Publications

2004
Marx S, Zaltsman A, Turyan I, Mandler D. Parathion Sensor Based on Molecularly Imprinted Sol-Gel Films. Anal. Chem.Analytical Chemistry. 2004;76 (1) :120 - 126.Abstract
Thin films of a molecularly imprinted sol-gel polymer with specific binding sites for parathion were developed. The films were cast on glass substrates and on glassy carbon electrodes and were used to detect parathion in aq. solns. Gas-phase binding measurements were performed on coated quartz crystal microbalance resonators. The binding of parathion to the imprinted films in the liq. phase was investigated by steady-state expts. with anal. by GC-FPD and cyclic voltammetry. The imprinted films showed high selectivity toward parathion in comparison to similar organophosphates. The binding was very sensitive to the type of functional monomer used for imprinting, and that rational design of the matrix components is an essential step in mol. imprinting. Specific binding in the gas phase proved to be less sensitive to the imprinting effect and exhibits relatively high nonspecific binding. The difference between mol. recognition in the gas- and liq.-phase imprinted polymer is discussed. [on SciFinder(R)]
Shustak G, Domb AJ, Mandler D. Preparation and Characterization of n-Alkanoic Acid Self-Assembled Monolayers Adsorbed on 316L Stainless Steel. LangmuirLangmuir. 2004;20 (18) :7499 - 7506.Abstract
The electrochem. formation and characterization of decanoic, myristic, palmitic, and stearic acid self-assembled monolayers on a native oxide surface of 316L stainless steel were studied. This work describes a new approach to surface modification of stainless steel in which the self-assembly of n-alkanoic acids is facilitated by applying a potential to the stainless steel in an org. electrolyte soln. While decanoic acid forms a disorganized monolayer of sweeping the potential in an MeCN soln. contg. 0.1 mM of the resp. acid, longer acids, i.e., myristic and palmitic acids, form highly ordered closed-packed monolayers. This electrochem. approach results in highly reproducible monolayers that are deposited within a shorter time than the traditional assembly process. The monolayers were characterized by cyclic voltammetry, double-layer capacity (a.c. voltammetry), contact angle measurements, XPS, and external reflection-absorption FTIR spectroscopy. The use and implications of this modification technique are discussed. [on SciFinder(R)]
Weiss Z, Mandler D, Shustak G, Domb AJ. Pyrrole derivatives for electrochemical coating of metallic medical devices. J. Polym. Sci., Part A: Polym. Chem.Journal of Polymer Science, Part A: Polymer Chemistry. 2004;42 (7) :1658 - 1667.Abstract
Electropolymn. of medical devices such as cardiovascular stents may possess advantages including a simple and reproducible process with the ability to control the thickness, adherence, and compn. of the coating by the duration and intensity of the applied current, the monomer compn. and concn., the solvent, and the reaction conditions. The properties of the polymer can also be controlled by copolymn. of different monomers, grafting substituents to a functionalized polymer, and by entrapping biomols. This article describes the synthesis of a range of pyrrole-based monomers and their electrocoating onto stainless steel surfaces. N-substituted pyrrole monomers with C1-C18 alkyl chains and polyethylene glycol chains were synthesized in good yields and purity. Electropolymn. of these monomers provided uniform coatings with different hydrophobicities. Studies now focus on the incorporation of drugs in the coated device for release from the surface. [on SciFinder(R)]
Shacham R, Avnir D, Mandler D. Electrodeposition of dye-doped titania thin films. J. Sol-Gel Sci. Technol.Journal of Sol-Gel Science and Technology. 2004;31 (1/2/3) :329 - 334.Abstract
We extend our novel low-voltage electrochem. method for oxide thin film formation from sol-gel monomers to include entrapment of org. mols. within the films. We also describe an extension of the method to titania thin films, which are obtained from titanium tetra-n-propoxide in alc. solns. by applying potentials in the range of +2.0 to -1.4 V to indium tin oxide electrodes. The film thickness (ranging between 20-1000 nm) is controllable by changing either the potential or the duration of its application. We demonstrate that this electrochem. method provides a convenient way for entrapment of org. dopants within the film. Four dyes were used for that purpose: Basic Blue 41, methylene-blue, tris(2,2'-bipyridine)iron(II) and tris(2,2'-bipyridine)ruthenium(II). [on SciFinder(R)]
