We present preliminary results obtained in the development of multiple-controlled drug delivery vehicles using magnetic nanoparticle-polymer composites. Two types of magnetic nanoparticle-polymer composites were prepared and tested for their potential as drug delivery systems with multiple controls (magnetically and thermally induced controlled delivery). These studies focused on the release of fluorescein isothiocyanate (FITC) from poly(methylmethacrylate) (PMMA), containing either magnetite or cobalt nanoparticles, by changing the sample temperature or by exposing it to an oscillating magnetic field. The magnetite-PMMA and cobalt-PMMA composites were 250 µm or less in size and were superparamagnetic. The investigations reported here demonstrated that the release of FITC from magnetite-PMMA particles can be induced thermally but not magnetically. There was no release of FITC from cobalt-PMMA composites either through thermal or magnetic induction. Characterization of the composites included transmission electron microscopy and scanning electron microscopy for size and morphology and elemental analysis for iron and cobalt content. Synchrotron radiation-based X-ray absorption near edge spectroscopy analysis was carried out to determine chemical, electronic, and geometric properties, and a superconducting quantum interference device magnetometer was utilized for measuring the magnetic properties of the composites.
Advances in nanotechnology have enabled the production and characterization of magnetic particles with nanometer-sized features that can be functionalized with biological recognition elements for numerous applications in biotechnology. In the present study, the synthesis of and interactions between self-assembled monolayers (SAMs) on gold and glass surfaces and functionalized magnetic nanoparticles have been characterized. Immobilization of 10-15 nm streptavidin-functionalized nanoparticles to biotinylated gold and glass surfaces was achieved by the strong interactions between biotin and streptavidin. Fluorescent streptavidin-functionalized nanoparticles, biotinylated surfaces, and combinations of the two were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electron and fluorescent microscopy to confirm that little or no functionalization occurred in nonbiotinylated regions of the gold and glass surfaces compared to the biotinylated sites. Together these techniques have potential use in studying the modification and behavior of functionalized nanoparticles on surfaces in biosensing and other applications.
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