Nonbiodegradable polymer coating based on N-(2-carboxyethyl)pyrrole (PPA) and Bu ester of PPA (BuOPy) were successfully electrodeposited on a stainless steel stent surface using cyclic voltammetry. Chem. compn. of the coating was examd. by XPS. Polymer stability was examd. by immersing the coated stent into 1:1 soln. of fetal calf serum:seline soln. up to 1 yr and implantation s.c. in mouse for 1 wk. Morphol. changes were then recorded by SEM. Paclitaxel loading was carried out by immersion into drug soln. and its release was detected by HPLC. The results show that thin (single micrometers), uniform coating with various morphol. and hydrophobicity can be created by electrochem. deposition. The polymer did not show significant histopathol. or morphol. changes in vitro and in vivo. The surface properties allow loading appropriate amts. of paclitaxel and release it slowly up to a month. [on SciFinder(R)]

This invention relates to medical devices having a matrix comprising a pharmaceutically active agent, the matrix being adhered to a surface of the medical device via an adherence to modulate a release of the pharmaceutically active agent. [on SciFinder(R)]

Articles-of-manuf. (for medical devices) comprising 1 aryl moiety electrochem. attached to the surface thereof are disclosed. Further disclosed herein are novel compds. comprising an aryl moiety and substituted by at least 2 diazonium moieties, which may optionally be used to the articles-of-manuf. Stents were electro-coated with tetrakis[(4-diazophenoxy)methyl]methane tetrafluoroborate. [on SciFinder(R)]

The reactions between Ag+ and AuCl4- ions with 3 different CdTe systems, i.e., thermally evapd. thin CdTe films, CdTe nanoparticles (NPs) stabilized by thioglycolic acid (TGA), and 20 layers of these CdTe NPs embedded in poly(diallyldimethylammonium) chloride (CdTe-20lbl), were studied. AuCl4- oxidized the CdTe, in all studied systems, to form metallic Au. However, the kinetics of the reaction was substantially sluggish for the thin CdTe films than with the CdTe NPs systems. However, the reaction with Ag+ was rather complex, and the findings alluded to different reaction for each system. Although it is possible that a Ag-SR bond was formed between Ag+ and the thiol group of the TGA-stabilized NPs, cation exchange between Ag+ and Cd2+ is evidenced when these CdTe NPs were embedded in a polymer (CdTe-20lbl). Also, Ag+ reacted with thin CdTe films to form a ppt. consisting of Ag. The authors studied the reactions between locally generated Ag+ and AuCl4- and CdTe surfaces using scanning electrochem. microscopy (SECM). A flux of Ag and Au chloride ions was electrochem. generated from their resp. microelectrodes upon applying a pos. potential close to thin CdTe films and CdTe-20lbl. The flux of AuCl4- resulted in the local formation of Au NPs on the CdTe surface, whereas local quenching of CdTe-20lbl was achieved by the flux of Ag+ ions. Finally, the current transients recorded during the SECM expts. provided invaluable information regarding the reactions at the CdTe surface below the microelectrodes. [on SciFinder(R)]

The etching of thin Cu films by scanning electrochem. microscopy (SECM) was studied. It is not trivial that locally injected charge by an oxidized mediator will lead to dissoln. of Cu as the charge can easily be dissipated by lateral charge propagation. The authors studied the effect of different parameters, such as thickness of the Cu film and concn. of the mediator, on the efficiency of etching. The feedback current is the sum of 3 charge transfer contributions: diffusion of mediator species, chem. reaction on the surface and lateral charge propagation across the Cu film. The authors have introduced an approach for isolating the lateral contribution and studied the parameters affecting the fate of the locally injected charge. Etching becomes effective once the lateral contribution cannot dissipate the locally injected charge. This occurs as the concn. of the etchant increases or the film thickness decreases. Measuring the steady-state current above Cu films with different thickness, allowed estg. the p.d. across the Cu area underneath the tip. Driving local processes, such as etching, depends on creating a mechanism which maintains the injected charge focused. [on SciFinder(R)]

Local and bulk deposition of gold particles was accomplished by the spontaneous reaction between chem. reduced polyaniline (PAN) thin films and AuCl4-. PAN layers were deposited on glass, ITO, and glassy C (GC) by the Langmuir-Blodgett method and spin-coating. Characterization of the PAN films was carried out by microscopy, UV-vis spectroscopy, and electrochem. The nature of the Au deposit was greatly affected by the thickness of the PAN. Scanning electrochem. microscopy was used as a means of locally depositing Au nanoparticles on an unbiased PAN film by anodically dissolving a Au microelectrode. This represents a generic approach whereby a variety of metal micro- and nanoparticles can be locally deposited on insulating supports. [on SciFinder(R)]

