Superparamagnetic Ferrite Nanoparticles Research Articles

Preparation and thermogenic performance of monodisperse ferromagnetic Fe/SiO2 nanoparticles for magnetic hyperthermia and thermal ablation*

Ferromagnetic nanoparticles have great potential to be used in the field of magnetic hyperthermia and thermal ablation due to its high saturation magnetization (Ms) and high heating efficiency. In this paper, monodisperse spherical α-Fe2O3 nanoparticles were prepared by hydrothermal method using FeCl3, NaHCO3 and Na2SO4 as reactants. Then monodisperse Fe/SiO2 nanoparticles with core/shell structure were obtained by coating SiO2 on the surface of α-Fe2O3 nanoparticles and reducing at 500℃ in hydrogen atmosphere. The diameter of Fe core is about 230 nm and the thickness of SiO2 coating is about 75 nm. Magnetic measurements show that Fe/SiO2 nanoparticles exhibit typical ferromagnetic properties with Ms about 132.5 emu/g at 25 ℃. As-obtained Fe/SiO2 nanoparticles have higher heating efficiency than superparamagnetic ferrite nanoparticles. The high heating ability of the Fe/SiO2 nanoparticles is estimated to be related to the hysteresis loss and Brownian relaxation mechanism during alternating magnetization. The results show that Fe/SiO2 nanoparticles are promising for the applications of magnetic hyperthermia and thermal ablation.

One-Step Preparation of Highly Stable Copper-Zinc Ferrite Nanoparticles in Water Suitable for MRI Thermometry.

Superparamagnetic ferrite nanoparticles coated with a polymer layer are widely used for biomedical applications. The objective of this work is to design nanoparticles as a magnetic resonance imaging (MRI) temperature-sensitive contrast agent. Copper–zinc ferrite nanoparticles coated with a poly(ethylene glycol) (PEG) layer are synthesized using a one-step thermal decomposition method in a polymer matrix. The resulting nanoparticles are stable in water and biocompatible. Using Mössbauer spectroscopy and magnetometry, it was determined that the grown nanoparticles exhibit superparamagnetic properties. Embedding these particles into an agarose gel resulted in significant modification of water proton relaxation times T1, T2, and T2* determined by nuclear magnetic resonance measurements. The results of the spin-echo T2-weighted MR images of an aqueous phantom with embedded Cu0.08Zn0.54Fe2.38O4 nanoparticles in the presence of a strong temperature gradient show a strong correlation between the temperature and the image intensity. The presented results support the hypothesis that CuZn ferrite nanoparticles can be used as a contrast agent for MRI thermometry.

Synthesis, Characterization and Hyperthermic Evaluation of PEGylated Superparamagnetic MnFe2O4 Ferrite Nanoparticles for Cancer Therapeutics Applications

AbstractPoly(ethylene glycol) (PEG)‐coated superparamagnetic MnFe2O4 ferrite nanoparticles are of great interest for application in magnetic fluid hyperthermia (MFH) due to their heat generation capability in an external alternating magnetic field, besides biocompatibility, and surface properties. MFH has emerged as a promising therapeutic approach for cancer treatment and is based on controlled heating tumor tissue through the accumulation of MnFe2O4 ferrite nanoparticles within cancer cells. In the present work, MnFe2O4 superparamagnetic ferrite nanoparticles via the chemical combustion method are synthesized. The preparation of PEGylated MnFe2O4 ferrite nanoparticles, which involves the attachment of such molecules at the surface, without the need for coupling agents or prior modification on the species involved. The conjugation of folate onto MnFe2O4 ferrite nanoparticles is confirmed by FTIR spectroscopy. The MnFe2O4 ferrite nanoparticles are colloidal stable. The obtained targeted PEGylated MnFe2O4 ferrite nanoparticles show superparamagnetic behavior with a saturation magnetization of 78.68 emu·g−1 at 300 K. Their specific absorption rate (SAR) ranged from 43.2 to 19.5 W g−1 in an alternating magnetic field of 5—20 kA m−1. The heat generated is sufficient to raise the sample temperature to the therapeutic range used in MFH establishing this system as promising candidates for use in MFH treatment.

