Templated Synthesis of Multifunctional Plasmonic Nanoparticles

Hollow nanoparticles play a critical role in microencapsulation – a process that has been widely exploited for controlled drug delivery. Here we report the fabrication of hollow flask-shaped plasmonic nanoparticles by a colloidal templating approach. The resulting nanoparticles exhibit tunable plasmonic properties which can be easily tuned by changing the templating particle size and the shell thickness. The experimental optical measurements match with the theoretical simulations using  finite-difference time-domain (FDTD) model. We observe strong in-situ optical adsorption and heating by the templated plasmonic nanoparticles. The interior of the hollow nanoparticles can be filled up with chemicals and the flask opening can then be sealed by a thin layer of heat-sensitive polymer. We have demonstrated that the encapsulated chemicals (e.g., a laser dye) can be delivered in a controlled manner when a near-IR laser beam is illuminated on these composite nanoparticles. Additionally, the plasmonic nanoparticles exhibit strong surface-enhanced Raman scattering (SERS), promising for in-situ biosensing.