High-Frequency Specific Absorption Rate of CoxFe1−xFe2O4 Ferrite Nanoparticles for Hipertermia Applications (original) (raw)
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Nanomaterials
Using magnetic nanoparticles for extracorporeal magnetic heating applications in bio-medical technology allows higher external field amplitudes and thereby the utilization of particles with higher coercivities (HC). In this study, we report the synthesis and characterization of high coercivity cobalt ferrite nanoparticles following a wet co-precipitation method. Particles are characterized with magnetometry, X-ray diffraction, Mössbauer spectroscopy, transmission electron microscopy (TEM) and calorimetric measurements for the determination of their specific absorption rate (SAR). In the first series, CoxFe3−xO4 particles were synthesized with x = 1 and a structured variation of synthesis conditions, including those of the used atmosphere (O2 or N2). In the second series, particles with x = 0 to 1 were synthesized to study the influence of the cobalt fraction on the resulting magnetic and structural properties. Crystallite sizes of the resulting particles ranged between 10 and 18 nm,...
Magnetic Nanoparticles for Biomedical Applications
Pharmaceutical Research, 2012
Magnetite nanoparticles covalently coated with polysaccharide arabic acid are investigated as possible constituents of aqueous ferrofluids for biomedical applications. The nanoparticles have been characterized by transmission electron microscopy and with magnetic measurements. 1 H nuclear magnetic resonance T 1 relaxation experiments of the coating which cover the nanoparticles have been also carried out in an attempt to probe the dynamic (superparamagnetic) behaviour of the magnetic nanoparticles. Finally, magnetic hyperthermia experiments of the synthesized ferrofluid have been performed and the dependence of the measured Specific Absorption Rate coefficient (SAR) as a function of the amplitude of the irradiation field is discussed.
Journal of Nanoparticles, 2013
Comparative studies are presented of iron oxide nanoparticles in the 7–15 nm average diameter range ball milled in hexane in the presence of oleic acid. Transmission electron microscopy identified spherical particles of decreasing size as milling time and/or surfactant concentration increased. Micromagnetic characterization via Mössbauer spectroscopy at room temperature yielded broadened magnetic spectroscopic signatures, while macromagnetic characterization via vibrating sample magnetometry of 7-8 nm diameter particles showed largely superparamagnetic behavior at room temperature and hysteretic at 2 K. Zero-field and field-cooled magnetization curves exhibited a broad maximum at ~215 K indicating the presence of strong interparticle magnetic interactions. The specific absorption rates of ferrofluids based on these nanoparticle preparations were measured in order to test their efficacies as hyperthermia agents.
Biomedical application of ferrofluids containing magnetite nanoparticles
MRS Proceedings, 2001
Ferrofluids containing superparamagnetic Fe 3 O 4 nanoparticles have been prepared by a controlled co-precipitation method. The aggregation of the particles was prevented by using a polymeric starch network as a coating agent. Structural and magnetic measurements reveal a particle size of around 6 nm, with a clear evidence of a uniform particle coating. The ferrofluids have been used as a contrast agent for MR imaging in biological tissue.
