Over the past decade the emphasis on single-molecule sensitivity of surface-enhanced Raman spectroscopy (SERS) has brought to prominence the special role played by so-called SERS hot spots, oftentimes nanometer-scale junctions between nanoparticles (NPs). In this work, molecular linkers are used to mediate the assembly of NPs to dimers and small clusters. When the SERS enhancement is optimized, the aggregation process is quenched by polymer and protein stabilizers that subsequently act as encapsulants resulting in SERS substrates with unprecedented enhancement uniformity, reproducibility, and stability. The polymer-stabilized NP junctions were then imprinted with a variety of small molecules that permeated the polymer coat and displaced the linker from the hot spot. The surface adsorption process can be monitored in real time with spectral analysis aiding optimization. The average SERS enhancement of these SERS “nanocapsules” was found to be at least 300× greater than for single NPs. Single-particle statistics showed that almost every nanocapsule produced intense SERS, suggesting that they are NP dimers and small clusters with the probe molecule resident in a hot spot. Nanocapsules were functionalized and shown to compete successfully with fluorescence imaging in multiplexed identification of cancer cell epitopes at the single-cell and single-nanotag level.
|Advisor:||Reich, Norbert O.|
|Commitee:||Ford, Peter C., Moskovits, Martin, Stucky, Galen D.|
|School:||University of California, Santa Barbara|
|School Location:||United States -- California|
|Source:||DAI-B 71/05, Dissertation Abstracts International|
|Keywords:||Bioimaging, Biosensing, Nanocapsules, Nanoparticles, Surface chemistry|
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