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

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.

Comparison of Iron Oxide Nanoparticles in Photothermia and Magnetic Hyperthermia: Effects of Clustering and Silica Encapsulation on Nanoparticles’ Heating Yield

“…Nanoparticle enclosures within endosomes do not decrease the nanoparticles' capacity to heat. Importantly, intracellular aggregation showed a small increase of the nanoparticles' photothermal heating [17,27]. Based on these findings, we herein investigated whether well-defined SPION clustering, and encapsulation by a silica shell (Figure 1), might affect the photothermal yield.…”

“…Iron oxides are also safe [21] and biocompatible [22], and they were already used for magnetic hyperthermia in clinical settings [23,24]. While several research groups reported the efficacy of photo-induced heating of iron oxides [19,[25][26][27], little is known about the effect of iron oxide's silica encapsulation and superparamagnetic iron oxide nanoparticles (SPIONs) clustering on the photothermal yield.…”

Synergistic Photothermal-Chemotherapy Based on the Use of Biomimetic Magnetic Nanoparticles

“…In addition, iron oxide nanoparticles exhibit an extended optical absorbance, which decreases from the near UV to the NIR, thanks to the electronic transition between Fe 2+ and Fe 3+ . In fact, recently, iron oxide nanoparticles have been tested for photothermal therapy in vitro and in vivo [ 13 , 14 , 22 , 27 , 28 , 29 , 30 ]. Therefore, they offer great possibilities to be considered for cancer therapy as a drug delivery system, magnetic hyperthermia and photothermal agent.…”

Superparamagnetic Nanoparticles with Efficient Near-Infrared Photothermal Effect at the Second Biological Window

“…It is worth noting that this transition is not present in maghemite [21]. The absorption spectrum of IONs shows a dip in the 700-800 nm region, which covers the largest part of the first biological widow, but it increases considerably in the second biological window range [34,35]. Figure 2a presents the magnetization-magnetic field (M-H) plots at 300 K of IONs.…”

“…In this way, Yuan et al demonstrated that IONs coated with polyethylene glycol (PEG) presented anti-cancer activity [33]. However, to the best of our knowledge, there are only few studies on the photothermal therapy application of IONs in the second biological window [34,35].…”