Can commercial ferrofluids be exploited in AC magnetic hyperthermia treatment to address diverse biomedical aspects? (original) (raw)
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Journal of Applied Physics, 2011
Magnetite (Fe 3 O 4 ) nanoparticles (MNPs) are suitable materials for Magnetic Fluid Hyperthermia (MFH), provided their size is carefully tailored to the applied alternating magnetic field (AMF) frequency. Since aqueous synthesis routes produce polydisperse MNPs that are not tailored for any specific AMF frequency, we have developed a comprehensive protocol for synthesizing highly monodispersed MNPs in organic solvents, specifically tailored for our field conditions (f ¼ 376 kHz, H 0 ¼ 13.4 kA/m) and subsequently transferred them to water using a biocompatible amphiphilic polymer. These MNPs (r avg. ¼ 0.175) show truly size-dependent heating rates, indicated by a sharp peak in the specific loss power (SLP, W/g Fe 3 O 4 ) for 16 nm (diameter) particles. For broader size distributions (r avg. ¼ 0.266), we observe a 30% drop in overall SLP. Furthermore, heating measurements in biological medium [Dulbecco's modified Eagle medium (DMEM) þ 10% fetal bovine serum] show a significant drop for SLP ($30% reduction in 16 nm MNPs). Dynamic Light Scattering (DLS) measurements show particle hydrodynamic size increases over time once dispersed in DMEM, indicating particle agglomeration. Since the effective magnetic relaxation time of MNPs is determined by fractional contribution of the Neel (independent of hydrodynamic size) and Brownian (dependent on hydrodynamic size) components, we conclude that agglomeration in biological medium modifies the Brownian contribution and thus the net heating capacity of MNPs.
Applications of magnetic nanoparticles in medicine: magnetic fluid hyperthermia
Puerto Rico health sciences journal, 2009
Nanoparticle systems are an intense subject of research for various biomedical applications. Colloidal suspensions of magnetic nanoparticles are of special interest, particularly in bioimaging, and more recently, in Magnetic Fluid Hyperthermia (MFH). MFH promises to be a viable alternative in the treatment of localized cancerous tumors. The treatment consists of locally injecting magnetic nanoparticles in fluid suspension into the tumor site and exposing the site to an oscillating magnetic field, where nanoparticles dissipate energy in the form of heat, causing a localized rise in temperature and tumor cell death. Here we will review methods of magnetic nanoparticle synthesis, and the role of the nanoparticle surface coating in achieving colloidal stability, minimizing toxicity, and targeting. Finally, we review in vitro and in vivo MFH experiments, and clinical studies in the treatment of glioblastoma multiforme and prostate cancer.
The effects of magnetic nanoparticle properties on magnetic fluid hyperthermia
Journal of Applied …, 2010
Magnetic fluid hyperthermia ͑MFH͒ is a noninvasive treatment that destroys cancer cells by heating a ferrofluid-impregnated malignant tissue with an ac magnetic field while causing minimal damage to the surrounding healthy tissue. The strength of the magnetic field must be sufficient to induce hyperthermia but it is also limited by the human ability to safely withstand it. The ferrofluid material used for hyperthermia should be one that is readily produced and is nontoxic while providing sufficient heating. We examine six materials that have been considered as candidates for MFH use. Examining the heating produced by nanoparticles of these materials, barium-ferrite and cobalt-ferrite are unable to produce sufficient MFH heating, that from iron-cobalt occurs at a far too rapid rate to be safe, while fcc iron-platinum, magnetite, and maghemite are all capable of producing stable controlled heating. We simulate the heating of ferrofluid-loaded tumors containing nanoparticles of the latter three materials to determine their effects on tumor tissue. These materials are viable MFH candidates since they can produce significant heating at the tumor center yet maintain the surrounding healthy tissue interface at a relatively safe temperature.
IEEE Transactions on Magnetics, 2016
Magnetic hyperthermia applications based on superparamagnetic nanoparticles, are behind many theragnostic developments, some of which are entering into a stage of commercial maturity (see Magforce). Theoretical frames, like the well established Rosensweig formulation, relay on studies performed on "ideal ferrofluids", in which viscosity, concentration, or pH are homogenous throughout the sample. However, biological environments are deeply complex, dynamic and heterogeneous, making the nano-bio interaction the leading variable controlling magnetic hyperthermia (MH) performance. Biological MH applications depend on a larger set of parameters than those currently studied: agglomeration; type of coating; viscosity, or local concentration, are marginally studied and produce intricate and non-linear responses in biological MH applications.
Iron oxide nanoparticles have become ubiquitous in many biomedical applications, acting as core elements in an increasing number of therapeutic and diagnostic modalities. These applications mainly rely on their static and dynamic magnetic properties, through which they can be remotely actuated. However, little attention has been paid to understand the variation of the magnetic response of nanoparticles inside cells or tissues, despite of the remarkable changes reported to date. In this article, we provide some hints to analyze the influence of the biological matrix on the magnetism of iron oxide nanoparticles. To this aim, we propose the assessment of the heating efficiency of magnetic colloids against nanoparticle aggregation, concentration, and viscosity in order to mimic the fate of nanoparticles upon cell internalization.
