Biomolecular Plasmonics: Fundamentals and Applications
- Author(s): Hong, Soon Gweon
- Advisor(s): Lee, Luke P.
- Lin, Liwei
- et al.
Decades of extensive research into metallic nanostructures have deepened our understanding of plasmonic phenomena. In turn, plasmonics have been utilized in various applications in a broad range of research fields. Plasmonic-aided biomolecular detection is highlighted due to its ability to obtain biomolecular fingerprint information in a non-invasive, in-situ, and single molecule resolution manner. However, its applicability to various fields still faces practical limitations such as reliable plasmonic structure fabrication, signal instability (or blinking), and signal variation amongst different plasmonic structures for the same molecule. In this respect, this thesis discusses the fundamentals of plasmonic phenomena and molecular interaction with excited plasmonic structures.
Here we demonstrate the designs of plasmonic structures: eagle-beak nanoantenna, gold nanoflake on photonic crystal, and gold viruses. The first two are for large-area uniform substrates that enable single-molecule sensitivity. The last one is a mobile nanoparticle that continuously interacts with a cellular system with multiple functions including molecular imaging, targeting, and drug delivery. We also suggest preconcentration-based non-blinking single-molecule detection. Electric and temperature fields were considered in moving molecules towards excited nanostructures. By using an eagle-beak nanoantenna, we demonstrate single-molecule, non-blinking surface-enhance Raman scattering. Furthermore, variation of molecular scattering from a curved Poynting vector and depolarized scattering from nonparallel electron motion to incident light are discussed as a new molecular detection scheme. Lastly, we provide a design concept that utilizes temperature and a thermal gradient to activate carrier molecules on nanoparticles, in particular for extrinsic gene delivery. By varying the thermal profile around plasmonic structures, diverse gene activation schemes are available for biological experiments.
When the electric and thermal fields around excited plasmonic structures are considered in terms of gradients and vectors, we can enhance detection capabilities while conferring multiple functionalities to structures. We believe this series of new approaches to plasmonic-aided molecular detection can elevate molecular imaging potential in real fields, and further expand to other types of applications such as plasmonic energy harvest, optical communication and biomedical applications.