Cell Interactions With Fibronectin-Coated Electrically Conducting Polypyrrole Thin Films

1993 ◽  
Vol 331 ◽  
Author(s):  
Joyce Y. Wong ◽  
Robert Langer ◽  
Donald E. Ingber
Keyword(s):  
Oxidation State ◽  
Aqueous Media ◽  
Aortic Endothelial Cells ◽  
Transparent Films ◽  
Electrically Conducting ◽  
Polypyrrole Films ◽  
Vis Spectroscopy ◽  
Electrically Conducting Polymers ◽  
The Stability ◽  
Charged Form

AbstractSurface properties of electrically conducting polymers, including charge-density and wettability, can be altered reversibly by oxidation or reduction. Thus, these materials are interesting systems on which to study the interactions of proteins and cells with surfaces. The properties of polypyrrole were studied in environments suitable for protein adsorption and cell culture. Optically transparent films of polypyrrole were synthesized, and the stability of the oxidized and reduced states in aqueous media were studied. UV/VIS spectroscopy, cyclic voltammetry, and spectroelectrochemistry measurements confirmed the oxidation state of the polymer films. The positively-charged form of polypyrrole could be changed to its neutral form by applying a constant potential (-0.5 V vs. Ag/AgCl reference). It was found that the shape of bovine aortic endothelial cells on fibronectin-coated polypyrrole films can be controlled by varying the oxidation state of the polypyrrole.

scholarly journals Directed Silica Co-Deposition by Highly Oxidized Silver: Enhanced Stability and Versatility of Silver Oxynitrate

2019 ◽  
Vol 9 (23) ◽  
pp. 5236 ◽  
Author(s):  
Carla J. Spina ◽  
Roohee Ladhani ◽  
Carlie Goodall ◽  
Michelle Hay ◽  
Rod Precht
Keyword(s):  
Oxidation State ◽  
Aqueous Media ◽  
Ph Gradients ◽  
Long Term Stability ◽  
Organic Precursors ◽  
The Stability ◽  
Silicic Acids ◽  
Silver Compounds ◽  
By Products

Novel silver compounds in higher oxidation states, Ag (II) and Ag (III), have emerged as desirable alternatives to existing forms of antimicrobial silver compounds. Offering enhanced efficacy without sacrificing biocompatibility. Unique physiochemical characteristics associated with higher oxidation state silver confer desirable therapeutic traits. However, these same characteristics create challenges in terms of long-term stability and chemical compatibility with conventional biomedical materials. Core-shell methodologies, utilizing silica as a mesoporous or amorphous shell, have been adopted to enhance the stability of reactive active ingredients or cores. These methodologies commonly utilize controlled condensation of silicic acids in non-aqueous media by way of hydrolyzing alkyl silicates: the Stöber process or modified processes thereof. However, these strategies are not conducive to cores of higher oxidation state silver wherein hydroxyl organic precursors and by-products are incompatible with strong oxidizing agents. Addressing these challenges, we present a strategy herein for the preparation of a self-directed silver oxynitrate-silica, Ag7NO11:SiO2, framework. The method described utilizes pH gradients generated from the oxidation reaction of soluble silver, Ag (I), with a strong oxidizing agent/alkaline silicate media to facilitate spatial control over the protonation and subsequent condensation of silicic acid from aqueous solution. The resulting Ag7NO11:SiO2 framework confers enhanced long term and thermal stability to silver oxynitrate without impairing aqueous degradation profiles or subsequent antimicrobial and antibiofilm activities.

Electrically conducting polymers: a review of the electropolymerization reaction, of the effects of chemical structure on polymer film properties, and of applications towards technology

1986 ◽  
Vol 64 (1) ◽  
pp. 76-95 ◽  
Author(s):  
R. J. Waltman ◽  
J. Bargon
Keyword(s):  
Conducting Polymers ◽  
Heterocyclic Compounds ◽  
Chemical Structure ◽  
Molecular Orbital Calculations ◽  
Film Properties ◽  
Intermediate Radical ◽  
Electrically Conducting ◽  
Electrically Conducting Polymers ◽  
The Stability ◽  
Aromatic Heterocyclic

The electrochemical oxidation of aromatic heterocyclic compounds thiophene, pyrrole, and indole and benzenoid and nonbenzenoid polycyclic hydrocarbons azulene, fluorene, and pyrene yield electrically conducting polymers with conductivities of 10−5–10 S/cm. The presence of substituents affects the electrical conductivity of these films and also their electroactive properties. Furthermore, substituents determine whether electropolymerization of these compounds can occur or whether soluble products are formed. The relative importance of these pathways is dependent on the stability of the intermediate radical cation. These effects are investigated by INDO molecular orbital calculations.