Avissar YY, Sagiv AE, Mandler D, Almog J. Identification of firearms holders by the [Fe(PDT)3]+2 complex. Quantitative determination of iron transfer to the hand and its dependence on palmar moisture levels. J. Forensic Sci.Journal of Forensic Sciences. 2004;49 (6) :1215 - 1219.Abstract
Quant. data are reported for the first time on the amts. of iron, which are transferred to the hand upon holding a firearm. Iron levels between 21-315 ng/cm2 were found on volunteers' palms after a single holding of a handgun. Detn. of the iron traces was accomplished spectrophotometrically using 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDT) as a complexing agent. The transfer of iron from firearms to the palm was found to be, by and large a chem. (dissoln.) rather than mech. dislodgement. The prime factor that dets. the amt. of iron transferred from the firearm to the hand is the moisture level on the palm. These findings are likely to be of importance in courts of law, as well as in the war against terrorism and serious crime. [on SciFinder(R)]
2003
Zhang J, Barker AL, Mandler D, Unwin PR. Effect of surface pressure on the insulator to metal transition of a langmuir polyaniline monolayer. J Am Chem SocJournal of the American Chemical Society. 2003;125 (31) :9312 - 3.Abstract
A remarkable change in the conductivity of a polyaniline (PAN) Langmuir monolayer in the conducting state, as a function of surface pressure, has been observed using scanning electrochemical microscopy (SECM). The film conductivity, as expressed by the SECM current response of a redox mediator, was measured in-situ in a Langmuir film balance. The conductivity of the film increases significantly with surface pressure, above a threshold value of ca. 20 mN m-1.[on SciFinder (R)]
Shustak G, Marx S, Turyan I, Mandler D. Application of sol-gel technology for electroanalytical sensing. ElectroanalysisElectroanalysis. 2003;15 (5-6) :398 - 408.Abstract
The applicability of thin sol-gel films as selective interfaces in electrochem. sensors has been examd. This requires not only to create a selective interface but also to enable facile diffusion of the analytes across the films. Creation of selectivity has been aimed by molecularly imprinting an electroactive species in the course of sol-gel formation. We have focused primarily on imprinting an iron(II) complex, i.e., tris(2,2'-bipyridine)iron(II) (Fe(bpy)2+3), as a means of selectively detg. iron(II) in aq. soln. Hence, the effect of different parameters, such as the compn. of the sol-gel film and the hydrolysis and drying time, on the diffusion of Fe(bpy)2+3, has been studied. We find that diffusion can be remarkably enhanced upon adding polyethylene glycol or a surfactant, such as decanoic acid. Nevertheless, so far we have not been able to develop thin films, which exhibit selectivity towards this inorg. species. The difficulties in designing such selective interfaces for heavy metals as opposed to org. species is demonstrated by successfully applying the same approach for designing a selective interface for diethyl-p-nitrophenyl phosphate (paraoxon). [on SciFinder(R)]
Zhang J, Barker AL, Mandler D, Unwin PR. Effect of Surface Pressure on the Insulator to Metal Transition of a Langmuir Polyaniline Monolayer. J. Am. Chem. Soc.Journal of the American Chemical Society. 2003;125 (31) :9312 - 9313.Abstract
A remarkable change in the cond. of a polyaniline (PANI) Langmuir monolayer in the conducting state, as a function of surface pressure, was obsd. using scanning electrochem. microscopy (SECM). The film cond., as expressed by the SECM current response of a redox mediator, was measured in-situ in a Langmuir film balance. The cond. of the film increases significantly with surface pressure, above a threshold value of ca. 20 mN m-1. [on SciFinder(R)]
Mandler D, Gal-Oz R, Burshtain D, Turyan I. Electrochemical metal speciation using self-assembled monolayers. J. Phys. IVJournal de Physique IV: Proceedings. 2003;107 (XIIth International Conference on Heavy Metals in the Environment, 2003, Volume 2) :801 - 804.Abstract
