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Modifying the Surface Properties of Superparamagnetic Iron Oxide Nanoparticles through A Sol−Gel Approach
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posted on 2002-01-11, 00:00 authored by Yu Lu, Yadong Yin, Brian T. Mayers, Younan XiaThis paper describes a sol−gel approach for the coating of superparamagnetic iron oxide nanoparticles with uniform shells of amorphous
silica. The coating process has been successfully applied to particles contained in a commercial ferrofluid (e.g., the EMG 304 of Ferrofluidics)
and those synthesized through a wet chemical process. The thickness of silica coating could be conveniently controlled in the range of 2−100
nm by changing the concentration of the sol−gel solution. Fluorescent dyes, for example, 7-(dimethylamino)-4-methylcoumarin-3-isothiocyanate
(DACITC) and tetramethylrhodamine-5-isothiocyanate (5-TRITC), have also been incorporated into the silica shells by covalently coupling
these organic compounds with the sol−gel precursor. These multifunctional nanoparticles are potentially useful in a number of areas because
they can be simultaneously manipulated with an externally applied magnetic field and characterized in situ using conventional fluorescence
microscopy.