Structural, dielectric and magnetic properties of superparamagnetic zinc ferrite nanoparticles synthesized through coprecipitation technique

Structural, dielectric and magnetic properties of superparamagnetic zinc ferrite nanoparticles synthesized through coprecipitation technique

PO-1735: Superparamagnetic nickel ferrite nanoparticles as contrast agents in Magnetic Resonance Imaging

PO-1735: Superparamagnetic nickel ferrite nanoparticles as contrast agents in Magnetic Resonance Imaging

Structure and magnetic properties of superparamagnetic ferrite nanoparticles

Superparamagnetic Mn-Zn ferrite nanoparticles have been emerging as an important material due to its potential application in the preparation of stable ferrofluids. The superparamagnetic ferrite nanoparticles were prepared through co-precipitation method. The Rietveld refinement of X-ray diffraction confirms the cubic spinel structure with fd-3m space group. The average crystallite size of the nanoparticles observed from X-ray diffraction is ∼5nm. The transmission electron microscope micrographs also confirm the nano phase of the Mn-Zn ferrite nanoparticles. The s-shape of the magnetic hysteresis loop indicates the superparamagnetic behaviour of the nanoparticles. The narrow electron paramagnetic resonance (EPR) spectra also confirm the superparamagnetic nature of the nanoparticles.

Magnetically Responsive Assemblies of Polymer-Brush-Decorated Nanoparticle Clusters That Exhibit Structural Color.

The development of new magnetic materials for applications such as magnetic-driven drug delivery, next-generation display materials, and magnetic resonance imaging is an important objective. To that end, we synthesized monodispersed, magnetically responsive particles grafted with well-defined polymer brushes and investigated the formation of their ordered arrays in organic solvents in response to a magnetic field. To achieve this, we prepared monodispersed magnetic nanoparticle clusters (MNCs) composed of large numbers of superparamagnetic ferrite ZnFe2O4 nanoparticles. The MNCs were subsequently coated with thin silica layers through the hydrolysis of tetraethoxysilane. The colloidal particles were surface-modified with initiating groups for atom transfer radical polymerization (ATRP) using a triethoxysilane derivative with an ATRP initiation site. To demonstrate the ability of the synthesized particles to produce well-defined polymer brushes on their surfaces, the ATRP-initiator-functionalized silica-coated MNCs were subjected to surface-initiated ATRP with methyl methacrylate. This polymerization proceeded in a living fashion to produce graft polymers with targeted molar masses and narrow molar mass distributions. The average graft density was determined to be 0.65 chains/nm2, which confirms the formation of concentrated polymer brushes on the MNCs. The hybrid particles were analyzed by dynamic light scattering and transmission electron microscopy techniques, which revealed excellent uniformity and solvent dispersibility. A suspension of the polymer-brush-decorated MNCs in acetone quickly developed intense structural color in response to approaching a magnet that depended on the strength of the magnetic field.

Brain Tumor Diagnostics and Therapeutics with Superparamagnetic Ferrite Nanoparticles.

Ferrite nanoparticles (F-NPs) can transform both cancer diagnostics and therapeutics. Superparamagnetic F-NPs exhibit high magnetic moment and susceptibility such that in presence of a static magnetic field transverse relaxation rate of water protons for MRI contrast is augmented to locate F-NPs (i.e., diagnostics) and exposed to an alternating magnetic field local temperature is increased to induce tissue necrosis (i.e., thermotherapy). F-NPs are modified by chemical synthesis of mixed spinel ferrites as well as their size, shape, and coating. Purposely designed drug-containing nanoparticles (D-NPs) can slowly deliver drugs (i.e., chemotherapy). Convection-enhanced delivery (CED) of D-NPs with MRI guidance improves glioblastoma multiforme (GBM) treatment. MRI monitors the location of chemotherapy when D-NPs and F-NPs are coadministered with CED. However superparamagnetic field gradients produced by F-NPs complicate MRI readouts (spatial distortions) and MRS (extensive line broadening). Since extracellular pH (pHe) is a cancer hallmark, pHe imaging is needed to screen cancer treatments. Biosensor imaging of redundant deviation in shifts (BIRDS) extrapolates pHe from paramagnetically shifted signals and the pHe accuracy remains unaffected by F-NPs. Hence effect of both chemotherapy and thermotherapy can be monitored (by BIRDS), whereas location of F-NPs is revealed (by MRI). Smarter tethering of nanoparticles and agents will impact GBM theranostics.

