Toledano R, Mandler D
. Electrochemical Codeposition of Thin Gold Nanoparticles/Sol-Gel Nanocomposite Films.
Chem. Mater.Chemistry of Materials. 2010;22 (13) :3943 - 3951.Abstract
The authors present a new method for deposition of thin nanocomposite films made of sol-gel-based Au nanoparticles using a single electrochem. step. Applying a neg. potential to an electrode (indium Sn oxide or stainless steel) immersed in a soln. of Au nanoparticles stabilized with N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDAS) caused the redn. of the protic solvent, which altered the pH and therefore catalyzed the deposition. The nanocomposite thin films were characterized by various techniques: the morphol. and structure of the layers were examd. by high-resoln. SEM and at. force microscopy; their thickness was detd. by profilometry; and the permeability of the films was studied by electrochem. Homogeneous defect-free layers could be deposited only upon adding tetramethoxysilane (TMOS) to the deposition soln. Also, the applied potential, the ratio between the TMOS and the Au nanoparticles, and the type of the substrate significantly affected the aggregation and d. of the Au nanoparticles in the nanocomposite. Finally, by applying a pos. potential to the nanocomposite films the authors succeeded to electrochem. dissolve the embedded Au nanoparticles, forming holes and channels. The oxidn. treatment had a remarkable effect on the permeability of the film and exposed the electrode to faradic activity. This method seems to be of general applicability in templating of nanometer-sized objects in thin films. [on SciFinder(R)]
. Formation, Characterization, and Applications of Organic and Inorganic Nanometric Films.
Isr. J. Chem.Israel Journal of Chemistry. 2010;50 (3) :306 - 311.Abstract
A review. The formation of thin coatings based on either self-assembled monolayers or polymeric films is discussed. These coatings are used to structure surfaces and control their phys. and chem. properties. Different examples are given from our work emphasizing the advantages of monolayers and polymeric films. Finally, different approaches, which benefit from both monolayers and polymeric films, are presented. [on SciFinder(R)]
. ISRANALYTICA 2010, Tel Aviv, Israel, January 19-20, 2010.
Isr. J. Chem.Israel Journal of Chemistry. 2010;50 (3) :262 - 264.
Ginzburg-Turgeman R, Mandler D
. Nanometric thin polymeric films based on molecularly imprinted technology: towards electrochemical sensing applications.
Phys. Chem. Chem. Phys.Physical Chemistry Chemical Physics. 2010;12 (36) :11041 - 11050.Abstract
A new approach for assembling selective electrodes based on molecularly imprinted polymers (MIPs) is presented. The approach is based on the radical polymn. of a mixt. of methacrylic acid (MAA) and ethyleneglycol dimethacrylate (EGDMA) in the presence of an initiator, benzoyl peroxide (BPO) and an activator, N,N'-dimethyl-p-toluidine (DMpT) at room temp. and atm. pressure. To form nanometric thin polymeric films the polymn. soln. was spin-coated in the course of polymn. The different phys. and chem. parameters that affected the properties of the films, such as the spinning rate and the EGDMA:MAA ratio, were studied and optimized. A variety of techniques, e.g., rheoscopy, SEM, AFM, profilometry and electrochem., were used to characterize the films and the polymn. process. By optimizing the conditions very thin and reproducible films could be prepd. and imprinted. The electrochem. behavior of the films showed that they were permeable to water-sol. electroactive species providing that either polyethylene glycol or template species were added to the polymn. mixt. Finally, we demonstrated that films imprinted with ferrocenylmethyl alc. (Fc-MeOH) successfully extd. the imprinted species after their removal from MIPs. [on SciFinder(R)]
Shacham R, Mandler D, Avnir D
. Pattern recognition in oxides thin-film electrodeposition: Printed circuits.