Evaluation of magnetic nanoparticles for magnetic fluid hyperthermia
International Journal of Hyperthermia, 2019
Background: Magnetic nanoparticles (MNPs) generate heat when exposed to an alternating magnetic field. Consequently, MNPs are used for magnetic fluid hyperthermia (MFH) for cancer treatment, and have been shown to increase the efficacy of chemotherapy and/or radiation treatment in clinical trials. A downfall of current MFH treatment is the inability to deliver sufficient heat to the tumor due to: insufficient amounts of MNPs, unequal distribution of MNPs throughout the tumor, or heat loss to the surrounding environment. Objective: In this study, the objective was to identify MNPs with high heating efficiencies quantified by their specific absorption rate (SAR). Methods: A panel of 31 commercially available MNPs were evaluated for SAR in two different AMFs. Additionally, particle properties including iron content, hydrodynamic diameter, core diameter, magnetic diameter, magnetically dead layer thickness, and saturation mass magnetization were investigated. Results: High SAR MNPs were identified. For SAR calculations, the initial slope, corrected slope, and Box–Lucas methods were used and validated using a graphical residual analysis, and the Box–Lucas method was shown to be the most accurate. Other particle properties were identified and examined for correlations with SAR values. Positive correlations of particle properties with SAR were found, including a strong correlation for the magnetically dead layer thickness. Conclusions: This work identified high SAR MNPs for hyperthermia, and provides insight into properties which correlate with SAR which will be valuable for synthesis of next-generation MNPs. SAR calculation methods must be standardized, and this work provides an in-depth analysis of common calculation methods.
A Single Picture Explains Diversity of Hyperthermia Response of Magnetic Nanoparticles
The Journal of Physical Chemistry C, 2015
Progress in the design of nanoscale magnets for localized hyperthermia cancer therapy has been largely driven by trial-and-error approaches, for instance, by changing of the stoichiometry composition, size, and shape of the magnetic entities. So far, widely different and often conflicting heat dissipation results have been reported, particularly as a function of the nanoparticle concentration. Thus, achieving hyperthermiaefficient magnetic ferrofluids remains an outstanding challenge. Here we demonstrate that diverging heat-dissipation patterns found in the literature can be actually described by a single picture accounting for both the intrinsic magnetic features of the particles (anisotropy, magnetization) and experimental conditions (concentration, magnetic field). Importantly, this general magnetichyperthermia scenario also predicts a novel non-monotonic concentration dependence with optimum heating features, which we experimentally confirmed in iron oxide nanoparticle ferrofluids by fine-tuning the particle size. Overall, our approach implies a magnetic hyperthermia trilemma that may constitute a simple strategy for development of magnetic nanomaterials for optimal hyperthermia efficiency.
Magnetism for Drug Delivery, MRI and Hyperthermia Applications: a Review
2020
Superparamagnetic nanoparticles contain unique magnetic properties that differ from the bulk materials and are able to function at a cellular level due to their size, shape, and surface characteristics. These features make them attractive candidates for drug delivery systems, thermal mediators in hyperthermia, and magnetic resonance imaging (MRI) contrast agents. This review provides an up-to-date overview of the application of iron oxide nanoparticles in cancer diagnosis, drug delivery, treatment, and safety concerns related to these materials are considered, as well. Furthermore, the general principles and challenges of the magnetic behavior of nanoparticles in the field of oncology are also discussed. Firstly, the basic requirements for magnetic nanoparticles for biomedical applications are outlined. The close link between structure, shape, size, and magnetic characterization are described, which is considered essential for non-invasive imaging modality, innovative magneticdriven...
Pharmaceutics
In this work we report on the synthesis and characterization of magnetic nanoparticles of two distinct origins, one inorganic (MNPs) and the other biomimetic (BMNPs), the latter based on a process of bacterial synthesis. Each of these two kinds of particles has its own advantages when used separately with biomedical purposes. Thus, BMNPs present an isoelectric point below neutrality (around pH 4.4), while MNPs show a zero-zeta potential at pH 7, and appear to be excellent agents for magnetic hyperthermia. This means that the biomimetic particles are better suited to be loaded with drug molecules positively charged at neutral pH (notably, doxorubicin, for instance) and releasing it at the acidic tumor environment. In turn, MNPs may provide their transport capabilities under a magnetic field. In this study it is proposed to use a mixture of both kinds of particles at two different concentrations, trying to get the best from each of them. We study which mixture performs better from dif...
Suitability of commercial colloids for magnetic hyperthermia
Journal of Magnetism and Magnetic Materials, 2009
Commercial nanoparticles supplied by Chemicell, Micromod and Bayer-Schering were characterised with regard to their nanocrystalline diameter, hydrodynamic diameter, total iron content and relative ferrous iron content. Additionally, calorimetric measurements were taken using a 900 kHz AC magnetic field of amplitude 5.66 kA/m. It was found that those samples containing relatively high (418%) ferrous content generated a substantially smaller (12% on average) intrinsic loss power (ILP) than those samples with a lower ferrous content. Two nominally identical Chemicell samples that differed only in their production date showed significantly different ILPs, attributed to a variation in batch-to-batch crystallite sizes. The highest ILP values in the cohort, ca. 3.1 nHm 2 /kg, were achieved for particles with hydrodynamic diameters of ca. 70 nm and nanocrystalline diameters of ca. 12 nm. These compare favourably with most samples prepared in academic laboratories, although they are not as high as the ca. 23.4 nHm 2 /kg reported for naturally occurring bacterial magnetosomes.