Templated Fabrication of Multifunctional Gold Nanoflask Particles for Controlled Drug Delivery

Hollow particles play an important role in microencapsulation – a process that has been widely exploited for controlled release of drugs. Here we report the fabrication of hollow gold nanoflask particles by a simple templating process. Non-close-packed colloidal monolayers prepared by a simple spin-coating process are used as templates. A thin film of gold can be sputtered on the surface of the particles and the silica templates can be removed later on to form flask-shape hollow nanoparticles. The resulting particles exhibit tunable plasmonic properties which can be easily tuned by changing the template particle size and the shell thickness. The interior of the hollow nanoshells can be filled up with chemicals (e.g., laser dye) and the opening can then be sealed by a thin layer of polymer. We have demonstrated that the encapsulated chemicals can be delivered in a controlled manner when a near-IR laser beam is illuminated on these composite nanoparticles. In addition, we observe the strong in-situ optical adsorption and heating by the gold nanoflask particles, promising for developing hypothermal treatment. Moreover, the templated nanoflask particles exhibit strong surface-enhanced Raman scattering and are promising for in-situ biosensing.