The application of self-assembled monolayers (SAMs) as a means of achieving speciation in heavy metal electrochem. detn. is demonstrated. SAMs are monomol. org. layers that can be chem. attached onto different electrode materials and used for the selective extn. of heavy metals. The selectivity is achieved by assembling monolayers that have pendant ligands, which interact selectively with the analytes in the soln. For example, the formation of a monolayer comprising a pyridine group was used to selectively ext. Cr(VI) from aq. solns., whereas the selective detn. of Fe(II) was accomplished using a covalently bound terpyridine monolayer. Yet, detg. the heterogeneous binding consts. of the metallic species by the SAMs is of significant importance and allows studying quant. the interactions between the monolayer and the metal ions. The authors have developed a few methods for detg. the binding consts. of heavy metal ions by SAMs of which two of them are briefly discussed here. [on SciFinder(R)]
Mandler D, Unwin PR. Measurement of Lateral Charge Propagation in Polyaniline Layers with the Scanning Electrochemical Microscope. J. Phys. Chem. BJournal of Physical Chemistry B. 2003;107 (2) :407 - 410.Abstract
The local injection and lateral propagation of charge in ultrathin polyaniline (PAN) layers were studied with the scanning electrochem. microscope (SECM). Monolayers of PAN were deposited on a glass substrate using the LB method and were chem. reduced using Na dithionite. A microelectrode held close to the PAN layer was used to generate a flux of an oxidant, i.e., Fe(phen)33+ (phen = 1,10-phenanthroline) which diffused to the surface and locally oxidized the reduced PAN. By simulating the current-time transients, the kinetics of lateral charge propagation were evaluated. [on SciFinder(R)]
Turyan I, Orel B, Reisfeld R, Mandler D. Studying electron transfer at electrochromic tungsten oxide sol-gel films with scanning electrochemical microscopy (SECM). Phys. Chem. Chem. Phys.Physical Chemistry Chemical Physics. 2003;5 (15) :3212 - 3219.Abstract
Electron transfer processes at tungsten oxide films prepd. by the sol-gel method were investigated and characterized by scanning electrochem. microscopy (SECM) and cyclic voltammetry. The feedback mode of the SECM was used for studying the localization and mechanism of the heterogeneous charge transfer at tungsten oxide thin films, which were deposited on conducting, i.e., tin oxide, and insulating substrates. Investigating the feedback current as a function of the mediator concn., thickness of the tungsten oxide film and the nature and concn. of the electrolyte, allow detn. of the rate limiting step and cond. of the film. [on SciFinder(R)]
Cohen-Atiya M, Mandler D. Studying thiol adsorption on Au, Ag and Hg surfaces by potentiometric measurements. J. Electroanal. Chem.Journal of Electroanalytical Chemistry. 2003;550-551 :267 - 276.Abstract
The adsorption of thiols on different metal surfaces has been studied using potentiometric measurements. The adsorption is a complex process that comprises a few steps. The first involves neg. charge transfer to the electrode surface as evidenced by a sharp neg. shift of the open circuit potential (ocp). The charge that is accumulated on the electrode surface is discharged through a redn. process that involves either water or oxygen redn. The rate of the discharging process depends strongly on the overpotential of the electrode material for water redn., the medium, and to some extent, on addnl. functional groups that the thiol bears. A detailed general mechanism that is in agreement with our findings is proposed and discussed. [on SciFinder(R)]
Sheffer M, Groysman A, Mandler D. Electrodeposition of sol-gel films on Al for corrosion protection. Corros. Sci.Corrosion Science. 2003;45 (12) :2893 - 2904.Abstract
