Light-activated functional mesostructured silica |
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Authors: | Erik Johansson Eunshil Choi Sarah Angelos Monty Liong Jeffrey I Zink |
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Institution: | (1) Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA |
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Abstract: | Mesostructured silica thin films and particles provide highly versatile supports or frameworks for functional materials where
a desired function (such as energy transfer, electron transfer, or molecular machines) is induced by molecules deliberately
placed in specific regions of the structure. The relatively gentle templated sol–gel synthesis methods allow a wide variety
of molecules to be used, and the optical transparency of the framework is very suitable for studies of light-induced functionality.
In this paper, three types of functionality are used to obtain fundamental understanding of the materials themselves and to
develop active materials that can trap and release molecules from the pores upon command. Photo-induced energy transfer is
used to verify that molecules can be placed in specific spatially separated regions of the framework; fluorescence resonance
energy transfer is used as a molecular ruler to measure quantitatively the distance between pairs of molecules. Secondly,
photo-induced electron transfer is used to obtain fundamental information about the electrical insulating properties of the
framework. Finally, two types of molecular machines, a light-driven impeller and a light activated nanovalve, are described.
Both machines contain moving parts attached to solid supports and do useful work. The valves trap and release molecules from
the mesopores, and the impellers expel molecules from the pores. Applications of the materials to drug delivery and the release
of drug molecules inside living cells is described. |
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Keywords: | Energy transfer Electron transfer Nano machines Nano valves |
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