Two different types of nanoparticles dissolved in organic solution, gold stabilized by n-alkanethiols and CdSe/ZnS stabilized by n-alkane-amine, adhere preferentially to the ridges of latent fingerprints; the gold deposits catalyze silver electroless deposition from "Silver Physical Developer" (Ag-PD), an aqueous solution containing silver colloids stabilized by cationic surfactants, to form dark impressions of the ridge details; the hydrophobic capped gold nanoparticles significantly improve the intensity and clarity of the developed prints compared with Ag-PD alone; finger marks treated with CdSe/ZnS nanoparticles can be viewed directly, due to their fluorescence under UV illumination.[on SciFinder (R)]

Organic coatings based on N-(2-carboxyethyl)pyrrole (PPA) and a butyl ester of PPA (BuOPy) were deposited via electrochemical oxidation. The homo- and copolymers were electropolymerized on glassy carbon and stainless steel in acetonitrile using tetrabutylammonium tetrafluoraborate (Bu4NF4B) as the electrolyte. The mechanism of deposition on stainless steel was studied by chronoamperometry and by the tapping and phase angle imaging modes of atomic force microscopy. The electrochemical properties and growth of the films were investigated by cyclic voltammetry. The composition of the copolymers was determined by reflection-absorption Fourier transform infrared spectroscopy. We found that while the hydrophilic monomer PPA undergoes progressive nucleation followed by instantaneous growth the hydrophobic BuOPy nucleates instantaneously. The rate of BuOPy electropolymerization was higher than that of PPA, and the resulting film was thicker yet fluffier. Copolymer films were enriched by BuOPy as compared with the electropolymerization solution, which is attributed to the faster rate of electropolymerization of BuOPy than PPA.[on SciFinder (R)]

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 positively charged SAM and the negatively charged PLA nanoparticles. The strategy used involves two steps in which a preliminary electrochemical coating of the ADA SAM is followed by a second step that involves immersing the SAM in a solution containing gold or PLA nanoparticles. The SAM was characterized by using cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), FTIR spectroscopy, and contact angle measurements, whereas scanning electron microscopy (SEM) was used to image the nanoparticles after electrostatic attachment was achieved. We found that the surface coverage of the nanoparticles could be controlled by modulating the electrostatic interactions between the negatively charged particles and the positively charged SAM surface by varying the pH of the nanoparticle solution, the immersion time, and the number of cyclic voltammetry scans under which the SAM was formed.[on SciFinder (R)]

Two different types of nanoparticles dissolved in org. soln., Au stabilized by n-alkanethiols and CdSe/ZnS stabilized by n-alkaneamine, adhere preferentially to the ridges of latent fingerprints,. The gold deposits catalyze silver electroless deposition from "Silver Phys. Developer" (Ag-PD), an aq. soln. contg. silver colloids stabilized by cationic surfactants, to form dark impressions of the ridge details. The hydrophobic capped gold nanoparticles significantly improve the intensity and clarity of the developed prints compared with Ag-PD alone. Fingermarks treated with CdSe/ZnS nanoparticles can be viewed directly, due to their fluorescence under UV illumination. [on SciFinder(R)]

The purpose of this study was to examine chem., mech. and Paclitaxel release properties of the new coating onto the stainless steel coronary stents. Stainless steel coronary stents were coated with elec. polymerizable pyrrole deriv., applying cyclic voltammetry technique in a simple 3 electrode cell, while stent represented a working electrode. Resulted polymer coating were examd. by cyclic voltammetry (elec. parameters), SEM (morphol. images), goniometer (hydrophobisity of the surface), profilometer ( thickness of the polymer coating). Polymer stability was examd. by placing the coated stent into 1:1 soln. of fetal calf serum:seline soln. up to 1 yr and under the mouse skin for 1 wk. Paclitaxel loading were carried out by immersion into drug soln. and its release was detected by HPLC. Reproducible one step method for coating different pyrrole derivs. on stainless steel coronary stents provided thin (single micrometers), uniform coating with various morphol. and hydrophobisity. These surface properties allow to load appropriate amt. of Paclitaxel and to release it slowly up to a month. [on SciFinder(R)]

Nanoparticles having reactive pyrrole residues were prepd. from poly(1-ethoxyethyl glycidyl ether)-block-poly(L,L-lactide) block copolymer. The nanoparticles were electropolymd. in aq. media through the oxidn. of the pyrrole residue and in the presence of pyrrole to form a nanocomposite thin film. The novel synthesis of these pyrrole-functionalized nanoparticles is described and the electrochem. deposition of the corresponding coating is characterized using electrochem., SEM and EDX. [on SciFinder(R)]

The formation and characterization of nanometer thick sol-gel films are reported. The films were prepd. by spin-coating of a dild. soln. of a silane precursor on a no. of different substrates. The effect of diln., rotation speed and nature of substrate on the thickness and homogeneity of the films was examd. Characterization of the films was carried out by profilometry, reflectance spectroscopy, at. force microscopy, adhesion test and electrochem. We find that the diln. factor has a pronounced effect on the film thickness. Moreover, the time of diln., namely, whether diln. was carried out before or after a period of hydrolysis, has a noticeable effect on the thickness as well as on the permeability of embedded species. [on SciFinder(R)]

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)]

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)]

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)]

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)]

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)]

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)]

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)]