Publications

2007
Okner R, Domb AJ, Mandler D. Electrochemical Formation and Characterization of Copolymers Based on N-Pyrrole Derivatives. BiomacromoleculesBiomacromolecules. 2007;8 (9) :2928 - 2935.Abstract
Org. coatings based on N-(2-carboxyethyl)pyrrole (PPA) and a Bu ester of PPA (BuOPy) were deposited via electrochem. oxidn. The homo- and copolymers were electropolymd. on glassy C and stainless steel in MeCN using Bu4NBF4B as the electrolyte. The mechanism of deposition on stainless steel was studied by chronoamperometry and by the tapping and phase angle imaging modes of at. force microscopy. The electrochem. properties and growth of the films were studied by cyclic voltammetry. The compn. of the copolymers was detd. by reflection-absorption FTIR spectroscopy. While the hydrophilic monomer PPA undergoes progressive nucleation followed by instantaneous growth the hydrophobic BuOPy nucleates instantaneously. The rate of BuOPy electropolymn. was higher than that of PPA, and the resulting film was thicker yet fluffier. Copolymer films were enriched by BuOPy as compared with the electropolymn. soln., which is attributed to the faster rate of electropolymn. of BuOPy than PPA. [on SciFinder(R)]
Shustak G, Shaulov Y, Domb AJ, Mandler D. Electrostatic attachment of gold and poly(lactic acid) nanoparticles onto ω-aminoalkanoic acid self-assembled monolayers on 316L stainless steel. Chem. - Eur. J.Chemistry - A European Journal. 2007;13 (22) :6402 - 6407.Abstract
The assembly of poly(lactic acid) (PLA) nanoparticles on a 12-aminodecanoic acid (ADA) self-assembled monolayer (SAM) is described. Assembly is accomplished through electrostatic interactions between the pos. charged SAM and the neg. charged PLA nanoparticles. The strategy used involves 2 steps in which a preliminary electrochem. coating of the ADA SAM is followed by a second step that involves immersing the SAM in a soln. contg. gold or PLA nanoparticles. The SAM was characterized by cyclic voltammetry (CV), XPS, FTIR spectroscopy, and contact angle measurements, whereas SEM was used to image the nanoparticles after electrostatic attachment was achieved. The authors found that the surface coverage of the nanoparticles could be controlled by modulating the electrostatic interactions between the neg. charged particles and the pos. charged SAM surface by varying the pH of the nanoparticle soln., the immersion time, and the no. of cyclic voltammetry scans under which the SAM was formed. [on SciFinder(R)]
Shapiro L, Mandler D. Formation of a molecular glue based on the electrochemical reduction of 4-hydroxyphenyldiazonium for the attachment of thin sol-gel film on glassy carbon. Z. Phys. Chem. (Muenchen, Ger.)Zeitschrift fuer Physikalische Chemie (Muenchen, Germany). 2007;221 (9-10) :1237 - 1243.Abstract
The covalent attachment of a sol-gel thin film onto a glassy carbon electrode was accomplished through the electrochem. redn. of 4-hydroxyphenyldiazonium. The latter forms a very thin layer on the glassy carbon with hydroxyl groups, through which the sol-gel is attached. This mol. glue improves the adhesion of thin layers of sol-gel to a carbonaceous surface. [on SciFinder(R)]
Cohen-Atiya M, Vadgama P, Mandler D. Preparation, characterization and applications of ultrathin cellulose acetate Langmuir-Blodgett films. Soft MatterSoft Matter. 2007;3 (8) :1053 - 1063.Abstract
The prepn. and characterization of mono- and multilayers of cellulose acetate (CA) Langmuir-Blodgett films on indium tin oxide and gold surfaces were studied in detail for the first time. These layers were characterized by their thickness, wettability, morphol. and structure using various surface techniques. The thickness of a monolayer of CA based on XPS measurement was one nanometer. Multilayers of CA Langmuir films were homogeneously transferred onto solid surfaces. The permeation of different mols. across these films was studied using electrochem. in various redox solns. Our findings suggest that a membrane like structure is formed, which is less permeable as the no. of layers increases. Finally, potential applications of these ultrathin films as supports for accommodating biomols. or metal nanoparticles are presented. [on SciFinder(R)]
Sheffer M, Vivier V, Mandler D. Self-assembled monolayers on Au microelectrodes. Electrochem. Commun.Electrochemistry Communications. 2007;9 (12) :2827 - 2832.Abstract
