steady-state conditions that is also applicable to other modes of coupling such as IT-ET and ET-ET (ET = electron transfer). The measured feedback curves demonstrate the effect of mass-transfer limitations in these processes on the potential across the interface, shedding new light on the dynamics of bioenergetics and phase-transfer catalysis systems as well as on previous SECM studies of liq./liq. interfaces. [on SciFinder(R)]
Selzer Y, Mandler D. Scanning Electrochemical Microscopy. Theory of the Feedback Mode for Hemispherical Ultramicroelectrodes: Steady-State and Transient Behavior. Anal. Chem.Analytical Chemistry. 2000;72 (11) :2383 - 2390.Abstract
This contribution represents the first comprehensive attempt to treat complex geometry configurations of the scanning electrochem. microscope (SECM) using the alternating direction implicit finite difference method (ADIFDM). Specifically, ADIFDM is used to simulate the steady-state as well as the transient (chronoamperometric) behavior of a hemispherical ultramicroelectrode (UME) tip of the SECM. The feedback effect in this configuration is less pronounced as compared with a disk-shaped UME system. The differences between the two systems are discussed. Anal. approxns. for the steady-state behavior and for characteristic features of the transient behavior are suggested. Finally, exptl. feedback currents measured above a conductor and an insulator are in excellent agreement with the theory. [on SciFinder(R)]
Turyan I, Krasovec UO, Orel B, Saraidorov T, Reisfeld R, Mandler D. "Writing-reading-erasing" on tungsten oxide films using the scanning electrochemical microscope. Adv. Mater. (Weinheim, Ger.)Advanced Materials (Weinheim, Germany). 2000;12 (5) :330 - 333.Abstract
The authors described fast electrochem.-spectroscopic "writ- ing-reading-erasing" system based on a scanning probe technique. The fast "reading" and "erasing" processes are due to the fact that there is no phase transition between the two states and that the ingression and egression of ions is very fast. In principle, the resoln. of patterning depends on the size of the microelectrodes, which currently can be reduced to the nanometer range. The uniqueness of this system is that the propagation of the lateral charge inside the thin film can be detected independently of its formation. This allows the study of lateral charge transport and enables the development of better systems in terms of resoln. and information storage capabilities. [on SciFinder(R)]
Muskal N, Mandler D. The electrochemistry of thiol self-assembled monolayers (SAMs) on a hanging mercury drop electrode (HMDE). Curr. Sep.Current Separations. 2000;19 (2) :49 - 54.Abstract
The electrochem. of functionalized self-assembled monolayers on Hg is studied by cyclic voltammetry and AC voltammetry. The results suggest that thiols can be adsorbed either chem. or phys. depending on the Hg potential. The transformation between these two states occurs via an oxidn.-redn. process. While a multi-layer of short chemisorbed thiols is formed under pos. potentials than the oxidn.-redn. process, a dense monolayer is self-assembled under more neg. potentials. [on SciFinder(R)]
Shacham R, Avnir D, Mandler D. Electrodeposition of methylated sol-gel films on conducting surfaces. Adv. Mater. (Weinheim, Ger.)Advanced Materials (Weinheim, Germany). 1999;11 (5) :384 - 388.Abstract
An approach to sol-gel film formation is described, involving electrochem. control of pH near a conductive surface, in which methyltrimethoxysilane (MeTMOS) is deposited onto indium tin oxide (ITO) and Au surfaces. The method is based on a 2-step sol-gel prepn. procedure in which MeTMOS is first pre-hydrolyzed and then polycondensed. A const. neg. potential is applied to the electrode surface, increasing the concn. of hydroxyl ions, which act as a catalyst in the condensation process. This results in greater control over the deposition process and thus over film properties. [on SciFinder(R)]
Selzer Y, Turyan I, Mandler D. Studying Heterogeneous Catalysis by the Scanning Electrochemical Microscope (SECM): The Reduction of Protons by Methyl Viologen Catalyzed by a Platinum Surface. J. Phys. Chem. BJournal of Physical Chemistry B. 1999;103 (9) :1509 - 1517.Abstract
The feedback mode of the scanning electrochem. microscope (SECM) was used for studying a surface-catalyzed electron-transfer reaction. As a model system the authors examd. the redn. of protons by reduced N,N'-dimethyl-4,4'-bipyridinium, methylviologen radical cation, MV+•, catalyzed by a platinum surface. The exptl. configuration comprises a biased amalgamated Au ultramicroelectrode (UME) that approaches an unbiased Pt UME substrate of the same radius. MV+• that is electrochem. generated at the amalgamated UME is oxidized at the Pt surface as a result of reducing protons. This novel configuration permits the simultaneous measurement of the catalytic current and the mixed potential (open-circuit potential) attained at the Pt surface. The results are interpreted by an electrochem. model which was previously suggested; however, the authors' approach makes it possible to measure, for the 1st time, the current-potential relation predicted by the theory. The authors' results indicate that methylviologen behaves reversibly under all the exptl. conditions, and that the rate const. of hydrogen evolution, that is calcd., is in perfect agreement with previous reports. The significant advantages of the authors' approach are discussed as well as its applicability for studying other electrochem. systems. [on SciFinder(R)]