Surface modified superparamagneticFe3O4 nanoparticles were prepared by alkaline co-precipitation of water soluble Fe(II) and Fe(III) salts.Fe3O4nanoparticles were surface modified with folic acid (FA) and ascorbic acid (AA).Samples were characterized by X-ray diffractometry, transmission electron microscopy, fourier transform infrared spectroscopy, thermogravimetry, vibrating sample magnetometry and induction heating study. X-ray diffractometry study has shown that the samples crystallize into a single cubic phase with a = b = c = 8.396±0.03 Å.The synthesized nanoparticles have maximum probable average size of 10 -12 nm. The nanoparticles prepared in presence of ascorbic acid was found to have more uniform particle and size distribution. The sufficiently high magnetization, induction heating abilities, high specific absorption rate (SAR) values and cell viability profiles on HeLa cells opened a scope for further in vivo study for cancer hyperthermia applications. The study observed that particle size and shape, reduced interparticle magnetic interactions and surface modification are necessary for practical applicability
Scientific Reports, 2020
This work reports the fabrication of magnetite (Fe 3 o 4) nanoparticles (NPs) coated with various biocompatible surfactants such as glutamic acid (GA), citric acid (CA), polyethylene glycol (PEG), polyvinylpyrrolidine (PVP), ethylene diamine (EDA) and cetyl-trimethyl ammonium bromide (CTAB) via co-precipitation method and their comparative inductive heating ability for hyperthermia (HT) applications. X-ray and electron diffraction analyses validated the formation of well crystallined inverse spinel structured fe 3 o 4 NPs (crystallite size of ~ 8-10 nm). Magnetic studies confirmed the superparamagnetic (SPM) behaviour for all the NPs with substantial magnetisation (63-68 emu/g) and enhanced magnetic susceptibility is attributed to the greater number of occupations of Fe 2+ ions in the lattice as revealed by X-ray photoelectron spectroscopy (XPS). Moreover, distinctive heating response (specific absorption rate, SAR from 130 to 44 W/g) of NPs with similar size and magnetisation is observed. The present study was successful in establishing a direct correlation between relaxation time (~ 9.42-15.92 ns) and heating efficiency of each surface functionalised NPs. Moreover, heat dissipated in different surface grafted NPs is found to be dependent on magnetic susceptibility, magnetic anisotropy and magnetic relaxation time. These results open very promising avenues to design surface functionalised magnetite NPs for effective HT applications. Magnetic hyperthermia (MHT) is one of the most propitious minimally invasive therapies for carcinogenic cell ablation 1,2. Aqueous stable biocompatible magnetic nanoparticles (MNPs), guided by an external magnetic field can potentially release heat selectively at the carcinogenic tumor sites and are often employed as efficient heat mediators for MHT 3,4. One of the key parameters to be monitored for a successful clinical outcome is to achieve the desired therapeutic temperature (42-46 °C) with minimal dosage of MNPs 5. In this regard, superparamag-netic iron oxide nanoparticles (SPIONs) are receiving increasing attention. SPIONs possess the potentiality to be directed by an AC magnetic field in order to specifically target the tumor regions and to dissipate heat locally. Superparamagnetism (SPM) results in negligible agglomeration between particles (feeble magnetic interactions) after the removal of field causing trivial side effects in the body 6,7. The SPM behaviour of NPs is very crucial for HT applications as these MNPs can be targeted towards the surface receptors upon an external magnetic field. Once the field is removed, MNPs persist zero magnetism at room temperature resulting negligible agglomeration thereby preventing phagocytic uptake 8. Due to this negligible aggregation, SPIONs will not elicit any adverse events that can lead to thrombosis. Heating efficacy of SPIONs, expressed in terms of specific absorption rate (SAR) is a pivotal factor determining the success of HT applications. SAR is solely related to the susceptibility loss mechanisms via either Néel relaxation and Brownian relaxation upon an AC magnetic field. If both processes take place concurrently, then the power dissipation is calculated by considering the relative contributions of both Neel and Brownian relaxation time denoted by τ N and τ B respectively. SAR value is consequently calculated in terms of the effective relaxation time, τ effective. Suitable surface modification of SPIONs with biocompatible materials is crucial for achieving desired particle size in nanometer scale with enhanced saturation magnetisation (M s) and stable ferro fluids. These biocompat-ible surface coatings can render a protective layer on the surface of SPIONs for proper attachment to the surface open
