UCLA

The primary focus of this thesis is the development of straightforward bottom-up methods for rationally incorporating gold nanoparticles (AuNPs) onto oxide materials, onto polymers, and within microfluidic devices. Plasmonic AuNPs strongly interact with light due to the localized surface plasmon resonance (LSPR) phenomenon. The position and quality of the LSPR peaks depend on the AuNP crystal structure, diameter, geometry, and local dielectric environment, which are easily modulated via wet-chemical synthesis. Beyond high optical extinction, the LSPR effect can also lead to efficient light-to-heat conversion, hot carrier generation, and intense localized electric fields. Moreover, when the individual particles are arranged into ordered arrays, even more complex optical responses and high-quality lattice plasmon resonances can be selected. Although wet-chemical synthesis yields individual plasmonic building blocks with superior qualities, precisely engineering plasmonic substrates from colloidal AuNPs is often challenging. The fabrication strategies developed herein have led to advances regarding in situ control over AuNP size and shape, pattern scalability, translatability, and versatility. I employ self-assembly and scalable subtractive soft lithography to produce arbitrary patterns from pre-synthesized AuNPs. I establish wet-chemical approaches for direct nucleation, growth, and shape-control that avoid time-consuming ligand exchange, self-assembly, and the need for costly equipment. Lastly, I explored in situ shape control to integrate thermoplasmonic gold nanostars within microfluidic platforms to target biomedical applications, including liquid biopsies. Overall, this work has potential impact for the fabrication of plasmonic biomedical devices, sensors, optoelectronics, and heterogeneous catalysts.