Iron Oxide Nanoparticles in a Dynamic Flux: Magnetic Hyperthermia Effect on Flowing Heavy Crude Oil.

An essential part for crude oil extraction is flow assurance, being critical to maintain a financially sustainable flow while getting the petroleum to the surface. When not well managed, it can develop into a significant issue for the O&G industry. By heating the fluids, problems with flow assurance, including paraffin deposition, asphaltene, and methane hydrate, can be reduced. Also, as the temperature rises, a liquid's viscosity decreases. Research focusing on the application of magnetic nanoparticles (NPs) in the oil industry is very recent. When magnetic nanofluids are exposed to an alternating magnetic field, the viscosity decreases by several orders of magnitude as a result of the fluid's temperature rising due to a phenomenon known as magnetic hyperthermia. This work focuses on the use of magnetic NPs (9 nm) in heavy crude oil (API 19.0). The frequency and strength of the magnetic field, as well as the characteristics of the fluid and the NPs intrinsic properties all affect the heating efficiency. For all of the experimental settings in this work, the flowloop's temperature increased, reaching a maximum of ΔT = 16.3 °C, using 1% wt NPs at the maximum available frequency of the equipment (533 kHz) and the highest field intensity for this frequency (14 kA/m), with a flow rate of 1.2 g/s. This increase in temperature causes a decrease of nearly 45% on the heavy crude oil viscosity, and if properly implemented, could substantially increase oil flow in the field during production.

Cell-Promoted Nanoparticle Aggregation Decreases Nanoparticle-Induced Hyperthermia under an Alternating Magnetic Field Independently of Nanoparticle Coating, Core Size, and Subcellular Localization.

Magnetic hyperthermia has a significant potential to be a new breakthrough for cancer treatment. The simple concept of nanoparticle-induced heating by the application of an alternating magnetic field has attracted much attention, as it allows the local heating of cancer cells, which are considered more susceptible to hyperthermia than healthy cells, while avoiding the side effects of traditional hyperthermia. Despite the potential of this therapeutic approach, the idea that local heating effects due to the application of alternating magnetic fields on magnetic nanoparticle-loaded cancer cells can be used as a treatment is controversial. Several studies indicate that the heating capacity of magnetic nanoparticles is largely reduced in the cellular environment because of increased viscosity, aggregation, and dipolar interactions. However, an increasing number of studies, both in vitro and in vivo, show evidence of successful magnetic hyperthermia treatment on several different types of cancer cells. This apparent contradiction might be due to the use of different experimental conditions. Here, we analyze the effects of several parameters on the cytotoxic efficiency of magnetic nanoparticles as heat inductors under an alternating magnetic field. Our results indicate that the cell-nanoparticle interaction reduces the cytotoxic effects of magnetic hyperthermia, independent of nanoparticle coating and core size, the cell line used, and the subcellular localization of nanoparticles. However, there seems to occur a synergistic effect between the application of an external source of heat and the presence of magnetic nanoparticles, leading to higher toxicities than those induced by heat alone or the accumulation of nanoparticles within cells.

Formation Mechanism of Maghemite Nanoflowers Synthesized by a Polyol-Mediated Process.

Magnetic nanoparticles are being developed as structural and functional materials for use in diverse areas, including biomedical applications. Here, we report the synthesis of maghemite (γ-Fe2O3) nanoparticles with distinct morphologies: single-core and multicore, including hollow spheres and nanoflowers, prepared by the polyol process. We have used sodium acetate to control the nucleation and assembly process to obtain the different particle morphologies. Moreover, from samples obtained at different time steps during the synthesis, we have elucidated the formation mechanism of the nanoflowers: the initial phases of the reaction present a lepidocrocite (γ-FeOOH) structure, which suffers a fast dehydroxylation, transforming to an intermediate "undescribed" phase, possibly a partly dehydroxylated lepidocrocite, which after some incubation time evolves to maghemite nanoflowers. Once the nanoflowers have been formed, a crystallization process takes place, where the γ-Fe2O3 crystallites within the nanoflowers grow in size (from ∼11 to 23 nm), but the particle size of the flower remains essentially unchanged (∼60 nm). Samples with different morphologies were coated with citric acid and their heating capacity in an alternating magnetic field was evaluated. We observe that nanoflowers with large cores (23 nm, controlled by annealing) densely packed (tuned by low NaAc concentration) offer 5 times enhanced heating capacity compared to that of the nanoflowers with smaller core sizes (15 nm), 4 times enhanced heating effect compared to that of the hollow spheres, and 1.5 times enhanced heating effect compared to that of single-core nanoparticles (36 nm) used in this work.