Exploiting Silica and Titania

Michael A. Brook Professor

Silica 

Silica is widely found in nature in both amorphous (e.g., diatoms) and crystalline (quartz) forms. It's surface characteristics make it exceptionally useful as a filler, as a chromatographic support among many other applications. In conjunction with John Brennan, we have developed new precursors [125] that permit the sol-gel synthesis of silica under very biocompatible conditions. It is possible to prepare protein doped silica monoliths for bioassay applications [111]. The chemistry also lends itself to the preparation of silica particles [169], which may have application in bioassays. 
 

Protein-doped monolithic silica structures

Titania

Among many interesting properties, titania is a photocatalyst for oxidiation of organic molecules. Its surface chemistry is normally anionic.  When a cationic organic layer was placed on the surface stable dispersions were formed in water. Photooxidation converts the cationic colloid back to anionic, which leads to flocculation in the presence of cationic organic latexes. Thus, photoactivity leads to interfacial control [159]. Titania could be modified with antibodies, which leads to biological targeting of the photocatalyst [170].

References

111. F Jorge A. Cruz-Aguado, Yang Chen, Zheng Zhang, Nadine H. Elowe, Michael A. Brook and John D.
Brennan, Ultrasensitive ATP Detection Using Firefly Luciferase Entrapped in Sugar-Modified Sol-
Gel Derived Silica, J. Am. Chem. Soc. 2004, 126, 6878-6879.

125. F Yang Chen, Zheng Zhang, Xihua Sui, John D. Brennan and Michael A. Brook, Reduced Shrinkage of
Sol-Gel Derived Silica Using Sugar-based Silsesquioxane Precursors, J. Mater. Chem. 2005, 15,
3132 – 3141.

129. F Hodgson, Richard J.; Besanger, Travis R.; Brook, Michael A.; Brennan, John D. Inhibitor Screening 
Using Immobilized Enzyme Reactor Chromatography/Mass Spectrometry. Anal. Chem. 2005, 77,
7512-7519.

159. F Lucy Ye, Chuanwei Miao, Michael A. Brook, and Robert Pelton, Photo-flocculation of TiO2
Microgel Mixed Suspensions, Langmuir, 2008; 24; 9341-9343.

169. F. Rebecca Cademartiri, Michael A. Brook, Robert Pelton, and John D. Brennan, Macroporous Silica
Using a “Sticky” Stöber Process, J. Mater. Chem., 2009, 19, 1583–1592.

170 F. Lucy Ye, Carlos D. M. Filipe, Mojgan Kavoosi, Charles A. Haynes, Robert Pelton, and Michael A.
Brook, Immobilization of TiO2 nanoparticles onto cellulose fibers through bioconjugation, J.
Mater. Chem., 2009, 19, 2189–2198.

Last revision: 2009-08-22; mab © 1998-2009, M. Brook