C. R. Chim.Comptes Rendus Chimie. 2010;13 (1-2) :237 - 241.Abstract
A novel method for a low-voltage electrodeposition of insulating oxide sol-gel thin films on complex conducting patterns is described. By this method gold meshes and printed chips were selectively coated with titania and zirconia thin films. This method solves a classical problem in the thin-films world: dip-coating, spin-coating, spraying without masks-all cannot be used for selective coating of a complex conductive pattern, because these methods do not differentiate between conducting vs non-conducting areas. The newly developed method provides an electrochem. pattern recognition, which solves this problem. [on SciFinder(R)]
Levy I, Magdassi S, Mandler D
. Potential induced pH change: Towards electrochemical coating of medical implants by organic nanoparticles.
Electrochim. ActaElectrochimica Acta. 2010;55 (28) :8590 - 8594.Abstract
The electrochem. deposition of org. nanoparticles on conducting surface, such as a coronary stents, in the absence of a polymeric matrix is demonstrated. A novel approach, whereby pH-responsive org. nanoparticles coagulate on a conducting surface as a result of applying pos. potential, has been studied. Specifically, latex nanoparticles stabilized by sodium oleate in aq. solns. were deposited by applying a pos. potential that oxidized the water and caused the decrease of pH on various conducting surfaces. It was found that the applied potential, its duration and the concn. of the dispersed nanoparticles govern the deposition characteristics of the coating. This generic approach allows coating objects with complex geometries with thickness ranging from nanometers to microns and therefore can be utilized for coating medical and other devices as well as for controlling drug release. [on SciFinder(R)]
Gofberg I, Mandler D
. Preparation and comparison between different thiol-protected Au nanoparticles.
J. Nanopart. Res.Journal of Nanoparticle Research. 2010;12 (5) :1807 - 1811.Abstract
We report on the synthesis of monolayer-protected gold cluster (MPCs) in aquatic phase under different conditions. Three thiols, i.e., 2-mercaptoethanesulfonic acid (MPS), 3-mercaptopropionic acid (MPA), and cystamine (CYS) have been used as the protecting monolayer. Furthermore, we studied the effect of varying the ratio between the concns. of the protecting layer, the gold ions, and the reducing agent in the prepn. soln. Comparison was based on measuring the av. diam., stability, and size distribution of the MPCs. Best results were obtained for MPS-based MPCs and that the optimum molar concn. ratio between the protecting layer, the gold ions, and the reducing agent was 1:1:2. [on SciFinder(R)]
Kraus S, Almog J, Mandler D
. Selective complexation between a novel bowl-shaped molecule and Fe3+ or PdCl42- ions.
Inorg. Chim. ActaInorganica Chimica Acta. 2010;363 (11) :2677 - 2681.Abstract
We report the selective assocn. of a novel bipolarofacial, bowl-shaped mol. (I) with Fe3+ and PdCl42- ions. UV-vis titrn. expts. and Langmuir isotherm measurements revealed stronger assocn. with the palladate over the iron ions, both in homogeneous org. medium as well as at the air-water interface. Interestingly, we found that the complexation is solvent-dependent, suggesting that I undergoes isomerization prior to assocn. with the metal ions. [on SciFinder(R)]
Okner R, Favaro G, Radko A, Domb AJ, Mandler D
. Electrochemical codeposition of sol-gel films on stainless steel: controlling the chemical and physical coating properties of biomedical implants.
