Structure-Directing Agent 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 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 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. My body is a template: A series of titanium oxides was prepared by using a surfactant-template method (STM) and used as carriers for the sustained release of ibuprofen, which was chosen as a model drug. This study will be useful for the development of TiO2-based drug-delivery procedures that can be specifically formulated for a particular therapeutic application. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Hydrogen production by ethanol steam reforming: effect of the synthesis parameters on the activity of Ni/TiO2 catalysts

Ethanol steam reforming is an attracting process to produce hydrogen in a sustainable way. In this work the performance of Ni/TiO2 catalysts in ethanol steam reforming was studied. In particular, the effect of the synthesis procedure on the properties of the catalysts and on their activity was deeply investigated. On the basis of the experimental results, it was evidenced that TiO2-supported Ni systems are very sensitive to the synthesis parameters. We found that a proper thermal activation by calcination at 800 degrees C allows to obtain stable catalysts by means of strong interactions between the active phase and the support, preserving the catalyst from sintering phenomena. Nevertheless, the synthesis conditions must be properly tuned in order to prevent Ni incorporation in scarcely reducible structures which would depress catalytic activity. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Towards the total syntheses of aspidospermidine and aspidofractinine : the curious chemistry of the indolinyl radical

This thesis is concerned with the total syntheses of the natural products aspidospermidine and aspidofractinine. These targets are noteworthy not only for the biological activity displayed within the class but also for their interesting molecular architecture. Herein, two routes towards the natural products are presented. Key features of the first route, a unified approach to both targets via the indolinyl radical, include the elegant construction of the core ABDE ring system, a mild lactam reduction and synthesis of the key cyclic imine. The second route features a highly efficient Stille coupling and a Wittig olefination. Attempts to effect a critical radical cyclisation reaction are also discussed. The chemistry of the C2 indolinyl radical is investigated, in particular the influence of the C3 indolinyl substitution upon the radical pathway followed. A discussion of the study and its findings is presented in Chapter 4. A review of synthetic approaches to these natural products since 2007 is presented in Chapter 1, in addition to details on their isolation, characterisation and biosynthesis, and an overview of their biological activity. Experimental procedures and characterisation data are provided in Chapter 6.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Ni/ZrO2 catalysts in ethanol steam reforming: Inhibition of coke formation by CaO-doping

In this work the performance of CaO-doped Ni/ZrO2catalysts in ethanol steam reforming was studied.The addition of CaO did not affect the morphology or the crystalline structure of the support. On thecontrary, Ni reducibility markedly increased. Moreover, the Lewis acidity of zirconia gradually decreasedas the CaO content increased, thus inhibiting coke deposition and improving the carbon balance. Theaddition of a basic oxide helps to prevent some of the side reactions responsible for coke formation anddeposition, that can gradually deactivate the catalyst

Ni/ZrO2 catalysts in ethanol steam reforming: Inhibition of coke formation by CaO-doping

In this work the performance of CaO-doped Ni/ZrO2 catalysts in ethanol steam reforming was studied. The addition of CaO did not affect the morphology or the crystalline structure of the support. On the contrary, Ni reducibility markedly increased. Moreover, the Lewis acidity of zirconia gradually decreased as the CaO content increased, thus inhibiting coke deposition and improving the carbon balance. The addition of a basic oxide helps to prevent some of the side reactions responsible for coke formation and deposition, that can gradually deactivate the catalyst

Ni/ZrO2 catalysts in ethanol steam reforming: Inhibition of coke formation by CaO-doping

In this work the performance of CaO-doped Ni/ZrO2catalysts in ethanol steam reforming was studied.The addition of CaO did not affect the morphology or the crystalline structure of the support. On thecontrary, Ni reducibility markedly increased. Moreover, the Lewis acidity of zirconia gradually decreasedas the CaO content increased, thus inhibiting coke deposition and improving the carbon balance. Theaddition of a basic oxide helps to prevent some of the side reactions responsible for coke formation anddeposition, that can gradually deactivate the catalyst

TiO2-supported catalysts for the steam reforming of ethanol

TiO2 was used as support for Ni, Co and Cu to prepare catalysts for the steam reforming of ethanol, due to its known tendency to form strong metal–support interaction (SMSI) with some metals. The samples were prepared following different procedures, tuning the reducibility of the active phase and its interaction with the support. The latter parameter showed pivotal to impart suitable catalytic activity and most of all stability towards coking. Indeed, the insurgence of SMSI may allow to keep the active phase dispersed, improving activity and inhibiting the formation of carbon filaments over the active phase. The comparison between different active phases (Ni, Co, Cu, 10 wt%) confirmed Ni as very active, although it has a higher tendency to form carbon filaments. This drawback may be at least partially controlled by favouring high Ni dispersion through the formation of a mixed oxide with the support. The calcination temperature, and in general the preparation procedure for the catalyst, showed of pivotal importance to establish SMSI. In particular, calcination at relatively low temperature (i.e. 500 °C) induced initially a higher dispersion of the active phase (mean Ni crystal size 7 nm), however not accompanied by sufficient stabilisation during activity testing (mean Ni crystal size increased to 44 nm). By contrast, calcination at higher temperature (i.e. 800 °C) favoured the instauration of a SMSI and the formation of a mixed oxide (NiTiO3), which, after activation, allowed the coexistence of smaller particles, more active and resistant to deactivation and sintering, together with the more sintered ones (mean Ni crystal size 27 nm before and after activity testing). Different characterisation data (XRD, FT-IR, TPR, TEM) allowed to conclude the need of calcination at high temperature to achieve sufficient activity and resistance of the catalyst for this application. Co and Cu proved more promising as for C balance, although their activity at low temperature was unsatisfactory, mainly due to poor activity for Csingle bondC bond cleavage. The characterisation of the spent catalysts by XRD, TEM and Raman allowed to evidence the different types of C deposed and to check for active phase stability against sintering