ANYL 263 |
| A novel multistep synthetic protocol is presented for the surface immobilization of a solvatochromic fluorophor, acrylodan [acryloyl-2-(dimethylamino)naphthalene], on alkylsilane-modified silica nanoparticles. A detailed understanding of solvation at liquid-monolayer-particle interfaces is necessary for a variety of fluorescence imaging applications. Acrylodan-modified silica nanoparticles are prepared by covalent attachment to amine-terminated silanes that are dopants in methyl-terminated silanes at different mole fractions to investigate the role of monolayer microenvironment on the solvatochromic fluorescence response. The resulting acrylodan-labeled silica nanoparticles are characterized by AFM and SEM. Solvents used for fluorescence studies include water, methanol, acetonitrile and hexane. At large acrylodan-to-methyl mole ratios, the majority of the acrylodan moieties are solvated by other acrylodan moieties and solvation by solvent molecules is limited. Blue shifts in the fluorescence emission between 50 and 20 nm are observed for such particles. In contrast, at small acrylodan-to-methyl mole ratios, the distance between acrylodan moieties increases but allows acrylodan moieties to strongly interact with surface methyl groups. Hence, for the lowest acrylodan-to-methyl mole ratios, a blue shift of less than 10 nm is observed. Intermediate ratios exhibit intermediate fluorescence emission shifts due to the influence of both surface microenvironment and solvent polarity. |
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Analytical Approaches, Spectroscopy
8:30 AM-12:00 PM, Wednesday, 13 September 2006 Moscone Center -- Room 124, Oral
Sci-Mix
Division of Analytical Chemistry |