Hybrid Gold Nanostructures with Unique Architectures: From Potential Applications in Drug Delivery to Photonic Devices

Abstract

The domain of nanotechnology has experienced remarkable progress through the engineering of hybrid nanostructures. These structures integrate diverse materials to create synergistic properties that are unachievable or less efficient when using individual components alone. Central to this progress are gold-based hybrid nanostructures, favored for their inherent advantages ranging from structural diversity and biocompatibility to remarkable optical properties. The present study focuses on the creation of gold-based hybrid systems with special nanostructures (rattle and bipyramid shapes), which have potential for medical and optical applications. The first project focuses on the design of a porous gold nanoarchitecture, termed nanorattles. These structures consist of a porous gold cage surrounding a core, offering two accessible surfaces within a single system. This design can enhance the surface area available for cargo loading, which is advantageous for drug delivery applications. Incorporated within these nanorattles are dendrons—highly branched nanopolymers—that play a crucial role in forming a hybrid structure. Dendrons not only act as catalysts, facilitating the formation of the porous cage and the overall nanorattle structure, but also serve as a nanosystem capable of covalently carrying cargo. Cisplatin, a widely used anticancer drug, is employed as a model cargo to demonstrate the potential of gold nanorattles in targeted drug delivery applications. The other project explores the directed assemblies of gold nanoparticles and quantum dots (QDs) to form a novel hybrid nanostructure yielding unique optical characteristics through plasmon-exciton coupling. The gold used in this assembly is in the form of bipyramids, chosen for their distinctive asymmetrical shape and sharp end tips. The sharp end tips of the gold nano bipyramids (AuBPs) are the designated locations for placing the QDs. Upon light irradiation, the excitons from the QDs couple with the plasmons resonating from the ends of the AuBPs, facilitating efficient plasmon-exciton coupling. The resulting coupling occurs through a selective copper-free click reaction between surface modified QDs and AuBPs. The significance of this plasmon-exciton coupling extends particularly to photonic devices, where it can greatly enhance device performance and efficiency in light manipulation, driving next-generation photonic technologies. The PhD dissertation comprehensively explains the foundational concepts, intrinsic properties, and importance of hybrid nanomaterials as outlined in the literature review. It details the experimental procedures for synthesizing the aforementioned gold nanostructures, presents characterizations and analyses to validate their structure, size, and properties, and discusses the results, interprets data, and explores potential applications.