The Langmuir-Blodgett (LB) method was used to deposit multilayers of polyaniline (PANI)- and mercaptoethanesulfonate (MES)-stabilized Au nanoparticles. The electrostatic interaction between the negatively charged nanoparticles in the subphase and the positively charged PANI at the air-water interface assisted the deposition of the nanocomposite film onto a solid support. These PANI/Au-NPs films were characterized using cyclic voltammetry, copper under potential deposition, scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. We found that the nanocomposite layers were uniform and reproducible. The density of Au-NPs in the monolayer depended on the acidity of the subphase as well as on the nanoparticles concentration. Moreover, the Au-NPs extrude above the PANI and therefore could be used as nanoelectrodes for the underpotential deposition (UPD) of copper.[on SciFinder (R)]

The Langmuir-Blodgett (LB) method was used to deposit multilayers of polyaniline (PANI)- and mercaptoethanesulfonate (MES)-stabilized Au nanoparticles. The electrostatic interaction between the neg. charged nanoparticles in the subphase and the pos. charged PANI at the air-H2O interface assisted the deposition of the nanocomposite film onto a solid support. These PANI/Au-NPs films were characterized using cyclic voltammetry, Cu underpotential deposition, SEM, at. force microscopy, and XPS. The nanocomposite layers were uniform and reproducible. The d. of Au-NPs in the monolayer depended on the acidity of the subphase as well as on the nanoparticles concn. Also, the Au-NPs extrude above the PANI and therefore could be used as nanoelectrodes for the underpotential deposition (UPD) of Cu. [on SciFinder(R)]

Local and bulk deposition of Au particles was accomplished by the spontaneous reaction between chem. reduced polyaniline (PAN) thin films and AuCl4- ions. PAN layers were electrodeposited on glassy C (GC). Characterization of the PAN films was carried out by microscopy and electrochem. Local deposition of Au particles was performed by scanning electrochem. microscopy, where a Au microelectrode was used to produce a flux of Au ions in close vicinity to an unbiased PAN film. The nature of the Au particles was greatly affected by the potential applied at the microelectrode as well as the oxidn. state of the PAN films. [on SciFinder(R)]

Drug-eluting stents (DES) have become an accepted technology in intravascular intervention. Manufacturing methodologies of DES are based mainly on mechanical processes, which tend to generate coatings that have poor stability properties; these were recently related as a potential hazard. A novel approach for significantly increasing the adhesion of polymer coatings onto DES is presented. The method is based on the electrochemistry of diazonium salts. These substances are organic compounds with the characteristic structure of R-N(2) (+) X(-), where R is an organic residue and X(-) is an anion. The objective of this article is to study the properties of a selected diazonium salt 4-(1-dodecyloxy)-phenyldiazonium tetrafluoroborate, referred as C(12)-phenyldiazonium. This material was found to be a superior adhesive promoter for polymeric coatings applied onto metallic stents. C(12)-phenyldiazonium was synthesized and electrocoated on metallic stents and plates. The multilayer films of C(12)-phenyldiazonium were further characterized through electrochemical (cyclic voltammetry, impedance spectroscopy), physical (light and scanning electron microscopy, X-ray photoelectron spectroscopy, peeling tests), and chemical methodology (high pressure liquid chromatography). Further biocompatibility properties of the electrocoated basecoat were evaluated using in vitro and in vivo models. Synthesized C(12)-phenyldiazonium was successfully electrocoated onto metallic surfaces. Electrochemical tests demonstrated its efficient and controllable electrocoating. C(12)-phenyldiazonium was found to increase polymeric coating stability as was reflected by a standard adhesion test. Electrocoated metallic stents spray-coated with a second polymeric film showed improved durability following incubation in physiological buffer. Furthermore, this improvement in durability exhibits stabilized drug release. In addition, biocompatibility evaluations have demonstrated basecoat’s inert properties.[on SciFinder (R)]

Drug-eluting stents (DES) have become an accepted technol. in intravascular intervention. Manufg. methodologies of DES are based mainly on mech. processes, which tend to generate coatings that have poor stability properties; these were recently related as a potential hazard. A novel approach for significantly increasing the adhesion of polymer coatings onto DES is presented. The method is based on the electrochem. of diazonium salts. These substances are org. compds. with the characteristic structure of R-N X-, where R is an org. residue and X- is an anion. The objective of this article is to study the properties of a selected diazonium salt 4-(1-dodecyloxy)-phenyldiazonium tetrafluoroborate, referred as C12-phenyldiazonium. This material was found to be a superior adhesive promoter for polymeric coatings applied onto metallic stents. C12-phenyldiazonium was synthesized and electrocoated on metallic stents and plates. The multilayer films of C12-phenyldiazonium were further characterized through electrochem. (cyclic voltammetry, impedance spectroscopy), phys. (light and SEM, XPS, peeling tests), and chem. methodol. (high pressure liq. chromatog.). Further biocompatibility properties of the electrocoated basecoat were evaluated using in vitro and in vivo models. Synthesized C12-phenyldiazonium was successfully electrocoated onto metallic surfaces. Electrochem. tests demonstrated its efficient and controllable electrocoating. C12-phenyldiazonium was found to increase polymeric coating stability as was reflected by a std. adhesion test. Electrocoated metallic stents spray-coated with a second polymeric film showed improved durability following incubation in physiol. buffer. Furthermore, this improvement in durability exhibits stabilized drug release. In addn., biocompatibility evaluations have demonstrated basecoat’s inert properties. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009. [on SciFinder(R)]

