Structure-Directing Agents for the Synthesis of TiO(2) -Based Drug-Delivery Systems

A series of titanium oxides was prepared by using a surfactant-template method (STM) and used as a carrier for the sustained release of ibuprofen, which was chosen as a model drug. This STM provides an efficient route to TiO(2) matrices with both high surface area (when compared with those that were obtained by using traditional synthetic approaches) and well-defined mesoporous textures. Some parameters of the synthetic procedure were varied: pH value, surfactant, and thermal treatment. The physicochemical nature of the surface carriers were investigated by means of N(2) -physisorption measurements and FTIR spectroscopy. The effect of the amount of drug on the release kinetics was also investigated. The drug delivery was evaluated in vitro in four different physiological solutions (that simulated the gastrointestinal tract) to analyze the behavior of the TiO(2) -based systems if they were to be formulated as oral DDSs. Our optimized approach is a good alternative to the classical methods that are used to prepare efficient TiO(2) -based drug-delivery systems.     

The quest for new mild and selective modifications of natural structures: laccase-catalysed oxidation of ergot alkaloids leads to unexpected stereoselective C-4 hydroxylation

Laccase-catalysed oxidation of ergot alkaloids in the absence of chemical mediators allowed the unexpected isolation of the mono-hydroxylated derivatives of compounds 2-7. Structure determination by NMR techniques clearly indicated that hydroxylation took place at the C-4 benzylic position. Quite notably, the proposed protocol allowed, for the first time, functionalisation at the C-4 position of the ergoline skeleton. Depending on the absence or on the presence of a C-10 α-methoxy substituent, hydroxylation was either stereoselective (furnishing C-4α OH derivatives) or gave rise to a C-4α/C-4β OH mixture in a 2:1 ratio, respectively.     

Infinitely many solutions to elliptic problems with variable exponent and nonhomogeneous Neumann conditions

The aim of this paper is to establish the existence of an unbounded sequence of weak solutions for a class of differential equations with p(x)$p\left(x\right)$-Laplacian and subject to small perturbations of nonhomogeneous Neumann conditions. The approach is based on variational methods.     

Smectic order parameters via liquid crystal NMR spectroscopy: Application to a partial bilayer smectic A phase

Solute molecules were dissolved in the liquid crystal 4-cyano-4??-n-octyloxybiphenyl (8OCB), known to form a partial bilayer smectic-A phase. Through measurement of solutes?? and solvent??s orientational order parameters via nuclear magnetic resonance spectroscopy, and their analysis via a statistical thermodynamic density functional theory, values of the solvent??s positional order parameters and solutes?? positional-orientational distribution functions were obtained. Near to the transition to the nematic phase, the main positional order parameter of the smectic liquid crystal turned out to be comprised in the interval 0.4?C0.6, though the quality of the fittings assuming the phase as nematic all across the temperature range investigated was only slightly worse. This may be ascribed to the looseness of the partial bilayer smectic structure. Solutes were found to preferentially lie in those regions where liquid crystal molecule terminal chains are located.      

The low-pressure focal plane detector of the MAGNEX spectrometer

The focal plane detector of the MAGNEX large acceptance magnetic spectrometer is presented. It is based on a large low-pressure gas-filled tracker followed by a wall of silicon detectors to stop the particles. It has been designed for the stringent requirements from the ion optics and the foreseen use with heavy ions. The performances of the device are demonstrated using 4MeV/u oxygen beams. The results of the tests are described and discussed in view of the application of the particle identification and trajectory reconstruction techniques to recover the kinematic properties of the reaction products. They demonstrate the suitability of such detector in a wide range of experiments where low-energy thresholds, large-accepted solid angle, precise momentum measurement and good particle identification are needed.     

Hydroxamate represents a versatile zinc binding group for the development of new carbonic anhydrase inhibitors

Hydroxamates (R-CONHOH) have been scarcely investigated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs). An inhibition/structural study of PhCONHOH is reported against all human isoforms. Comparing aliphatic (R = Me and CF(3)) and aromatic (R = Ph) hydroxamates as CAIs, we prove that CONHOH is a versatile zinc binding group. Depending on the nature of the R moiety, it can adopt different coordination modes to the catalytic ion within the CA active site.     

Surface science aspects of supramolecular conformation in elastin‐like polypeptides

Polypeptides can form helical fibres in aqueous media: potentially useful for the production of biocompatible fabric and yarns. A previous work has shown that fibre formation occurs readily with elastin‐like polypeptides constructed from hydrophobic amino acids, such as valine, glycine and leucine. However, elastin‐like polypeptides, when suspended in methyl alcohol, are observed to form globules and ‘string of bead’ structures. Thus, it seems probable that the interface energy is important. Interface energy is minimised by the formation of bonds extending from one phase to the other: a phenomenon that is central to adhesion science. We have looked for evidence of such bonding using XPS to study structures formed by poly(ValGlyGlyLeuGly). The structures formed were first characterised by atomic force microscopy. Differences were found between structures and spectra formed in either water or methanol. No evidence for the presence of unique bonds characterising the interface was found, but evidence was found for the influence of a water environment on the internal structure, suggesting that it is the increase in intermolecular bonding opportunities associated with the influence of water on the growth of fibres that is the thermodynamic driver for the observed transformation into fibre deposits. Copyright © 2011 John Wiley & Sons, Ltd.     

Structure‐Directing Agents for the Synthesis of TiO2‐Based Drug‐Delivery Systems

A series of titanium oxides was prepared by using a surfactant‐template method (STM) and used as a carrier for the sustained release of ibuprofen, which was chosen as a model drug. This STM provides an efficient route to TiO₂ matrices with both high surface area (when compared with those that were obtained by using traditional synthetic approaches) and well‐defined mesoporous textures. Some parameters of the synthetic procedure were varied: pH value, surfactant, and thermal treatment. The physicochemical nature of the surface carriers were investigated by means of N₂‐physisorption measurements and FTIR spectroscopy. The effect of the amount of drug on the release kinetics was also investigated. The drug delivery was evaluated in vitro in four different physiological solutions (that simulated the gastrointestinal tract) to analyze the behavior of the TiO₂‐based systems if they were to be formulated as oral DDSs. Our optimized approach is a good alternative to the classical methods that are used to prepare efficient TiO₂‐based drug‐delivery systems.