Synthesis of core-shell LiNbO3@Au nanoparticles as multifunctional bio-imaging and cancer photothermal therapy probes
Résumé
Advances in nanosciences and nanotechnologies during the past two decades have greatly progressed the therapies and diagnostic tools possible in medicine and biology today. Nanoparticles in particular, can exhibit enhanced optical, magnetic and other physico-chemical properties as a result of their size, shape and composition, and have been the subject of special interest in their application to targeted cancer therapy. This work presents core-shell nanoparticles, the core material being LiNbO3 (LN) and the shell material being gold, designed for cancer theranostics. LN is a non-centrosymmetric metal oxide, capable of the second harmonic generation (SHG) of light. This property allows for SHG imaging, whose wavelength tuneability, photostability and inherent high spatial resolution gives it an advantage over traditional optical microscopy probes that rely on fluorescence/luminescence [1]. Gold nanoshells can convert light to thermal energy when the incident light absorbed is resonant to its plasmon oscillation, inducing a localized temperature elevation of the surrounding media, which in cellular media can cause cell death [2]. In addition, the resonant plasmon band of gold shells can be tuned by varying the ratio of the shell to core particle thickness. This work reports on the synthesis of LN@Au core-shell nanoparticles using a seeded-growth chemistry protocol, the pH and Au salt concentration effect on the gold shell growth onto the core, and the tuning of the plasmon band to the NIR region. The gold shell growth process was characterized by UV-vis absorption spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDS). Using a continuous wave laser, photothermal experiments were performed on the nanoparticles dispersed in water and the results are included in this work. References: [1] P. Campagnola & C. Y. Dong, Second harmonic generation imaging microscopy: applications to disease diagnostics, Laser & Photonics Rev, 5, 13-26 (2011) [2] C. Loo, A. Lin, L. Hirsch, M. Lee, J. Barton, N. Halas, J. West & R. Drezek, Nanoshell-enabled photononics-based imaging and therapy of cancer, Technology in Cancer and Research Treatment, 3, 33-40 (2004)