Sorption of Flu Viruses from Aqueous Media by Composites of Electrically Conducting Polymers: Polyaniline and Polypyrrole

2016 ◽  
Vol 52 (2) ◽  
pp. 291-296
Author(s):  
V. F. Ivanov ◽  
E. O. Garina ◽  
I. Yu. Sapurina ◽  
O. L. Gribkova ◽  
E. I. Burtseva ◽  
...  
Keyword(s):  
Conducting Polymers ◽  
Aqueous Media ◽  
Electrically Conducting ◽  
Electrically Conducting Polymers

Host-Guest Interactions on Electrode Surfaces for Immobilization of Molecular Catalysts

2020 ◽  
Author(s):  
Laurent Sévery ◽  
Jacek Szczerbiński ◽  
Mert Taskin ◽  
Isik Tuncay ◽  
Fernanda Brandalise Nunes ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Heterogeneous Systems ◽  
Catalytic Systems ◽  
New Approach ◽  
Molecular Systems ◽  
Electrode Surfaces ◽  
Catalytic Surfaces ◽  
Oxide Electrodes ◽  
The Stability ◽  
Molecular Catalysts

The strategy of anchoring molecular catalysts on electrode surfaces combines the high selectivity and activity of molecular systems with the practicality of heterogeneous systems. The stability of molecular catalysts is, however, far less than that of traditional heterogeneous electrocatalysts, and therefore a method to easily replace anchored molecular catalysts that have degraded could make such electrosynthetic systems more attractive. Here, we apply a non-covalent “click” chemistry approach to reversibly bind molecular electrocatalysts to electrode surfaces via host-guest complexation with surface-anchored cyclodextrins. The host-guest interaction is remarkably strong and allows the flow of electrons between the electrode and the guest catalyst. Electrosynthesis in both organic and aqueous media was demonstrated on metal oxide electrodes, with stability on the order of hours. The catalytic surfaces can be recycled by controlled release of the guest from the host cavities and readsorption of fresh guest. This strategy represents a new approach to practical molecular-based catalytic systems.

scholarly journals Investigations of ternary complexes of Co(II) and Ni(II) with thiodiacetate anion and 1,10-phenanthroline or 2,2’-bipyridine in aqueous solutions

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Dariusz Wyrzykowski ◽  
Joanna Pranczk ◽  
Dagmara Jacewicz ◽  
Aleksandra Tesmar ◽  
Bogusław Pilarski ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Substitution Reactions ◽  
Experimental Conditions ◽  
Kinetic Measurements ◽  
Hydroxo Complexes ◽  
Binary Complexes ◽  
Vis Spectroscopy ◽  
Potentiometric Titration Method ◽  
The Stability ◽  
Ph Range

AbstractA potentiometric titration method (PT) and a stopped-flow kinetic technique monitored by a UV−Vis spectroscopy have been used to characterize the stability of series of Co(II)- and Ni(II)-thiodiacetato complexes, M(TDA), in the presence of 1,10-phenanthroline (phen) or 2,2’-bipyridine (bipy) in aqueous solutions. The stability constants of the binary (1:1), ternary (1:1:1) as well as the resulting hydroxo complexes were evaluated and compared to the corresponding oxydiacetate complexes. Based on the species distribution as a function of pH the relative predominance of the species in the system over a pH range was discussed. Furthermore, the kinetic measurements of the substitution reactions of the aqua ligands to phen or bipy in the coordination sphere of the binary complexes M(TDA) were performed in the 288–303 K temperature range, at a constant concentration of phen or bipy and at seven different concentrations of the binary complexes (0.2–0.5 mM). The kinetic stability of the M(TDA) complexes was discussed in relation to the experimental conditions and the kind of the auxiliary ligands (phen/bipy). Moreover, the influence of the type of primary ligand (thiodiacetate/oxydiacetate) on the substitution rate of the auxiliary ligands was also compared.

Synthesis and properties of a sterically encumbered poly(thienylene vinylene): poly[E-1,2-(4,4prime-dihexyl-2,2prime-dithienyl)ethylene]

1998 ◽  
Vol 76 (11) ◽  
pp. 1524-1529
Author(s):  
Jimmy Lowe ◽  
Carl Bartels ◽  
Steven Holdcroft
Keyword(s):  
Ftir Spectroscopy ◽  
Electrically Conducting ◽  
H Nmr ◽  
Visible Photoluminescence ◽  
Micron Size ◽  
Visible Irradiation ◽  
Uv Visible ◽  
The Stability ◽  
Doped Polymer ◽  
Polythiophene Derivative

Electrically conducting poly[E-1,2-(4,4prime-dihexyl-2,2prime-dithienyl)ethylene] was synthesized and structurally characterized by UV-visible, 1H NMR, and FTIR spectroscopy. The head-to-head arrangement of the alkylthiophene dyads directly affects the UV-visible, photoluminescence, and electroluminescence maxima of the polymer. The conductivity of the doped polymer was measured to be ~2 S cm-1 and the stability of the oxidized polymer possessing various dopants was compared. UV-visible irradiation of PDHDTE rendered the films insoluble and photolithography was used to produce micron-size images. FTIR was used to monitor the photoproducts during photolysis of PDHDTE. Mechanisms of photooxidation were proposed, based on the photoproducts observed.Key words: polythiophene derivative, head-to-head dyad, photolithography, photooxidation, electroluminescence.

scholarly journals UV-VIS spectroscopy for monitoring yogurt stability during storage time

2016 ◽  
Vol 8 (30) ◽  
pp. 5962-5969 ◽  
Author(s):  
B. Aliakbarian ◽  
L. Bagnasco ◽  
P. Perego ◽  
R. Leardi ◽  
M. Casale
Keyword(s):  
Storage Time ◽  
Dairy Product ◽  
Entire Period ◽  
Vis Spectroscopy ◽  
The Stability ◽  
Color Texture

Color, texture and taste are key elements of a consumer's buying decision; thus, monitoring the stability of these features throughout the entire period of yogurt validity is fundamental for dairy product producers.

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