Phys. Chem. Chem. Phys.Physical Chemistry Chemical Physics. 2010;12 (46) :15265 - 15273.Abstract
The electrochem. assisted codeposition of sol-gel thin films on stainless steel is described. Specifically, electrodeposition of films based on aminopropyltriethoxysilane (APTS), and its codeposition with propyltrimethoxysilane (PrTMOS) and phenyltrimethoxysilane (PhTMOS) has been accomplished by applying neg. potentials. The latter increases the concn. of hydroxyl ions on the stainless steel surface and thus catalyzes the condensation and deposition of the sol-gel films. The films were characterized by profilometry, electrochem. impedance spectroscopy (EIS), a.c. voltammetry (ACV), goniometry, at. force microscopy (AFM) and SEM. AFM and SEM anal. of codeposited APTS:PrTMOS films disclosed the structural changes induced by altering the deposition soln. compn. and the applied potential. Codeposited APTS:PhTMOS did not show any structural differences from their electrodeposited homopolymers, while Nano Scratch Test clearly revealed the changes in the elastic and adhesion properties, suggesting the formation of an APTS:PhTMOS composite. EIS of the films showed good resistance towards penetration of hydrophilic species, such as hexacyanoferrate. ACV measurements of the homo and codeposits showed the decrease of the interfacial capacity as a result of the electrochem. deposition. In essence, controllable sol-gel films with tunable chem. and phys. properties based on controlling the combination of the precursors, pH and electrochem. properties can be electrodeposited on conducting surfaces. The application of this approach has been demonstrated by coating a stainless steel coronary stent. [on SciFinder(R)]
Lev O, Mandler D, Editors. Exciting New Directions in Electrochemistry. [In: Isr. J. Chem., 2010; 50(3)].
Wiley-VCH Verlag GmbH & Co. KGaA; 2010 pp. 136 pp.
Malel E, Ludwig R, Gorton L, Mandler D
. Localized deposition of Au nanoparticles by direct electron transfer through cellobiose dehydrogenase.
Chem. - Eur. J.Chemistry - A European Journal. 2010;16 (38) :11697 - 11706.Abstract
Cellobiose dehydrogenase (CDH) is a fascinating extracellular fungal enzyme that consists of two domains, one carrying a FAD and the other a cytochrome-type heme b group as cofactors. The two domains are interconnected by a linker, and electrons can shuttle from the FAD to the heme group by intramol. electron transfer. Electron transfer between CDH and an electrode can occur by direct electron transfer (DET) and by mediated electron transfer (MET). This characteristic makes CDH an interesting candidate for integration in systems such as biosensors and biofuel cells. Moreover, it makes CDH an alternative for the redn. of metal ions through DET and MET. In this work we have explored the localized deposition of gold on Pd substrates by CDH through DET and MET. For this purpose we exploited the advantage of scanning electrochem. microscopy (SECM) as a patterning tool. We first demonstrated that gold nanoparticles can be formed in homogeneous soln. Then we showed that Au nanoparticles can also be locally formed and deposited on surfaces through DET at low pH and by MET at neutral pH using benzoquinone/hydroquinone as mediator. [on SciFinder(R)]
Fink L, Mandler D
. Thin functionalized films on cylindrical microelectrodes for electrochemical determination of Hg(II).
J. Electroanal. Chem.Journal of Electroanalytical Chemistry. 2010;649 (1-2) :153 - 158.Abstract
Cylindrical carbon fiber microelectrodes (CFMEs) were used for the detn. of Hg(II) in aquatic solns. using anodic stripping voltammetry (ASV). Optimizing the parameters, such as the potential and time of deposition, resulted in linear response of the fiber over a large range of Hg(II) concns. (5 × 10-8 - 1 × 10-5 M). Furthermore, three methods of modification of glassy carbon and CFMEs with thiol or other Hg(II)-complexing groups, have also been examd. Electrodes were modified by electrochem. reducing 4,4'-disulfanediyldibenzenediazonium, followed by redn. of the disulfide bond, by electrodepositing sol-gel based on 3-mercaptopropyltrimethoxysilane and by spin-coating or adsorbing cellulose acetate thin films in which 4,13-didecyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane (Kryptofix 22DD) was incorporated. We found that all modified glassy carbon electrodes extd. Hg(II) under open-circuit potential, however, only the cylindrical microelectrode modified via the electrochem. redn. of the diazonium was capable of extg. mercuric ions. The interference of Pb(II), Cd(II), and Cu(II) with the detn. of Hg(II) with 4,4'-disulfanediyldibenzenediazonium modified CFME was also studied. [on SciFinder(R)]