Compositional Tuning of Light-to-Heat Conversion Efficiency and of Optical Properties of Superparamagnetic Iron Oxide Nanoparticles

Abstract

Superparamagnetic iron oxide nanoparticles have played a fundamental role in the recent development on nanomedicine, being one of the most popular imaging and therapeutic agents. Recently, the ability of iron magnetic nanoparticles for efficient heat generation under infrared optical excitation has even boosted the interest of scientific community in this family of nanomaterials. Combination of magnetic and optical heating into a single nanostructure makes possible the development of advanced therapy treatments based on synergetic effects between these two heat sources that, in addition, could be combined with high penetration magnetic imaging. Despite of its potential, the application of iron oxide nanoparticles in photothermal treatments is limited because the lack of knowledge about the physical mechanisms behind their light-to-heat conversion capacity. In this work we have systematically investigated the photothermal efficiency of iron oxide nanoparticles with a variable composition achieved by partial replacement of iron by zinc atoms. We have experimentally found that the light-to-heat conversion efficiency gradually increases with the iron content, suggesting a dominant role of iron related transitions in the heating processes. Experimental data included in this work reveal a simple route to tailor the light activated heating processes in iron oxide nanoparticles towards fully controllable treatments.

Influence of Magnetic Nanoparticle Degradation in the Frame of Magnetic Hyperthermia and Photothermal Treatments

“…In contrast, in the frame of photothermal experiments, not so many studies have evaluated the role that particle size has on the heating properties of iron oxides, and in some cases, the obtained results are contradictory and remain under study. 34 If the photothermal heating is related to the band structures of magnetite/maghemite, 35 size should not have a strong impact on the heating, and the changes observed in this work would be attributed to a decrease in the total amount of magnetite/ maghemite mass in the sample due to the formation of other iron-containing species, related to the paramagnetic contributions observed in the magnetic characterization data (Figure 4). Our observations indicated a smaller influence of the particle size on the heating properties of particles when exposed to an NIR light than to an AMF, pointing to the fact that the particle degradation along time could have a smaller impact on photothermal therapies in magnetic hyperthermia treatments when performed along long periods of time after particle administration.…”

Multiwavelength Phototactic Micromotor with Controllable Swarming Motion for “Chemistry-on-the-Fly”

“…It should be noted that this dependence is quite similar to the relationship between the micromotor speed and the light wavelength (Figure B). Given that higher concentration of photothermal material generates more heat, , the influence of Fe 3 O 4 @PGS concentration on the swarming motion was investigated. As seen in Figure D, the speed of Fe 3 O 4 @PGS increased almost linearly with particle concentration.…”

Light-driven MOF-based micromotors with self-floating characteristics for water sterilization

“…Hence, the distinct NIR adsorption and photothermal conversion ability of PPy is crucial for triggering the fastest speed of the micromotors under NIR light irradiation in our study. Given the widely accepted mechanism that the concentration of photothermally active particles is positively correlated with the heat generated by light irradiation, 2,51 we also investigated the effect of the concentration of the micromotors on the light-driven speed, as shown in Fig. 3f.…”