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Open accessJournal ArticleDOI: 10.3390/NANO11030618

Nanomagnetic Actuation of Hybrid Stents for Hyperthermia Treatment of Hollow Organ Tumors

02 Mar 2021-Nanomaterials (Multidisciplinary Digital Publishing Institute)-Vol. 11, Iss: 3, pp 618
Abstract: This paper describes a magnetic nanotechnology that locally enables hyperthermia treatment of hollow organ tumors by using polymer hybrid stents with incorporated magnetic nanoparticles (MNP). The hybrid stents are implanted and activated in an alternating magnetic field to generate therapeutically effective heat, thereby destroying the tumor. Here, we demonstrate the feasibility of nanomagnetic actuation of three prototype hybrid stents for hyperthermia treatment of hollow organ tumors. The results show that the heating efficiency of stent filaments increases with frequency from approximately 60 W/gFe (95 kHz) to approximately 250 W/gFe (270 kHz). The same trend is observed for the variation of magnetic field amplitude; however, heating efficiency saturates at approximately 30 kA/m. MNP immobilization strongly influences heating efficiency showing a relative difference in heating output of up to 60% compared to that of freely dispersed MNP. The stents showed uniformly distributed heat on their surface reaching therapeutically effective temperatures of 43 °C and were tested in an explanted pig bile duct for their biological safety. Nanomagnetic actuation of hybrid stents opens new possibilities in cancer treatment of hollow organ tumors.

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Open accessJournal ArticleDOI: 10.3390/IJMS22147651
Abstract: Magnetic nanoparticles (MNPs) have a wide range of applications; an area of particular interest is magnetic particle imaging (MPI). MPI is an imaging modality that utilizes superparamagnetic iron oxide particles (SPIONs) as tracer particles to produce highly sensitive and specific images in a broad range of applications, including cardiovascular, neuroimaging, tumor imaging, magnetic hyperthermia and cellular tracking. While there are hurdles to overcome, including accessibility of products, and an understanding of safety and toxicity profiles, MPI has the potential to revolutionize research and clinical biomedical imaging. This review will explore a brief history of MPI, MNP synthesis methods, current and future applications, and safety concerns associated with this newly emerging imaging modality.

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4 Citations


Journal ArticleDOI: 10.1016/J.JMMM.2021.168134
M. S. Gopika1, B.B. Lahiri2, B. Anju1, John Philip2  +1 moreInstitutions (2)
Abstract: We study the magnetic hyperthermia efficiency of magnetite ferrofluids based on bio-friendly oils extracted from Calophyllum inophyllum (punnaga), Brassica juncea (mustard), Ricinus communis (castor) and Madhuca longifolia (iluppai) seeds. Reported medicinal uses of these bio-friendly oils make them interesting candidates for hyperthermia from a perspective of topical skin applications. Magneto-caloric experiments are performed at a fixed frequency of 126 kHz and varying field amplitudes of 33.1–25.7 kA/m. Experimental findings show that field induced heating efficiency is the highest for the punnaga oil based ferrofluids (~170.0 ± 8.2 W/gFe) and the estimated intrinsic loss power of ~ 1.26 nHm2kg−1 is found to be comparable to several commercially available ferrofluids. The obtained results further indicate that field induced heating efficiency increased by ~ 11 times on ~ 88% reduction in medium viscosity, which is due to the reduction in Brownian relaxation time of the dispersed magnetite nanoparticles at lower medium viscosity. Dynamic hysteresis loop simulations are carried out to theoretically estimate the heating efficiencies and the experimental and theoretical data are found to exhibit similar trends. The obtained results are beneficial for optimal design of bio-friendly oil based ferrofluids for possible topical hyperthermia applications over skin surfaces.

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3 Citations


Open accessJournal ArticleDOI: 10.3390/NANO11113013
Julian Palzer1, Lea Eckstein1, Ioana Slabu1, Oliver Reisen1  +2 moreInstitutions (1)
10 Nov 2021-Nanomaterials
Abstract: Iron oxide nanoparticle-based hyperthermia is an emerging field in cancer treatment. The hyperthermia is primarily achieved by two differing methods: magnetic fluid hyperthermia and photothermal therapy. In magnetic fluid hyperthermia, the iron oxide nanoparticles are heated by an alternating magnetic field through Brownian and Neel relaxation. In photothermal therapy, the hyperthermia is mainly generated by absorption of light, thereby converting electromagnetic waves into thermal energy. By use of iron oxide nanoparticles, this effect can be enhanced. Both methods are promising tools in cancer treatment and are, therefore, also explored for gastrointestinal malignancies. Here, we provide an extensive literature research on both therapy options for the most common gastrointestinal malignancies (esophageal, gastric and colorectal cancer, colorectal liver metastases, hepatocellular carcinoma, cholangiocellular carcinoma and pancreatic cancer). As many of these rank in the top ten of cancer-related deaths, novel treatment strategies are urgently needed. This review describes the efforts undertaken in vitro and in vivo.