Spin canting in ferrite nanoparticles

Recently, an easily scalable process for the production of small (3 −7 nm) monodisperse superparamagnetic ferrite nanoparticles MeFe2O4 (Me = Zn, Mn, Co) from iron metal and octanoic acid has been reported (Salih et al., Chem. Mater. 25 1430–1435 2013). Here we present a Mossbauer spectroscopic study of these ferrite nanoparticles in external magnetic fields of up to B = 5 T at liquid helium temperatures. Our analysis shows that all three systems show a comparable inversion degree and the cationic distribution for the tetrahedral A and the octahedral B sites has been determined to (Zn0.19Fe0.81)A[Zn0.81Fe1.19] BO4, (Mn0.15Fe0.85)A[Mn0.85Fe1.15] BO4 and (Co0.27Fe0.73)A[Co0.73Fe1.27] BO4. Spin canting occurs presumably in the B-sites and spin canting angles of 33°, 51° and 59° have been determined for the zinc, the manganese, and the cobalt ferrite nanoparticles.

Engineered atherosclerosis-specific zinc ferrite nanocomplex-based MRI contrast agents.

BackgroundCardiovascular diseases are the most prevalent cause of morbidity and mortality affecting millions of people globally. The most effective way to counter cardiovascular complications is early diagnosis and the safest non-invasive diagnostic approach is magnetic resonance imaging (MRI). In this study, superparamagnetic ferrite nanoparticles doped with zinc, exhibiting highly enhanced saturation magnetization and T2 and computed tomography (CT) contrast were synthesized. These nanoparticles have been strategically engineered using bovine lactoferrin (Lf), polyethylene glycol (PEG), and heat shock protein (Hsp)-70 antibody specifically targeting atherosclerosis with potential therapeutic value. The nanocomplexes were further validated in vitro to assess their cytotoxicity, internalization efficiency, effects on cellular proliferation and were assessed for MRI as well as X-ray CT in ex vivo Psammomys obesus rat model.ResultsOptimized zinc doped ferrite nanoparticles (Zn0.4Fe2.6O4) with enhanced value of maximum saturation magnetization value on 108.4 emu/g and an average diameter of 24 ± 2 nm were successfully synthesized. Successfully incorporation with bovine lactoferrin, PEG and Hsp-70 (70 kDa) antibody led to synthesis of spherical nanocomplexes (size 224.8 nm, PDI 0.398). A significantly higher enhancement in T2 (p < 0.05, 1.22-fold) and slightly higher T1 (1.09-fold) and CT (1.08-fold) contrast compared to commercial ferrite nanoparticles was observed. The nanocomplexes exhibited effective cellular internalization within 2 h in both THP-1 and Jurkat cells. MRI scans of contrast agent injected animal revealed significant arterial narrowing and a significantly higher T2 (p < 0.05, 1.71-fold) contrast in adult animals when compared to juvenile and control animals. The excised heart and aorta agar phantoms exhibited weak MRI contrast enhancement in juvenile animal but significant contrast enhancement in adult animal specifically at the aortic arch, descending thoracic aorta and iliac bifurcation region with X-ray CT scan. Histological investigation of the contrast agent injected aorta and heart confirmed site target-specific accumulation at the atherosclerotic aortic arch and descending thoracic aorta of the adult animal with severely damaged intima full of ruptured microatheromas.ConclusionOverall, the study demonstrates the strategic development of nanocomplex based bimodal MRI and CT contrast agents and its validation on Psammomys obesus for atherosclerosis diagnostics.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-016-0157-1) contains supplementary material, which is available to authorized users.

Star–block copolymer micellar nanocomposites with Mn,Zn-doped nano-ferrite as superparamagnetic MRI contrast agent for tumor imaging

Superparamagnetic nanoparticles can be used as contrast agents for magnetic resonance imaging (MRI), which improve sensitivity and enhance biological information imaging at tissue, cellular or even molecular levels. In this study, manganese and zinc-doped superparamagnetic ferrite nanoparticles were used to form MRI contrast agent for tumor imaging. Hydrophobic Mn0.6Zn0.4Fe2O4 (MZF) nanocrystals with mean diameter of about 8nm were synthesized in organic phase and then transferred into water to self-assemble into small clusters inside micelles with the help of biocompatible and amphiphilic star–block copolymers. The MZF-loaded micellar nanocomposites are superparamagnetic and could serve as a new T2 MRI contrast agent in cancer diagnosis. The new MRI contrast agent shows a low cytotoxicity in human hepatoma cell line, HepG2, and a high r2 relaxivity value. Thus, it could improve sensitivity of tumor imaging and be promising MRI contrast agent for tumor theranostic applications.

