Design and characterization of plasmonic nanoprobes and interparticle interactions for surface enhanced raman scattering and biomolecular detection

Functional nanoparticles serve as an intriguing class of probes in medical theranostics for enabling rapid, sensitive, multiplexing, and point-of-care treatment and diagnosis. One important aspect of these applications is the exploitation of the unique plasmonic properties of certain metal nanoparticles. A key challenge is the understanding of effective harnessing of the plasmonic coupling of the nanoparticles upon interacting with the targeted biomolecular species. This thesis work focuses on investigating the interparticle interactions of chemcially-labled and bioconjugated gold and silver based nanoparticles and their influences on the plasmonic coupling for specctroscopic detection of biomolecules. Examples of the interparticle interactions include dye-mediated π–π stacking, antigen-antibody recognition, and DNA complementary binding. These molecular and biomolecular interactions lead to the formation of interparticle “hot-spot” in terms of plasmonic coupling of the nanoparticles responsible for the surface enhanced Raman scattering (SERS) and the localized surface plasmon resonance (LSPR). The interparticle plasmonic coupling induced SERS and LSPR characteristics are probed by experimental measurements and theoretical simulations for establishing the correlation between the interparticle structures and the spectroscopic properties. The results have provided new insights for a better understanding of the design and control parameters of multifunctional nanoparticles and interparticle interactions for spectroscopic enhancements in biomolecular recognition and detection