Electrochemical and electrochromic investigation of poly-bithiophene films on a mesoporous TiO2 surface

The electrochemical behaviour and the electrochromic properties of a film of poly-bithiophene (PBT) deposited onto a mesoporous TiO2 surface layered on an optically transparent electrode (OTE) were investigated. The polymeric film was prepared by anodic polymerisation of 2,2'-bithiophene (BT) and, interestingly, a cyclic voltammetric (CV) behaviour very similar to that observed on platinum or other conducting substrates was obtained. Furthermore, both the CV pattern and the absorption properties of the film grown on TiO2 indicated that a significantly larger amount of PBT could be deposited onto the mesoporous TiO2 layer with respect to Pt or conducting SnO2 substrates having the same geometric area. This suggested that PBT growth, besides at the exposed SnO2 surface within the pores of the mesoporous network, might also occur onto the (very large) surface of the TiO2 nanocrystals. Finally, the PBT/TiO2 heterojunction was investigated for its electrochromic properties. Because of the very large specific surface concentrations of PBT and the high volume density of surface-related defects in the mesoporous TiO2 film, the hetrojunction was shown to undergo sharp optical transition upon either oxidation of the PBT film or intercalation of Li+ ions in the reduced TiO2 film. (C) 2005 Elsevier B.V. All rights reserved

Ground- and Excited-State Acid-Base Equilibria of (2,2'-bipyridine)tetracyano- ruthenate(II)

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Near-field optical addressing of luminescent photoswitchable supramolecular systems embedded in inert polymer matrices

Optical recording and luminescence readout of novel covalently linked photochrome/luminophore supramolecular complexes has been demonstrated by near-field scanning optical microscopy (NSOM). Localized UV irradiation of these complexes dispersed in polymeric matrices resulted in photoinduced state switching and a concomitant increase in emission intensity. Subsequent luminescence imaging showed well-resolved luminescent data bit arrays with good signal-to-noise ratios. Spatially resolved emission spectra of the luminescent data bits confirmed the switching mechanism

Efficient dye sensitized solar cells using red turnip and purple wild sicilian prickly pear fruits

Dye-sensitized solar cells (DSSCs) were assembled by using the bougainvillea flowers, red turnip and the purple wild Sicilian prickly pear fruit juice extracts as natural sensitizers of TiO(2) films. The yellow orange indicaxanthin and the red purple betacyanins are the main components in the cocktail of natural dyes obtained from these natural products. The best overall solar energy conversion efficiency of 1.7% was obtained, under AM 1.5 irradiation, with the red turnip extract, that showed a remarkable current density (Jsc = 9.5 mA/cm(2)) and a high IPCE value (65% at λ = 470 nm). Also the purple extract of the wild Sicilian prickly pear fruit showed interesting performances, with a Jsc of 9.4 mA/cm(2), corresponding to a solar to electrical power conversion of 1.26%

Zirconium oxide coating improves implant osseointegration in vivo.

Zirconium is widely used as material for prosthetic devices because of its good mechanical and chemical properties. When exposed to oxygen, zirconium becomes zirconium oxide (ZO, chemically ZrO(2)) which is biocompatible. ZO can be also prepared as a colloidal suspension and then used to coat surfaces. Zirconium oxide coating (ZOC) can potentially have specific biologic effects. The effect of ZOC on bone throughout an in vivo study using dental implants covered with ZOC and then inserted in rabbit tibia was tested in this study. The histologic analysis demonstrated that (1) bone growth is more evident around ZOC fixtures than in controls and (2) a more mature bone is present in the peri-implant ZOC surface than in controls. ZOC can enhance implant osseointegration