Sol-gel films were electrodeposited on Al electrodes following the methodol. the authors have developed and is based on applying neg. potentials. This increases the pH at the surface, causing acceleration of the polymn. The authors' process follows the two step method, in which the monomer is 1st hydrolyzed in acidic soln. (pH ∼ 4) and only then the neg. potential is applied, which consumes protons and releases hydroxyl ions, thus enhancing the condensation. Films made of different monomers, i.e., tetraethoxysilane (TEOS), Me trimethoxysilane and Ph trimethoxysilane (PTMOS), were prepd., characterized and examd. for their corrosion inhibition properties. Potentiodynamic polarization, electrochem. impedance spectroscopy, optical and SEM as well as at. force microscopy were used as a means of film characterization. Hydrophobic and steric silanes, such as PTMOS showed a considerable corrosion inhibition capacity as compared to the capacity exhibited by less hydrophobic and steric derivs. such as TEOS. The difference between the conventional dip-coating method and the electrodeposition approach for depositing sol-gel films was also examd., indicating a clear advantage of the latter. [on SciFinder(R)]
2002
Yatziv Y, Turyan I, Mandler D. A new approach to micropatterning: application of potential-assisted ion transfer at the liquid-liquid interface for the local metal deposition. J Am Chem SocJournal of the American Chemical Society. 2002;124 (20) :5618 - 9.Abstract
A new approach to micropatterning is demonstrated. The approach is based on driving an electrochemical process at the solid-liquid interface through the formation of a flux of ions from a micropipet that is held in close proximity to the surface. The flux of ions is generated by the so-called potential assisted ion transfer at the interface between two immiscible electrolyte solutions (ITIES). As a model system, the local deposition of silver was examined. Specifically, a constant potential, which was applied to a micropipet filled with an aqueous solution of silver ions, caused the transfer of Ag(+) into the outer nitrobenzene (NB) solution that consisted of an electrolyte, tetrabutylammonium tetrakis[4-chlorophenyl]borate (TBATPBCl). To facilitate the transfer of silver ions a macrocyclic ligand, that is, dibenzo-24-crown-8 (DB24C8), was added to the organic phase. The Faradaic current of this micro-ITIES was used as a means of controlling the tip-surface distance in scanning electrochemical microscopy (SECM) and depositing silver microstructures on a gold substrate.[on SciFinder (R)]
Joy VT, Mandler D. Surface functionalization of H-terminated silicon surfaces with alcohols using lodoform as an in situ iodinating agent. ChemphyschemChemphyschem : a European journal of chemical physics and physical chemistry. 2002;3 (11) :973 - 5.
Yatziv Y, Turyan I, Mandler D. A New Approach to Micropatterning: Application of Potential-Assisted Ion Transfer at the Liquid-Liquid Interface for the Local Metal Deposition. J. Am. Chem. Soc.Journal of the American Chemical Society. 2002;124 (20) :5618 - 5619.Abstract
A new approach to micropatterning is demonstrated. The approach is based on driving an electrochem. process at the solid-liq. interface through the formation of a flux of ions from a micropipet that is held in close proximity to the surface. The flux of ions is generated by the so-called potential assisted ion transfer at the interface between two immiscible electrolyte solns. (ITIES). As a model system, the local deposition of silver was examd. Specifically, a const. potential, which was applied to a micropipet filled with an aq. soln. of silver ions, caused the transfer of Ag+ into the outer nitrobenzene (NB) soln. that contained an electrolyte, tetrabutylammonium tetrakis[4-chlorophenyl]borate (TBATPBCl). To facilitate the transfer of silver ions a macrocyclic ligand, i.e., dibenzo-24-crown-8 (DB24C8), was added to the org. phase. The faradaic current of this micro-ITIES was used as a means of controlling the tip-surface distance in scanning electrochem. microscopy (SECM) and depositing silver microstructures on a gold substrate. [on SciFinder(R)]
Stefan IC, Mandler D, Scherson DA. In Situ FTIR-ATR Studies of Functionalized Self-Assembled Bilayer Interactions with Metal Ions in Aqueous Solutions. LangmuirLangmuir. 2002;18 (18) :6976 - 6980.Abstract
