Highly crystallized iron oxide nanoparticles as effective and biodegradable mediators for photothermal cancer therapy

Abstract

We report that highly crystallized iron oxide nanoparticles (HCIONPs) made by thermal decomposition and further coating with a polysiloxane-containing copolymer can be used as effective mediators for photothermal therapy. Irradiation of a HCIONP solution containing 0.5 mg mL À1 Fe, for instance, with an 885 nm diode laser at a power of 2.5 W cm À2 , induces a temperature increase of 33 C from room temperature, while water produced only a $3 C increase as the control. In vivo studies are further evaluated for effective photothermal therapy using the as-prepared HCIONPs. Benefiting from the great antibiofouling property of the polymer coating and minimized hydrodynamic size (whole particle size: 24 nm), the nanoparticles intravenously administered to SUM-159 tumor-bearing mice can effectively accumulate within the tumor tissue (5.3% of injection dose) through the enhanced permeability and retention effect. After applying the same laser conditions to irradiate the tumors, complete tumor regression is observed within three weeks without disease relapse over the course of three months. Conversely, control mice exhibit continuous tumor growth leading to animal mortality within four weeks.To better understand the photothermal effect of HCIONPs and potentially improve their photothermal efficiency, we compare their photothermal effect and crystal structures with commercially available magnetic nanoparticles. Our data show that after applying the same laser to commercially available magnetic nanoparticles from FeREX at the same iron concentration, the temperature is only increased by 7.4 C. We further use synchrotron-XRD and high-resolution TEM to compare the crystal structures of both magnetic nanoparticles. The data show that both magnetic nanoparticles are Fe 3 O 4 but asprepared HCIONPs are highly crystalline and have preferred lattice plane orientations, which may be the cause of their enhanced photothermal efficiency. Taken together, these data suggest that HCIONPs, with unique lattice orientations and small size as well as antifouling coating, can be used as promising mediators for photothermal cancer therapy.

Revisiting the classification of NIR-absorbing/emitting nanomaterials for in vivo bioapplications

“…Indeed, Sun and co-workers reported fabricating highly crystalline iron oxide NPs (24 nm) via thermal decomposition, which were then coated with a polysiloxane-containing copolymer for effective photothermal ablation. 70 The authors also evaluated the highly crystalline iron oxide NPs combined with an 885 nm laser at a power of 41 W cm − 2 in an in vitro system and in SUM-159 tumorbearing mice. Despite these successful results, most reported synthesized Fe 3 O 4 NPs possess a nonstoichiometric structure and do (Figure 7a).…”

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“…The unique properties of iron oxide magnetic nanoparticles are suitable for using in biocatalysis and bioseparation areas 160 .…”

Hyaluronan-modified superparamagnetic iron oxide nanoparticles for bimodal breast cancer imaging and photothermal therapy

“…9,[12][13][14][15] Chen et al 14 reported that the highly crystallized iron oxide nanoparticles administered through the tail vein for PTT as effective and biodegradable mediators. These injected nanoparticles are likely to be applied for PTT as a result of the enhanced permeability and retention (EPR) effect and is cleared from the body through urinary excretion without long-term toxicity.…”