Genetic effect of zirconium oxide coating on osteoblast-like cells

Zirconium is widely used as material for prosthetic devices because its good mechanical and chemical properties. When exposed to oxygen, zirconium becomes zirconium oxide (ZrO(2)), which is biocompatible. ZrO(2) can be also prepared as a colloidal suspension and then used to coat surfaces. Zirconium oxide coating (ZrO(2)C) can potentially have specific biologic effects, and among them is bone formation related to implant osseointegration. How this biomaterial alters osteoblast activity to promote bone formation is poorly understood. We therefore attempted to address this question by using microarray techniques to identify genes that are differently regulated in osteoblasts exposed to ZrO(2)C. By using DNA microarrays containing 20,000 genes, we identified in osteoblast-like cell lines (MG-63) cultured with ZrO(2)C several genes whose expression was significantly upregulated or downregulated. The differentially expressed genes cover a broad range of functional activities: (a) cell cycle regulation, (b) signal transduction, (c) immunity, and (d) cytoskeleton component. The data reported are, to our knowledge, the first genetic portrait of ZrO(2)C effects. They can be relevant to better understand the molecular mechanism of bone regeneration and as a model for comparing other materials with similar clinical effects

Zinc plus octenidine: a new formulation for treating periodontal pathogens. A single blind study

Periodontal treatment has the aim to reduce oral infection, and prevent the progression of the disease. The potential benefits of new chemical devices for periodontal therapy, include improved patient compliance, an easier access to periodontal pocket and a lower dosage of antimicrobial agent. The objective of this study was to explore the efficacy of a chemical device containing zinc and octenidine in the treatment of chronic periodontitis in adult patients. Ten patients with a diagnosis of chronic periodontitis (20 localized chronic periodontitis sites) in the age group of 35 to 55 were selected. None of these patients received any surgical or non-surgical periodontal therapy and demonstrated radiographic evidence of moderate bone loss. The chemical device zinc plus octenedine was used by each patient after daily oral hygiene. Microbial analysis were analyzed at baseline and on the 15th day. After the treatment, a remarkable decrease in bacteria amount, both for some species and for the total count was observed in the study group. Specifically T. Forsythia and T. Denticola were eradicated whereas Total Bacteria Loading and Fusobacterium Nucleatum showed a reduction of 38% and 55%, respectively. Our study demonstrated the efficacy of the new chemical device containing zinc and octenidine in a sustained release drug delivery system in the management of moderate to severe chronic periodontitis

Tetracoordinated Bis-phenanthroline Copper-Complex Couple as Efficient Redox Mediators for Dye Solar Cells

A tetracoordinated redox couple, made by [Cu(2-mesityl-4,7-dimethyl-1,10-phenanthroline)(2)][PF6], 1, and its Cu(II) form [Cu(2-mesityl-4,7-dimethyl-1,10-phenanthroline)(2)] [PF6](2), 2, has been synthesized, and its electrochemical and photochemical features have been investigated and compared with those of a previously published Cu2+/Cu+ redox shuttle, namely, [Cu(2,9-dimethyl-1,10-phenanthroline)(2)][PF6], 3, and its pentacoordinated oxidized form [Cu(2,9-dimethyl-1,10-phenanthroline)(2)Cl][PF6], 4. The detrimental effect of the fifth Cl- ancillary ligand on the charge transfer kinetics of the redox shuttles has been exhaustively demonstrated. Appropriately balanced Cu-based electrolytes have been then formulated and tested in dye solar cells in combination with a pi-extended benzothiadiazole dye. The bisphenanthroline Cu-complexes, 1 and 2, have been found to provide an overall 4.4% solar energy conversion efficiency, which is more than twice that of the literature benchmark couple, 3 and 4, employing a Cl-coordinated oxidized species and even comparable with the performances of a I-/I-3(-) electrolyte of analogous concentration. A fast counter-electrode reaction, due to the excellent electrochemical reversibility of 2, and a high electron collection efficiency, allowed through the efficient dye regeneration kinetics exerted by 1, represents two major characteristics of these copper-based electron mediators and may constitute a pivotal step toward the development of a next generation of copper-based efficient iodine-free redox shuttles