Poly(ethylene glycol) (PEG) was modified with 3-isocyanatopropyltriethoxysilane (IPTS) to obtain PEG-disilane. This monomer was electrochem. polymd. and deposited onto a stainless steel surface to form a thin PEGylated sol-gel film. The monomer was characterized by 1H-NMR and FTIR spectroscopy. The sol-gel film was characterized by absorption-reflection IR spectroscopy (AR-FTIR), energy dispersive X-ray anal. (EDX), cyclic voltammetry (CV), profilometry, SEM and potentiodynamic polarization. AR-FTIR confirmed the formation of a polymer, while the stability of the polymeric film on stainless steel in buffer phosphate was studied by SEM. The polymer was successfully electrodeposited onto 316L coronary stents. Its flexibility was examd. by dilating the coated stents and inspecting it by SEM. The hydrophilic, smooth PEGylated sol-gel coating significantly reduced the activation and adhesion of platelets as compared with the bare stainless steel surface. This coating, which can be applied to complex geometries, such as stents, is likely to serve as an excellent biomaterial. [on SciFinder(R)]

Drug-eluting stents (DES) revolutionized cardiovascular treatment by virtually eliminating in-stent restenosis. However, in the past 3 years the U.S. Food and Drug Administration and published studies have raised several safety issues regarding DES such as late state thrombosis and increased mortality. Recent publications have described DES coating delaminating, cracking, and peeling in com. available stents. It has been suggested that these properties are responsible for the deleterious effects. The goal of this work is to describe a quant. in vitro durability tests for DES, referred to as Quantified Defects (QD). The technique was implemented on various stent polymer-coated models to det. its ability to differentiate between coating properties. Stents' coating defects were tested using light microscopy, SEM, and a micro-balance. High-performance liq. chromatog. was used for measuring drug release. Stents were incubated at either 37° or 60° and sampled at 0, 3, and 30 days. Stent coating durability was tested using stainless steel control stents vs. stents having increased surface adhesion, both of which were then coated with conventional spray-coating methods. Drug-coated stents tested for defects demonstrated a deteriorating durability profile as reflected by QD indexes. Different coating models showed unique QD indexes that reflected their superior or inferior coating durability. These results indicated that the methodol. was able to differentiate between different models. In conclusion, this simple low-cost testing methodol. can be easily used during DES development, with either durable or biodegradable polymers. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009. [on SciFinder(R)]

A novel method for monitoring heavy metals in seawater is presented. The method is based on the electrochem. codeposition of metal hydroxides driven by the change of pH at the surface of a gold electrode. Altering the pH is achieved by applying a neg. potential or current that reduces the water and thereby increases the concn. of hydroxyl ions. This, in turn, causes metals to coppt. with Mg(OH)2. The continuous deposition enriches the ppt. with the metals (as compared with their concn. in the aq. phase) and allows their detn. by ICP-MS upon dissolving the deposit. A set of expts. in which seawater was spiked with 1-10 ppm of Cu, Cr, Co, Zn and Pb, was conducted. It was obsd. that metals were accumulated in the ppt. as a function of time and their concn. in seawater. The ppts. were analyzed by SEM, EDS and XPS indicating that the metal hydroxides formed a sep. phase from Mg(OH)2 and even water electroreducible metals, e.g., Cu2+, preferentially pptd. as hydroxides. Distribution consts. correlating the concns. of the metals in the deposited salts to their concns. in seawater were calcd. These calcns. imply that the mechanism governing the pptn. of the metal hydroxides by the electrochem. induced process is likely to be kinetically and mass-transport driven rather than thermodynamically controlled. [on SciFinder(R)]

