Bifunctional Gold Nanoshells with a Superparamagnetic Iron Oxide−Silica Core Suitable for Both MR Imaging and Photothermal Therapy

Abstract

We describe the synthesis, characterization, and use of hybrid nanoparticles with a superparamagnetic iron oxide (SPIO) core and a gold nanoshell. These multifunctional nanoparticles, designated SPIO-Au nanoshells, displayed superparamagnetic characteristics and a significant absorbance in the near-infrared (NIR) region of the electromagnetic spectrum. In addition, they exhibited high transverse relaxivity, r 2 , and a large r 2 /r 1 ratio and therefore could be imaged by MRI to obtain T 2 -weighted images. Moreover, SPIO-Au nanoshells showed efficient photo-thermal effect when exposed to NIR light. The use of SPIO-Au nanoshells, with their combination of unique magnetic and optical properties, should enhance the efficacy of nanoshellmediated photo-thermal therapy by making it possible to direct more nanoparticles to tumors through the application of external magnetic field and by permitting real-time in vivo MRI imaging of the distribution of the nanoparticles before, during, and after photo-thermal therapy.

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

“…To this end, gold-coated MNPs have been shown as promising agents for MRI/PAI dual imaging applications. In a study performed by Ji et al [838] nanohybrids consisting of iron oxide core and a gold nanoshell were synthesized to investigate their potential for MRI and photothermal therapy. Along with the superparamgnetic behavior, they showed a significant absorbance in the near-infrared region which is essential for PAI.…”

Synthesis of γ-Fe2O3/SiO2/Au magnetic composites for immobilization of bovine serum albumin

“…The spectrum of the γ-Fe 2 O 3 /SiO 2 composite (Figure 2(a) [19], and bands at 1071 and 614 cm −1 corresponding to C-O and Fe-O stretching vibrations, respectively [13]. The spectrum of the thiol-functionalized γ- …”

“…Silica is one of the most common linkers used to minimize contact between the interface of gold and magnetic particles. Ji et al [13] synthesized hybrid nanoparticles with a γ-Fe 2 O 3 -silica core and a gold nanoshell using the Stöber process following two-step reduction of HAuCl 4 solution. Salgueiriño-Maceira et al [14] developed a method to prepare composites of Fe 3 O 4 / γ-Fe 2 O 3 surrounded by a thick silica shell and further covered these composites with an outer shell of gold.…”

One-step deposition of Au nanoparticles onto chemically modified ceramic hollow spheres via self-assembly

“…Apart from Au-'Si' composites, the preparation of multifunctional Au-'Si'-Fe composite spheres has also received more attention [30][31][32][33][34][35][36][37]. Au-'Si'-Fe composite spheres are useful as magnetic drug delivery vectors or catalyst supports [32].…”

“…Au-'Si'-Fe composite spheres are useful as magnetic drug delivery vectors or catalyst supports [32]. These type of structures can be built layer-by-layer (LBL) [33][34][35][36], or by covering the 'Si' surface with a single layer made up of Au and iron oxide [30,31]. The LBL approach involves coating the iron oxide-based magnetic NPs with a layer of either 'Si', followed by an over coat of Au NPs [34][35][36], or Au-'Si' core-shell NPs [33].…”