Iron Oxide Mediated Photothermal Therapy in the Second Biological Window: A Comparative Study between Magnetite/Maghemite Nanospheres and Nanoflowers

Sonia Cabana,Claire Wilhelm,Ali Abou-Hassan,Alberto Curcio,Aude Michel

doi:10.3390/nano10081548

Abstract

The photothermal use of iron oxide magnetic nanoparticles (NPs) is becoming more and more popular and documented. Herein, we compared the photothermal (PT) therapy potential versus magnetic hyperthermia (MHT) modality of magnetic nanospheres, largely used in the biomedical field and magnetic multicore nanoflowers known among the best nanoheaters. The NPs were imaged using transmission electron microscopy and their optical properties characterized by UV-Vis-NIR-I-II before oxidation (magnetite) and after oxidation to maghemite. The efficiency of all NPs in MHT and PT in the preferred second near-infrared (NIR-II) biological window was carried out in water and in cancer cells. We show that, in water, magnetite nanoflowers are the most efficient nanoheaters for both modalities. Moreover, PT appears much more efficient than MHT at low NP dose, whatever the NP. In the cellular environment, for PT, efficiency was totally conserved, with magnetite nanoflowers as the best performers compared to MHT, which was totally lost. Finally, cell uptake was significantly increased for the nanoflowers compared to the nanospheres. Finally, the antitumor therapy was investigated for all NPs at the same dose delivered to the cancer cells and at reasonable laser power density (0.3 W/cm2), which showed almost total cell death for magnetite nanoflowers.

Highlights

Iron oxide magnetic nanoparticles (MNPs), such as magnetite (Fe3O4) and its oxidized form maghemite (γ-Fe2O3), emerged as promising nanotheranostic agents due to their versatile magnetic properties, their biocompatibility, and their biodegradability [1]
The XRD gives the size of the small grains composing the nanoflowers, which was almost identical to what was observed by TEM; in the case of the spherical nanoparticles, the diameter as deduced from XRD (10.6 nm) was below the physical size obtained by TEM, which shows that magnetic nanospheres are less crystalline than the magnetic nanoflowers
In this paper we investigated the thermal modalities in magnetic hyperthermia (MHT) and PT in aqueous solution and in cancer cells of two renown magnetic nanoparticles in the biomedical field

Summary

Introduction

Iron oxide magnetic nanoparticles (MNPs), such as magnetite (Fe3O4) and its oxidized form maghemite (γ-Fe2O3), emerged as promising nanotheranostic agents due to their versatile magnetic properties, their biocompatibility, and their biodegradability [1]. Several approaches have been suggested to overcome these limitations: among them, one is based on the synthesis of novel nanostructures having an optimized heating [12,13,14]; another consists of the association of MNPs with other heat-generating materials, such as plasmonic ones, designed for photothermal (PT) therapy, resulting in a multifunctional magneto-plasmonic nanohybrid platform Such plasmonic materials include metals, such as gold (Au), providing the hybrids with an absorption in the first near-infrared (NIR-I) optical window in biological tissues or semiconductors, such as copper sulfide (CuS), which possesses a strong absorption in the second (NIR-II) window [15,16,17,18]. Despite the versatility of these approaches, synthesis and optimization of any new structure is both time- and money-consuming, can be difficult to control, and the biocompatibility of the final structures is not always very studied, which may limit the applications

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