The oriented attachment of magnetic nanoparticles is recognized as an important pathway in the magnetic-hyperthermia cancer treatment roadmap, thus, understanding the physical origin of their enhanced heating properties is a crucial task for the development of optimized application schemes. Here, we present a detailed theoretical analysis of the hysteresis losses in dipolar-coupled magnetic nanoparticle assemblies as a function of both the geometry and length of the array, and of the orientation of the particles' magnetic anisotropy. Our results suggest that the chain-like arrangement biomimicking magnetotactic bacteria has the superior heating performance, increasing more than 5 times in comparison with the randomly distributed system when aligned with the magnetic field. The size of the chains and the anisotropy of the particles can be correlated with the applied magnetic field in order to have optimum conditions for heat dissipation. Our experimental calorimetrical measurements performed in aqueous and agar gel suspensions of 44 nm magnetite nanoparticles at different densities, and oriented in a magnetic field, unambiguously demonstrate the important role of chain alignment on the heating efficiency. In low agar viscosity, similar to those of common biological media, the initial orientation of the chains plays a minor role in the enhanced heating capacity while at high agar viscosity, chains aligned along the applied magnetic field show the maximum heating. This knowledge opens new perspectives for improved handling of magnetic hyperthermia agents, an alternative to conventional cancer therapies.

Published by the American Institute of Physics. Related ArticlesFe3O4-citrate-curcumin: Promising conjugates for superoxide scavenging, tumor suppression and cancer hyperthermia J. Appl. Phys. 111, 064702 (2012) Integrated intravital microscopy and mathematical modeling to optimize nanotherapeutics delivery to tumors AIP Advances 2, 011208 (2012) In vitro cytotoxicity of Selol-loaded magnetic nanocapsules against neoplastic cell lines under AC magnetic field activation J. Appl. Phys. 111, 07B335 (2012) Magnetically driven spinning nanowires as effective materials for eradicating living cells J. Appl. Phys. 111, 07B329 (2012) Experimental characterization of electrochemical synthesized Fe nanowires for biomedical applications J. Appl. Phys. 111, 056103 (2012) Additional information on J. Appl. Phys. We show both experimental evidences and Monte Carlo modeling of the effects of interparticle dipolar interactions on the hysteresis losses. Results indicate that an increase in the intensity of dipolar interactions produce a decrease in the magnetic susceptibility and hysteresis losses, thus diminishing the hyperthermia output. These findings may have important clinical implications for cancer treatment.

The Fe‐MgO core‐shell morphology is proposed within the single‐domain nanoparticle regime as an enhanced magnetically driven hyperthermia carrier. The combinatory use of metallic iron as a core material together with the increased particle size (37–65 nm) triggers the tuning of dipolar interactions between particles and allows for further enhancement of their collective heating efficiency via concentration control. A theoretical universal estimation of hysteresis losses reveals the role of dipolar interactions on heating efficiency and outlines the strong influence of coupling effects on hyperthermia opening a novel roadmap towards multifunctional heat‐triggered theranostics particles.

The interest of the scientific community in the potential applications of inorganic engineered nanoparticles for drinking water treatment is continuously increasing. This review paper is an up to date summary of recent research progress in this field with respect to the removal of heavy metals, microorganisms and organic pollutants. In parallel, a critical investigation on the applicability of developed nanomaterials is attempted, considering the economic viability, environmental safety and sustainability of proposed processes. On this, the manuscript discusses issues like the stability and fate of engineered nanoparticles during and after use whereas it suggests a generalized approach for excluding reliable and comparable results by laboratory experiments. AbstractThis review summarizes recent research in the field of inorganic engineered nanoparticles development with direct or potential interest for drinking water treatment. The incorporation of engineered nanoparticles in drinking water treatment technologies against the removal of heavy metals, microorganisms and organic pollutants appears as a very dynamic branch of nanotechnology. Nanoparticles owe their potential on the high specific surface area and surface reactivity compared to conventional bulk materials. Depending on the mechanism of uptake, nanoparticles can be designed to establish high selectivity against specific pollutants and provide the required efficiency for application. However, despite early encouraging results, nanoparticles meet a number of limitations to get promoted and become part of large-scale water treatment plants. The most important is their availability in the required large quantities and their efficiency to fulfil the strict regulations for drinking water consumption and environmental safety. Both deal with the particles preparation cost and the cost of treatment operation with respect to the increase of supplied water price for the consumers. Under this view, this work attempts to evaluate reported studies according to their possibility to meet reliable requirements of water technology and also suggests an experimental approach to allow validation of tested nanoparticles.

In this work, we present the arrangement of Fe3O4 magnetic nanoparticles into 3D linear chains and its effect on magnetic particle hyperthermia efficiency. The alignment has been performed under a 40 mT magnetic field in an agarose gel matrix. Two different sizes of magnetite nanoparticles, 10 and 40 nm, have been examined, exhibiting room temperature superparamagnetic and ferromagnetic behavior, in terms of DC magnetic field, respectively. The chain formation is experimentally visualized by scanning electron microscopy images. A molecular Dynamics anisotropic diffusion model that outlines the role of intrinsic particle properties and inter-particle distances on dipolar interactions has been used to simulate the chain formation process. The anisotropic character of the aligned samples is also reflected to ferromagnetic resonance and static magnetometry measurements. Compared to the non-aligned samples, magnetically aligned ones present enhanced heating efficiency increasing specific loss power value by a factor of two. Dipolar interactions are responsible for the chain formation of controllable density and thickness inducing shape anisotropy, which in turn enhances magnetic particle hyperthermia efficiency.