Multifunctional Hybrid Fe₂O₃-Au Nanoparticles for Efficient Plasmonic Heating

Abstract

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl 4 ) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe 2 O 3 -Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe 2 O 3 . Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe 2 O 3 -Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe 2 O 3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe 2 O 3 -Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe 2 O 3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.

Colloidal Metal Oxide Nanoparticles Prepared by Laser Ablation Technique and Their Antibacterial Test

“…Because the ideal plasmonic photocatalysts should simultaneously act as an absorber to capture light as well as a catalytic surface to interact properly with surface intermediates, metal nanoparticles with strong light absorption capability have been demonstrated as a new family of plasmonic photocatalysts that offer distinctly different benefits compared to conventional semiconductor photocatalysts. As an example of this, Jianlong Wang et al 2010 have demonstrated that Fe 3 O 4 magnetic nanoparticle can greatly enhance the localized surface plasmon resonance of metal nanoparticles in biological systems, and Nayareth Soltani et al 2012 have reported the degradation of methylene blue by visible light induced in the presence of photocatalytic ZnS and CdS nanoparticles [10][11][12][13][14].…”

Morphology of Composite Fe@Au Submicron Particles, Produced with Ultrasonic Spray Pyrolysis and Potential for Synthesis of Fe@Au Core–Shell Particles

“…However, the particles already produced in this work are suitable as catalysts for carbon monoxide (CO) oxidation [5,25], selective reduction of nitrogen-containing compounds [5], plasmonic heating [26] and magnetic hyperthermia [26,27]. A nano-sized gold catalyst, supported on iron oxides, can be highly effective for hydrogenation and oxidation reactions [28].…”

“…Fe 2 O 3 particles decorated with AuNPs, with a similar morphology as the particles in this work, were also produced for plasmonic heating [26]. The presented Fe 2 O 3 -Au nanoparticles retained both magnetic and plasmonic properties.…”

Porous Iron oxide nanorods and their photothermal applications

“…The photothermal experimental setup consists of a laser with wavelength λ = 532 nm (Del Mar Photonics, DMPV-532-1, beam diameter focused to ~20 µm at 1200 mW), where the beam path is directed onto the top surface of 3 mL nanoparticle solution contained in a methacrylate cuvette [15]. The cuvette is resting on scale (Mettler Toledo XP205) that provides dynamic mass measurements.…”