Assessing the hyperthermic properties of magnetic heterostructures: the case of gold–iron oxide composites

Abstract

Gold-iron oxide composites were obtained by in situ reduction of an Au(III) precursor by an organic reductant (either potassium citrate or tiopronin) in a dispersion of preformed iron oxide ultrasmall magnetic (USM) nanoparticles. X-ray diffraction, transmission electron microscopy, chemical analysis and mid-infrared spectroscopy show the successful deposition of gold domains on the preformed magnetic nanoparticles, and the occurrence of either citrate or tiopronin as surface coating. The potential of the USM@Au nanoheterostructures as heat mediators for therapy through magnetic fluid hyperthermia was determined by calorimetric measurements under sample irradiation by an alternating magnetic field with intensity and frequency within the safe values for biomedical use. The USM@Au composites showed to be active heat mediators for magnetic fluid hyperthermia, leading to a rapid increase in temperature under exposure to an alternating magnetic field even under the very mild experimental conditions adopted, and their potential was assessed by determining their specific absorption rate (SAR) and compared with the pure iron oxide nanoparticles. Calorimetric investigation of the synthesized nanostructures enabled us to point out the effect of different experimental conditions on the SAR value, which is to date the parameter used for the assessment of the hyperthermic efficiency.

Multimodal Magnetic-Plasmonic Nanoparticles for Biomedical Applications

“…Hydroxylamine has frequently been utilised as a seeding and reducing agent in a number of cases for coating of magnetic nanoparticles with a plasmonic shell [24,27,28]. For example, Fantechi et al first synthesised ultrasmall Fe3O4 NPs using Massart's coprecipitation; then, hydroxylamine was used as a seeding agent for the gold NPs ( Figure 2) [28].…”

“…Hydroxylamine has frequently been utilised as a seeding and reducing agent in a number of cases for coating of magnetic nanoparticles with a plasmonic shell [24,27,28]. For example, Fantechi et al first synthesised ultrasmall Fe3O4 NPs using Massart's coprecipitation; then, hydroxylamine was used as a seeding agent for the gold NPs ( Figure 2) [28]. A scheme of the synthetic approach utilised (a-d) to obtain first ultra-small magnetite (USM) nanoparticles, followed by addition of gold to form Fe3O4@Au nanoparticles, and lastly the formation of the composites using either citrate or tiopronin as a reducing agent, and purification using magnetic separation.…”

“…A scheme of the synthetic approach utilised (a-d) to obtain first ultra-small magnetite (USM) nanoparticles, followed by addition of gold to form Fe 3 O 4 @Au nanoparticles, and lastly the formation of the composites using either citrate or tiopronin as a reducing agent, and purification using magnetic separation. Reprinted with permission from [28]. Copyright The Royal Society Publishing, 2016.…”

Exploring Factors for the Design of Nanoparticles as Drug Delivery Vectors

“…In drug delivery, ferumoxytol, contained in magnetic iron oxide NPs, is employed to treat anemia in chronic renal malfunction patients . Apart from drug delivery of hydrophobic drugs, such as CPT or curcumin and contrast agents, magnetic NPs (alone or gold‐coated), have been applied to destroy tumoral cells by hyperthermia, protein detection, magnetic separation of cells and biomolecule purification by magnetic field application …”

“…[61] In drug delivery, ferumoxytol, contained in magnetic iron oxide NPs, is employed to treat anemia in chronic renal malfunction patients. [2] Apart from drug delivery of hydrophobic drugs, such as CPT [62] or curcumin [63] and contrast agents, [64] magnetic NPs (alone or gold-coated) [65,66] have been applied to destroy tumoral cells by hyperthermia, [67] protein detection, [68] magnetic separation of cells and biomolecule purification by magnetic field application. [69] As for platinum NPs, most of the bibliography refers to different NP types holding chemotherapeutic Platinum IV complexes, like Cisplatin (cis-diamminedichloplatinum, CDDP, Figure 1) or derivatives like Oxaliplatin, Nedaplatin, Lobaplatin, Carboplatin and Heptaplatin.…”