The effect of water on the reaction of 3-aminopropyltriethoxysilane (APTES) with mesoporous silica is investigated on two model systems. A MCM-41type material with a well-defined pore size is used to investigate changes in the pore size distribution upon reaction with APTES in toluene containing various amounts of water. It is found that, with increasing amount of water, clustering of APTES occurs, leading to a nonuniform distribution of the grafted amino groups and a scarcely functionalized pore body. A second model system with defined particle morphology and one-dimensional channels is employed to visualize the distribution of the grafted amino groups by fluorescent labeling and confocal laser scanning microscopy. The combination of nitrogen sorption and confocal laser scanning microscopy provides valuable insights concerning the role of trace water in the functionalization of mesoporous silica with alkoxysilanes.
SECTION Nanoparticles and Nanostructures
BIBW 2669 and BIBW 2992 showed a clear antiproliferative effect in vitro, whereas radiosensitization was only marginal. The present data are the first to show an effect of combined irradiation and dual EGFR/ErbB2 inhibition on tumor growth delay in vivo. Further preclinical investigations using fractionated irradiation schedules and local tumor control as experimental endpoint are needed to evaluate a possible curative potential for the combination treatment.
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