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Topics: Hyperthermia (51%), Photothermal therapy (50%)

28 Sep 2021-
Abstract: Magnetic nanoparticles offer numerous promising biomedical applications, e. g. magnetic drug targeting. Here, magnetic drug carriers inside the human body are manipulated towards tumorous tissue by an external magnetic field. However, the success of the treatment depends strongly on the amount of drug carries, reaching the desired tumor region. This steering process is still an open research topic. In the proposed paper, an adjustable linear Halbach array to steer magnetic nanoparticles is investigated numerically using COMSOL Multiphysics. This Halbach array produces a relatively large region of a high magnetic field, while having a strong gradient. This results in a strong magnetic force, trapping many particles at the magnet. To avoid particle agglomeration, the Halbach array is rotated to its weak side. In this context, the force on the nanoparticles is evaluated for different magnet rotation angles. Comparing the weak and the strong magnetic side, the maximum and average magnetic force is a factor of 2.1 and 1.5 higher, respectively. Overall, the results depict the magnetic force and, thus, the region where the particles are able to get washed out, can be adjusted.

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Topics: Halbach array (66%), Magnetic nanoparticles (61%), Magnet (57%) ... read more

Journal ArticleDOI: 10.1109/TMAG.2021.3097915
Abstract: Hyperthermia therapy (HT) is becoming a well-recognized method for the treatment of cancer when combined with radiation or chemotherapy. There are many ways to heat a tumor and the optimum approach depends on the treatment site. This study investigates a composite ferromagnetic surgical implant inserted in a tumor bed for the delivery of local HT. Heating of the implant is achieved by inductively coupling energy from an external magnetic field of sub-megahertz frequency. Implants are formed by mechanically filling a resected tumor bed with self-polymerizing plastic mass mixed with small ferromagnetic thermoseeds. Model implants were manufactured and then heated in a 35 cm-diameter induction coil of our own design. Experimental results showed that implants were easily heated to temperatures that allow either traditional HT (39 °C–45 °C) or thermal ablation therapy (>50 °C) in an external magnetic field with a frequency of 90 kHz and amplitude not exceeding 4 kA/m. These results agreed well with a numerical solution of combined electromagnetic and heat transfer equations solved using the finite-element method.

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Topics: Hyperthermia therapy (58%), Induction heating (52%)
References
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100 results found


Journal ArticleDOI: 10.1107/S0021889878012844
Abstract: Existing knowledge about Scherrer constants is reviewed and a summary is given of the interpretation of the broadening arising from small crystallites. Early work involving the half-width as a measure of breadth has been completed and Scherrer constants of simple regular shapes have been determined for all low-angle reflections (h2 + k2 + l2 ≤ 100) for four measures of breadth. The systematic variation of Scherrer constant with hkl is discussed and a convenient representation in the form of contour maps is applied to simple shapes. The relation between the `apparent' crystallite size, as determined by X-ray methods, and the `true' size is considered for crystallites having the same shape. If they are of the same size, then the normal Scherrer constant applies, but if there is a distribution of sizes, a modified Scherrer constant must be used.

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Topics: Scherrer equation (70%)

2,559 Citations


Open accessBook
22 May 2009-
Abstract: Polymers are the compounds that includes platics, artificial fibers, rubber, cellulose, and many other materials, including coatings and adhesives. This book presents key data on approximately 200 important polymers currently in industrial use or under study in industrial or academic research. No other single source covers so many polymers or offers such a depth of data. The book standardizes and makes accessible a wealth of essential data for students, teachers, researchers, and other professionals in chemistry and chemical engineering.

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2,209 Citations


Journal ArticleDOI: 10.1016/S0304-8853(02)00706-0
Abstract: This study develops analytical relationships and computations of power dissipation in magnetic fluid (ferrofluid) subjected to alternating magnetic field. The dissipation results from the orientational relaxation of particles having thermal fluctuations in a viscous medium.

