A Facile Strategy for In Situ Core-Template-Functionalizing Siliceous Hollow Nanospheres for Guest Species Entrapment

The shell wall-functionalized siliceous hollow nanospheres (SHNs) with functional molecules represent an important class of nanocarriers for a rich range of potential applications. Herein, a self-templated approach has been developed for the synthesis of in situ functionalized SHNs, in which the biocompatible long-chain polycarboxylates (i.e., polyacrylate, polyaspartate, gelatin) provide the framework for silica precursor deposition by simply controlling chain conformation with divalent metal ions (i.e., Ca2+, Sr2+), without the intervention of any external templates. Metal ions play crucial roles in the formation of organic vesicle templates by modulating the long chains of polymers and preventing them from separation by washing process. We also show that, by in situ functionalizing the shell wall of SHNs, it is capable of entrapping nearly an eightfold quantity of vitamin Bc in comparison to the bare bulk silica nanospheres. These results confirm the feasibility of guest species entrapment in the functionalized shell wall, and SHNs are effective carriers of guest (bio-)molecules potentially for a variety of biomedical applications. By rationally choosing the functional (self-templating) molecules, this concept may represent a general strategy for the production of functionalized silica hollow structures

Mesoporous silica encapsulating Rh(0) colloids : structure and catalytic properties

International audienceColloidal metallic precursors have been used successfully to prepare new rhodium(0) supported mesoporous catalysts. The aqueous dispersion of Rh(0) previously synthesized was added either (i) to preformed mesoporous silica (MCM-41 or SBA-15) or (ii) to the gel mixture used for the solid synthesis. The different materials have been characterized by TEM, N2 adsorption-desorption, PXRD and elemental analysis. All the solids, especially those obtained by the direct route, reveal well-organized mesoporous structures. Their catalytic activity was investigated in the hydrogenation of aromatic ring (conversion of styrene into ethylcyclohexane) and was shown to be better in hexane than in ethanol. The solids prepared by impregnation of MCM-41 and SBA-15 with Rh(0) colloids (pathway (i)) afforded the best yields of ethylcyclohexane (up to 100% in hexane and 72% in ethanol, respectively)