Long chain alkanethiols self-assembled monolayers (SAMs) formed on Au microelectrodes showed higher sensitivity towards defects than the same monolayers on macroelectrodes. The anal. of cyclic voltammetry and electrochem. impedance spectroscopy (EIS) expts. performed on covered microelectrodes were consistent with the formation of pinholes of about 10 nm in diam. Moreover, the EIS data exhibited a specific behavior that was interpreted invoking the short circuiting of the pinholes impedance by the surrounding surface of the microelectrode in the high frequency domain, whereas in the low frequencies, the surface covered by the SAM was assume to act as an insulator. [on SciFinder(R)]
Palmisano G, Mandler D, Ciriminna R, Pagliaro M. Structural insight on organosilica electrodes for waste-free alcohol oxidations. Catal. Lett.Catalysis Letters. 2007;114 (1-2) :55 - 58.Abstract
Org. modification of sol-gel catalytic glassy electrodes made of a thin layer of organosilica doped with nitroxyl radical TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) crucially enhances stability in the waste-free oxidn. of alcs. to carbonyls in H2O. Structural comparison between analogous films made of organosilica and unmodified SiO2 shows that the origin of the pronounced stable activity of the ORMOSIL film lies in high hydrophobic and also in the pronounced low degree of hydrophilicity. [on SciFinder(R)]
2006
Burshtain D, Mandler D. The effect of surface attachment on ligand binding: studying the association of Mg2+, Ca2+ and Sr2+ by 1-thioglycerol and 1,4-dithiothreitol monolayers. Phys Chem Chem PhysPhysical chemistry chemical physics : PCCP. 2006;8 (1) :158 - 64.Abstract
The difference in the heterogeneous binding of Mg(2+), Ca(2+) and Sr(2+) ions by 1-thioglycerol (TG) and 1,4-dithiothreitol (DTT) spontaneously adsorbed monolayers on Au has been studied following the changes in the double layer capacity. A mathematical treatment, based on calculating the electrochemical potential difference at the monolayer-electrolyte interface, has followed our recent work which dealt with the acid-base equilibrium at the interface as a means of calculating the pK of ionizable SAMs and their binding with Cd(2+). Experimentally, spontaneously adsorbed monolayers of TG and DTT were assembled on Au surfaces and studied by impedance spectroscopy and alternating current voltammetry (ACV). The capacity was measured for each of the modified surfaces at increasing concentrations of the divalent metal ions separately. The goal of this study has been to examine the effect of metal ion binding by similar ligands that are differently attached onto the surface. TG and DTT monolayers differ in their flexibility, which is a result of their attachment to the surface through one and two arms, respectively. The general trend of the apparent heterogeneous association constants of the divalent metal ions, which were calculated from the capacity measurements, was substantially different from the classical Irving-Williams series that is applicable to homogeneous systems. This difference could be nicely explained by the reduction of the degree of freedom and flexibility of the attached ligands.[on SciFinder (R)]
Kraus S, Mandler D. Complexation of ferrous and cupric ions by phenanthroline and terpyridine langmuir films. LangmuirLangmuir : the ACS journal of surfaces and colloids. 2006;22 (18) :7462 - 4.Abstract
The complexation of Fe(II) and Cu(II) ions by phenanthroline and terpyridine-based Langmuir films was studied by the effect the added ions in the subphase on the isotherms. We found that Cu(II) had a pronounced effect on the isotherm consisting of phenanthroline moieties forming a square-planar 1:2 (Cu(II)/phenanthroline) complex. However, Fe(II) affected the isotherm made of 1:1 phenanthroline/terpyridine amphiphiles as a result of forming a pentacoordinate complex.[on SciFinder (R)]
Shustak G, Domb AJ, Mandler D. n-Alkanoic acid monolayers on 316L stainless steel promote the adhesion of electropolymerized polypyrrole films. LangmuirLangmuir : the ACS journal of surfaces and colloids. 2006;22 (12) :5237 - 40.Abstract
The formation of a self-assembled monolayer significantly promotes the adhesion of electrodeposited polypyrrole on stainless steel. The monolayer affects the nucleation and growth mechanism of polypyrrole as a result of its hydrophobic nature. This was confirmed by analyzing current-time transients of the initial stages of electropolymerization and was in agreement with AFM images.[on SciFinder (R)]
