Synthesis, characterization, and application of magnetic gold nanoclusters
Au–Fe3O4 nanocomposites are of great interest for technological reasons due to their combined optical and magnetic properties. Nanosized Fe3O4 particles are superparamagnetic and can also be coated with a layer of Au, which supports localized plasmon resonances for useful optical properties. The dual properties of Au–Fe3O 4 nanoparticles have inspired chemists to design a variety of synthetic routes, some with good control of overall shape and size. However, most approaches require organic solvents, surfactants, or harsh chemical conditions. In this thesis we describe a simple and highly reproducible synthesis of magnetically active gold nanoclusters (MGNCs) with average particle sizes under 100 nm. This synthesis has two appealing features: (1) the synthesis is conducted entirely in water, with no amphiphilic surfactants that require subsequent removal, and (2) the chemical conditions used in MGNC synthesis are extremely mild, with minimum waste or by-products generated. The MGNCs can be used to support numerous applications in chemistry, biology, and materials science. In these thesis we describe two very different applications: (1) surface-modified chemical sensors based on surface-enhanced Raman scattering (SERS), for the detection of trace environmental pollutants such as tetrabromobisphenol A (TBBPA), and (2) magnetically guided “chisels” for the generation of nanosized channels in thermoplastic and glass films. The high aspect-ratio nanochannels were characterized by scanning electron microscopy and 3D confocal fluorescence imaging, and insights into the photothermal mechanism of nanopore generation were obtained by finite-element modeling simulations.
Wei, Purdue University.
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