Uranyl, UO(2)(2+), was electrochemically determined by a phosphate based self-assembled monolayer. A pretreated gold electrode with 2-mercatpoethanol was chemically modified by POCl(3) or POBr(3) to obtain the surface phosphate active sites. The different stages were characterized by reflection-absorption Fourier transform-infrared (FT-IR) spectroscopy, capacity, and X-ray photoelectron spectroscopy (XPS). The electrochemical determination of UO(2)(2+) was accomplished, after preconcentration under open circuit potential, by square wave voltammetry.[on SciFinder (R)]

Uranyl, UO22+, was electrochem. detd. by a phosphate based self-assembled monolayer. A pretreated Au electrode with 2-mercatpoethanol was chem. modified by POCl3 or POBr3 to obtain the surface phosphate active sites. The different stages were characterized by reflection-absorption FTIR spectroscopy, capacity, and XPS. The electrochem. detn. of UO22+ was accomplished, after preconcn. under open circuit potential, by square wave voltammetry. [on SciFinder(R)]

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)]

Nonbiodegradable polymer coating based on N-(2-carboxyethyl)pyrrole (PPA) and butyl ester of PPA (BuOPy) were successfully electrodeposited on a stainless steel stent surface using cyclic voltammetry. Chemical composition of the coating was examined by X-ray photoelectron spectroscopy. Polymer stability was examined by immersing the coated stent into 1:1 solution of fetal calf serum:seline solution up to 1 year and implantation subcutaneously in mouse for 1 week. Morphology changes were then recorded by scanning electron microscopy. Paclitaxel loading was carried out by immersion into drug solution and its release was detected by HPLC. The results show that thin (single micrometers), uniform coating with various morphology and hydrophobicity can be created by electrochemical deposition. The polymer did not show significant histopathological or morphological changes in vitro and in vivo. The surface properties allow loading appropriate amounts of paclitaxel and release it slowly up to a month.[on SciFinder (R)]

The coating of medical implants by polymeric films aims at increasing their biocompatibility as well as providing a durable matrix for the controlled release of a drug. In many cases, the coating is divided into a primer layer, which bridges between the medical implant and the drug-eluting matrix. The primer coating must be very carefully designed in order to provide optimal interactions with the surface of the medical implant and the outer layer. Here we present a simple and versatile approach for designing the primer layer based on electropolymn. of a carefully chosen blend of three different pyrrole derivs.: N-methylpyrrole (N-me), N-(2-carboxyethyl)pyrrole (PPA), and the Bu ester of N-(2-carboxyethyl)pyrrole (BuOPy). The compn. and phys. properties of the primer layer were studied in detail by at. force microscopy (AFM) and a nano scratch tester. The latter provides the in-depth anal. of the adhesion and viscoelasticity of the coating. AFM phase imaging reveals a uniform distribution of the three monomers forming rough morphol. This primer layer significantly improved the morphol., stability, and paclitaxel release profile of a paclitaxel-eluting matrix based on Me and lauryl methacrylates. [on SciFinder(R)]

The coating of medical implants by polymeric films aims at increasing their biocompatibility as well as providing a durable matrix for the controlled release of a drug. In many cases, the coating is divided into a primer layer, which bridges between the medical implant and the drug-eluting matrix. The primer coating must be very carefully designed in order to provide optimal interactions with the surface of the medical implant and the outer layer. Here we present a simple and versatile approach for designing the primer layer based on electropolymerization of a carefully chosen blend of three different pyrrole derivatives: N-methylpyrrole (N-me), N-(2-carboxyethyl)pyrrole (PPA), and the butyl ester of N-(2-carboxyethyl)pyrrole (BuOPy). The composition and physical properties of the primer layer were studied in detail by atomic force microscopy (AFM) and a nano scratch tester. The latter provides the in-depth analysis of the adhesion and viscoelasticity of the coating. AFM phase imaging reveals a uniform distribution of the three monomers forming rough morphology. This primer layer significantly improved the morphology, stability, and paclitaxel release profile of a paclitaxel-eluting matrix based on methyl and lauryl methacrylates.[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)]

Drug-eluting stents (DES) revolutionized cardiovascular treatment by virtually eliminating in-stent restanosis. 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 commercially available stents. It has been suggested that these properties are responsible for the deleterious effects. The goal of this work is to describe a quantitative in vitro durability tests for DES, referred to as Quantified Defects (QD). The technique was implemented on various stent polymer-coated models to determine its ability to differentiate between coating properties. Stents’ coating defects were tested using light microscopy, scanning electron microscopy, and a micro-balance. High-performance liquid chromatography was used for measuring drug release. Stents were incubated at either 37 or 60 degrees C and sampled at 0, 3, and 30 days. Stent coating durability was tested using stainless steel control stents versus 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 indices. Different coating models showed unique QD indices that reflected their superior or inferior coating durability. These results indicated that the methodology was able to differentiate between different models. In conclusion, this simple low-cost testing methodology can be easily used during DES development, with either durable or biodegradable polymers.[on SciFinder (R)]