Cohen-Atiya M, Mandler D. Studying electron transfer through alkanethiol self-assembled monolayers on a hanging mercury drop electrode using potentiometric measurements. Phys Chem Chem PhysPhysical chemistry chemical physics : PCCP. 2006;8 (38) :4405 - 9.Abstract
A new approach based on measuring the change of the open-circuit potential (OCP) of a hanging mercury drop electrode (HMDE), modified with alkanethiols of different chain length conducted in a solution containing a mixture of Ru(NH3)6(2+) and Ru(NH3)6(3+) is used for studying electron transfer across the monolayer. Following the time dependence of the OCP allowed the extraction of the kinetic parameters, such as the charge transfer resistance (R(ct)) and the electron transfer rate constant (k(et)), for different alkanethiol monolayers. An electron tunneling coefficient, beta, of 0.9 A(-1) was calculated for the monolayers on Hg.[on SciFinder (R)]
Cohen-Atiya M, Nelson A, Mandler D. Characterization of n-alkanethiol self-assembled monolayers on mercury by impedance spectroscopy and potentiometric measurements. J. Electroanal. Chem.Journal of Electroanalytical Chemistry. 2006;593 (1-2) :227 - 240.Abstract
Long chain n-alkanethiol self-assembled monolayers (SAMs) on a hanging Hg drop electrode were studied in detail for the 1st time by impedance spectroscopy (IS) and potentiometry. IS reveals the detailed behavior of the monolayers in the absence and presence of 2 1-electron redox couple: hexaammineruthenium(III) (Ru(NH3)63+) and tris(2,2'-bipyridine)cobalt(III) (Co(bpy)33+). The pinholes-free layers behave as almost ideal capacitors and are permeable to some extent to redox species, depending on their hydrophobicity. Co(bpy)33+ that exhibits sluggish kinetics on a bare Hg electrode reveals a more facile kinetics than Ru(NH3)63+ on an n-octadecanethiol/Hg interface. Potentiometric measurements recorded upon immersing the bare and SAM modified Hg electrode into a soln. contg. a mixt. of the oxidized and reduced forms of the redox couples provide invaluable information on the charge transfer across the monolayer and its ohmic resistance. While Ru(NH3)63+ cannot freely penetrate into the monolayer and therefore establishes a p.d. across the monolayer; penetration of Co(bpy)32+ into the film causes the Fermi level of the Hg surface to attain the Nernst potential of the soln. Finally, increasing the length of the alkane chain of the thiols increases linearly the ohmic resistance of the layer. [on SciFinder(R)]
Kraus S, Mandler D. Complexation of Ferrous and Cupric Ions by Phenanthroline and Terpyridine Langmuir Films. LangmuirLangmuir. 2006;22 (18) :7462 - 7464.Abstract
The complexation of FeII and CuII ions by phenanthroline and terpyridine-based Langmuir films was studied by the effect the added ions in the subphase on the isotherms. We found that CuII had a pronounced effect on the isotherm consisting of phenanthroline moieties forming a square-planar 1:2 (CuII/phenanthroline) complex. However, FeII affected the isotherm made of 1:1 phenanthroline/terpyridine amphiphiles as a result of forming a pentacoordinate complex. [on SciFinder(R)]
Burshtain D, Mandler D. The effect of surface attachment on ligand binding: studying the association of Mg2+, Ca2+ and Sr2+ by 1-thioglycerol and 1,4-dithiothreitol monolayers. Phys. Chem. Chem. Phys.Physical Chemistry Chemical Physics. 2006;8 (1) :158 - 164.Abstract
The difference in the heterogeneous binding of Mg2+, Ca2+ and Sr2+ ions by 1-thioglycerol (TG) and 1,4-dithiothreitol (DTT) spontaneously adsorbed monolayers on Au has been studied following the changes in the double layer capacity. A math. treatment, based on calcg. the electrochem. p.d. at the monolayer-electrolyte interface, has followed our recent work1 which dealt with the acid-base equil. at the interface as a means of calcg. the pK of ionizable SAMs and their binding with Cd2+. Exptl., spontaneously adsorbed monolayers of TG and DTT were assembled on Au surfaces and studied by impedance spectroscopy and a.c. voltammetry (ACV). The capacity was measured for each of the modified surfaces at increasing concns. of the divalent metal ions sep. The goal of this study has been to examine the effect of metal ion binding by similar ligands that are differently attached onto the surface. TG and DTT monolayers differ in their flexibility, which is a result of their attachment to the surface through one and two arms, resp. The general trend of the apparent heterogeneous assocn. consts. of the divalent metal ions, which were calcd. from the capacity measurements, was substantially different from the classical Irving-Williams series2-4 that is applicable to homogeneous systems. This difference could be nicely explained by the redn. of the degree of freedom and flexibility of the attached ligands. [on SciFinder(R)]