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Topics: Magnetic pressure (63%), Ferrofluid (62%), Magnetic energy (62%) ... read more

1,850 Citations


Open accessJournal ArticleDOI: 10.1063/1.3551582
Abstract: To optimize the heating properties of magnetic nanoparticles (MNPs) in magnetic hyperthermia applications, it is necessary to calculate the area of their hysteresis loops in an alternating magnetic field. The three types of theories suitable for describing the hysteresis loops of MNPs are presented and compared to numerical simulations: equilibrium functions, Stoner-Wohlfarth model based theories (SWMBTs) and linear response theory (LRT). Suitable formulas to calculate the hysteresis area of major cycles are deduced from SWMBTs and from numerical simulations; the domain of validity of the analytical formula is explicitly studied. In the case of minor cycles, the hysteresis area calculations are based on the LRT. A perfect agreement between LRT and numerical simulations of hysteresis loops is obtained. The domain of validity of the LRT is explicitly studied. Formulas to calculate the hysteresis area at low field valid for any anisotropy of the MNP are proposed. Numerical simulations of the magnetic field dependence of the area show it follows power-laws with a large range of exponents. Then, analytical expressions derived from LRT and SWMBTs are used for a theoretical study of magnetic hyperthermia. It is shown that LRT is only pertinent for MNPs with strong anisotropy and that SWMBTs should be used for weak anisotropy MNPs. The optimum volume of MNPs for magnetic hyperthermia as function of material and experimental parameters is derived. The maximum specific absorption rate (SAR) achievable is calculated versus the MNP anisotropy. It is shown that an optimum anisotropy increases the SAR and reduces the detrimental effects of size distribution. The optimum anisotropy is simple to calculate and depends on the magnetic field used in the hyperthermia experiments and on the MNP magnetization only. The theoretical optimum parameters are compared to the one of several magnetic materials.

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Topics: Hysteresis (54%), Anisotropy (53%), Magnetization (52%) ... read more

660 Citations


Open accessJournal ArticleDOI: 10.1063/1.3551582
Abstract: To optimize the heating properties of magnetic nanoparticles (MNPs) in magnetic hyperthermia applications, it is necessary to calculate the area of their hysteresis loops in an alternating magnetic field. The separation between “relaxation losses” and “hysteresis losses” presented in several articles is artificial and criticized here. The three types of theories suitable for describing hysteresis loops of MNPs are presented and compared to numerical simulations: equilibrium functions, Stoner–Wohlfarth model based theories (SWMBTs), and a linear response theory (LRT) using the Neel–Brown relaxation time. The configuration where the easy axis of the MNPs is aligned with respect to the magnetic field and the configuration of a random orientation of the easy axis are both studied. Suitable formulas to calculate the hysteresis areas of major cycles are deduced from SWMBTs and from numerical simulations; the domain of validity of the analytical formula is explicitly studied. In the case of minor cycles, the hysteresis area calculations are based on the LRT. A perfect agreement between the LRT and numerical simulations of hysteresis loops is obtained. The domain of validity of the LRT is explicitly studied. Formulas are proposed to calculate the hysteresis area at low field that are valid for any anisotropy of the MNP. The magnetic field dependence of the area is studied using numerical simulations: it follows power laws with a large range of exponents. Then analytical expressions derived from the LRT and SWMBTs are used in their domains of validity for a theoretical study of magnetic hyperthermia. It is shown that LRT is only pertinent for MNPs with strong anisotropy and that SWMBTs should be used for weakly anisotropic MNPs. The optimum volume of MNPs for magnetic hyperthermia is derived as a function of material and experimental parameters. Formulas are proposed to allow to the calculation of the optimum volume for any anisotropy. The maximum achievable specific absorption rate (SAR) is calculated as a function of the MNP anisotropy. It is shown that an optimum anisotropy increases the SAR and reduces the detrimental effects of the size distribution of the MNPs. The optimum anisotropy is simple to calculate; it depends only on the magnetic field used in the hyperthermia experiments and the MNP magnetization. The theoretical optimum parameters are compared to those of several magnetic materials. A brief review of experimental results as well as a method to analyze them is proposed. This study helps in the determination of suitable and unsuitable materials for magnetic hyperthermia and provides accurate formulas to analyze experimental data. It is also aimed at providing a better understanding of magnetic hyperthermia to researchers working on this subject.

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Topics: Magnetic anisotropy (59%), Magnetic hyperthermia (56%), Magnetic hysteresis (56%) ... read more

647 Citations


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