Nanomaterials with magnetic and plasmonic properties: gold nanotriangles decorated with superparamagnetic iron oxide nanoparticles

Abstract

Simple approaches to synthesize multimaterial nanoparticles that exhibit more than one functional property remain a huge challenge. Here, the fabrication of hybrid nanoparticles combination of iron oxide and gold on a single particle by a simple, fast and environmentally-friendly two-step microwave-assisted polyol synthesis is presented. Microwave assisted heating allows the fabrication of multicomponent, multifunctional nanostructures by promoting selective heating at desired sites. The resulting complex nanoparticles have magnetic and plasmonic properties, and are obtained with high control of their shape and avoiding cytotoxic reactants, being able to use them for novel applications in bio-sensing, medical imaging, or therapeutics. These nanocomposites consist of monodisperse gold nanotriangles around 200 nm in size with a homogeneous and uniform coating of superparamagnetic iron oxide nanoparticles of 14 nm. These nanotriangles are readily dispersible in water, display a strong magnetic response and exhibit a localized surface plasmon resonance band in the near-infrared region (800 nm). Moreover, these hybrid particles can be easily self-assembled at the liquid–air interfaces. A method to remove the iron oxide nanoparticles from the gold nanocrystals surface and some insights on crystal nucleation and growth mechanisms are also provided.

Keywords: Gold nanotriangles, plasmonic materials, iron oxide nanoparticles, superparamagnetism, microwave-assisted synthesis.