Milk is one of the most fundamental ingredients in our diet. It is a complex biol. fluid, which contains numerous substances, ranging from metal ions to enzymes. There is a const. search for an improved way of monitoring its quality and freshness. These are highly affected by the redox state of milk, which is governed by different species. In this study, we investigated the redox state and capacity of milk. Specifically, milk was potentiometrically titrated using different redox mediators, which enabled facilitation of electron transfer between different oxidizable species and the electrode. We found that the iodine/iodide redox couple was superior for measuring the redox capacity of milk. These measurements revealed that milk is not a well-poised system due to the presence of at least two different oxidizable species, one of which is hydrophobic while the other is hydrophilic and therefore could be sepd. by phase sepn. of milk. [on SciFinder(R)]

The deposition and characterization of Langmuir-Blodgett (LB) layers of polyaniline (PAN) on solid supports is described. Langmuir films were spread as a mixt. of PAN and dodecylbenzenesulfonic acid (DBSA) at the water/air interface and deposited on either glass or indium tin oxide (ITO). Mono- and multi-layer films of PAN/DBSA were characterized by XPS, at. force microscopy (AFM), absorption spectroscopy and cyclic voltammetry (CV). The ultrathin films produced are highly uniform and very stable. Further characterization of the films was accomplished by scanning electrochem. microscopy (SECM) in the feedback mode. The cond. depended strongly on the pH of the soln. and the no. of layers deposited. Values for the pH-dependent lateral cond. of PAN LB films are reported. [on SciFinder(R)]

Drug-eluting stents (DESs) have been assocd. with adverse clin. effects. Moreover, recent publications have shown that the coating of DESs suffers from defects. The purpose of this contribution is to examine a three-step process for surface modification as a means of improving the durability of DESs. In the first step, 4-(2-bromoethyl)benzenediazonium tetrafluoroborate was electrografted onto a stainless steel (SS) stent. XPS of the modified stent confirmed the formation of the org. layer. In the second step, Me methacrylate was polymd. onto the grafted surface by atom-transfer radical polymn. XPS, electrochem. impedance spectroscopy, and contact-angle measurements were used to characterize the polymer brushes. The last step involved spray-coating of the stent with a drug-in-polymer matrix [poly(Bu methacrylate)/poly(ethylene-co-vinyl acetate) + paclitaxel]. SEM confirmed the considerably improved durability of the drug-in-polymer matrix. Bare controls showed greater cracking and delamination of the coating than did the two-step modified stents after incubation under physiol. (37°) and accelerated (60°) conditions. Finally, paclitaxel controlled release from the modified SS DESs was moderate compared with that of nontreated samples. In conclusion, the proposed method significantly improves the durability of drug-in-polymer matrixes on a SS DESs. [on SciFinder(R)]

The inhibition of Mg (AZ91D) corrosion by thin sol-gel films was studied. The sol-gel films were prepd. by the traditional acid or base-catalyzed hydrolysis and condensation, and finally deposited by dip coating. Two different sol-gel monomers were used: phenyltrimethoxysilane (PTMOS) and Zr(IV) tetra-1-propoxide (ZrTPO). Films were made of each of the individual monomers and by depositing 1st a PTMOS film followed by ZrTPO-based film. The corrosion inhibition of the films and their characterization were examd. by different methods including potentiodynamic polarization, contact angle measurement, adhesion test, XPS, SEM and electrochem. impedance spectroscopy (EIS). While the ZrTPO-based film did not show a significant corrosion inhibition, the PTMOS-based film provided moderate protection. The combined film exhibited superior corrosion inhibition as compared with the other films. [on SciFinder(R)]

The invention provides a new method for the electrochem. co-deposition of sol-gel and one or more additives selected amongst a great variety of agents such as monomers, oligomers, polymers, metals and others. The method affords continuous films of high stability and precision. [on SciFinder(R)]