Domb AJ, Mandler D, Danziger I, Orom M, Okner R, Shustak G, Swed A, Tal N.; 2006. Modified conductive surfaces having active substances attached thereto and uses thereof.Abstract
Novel processes for coating metal surfaces and/or for attaching active substances to metal surfaces, objects having coated metal surfaces and/or active substances attached thereto and uses thereof in the prepn. of implantable devices are disclosed. Thus, cyclic voltammetry of a stainless steel electrode in an acetonitrile soln. contg. 0.1 mM decanoic acid was performed to give a self-assembled monolayer on the electrode, showing advancing contact angle 59° and receding contact angle 45°. [on SciFinder(R)]
Shustak G, Domb AJ, Mandler D. n-Alkanoic Acid Monolayers on 316L Stainless Steel Promote the Adhesion of Electropolymerized Polypyrrole Films. LangmuirLangmuir. 2006;22 (12) :5237 - 5240.Abstract
The formation of a self-assembled monolayer significantly promotes the adhesion of electrodeposited polypyrrole on stainless steel. The monolayer affects the nucleation and growth mechanism of polypyrrole of its hydrophobic nature. This was confirmed by analyzing current-time transients of the initial stages of electropolymn. and was in agreement with AFM images. [on SciFinder(R)]
Cohen-Atiya M, Mandler D. Studying electron transfer through alkanethiol self-assembled monolayers on a hanging mercury drop electrode using potentiometric measurements. Phys. Chem. Chem. Phys.Physical Chemistry Chemical Physics. 2006;8 (38) :4405 - 4409.Abstract
A new approach based on measuring the change of the open-circuit potential (OCP) of a hanging Hg drop electrode (HMDE), modified with alkanethiols of different chain length conducted in a soln. contg. a mixt. of Ru(NH3)62+ and Ru(NH3)63+ is used for studying electron transfer across the monolayer. Following the time dependence of the OCP allowed the extn. of the kinetic parameters, such as the charge transfer resistance (Rct) and the electron transfer rate const. (ket), for different alkanethiol monolayers. An electron tunneling coeff., β, of 0.9 Å-1 was calcd. for the monolayers on Hg. [on SciFinder(R)]
2005
Fireman-Shoresh S, Turyan I, Mandler D, Avnir D, Marx S. Chiral electrochemical recognition by very thin molecularly imprinted sol-gel films. LangmuirLangmuir : the ACS journal of surfaces and colloids. 2005;21 (17) :7842 - 7.Abstract
Thin films with enantioselective properties for electrochemically active chiral probes were developed. Enantioselectivity was accomplished via molecular imprinting. The films were fabricated through the sol-gel technique and were spin-coated on ITO electrodes. The chiral selectivity recognition was detected using two enantiomer pairs: D- and L-3,4-dihydroxyphenylalanine (D- and L-dopa) and (R)- and (S)-N,N'-dimethylferrocenylethylamine [(R)-Fc and (S)-Fc]. A defined chiral cavity was obtained by selection of functional monomers that interact with the template molecule, followed by its removal. Chiral selection properties were measured by cyclic voltammetry and square wave voltammetry. For both template molecules, very good chiral recognition was revealed by electrochemical measurement. The nonspecific adsorption measured for reference nonimprinted films was negligible (less than 5%). Dopa imprinted films revealed both high sensitivity, by the detection of 1 nM (0.2 ppb) concentration, and excellent selectivity, when challenged with a series of catechol derivatives. Fc-imprinted films were able to detect ca. 2 ppm of the target molecule, with very good enantioselectivity and low nonspecific adsorption. To our knowledge, this is the first report of successful molecular imprinting of a ferrocene derivative.[on SciFinder (R)]
Mandler D. Daniel Mandler, Hebrew University of Jerusalem. AnalystThe Analyst. 2005;130 (2) :131 - 3.