Mössbauer studies of superparamagnetic ferrite nanoparticles for functional application

Nanoparticles of CoFe2O4 and MnFe2O4 prepared for functional applications in nanomedicine were studied using Mossbauer spectrometry. Superparamagnetic properties of nanoparticles of different size and composition were compared applying collective excitations and multilevel models for the description of the Mossbauer spectra.

Protein-passivated FeNi3 particles with low toxicity and high inductive heating efficiency for thermal therapy

Magnetic micro/nanoparticles have great potential to be used in drug delivery and magnetic hyperthermia for cancer therapy. Here we report a novel chemical approach for the fabrication of protein-coated FeNi3 particles for use as thermal therapeutic agents. The particles are composed of metallic FeNi3 cores and coated with bovine serum albumin (BSA). The FeNi3@BSA composite particles demonstrate typical ferromagnetism with saturation magnetization (Ms) about 50emu/g and coercivity 150Oe or so. Due to the encapsulation of protein layer, the FeNi3@BSA composite particles exhibit low toxicity and superior biocompatibility. As-prepared FeNi3@BSA particles demonstrate higher heating efficiency compared with that of superparamagnetic ferrite nanoparticles (NPs).

Superparamagnetic MFe2O4 (M = Fe, Co, Mn) Nanoparticles: Tuning the Particle Size and Magnetic Properties through a Novel One-Step Coprecipitation Route

Superparamagnetic ferrite nanoparticles (MFe2O4, where M = Fe, Co, Mn) were synthesized through a novel one-step aqueous coprecipitation method based on the use of a new type of alkaline agent: the alkanolamines isopropanolamine and diisopropanolamine. The role played by the bases on the particles’ size, chemical composition, and magnetic properties was investigated and compared directly with the effect of the traditional inorganic base NaOH. The novel MFe2O4 nanomaterials exhibited high colloidal stability, particle sizes in the range of 4–12 nm, and superparamagnetic properties. More remarkably, they presented smaller particle sizes (up to 6 times) and enhanced saturation magnetization (up to 1.3 times) relative to those prepared with NaOH. Furthermore, the nanomaterials exhibited improved magnetic properties when compared with nanoferrites of similar size synthesized by coprecipitation with other bases or by other methods reported in the literature. The alkanolamines were responsible for these achievem...

Fe 3O 4 inverse spinal super paramagnetic nanoparticles

The present article reports an energy efficient method for the synthesis of superparamagnetic ferrite (Fe 3O 4) nanoparticles (10–40 nm) and their annealing effect on the morphology, size, curie temperature and magnetic behavior at 50, 300, 400 and 500 °C. The synthesized nanoparticles were characterized by various spectroscopic techniques like FT-IR and UV–visible. The crystalline structure and particle size were estimated through solid phase as well as the liquid phase using XRD, TEM and DLS techniques. Superparamagnetic behavior of nanoparticles was confirmed by VSM. The EPR study reveals that the main feature of X-Band solid state EPR spectrum has strong transition at g eff ∼ 3.23 (2100G) and a relatively weak transition at g eff ∼ 2.05 (3300G). The later transition further confirms the super paramagnetic nature of these nano ferrites. The activation energy and order of weight losses of nano ferrites were found to be: 39.6 KJ mol −1 and 0.21 orders (600–800 °C), respectively, analyze with the help of TGA while the specific surface area (23.1 m 2 g −1) and pore size (9 Å) were determined by Quanta chrome BET instrument.

Remote control of ion channels and neurons through magnetic-field heating of nanoparticles

Recently, optical stimulation has begun to unravel the neuronal processing that controls certain animal behaviours. However, optical approaches are limited by the inability of visible light to penetrate deep into tissues. Here, we show an approach based on radio-frequency magnetic-field heating of nanoparticles to remotely activate temperature-sensitive cation channels in cells. Superparamagnetic ferrite nanoparticles were targeted to specific proteins on the plasma membrane of cells expressing TRPV1, and heated by a radio-frequency magnetic field. Using fluorophores as molecular thermometers, we show that the induced temperature increase is highly localized. Thermal activation of the channels triggers action potentials in cultured neurons without observable toxic effects. This approach can be adapted to stimulate other cell types and, moreover, may be used to remotely manipulate other cellular machinery for novel therapeutics.