The aim of this study is to locally deposit nanoparticles on an unbiased surface by electroless deposition (ED) using scanning electrochem. microscopy (SECM). We have developed an ED process that is based on the redn. of gold ions by hydroquinone (H2Q) and catalyzed by a metallic surface, such as palladium. One of the advantages of this system is the ability to drive the ED at pH 1-7. The metal ions were electrogenerated in a soln. consisting of H2Q and KCl by anodic dissoln. of a gold microelectrode. AuCl4- reacted with H2Q at the electrolyte/metallic interface to form benzoquinone and gold deposit. The ED was studied initially in bulk soln. contg. KCl, H2Q, and HAuCl4, and then by SECM. We found that the pH had a significant effect on the nature of the deposited gold and could be correlated with the kinetics of gold ions redn. by H2Q. Hence, either nanoparticles or much larger crystals could be formed, depending on the pH of the deposition soln. Time of deposition and H2Q concn. also affected the shape and d. of the deposition. [on SciFinder(R)]

An approach for patterning surface with different structures in a single step is demonstrated. The approach is based on the construction of nondisk shape microelectrodes combined with the feedback mode of scanning electrochem. microscopy (SECM) for generating an anisotropic flux of electroactive species. The latter attains the shape of the microelectrode and imprints its shape upon reaction with the surface. The authors have demonstrated this approach in two model systems. The etching of GaAs using electrogenerated bromine resulted in the formation of etching structures imprinting the shape of the Pt microelectrode on the GaAs. The second system comprised the electrogeneration of silver ions from a silver microelectrode, which reacted with a copper surface causing the deposition of silver patterns matching the shape of the silver microelectrode. SECM tips with different shapes were constructed by different methods, including electron-beam lithog. [on SciFinder(R)]

This work describes attempts to develop a new type of modified electrode with high selectivity for uranyl ions, UO22+. The goal was addressed by binding derivs. of calix[6]arene, a macrocyclic mol. composed of 6 phenol units known as a super uranophile, to the electrode surface. Selective extn. of UO22+ onto the electrode surface, followed by a voltammetric measurement provides a quant. uranyl anal. The initial approach to binding calix[6]arene mols. onto electrodes involved an ionic deriv., 4-sulfonic-calix[6]arene, electrostatically attached to a pos.-charged, self-assembled monolayer of cysteamine (2-aminoethanethiol) on a Au electrode. Attachment of the 4-sulfonic-calix[6]arene to the cysteamine monolayer was verified by XPS, IR spectroscopy, and capacitance measurements. Voltammetric expts. showed UO22+ can be pre-concd. and measured using these modified electrodes. [on SciFinder(R)]

A single-step method for the prepn. of thin sol-gel/Cu mixed films is described, which is based on a novel electrochem. sol-gel methodol., resulting in nanocomposite coating. The method combines electrochem. with the acceleration of sol-gel hydrolysis and condensation processes. While sol-gel is deposited of increasing the pH in the vicinity of the electrode surface, Cu ions are electrochem. reduced. Characterization of the deposited films was accomplished by SEM, XPS, tunneling at. force microscopy, and other surface techniques. The different parameters that affect the structure and compn. of the deposited films were examd. The morphol. and grain size of the films are strongly affected by the ratio between the sol-gel monomer and Cu ions. Also, the potential of deposition affects also the compn. of the films as it controls the kinetics of sol-gel and Cu deposition. [on SciFinder(R)]

The application of 1,9-nonanedithiol (NDT) self-assembled monolayer (SAM) on gold for the electrochem. detn. of Cd2+ was studied. A NDT SAM strongly affects the stripping wave of Cd, resulting in a sharp peak that was used for electroanal. detn. of Cd2+ in aq. solns. The different parameters, such as potential and time of deposition of Cd, were examd. Also, polarization-modulated IR reflection absorption spectroscopy (PM IRRAS) and XPS were used for exploring the interaction between the deposited Cd and the thiol groups on Au. FTIR measurements clearly indicate that NDT is assembled in a disordered liq. type monolayer interacting with the Au electrode via both thiol moieties. XPS reveals that Cd is stripped at two different potentials and that the signal of sulfur is almost unchanged by deposition and desorption of Cd. All these finding allude to the interesting conclusion that Cd is deposited on Au lifting to some extent the thiol groups. [on SciFinder(R)]