Field-directed Self-assembly of Multifunctional Magnetic-Plasmonic Core-shell Nanoparticles with Applications to Photonics

摘要

Interest in the manipulation and self-assembly of magnetic nanoparticles has grown in recent years due to advances in particle synthesis and functionalization, which have led to a proliferation of applications that include the bio molecular transport, drug targeting, gene trans fection, bioseparation, microfluidic mixers and bio and chemical sensors, among others. However, despite the growing application of magnetic nanoparticles, many fundamental aspects of their collective behavior remain unknown. In this presentation, we use computational modeling to demonstrate the self-assembly of magnetic core-shell particles into chain structures and the control of this process by carefully choosing particle properties and an applied field. Our analysis takes into account several competitive effects, including the induced magnetic dipole-dipole interactions, the electrostatic repulsion between particles based on DLVO theory, Brownian dynamics, Van der Waals interaction and a steric repulsive force caused by surfactant-surfactant contact. The model is used to study the self-assembly (chaining) of magnetic-plasmonic Fe_3O_4@Au core-shell nanoparticles that are confined to a nanochannel. Computational photonic analysis is used to compute the optical behavior of 1D multiparticle chains. Moreover, an analysis is performed to study the local profiles of thermal loss and electric field enhancement between adjacent nanoparticles. The ability to self-assemble the particles with tunable field enhancement holds potential for fundamental studies of light-matter interactions as well as applications of bio and chemical sensing.