Hyperthermia Effect of Nanoclusters Governed by Interparticle Crystalline Structures

Abstract

Magnetic nanoparticles have an important role as heat generators in magnetic fluid hyperthermia, a type of nextgeneration cancer treatment. Despite various trials to improve the heat generation capability of magnetic nanoparticles, iron oxide nanoparticles are the only approved heat generators for clinical applications, which require a large injection dose due to their low hyperthermia efficiency. In this study, iron oxide nanoclusters (NCs) with a highly enhanced hyperthermia effect and adjustable size were synthesized through a facile and simple solvothermal method. Among the samples, the NCs with a size of 25 nm showed the highest hyperthermia efficiency. Differently sized NCs exhibit inconsistent interparticle crystalline alignments, which affect their magnetic properties (e.g., coercivity and saturation magnetization). As a result, the optimal NCs exhibited a significantly enhanced heat generation efficiency compared with that of isolated iron oxide nanoparticles (ca. 7 nm), and their hyperthermia effect on skin cancer cells was confirmed.

LAPONITE® nanodisk-“decorated” Fe3O4 nanoparticles: a biocompatible nano-hybrid with ultrafast magnetic hyperthermia and MRI contrast agent ability

“…2(h) and (i)), together with the high net magnetization value (90.8 emu g À1 at 2 T), which is close to the bulk magnetite properties, and the successful decoration with the diamagnetic clay, which favors the suppression of the interparticle magnetic interactions is well known to enhance the T 2 -weighted MRI contrast ability 69,73 and is probably responsible for the superior magnetic hyperthermia performance. 74 Regarding iron oxide nanomaterials, the SAR values presented here are among the highest compared to the literature (Table S1, ESI †) in terms of magnetic field and frequency conditions and are comparable or even better than the iron oxide cubes, 50,75 rods, 20 tubes, rings/hollow, 49 multicores, 71 assemblies, 76,77 branched, 72 and cube assemblies, 23 which have been recently reported. Among them, some materials reveal extremely high SAR values, in the order of a few thousand W g À1 , but we have to notice, taking into consideration the linear dependence with the frequency 52,78 that this is mainly due to the very high frequency up to 700 kHz.…”

Magnetic Particle Imaging of Magnetotactic Bacteria as Living Contrast Agents Is Improved by Altering Magnetosome Arrangement

“…Magnetic hyperthermia could be used to ablate cancer cells by heating the magnetosomes in the tumor-associated bacteria, or alternatively, the magnetosomes could be heated to temperatures that do not kill cells and used to thermally activate the expression of therapeutic genes to elicit antitumoral effects. Efficient magnetothermal heating has been observed in synthetic nanoparticles in both linear and clustered , arrangements. The magnetothermal heating of magnetosomes in different forms (whole cell and isolated linear chains and individual magnetosomes) ,,, has shown improved heating properties in comparison to synthetic particles.…”

Improvement of Hyperthermia Properties of Iron Oxide Nanoparticles by Surface Coating

“…Regarding the state of aggregation, the formation of NP clusters or chains driven by magnetostatic dipole–dipole interactions can be responsible for a significant variation in the SLP, , e.g., the arrangement in chains typically results in larger SLP values, while large clusters usually lead to worse heating performance. However, the collective magnetic behavior due to interparticle interactions can be beneficial to hyperthermia for small aggregates, whose optimal size depends on the material composition. , …”

“…However, the collective magnetic behavior due to interparticle interactions can be beneficial to hyperthermia for small aggregates, whose optimal size depends on the material composition. 26 , 36 …”

“…However, the collective magnetic behavior due to interparticle interactions can be beneficial to hyperthermia for small aggregates, whose optimal size depends on the material composition. 26,36 One of the best strategies to minimize detrimental magnetostatic interactions is to functionalize the surface of the NPs with organic or inorganic coatings, which favor their dispersion via the formation of a steric hindrance and/or a surface charge that triggers repulsive electrostatic interactions. 37−39 The coatings not only increase the colloidal stability but can also improve the biocompatibility of NPs, allowing their suspension in aqueous or organic media and enabling the binding with other functional groups or molecules useful for addressing specific functions in therapeutics and diagnostics.…”