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2006
In this study, lauric acid-coated, superparamagnetic, nanoparticle-based magnetic fluids of different ferrites (Fe 3 O 4 , MnFe 2 O 4 , and CoFe 2 O 4 ) were prepared and compared in terms of heating ability and biocompatibility to evaluate the feasibility of use in hyperthermia treatment of cancer. All the magnetic fluids prepared had particles of average sizes 9-11 nm. Heating ability of these magnetic fluids was evaluated by calorimetric measurement of specific absorption rate (SAR) at 300 kHz frequency and 15 kA/m field. Fe 3 O 4 and MnFe 2 O 4 showed higher SAR (120 and 97 W/g of ferrite, respectively) than CoFe 2 O 4 (37 W/g of ferrite) . In vitro study on BHK 21 cell lines showed dose-dependent cell viability for all the magnetic fluids. Threshold-biocompatible ferrite concentration for all the magnetic fluids was 0.1 mg/mL. Above 0.2 mg/mL, CoFe 2 O 4 was more toxic than the other magnetic fluids. On intravenous injection of different doses (50, 200, and 400 mg/kg body weight) of magnetic fluids in mice, no significant changes in hematological and biochemical parameters were observed for Fe 3 O 4 and MnFe 2 O 4 . With CoFe 2 O 4 , an increase in SGPT levels at a dose rate of 400 mg/kg body weight was observed, indicating its mild hepatotoxic effect. However, histology of different vital organs showed no pathological changes for all the three magnetic fluids. Further, long term in vivo evaluation of biocompatibility of the lauric acid-coated ferrites is warranted. This study shows that lauric acid-coated, superparamagnetic Fe 3 O 4 and MnFe 2 O 4 may be used for hyperthermia treatment and are to be preferred over CoFe 2 O 4. '
Highly crystalline superparamagnetic Fe3O4 nanoparticles coated by polyvinylpyrrolidone (PVP) were prepared by simultaneous thermal decomposition of ferrous and ferric inorganic salts in polyethylene glycol (PEG) with molecular weight 200. The magnetic particles have a diameter in the range of 8-15 nm, and after exchange with citric acid diammonium salt, they transform into very stable super hydrophilic colloidal solutions. The presence of magnetite phase was confirmed using powder X-rays diffraction (XRD) and Mössbauer spectroscopy, while thermogravimetric analysis and FT-IR spectroscopy confirmed the presence of PVP or citrate anions on the nanoparticles surface. The magnetic properties revealed superparamagnetic behavior, with the composite material showing a saturation magnetization up to 57 emu/g. The Fe3O4 nanoparticles prepared by this modified polyol process are suitable for biomedical applications because of the biocompatibility of citrate anions. Magnetic hyperthermia experiments in neutral water solutions shows that the particles induce fast heating rates with specific absorption rate (SAR) values which reached 57.53 W/gFe, when the concentration of iron is 11.2 mgFe/ml
Journal of Applied Physics, 2014
Rate of heat generated by magnetic nanoparticles in a ferrofluid is affected by their magnetic properties, temperature, and viscosity of the carrier liquid. We have investigated temperature dependent magnetic hyperthermia in ferrofluids, consisting of dextran coated superparamagnetic Fe 3 O 4 nanoparticles, subjected to external magnetic fields of various frequencies (188-375 kHz) and amplitudes (140-235 Oe). Transmission electron microscopy measurements show that the nanoparticles are polydispersed with a mean diameter of 13.8 6 3.1 nm. The fitting of experimental dc magnetization data to a standard Langevin function incorporating particle size distribution yields a mean diameter of 10.6 6 1.2 nm, and a reduced saturation magnetization ($65 emu/g) compared to the bulk value of Fe 3 O 4 ($95 emu/g). This is due to the presence of a finite surface layer ($1 nm thickness) of non-aligned spins surrounding the ferromagnetically aligned Fe 3 O 4 core. We found the specific absorption rate, measured as power absorbed per gram of iron oxide nanoparticles, decreases monotonically with increasing temperature for all values of magnetic field and frequency. Using the size distribution of magnetic nanoparticles estimated from the magnetization measurements, we have fitted the specific absorption rate versus temperature data using a linear response theory and relaxation dissipation mechanisms to determine the value of magnetic anisotropy constant (28 6 2 kJ/m 3) of Fe 3 O 4 nanoparticles. V