Research status of magnetic nanoparticles mediated tumor MR imaging and hyperthermia

Magnetic nanoparticles mediated hyperthermia, as a new kind of tumor therapy, promotes tumor hyperthermia to targered localization and precise control. In recent years, researchers stvdy deeply on surface modification of magnetic nanoparticles, combination with radiotherapy and chemotherapy, as well as clinical application, at the same time, researchers find that superparamagnetic ferrite nanoparticles after obtai-ning water-soluble by surface modification, can be as the MR imaging agent. Magnetic nanoparticles both for tumor diagnosis and treatment, will further promote tumor therapy to a more safe and effective direction. Key words: Neoplasms; Hyperthermia, induced; Magnetic resonance imaging; Magnetics; Nanostruc-tures

Magnetic Nanoparticles for Early Detection of Cancer by Magnetic Resonance Imaging.

This article provides a brief overview of recent progress in the synthesis and functionalization of magnetic nanoparticles and their applications in the early detection of malignant tumors by magnetic resonance imaging (MRI). The intrinsic low sensitivity of MRI necessitates the use of large quantities of exogenous contrast agents in many imaging studies. Magnetic nanoparticles have recently emerged as highly efficient MRI contrast agents because these nanometer-scale materials can carry high payloads while maintaining the ability to move through physiological systems. Superparamagnetic ferrite nanoparticles (such as iron oxide) provide excellent negative contrast enhancement. Recent refinement of synthetic methodologies has led to ferrite nanoparticles with narrow size distributions and high crystallinity. Target-specific tumor imaging becomes possible through functionalization of ferrite nanoparticles with targeting agents to allow for site-specific accumulation. Nanoparticulate contrast agents capable of positive contrast enhancement have recently been developed in order to overcome the drawbacks of negative contrast enhancement afforded by ferrite nanoparticles. These newly developed magnetic nanoparticles have the potential to enable physicians to diagnose cancer at the earliest stage possible and thus can have an enormous impact on more effective cancer treatment.

초상자성 코발트 페라이트 나노입자에 대한 자화 및 자기엔트로피 변화

초상자성 코발트 페라이트 나노입자를 제조하여 자화 및 자기엔트로피 변화를 조사하였다. 제조된 시료는 전형적인 입방 스피넬 구조를 띠고 있었다. 5K와 300K에서의 최대 자화는 덩어리 상태에서의 최대 자화보다 작은 값을 가졌다. 시료의 초상자성적 거동은 M vs. H/T 곡선의 겹침에 의해 확인되었다. 열역학적 이론을 바탕으로 자기엔트로피의 변화에 대한 온도 의존성을 도출한 결과, 온도가 높을수록 자기엔트로피의 변화는 더 크게 감소하는 것으로 나타났다. In order to the magnetization and magnetic entropy change for superparamagnetic ferrite nanoparticles, ultrafine cobalt ferrite particles were synthesized using a mircoemulsion method. The peak of X-ray diffraction pattern corresponds to a cubic spinel structure with the lattice constant 8.40 <TEX>$\AA$</TEX>. The average particle size, determined from X-ray diffraction line-broadening using Scherrer's, is 7.9 nm. The maximal magnetizations measured at 5 and 300 K are 24.3 emu/g and 17.2 emu/g, respectively. Superparamagnetic behavior of the sample is confirmed by the coincidence of the M vs. H/T plots at various temperatures. According to the thermodynamic theory, magnetic entropy change decreases with increasing temperature.

Synthesis and physicochemical response of polyethylene glycol encapsulated nickel ferrite nanoparticles

The authors describe here the chemical processing methodology and physicochemical response of superparamagnetic nickel ferrite nanoparticles, which were encapsulated and functionalised with polyethylene glycol to form a core shell structure. The outer shell was subsequently conjugated with tumour recognition moiety, folic acid and loaded with doxorubicin drug to achieve tumour specific drug delivery. Fourier transform infrared spectroscopy confirmed the functionalisation and conjugation steps used in the synthesis of the nanocarrier. The drug release response was characterised by an initial rapid release followed by a controlled release. The study also indicated that it is important to optimise the thickness of the polyethylene glycol shell on the magnetic nickel ferrite core to avoid reduction in the ability of the nanocarrier to experience alternate compressive and tensile stresses caused by the external magnetic field because this leads to reduction in the percentage of drug release.