The affinity of selected metal ions for palmitic (PAL) and hexadecanesulfonic acid (HDSA) monolayers self-assembled onto an octadecyl silane (ODS) monolayer covalently bound to a Ge internal reflection element has been examd. in situ in aq. electrolytes by attenuated total reflection Fourier transform IR spectroscopy. Marked changes in the bands assocd. with the sym. and asym. stretches of the carboxylate groups induced by metal-ion binding could be discerned for PAL/ODS self-assembled bilayers (SABs) in contact with Cd2+ solns. of pH = 6 even at concns. in the sub-μM range. Subsequent exposure of Cd2+/PAL/ODS SABs to solns. of pH < 4 devoid of Cd2+ led to the removal of Cd2+ from the bilayer leaving behind a better ordered structure, as judged by the shift of the C-H stretching modes toward lower wavenumbers. Spectral evidence for strong metal-terminal sulfonate group interactions was also obtained for HDSA/ODS SABs immersed in solns. contg. Cd2+, Fe3+, and Fe2+, for which the effects on the characteristic sym. and asym. modes of the terminal sulfonate moieties were found to be unique to the nature of each of the metal ions. [on SciFinder(R)]
Joy VT, Mandler D. Surface functionalization of H-terminated silicon surfaces with alcohols using iodoform as an in situ iodinating agent. ChemPhysChemChemPhysChem. 2002;3 (11) :973 - 975.Abstract
High-quality self-assembled monolayers of long-chain alcs. were formed on H-terminated cryst. and porous Si surfaces under mild conditions in a 1-step reaction using iodoform as an in-situ iodinating agent. Besides the convenient conditions under which the procedure is carried out, it yields a high surface coverage and suppresses oxide formation. In-situ iodination is advantageous over other direct methods as it probably forms very reactive intermediate species, e.g. Si-I, that channel the reaction via a nucleophilic attack to form highly dense monolayers. [on SciFinder(R)]
2001
Markovich I, Mandler D. Disorganised self-assembled monolayers (SAMs): the incorporation of amphiphilic molecules. AnalystThe Analyst. 2001;126 (11) :1850 - 6.Abstract
A new approach for designing a voltammetric selective electrode is presented. The approach is based on the formation of a disorganised inert self-assembled monolayer (SAM), in which an amphiphilic molecule is incorporated. The latter serves as the selectivity factor, which extracts the analyte. The purpose of these experiments is to study the parameters that affect the capability of a monolayer to host amphiphiles. As model systems we focused on the incorporation of simple amphiphilic molecules (quaternary alkyl ammonium salts), electroactive amphiphiles (dialkylviologens) and a macrocycle ligand (tetramethylcyclam) into octadecyl silane monolayers formed on indium tin oxide (ITO) and purposely made disorganised alkanethiols on gold. We find that basically, the incorporation of amphiphiles into a hydrophobic inert SAM resembles a reversed stationary phase in liquid chromatography and this configuration can be used for designing selective electrodes.[on SciFinder (R)]
Turyan I, Atiya M, Mandler D. Comparing different approaches for assembling selective electrodes for heavy metals. ElectroanalysisElectroanalysis. 2001;13 (8-9) :653 - 659.Abstract
Different approaches for increasing the sensitivity and selectivity of voltammetric probes for heavy metals were examd. These have involved adsorbed monolayers of host mols., functionalized self-assembled monolayers and thin polymeric films. Two systems are presented that focus on the selective anal. of Hg(II) and Fe(II). The electrode for Hg(II) is based on a macrocyclic ligand, i.e., Kryptofix-222, while that for Fe(II) relies on the selective complexation by ferroin ligands, such as 1,10-phenanthroline. The monomeric and polymeric approaches were examd. and compared for both systems. The principal aim of this manuscript is to highlight the ability of fine-tuning the selectivity characteristics of the solid-liq. interface as a result of considering and optimizing analyte-interface interactions. Basically, an interface comprising a monolayer, which is capable of forming a strong and selective complex with the analyte, is likely to exhibit sensitivity that is at least as good as a polymeric film. However, the stability and durability of the latter usually makes it a superior interface for repetitive anal. and will therefore be the preferred choice for flow anal. systems. [on SciFinder(R)]

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