Photothermal Killing of Cancer Cells by the Controlled Plasmonic Coupling of Silica-Coated Au/Fe sub(2)O sub(3) Nanoaggregates

• Published in: Advanced functional materials 2014-05, Vol.24 (19), p.2818-2827
• Main Authors: Sotiriou, Georgios A, Starsich, Fabian, Dasargyri, Athanasia, Wurnig, Moritz C, Krumeich, Frank, Boss, Andreas, Leroux, Jean-Christophe, Pratsinis, Sotiris E
• Format: Article
• Language: English
• Subjects: Cancer; Gold; Irradiation; Killing; Lasers; Nanoparticles; Nanostructure; Silicon dioxide
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201303416

Tumor ablation by thermal energy via the irradiation of plasmonic nanoparticles is a relatively new oncology treatment. Hybrid plasmonic-superparamagnetic nanoaggregates (50-100 nm in diameter) consisting of SiO sub(2)-coated Fe sub(2)O sub(3) and Au ( approximately 30 nm) nanoparticles were fabricated using scalable flame aerosol technology. By finely tuning the Au interparticle distance using the SiO sub(2) film thickness (or content), the plasmonic coupling of Au nanoparticles can be finely controlled bringing their optical absorption to the near-IR that is most important for human tissue transmittance. The SiO sub(2) shell facilitates also dispersion and prevents the reshaping or coalescence of Au particles during laser irradiation, thereby allowing their use in multiple treatments. These nanoaggregates have magnetic resonance imaging (MRI) capability as shown by measuring their r2 relaxivity while their effectiveness as photothermal agents is demonstrated by killing human breast cancer cells with a short, four minute near-IR laser irradiation (785 nm) at low flux (4.9 W cm super(-2)). Twin or Janus-like gold-iron-oxide plas-monic-superparamagnetic nano-aggregates are made by flame aerosol technology and wrapped up "in-flight" by a transparent silica nanothin film. Its thickness finely tunes the near-infrared absorption of Au nanoparticles allowing for a high light-to-heat efficiency, while iron-oxide facilitates their magnetic placement and in-vivo monitoring by MRI, and killing human breast cancer cells with a short, 4-minute laser irradiation.