Burt DP, Cervera J, Mandler D, Macpherson JV, Manzanares JA, Unwin PR. Scanning electrochemical microscopy as a probe of Ag+ binding kinetics at Langmuir phospholipid monolayers. Phys Chem Chem PhysPhysical chemistry chemical physics : PCCP. 2005;7 (15) :2955 - 64.Abstract
A new method has been developed for measuring local adsorption rates of metal ions at interfaces based on scanning electrochemical microscopy (SECM). The technique is illustrated with the example of Ag+ binding at Langmuir phospholipid monolayers formed at the water/air interface. Specifically, an inverted 25 microm diameter silver disc ultramicroelectrode (UME) was positioned in the subphase of a Langmuir trough, close to a dipalmitoyl phosphatidic acid (DPPA) monolayer, and used to generate Ag+ via Ag electro-oxidation. The method involved measuring the transient current-time response at the UME when the electrode was switched to a potential to electrogenerate Ag+. Since the Ag+/Ag couple is reversible, the response is highly sensitive to local mass transfer of Ag+ away from the electrode, which, in turn, is governed by the interaction of Ag+ with the monolayer. The methodology has been used to determine the influence of surface pressure on the adsorption of Ag+ ions at a phospholipid (dipalmitoyl phosphatidic acid) Langmuir monolayer. It is shown that the capacity for metal ion adsorption at the monolayer increased as the density of surface adsorption sites increased (by increasing the surface pressure). A model for mass transport and adsorption in this geometry has been developed to explain and characterise the adsorption process.[on SciFinder (R)]
Avissar YY, Sagiv AE, Mandler D, Almog J. Identification of firearms handling by the [Fe(PDT)(3)](2+) complex: Chemical and time-dependent factors. TalantaTalanta. 2005;67 (2) :328 - 33.Abstract
Handling of a gun results in the formation of invisible impressions, caused by transfer of iron traces to the skin surface. Visualization of these impressions is possible by spraying the palms with a solution of 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDT), which forms a magenta complex with iron(II) residues. Hence, mark intensity is directly related to the amounts of iron transferred to the palm. Palmar sweat plays a major role in iron transfer from the firearm to the hand. More factors, however, are involved in this process. Three time-dependent factors have been studied with relation to their effect on the developed mark: the gripping duration of the weapon; the time elapsed from the contact; and the rate of iron dissolution in aqueous solutions containing sweat components in physiological concentrations. We found that the amounts of iron transferred to the palm depend on both, the gripping period and the levels of palmar moisture. Thus, only a few seconds of gripping were required for developing good marks (corresponding to 80ngcm(-2) of iron) on highly-moistured hands, much longer gripping periods were necessary for developing marks of similar intensity on relatively dry hands. Experiments that aimed at studying the effect of sweat components on metallic iron dissolution were carried out in aqueous solutions. It was found that chloride ions in physiological concentrations remarkably enhanced the dissolution, while l-serine, the major amino acid in palmar sweat, had a detrimental effect on this process. Urea, another sweat component, had only a minor effect on the dissolution rate.[on SciFinder (R)]

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