Biocompatible Magnetic Fluids Research Articles

Investigating the effect of outer layer of magnetic particles on cervical cancer cells HeLa by magnetic fluid hyperthermia

BackgroundMagnetic fluid hyperthermia (MFH) is a successful nanotechnology application in recent decade where a biocompatible magnetic fluid is used to kill cancer cells in a controlled heating using AC magnetic field. In the present study, two ferrite-based magnetic fluids, with and without surfactant coating, were synthesized to study the effect of the outer layer of magnetic nanoparticles on cervical cancer cells. The magnetic fluid without surfactant coating (MFWI) was made stable by providing negative charge on the surface of each particle. On the other hand, lauric acid was used as a surfactant to have a stable dispersion of particles in aqueous media (MFWL).MethodsThe structural, magnetic properties and induction heating response of both the fluids were investigated using XRD, VSM, DLS, TGA, FTIR, and a high-frequency induction heater. The in vitro cytotoxicity of the synthesized fluids was observed on HeLa cells by performing MTT assay, and the effect of magnetic fluid hyperthermia was examined using Trypan blue assay.ResultsThe crystallite size of surfactant stabilized particles was higher (11.0 ± 0.5 nm) compared to the charge stabilized particles (8.3 ± 0.5 nm). Induction heating experiments showed that the specific absorption rate of the surfactant-coated particles was almost double compared to ionic particle fluid. Magnetic fluid hyperthermia up to 1 hour at a concentration of 0.25 mg/mL of surfactant-coated magnetic fluid and 0.2 mg/mL concentration of charged fluid resulted in approximately 66 and 80% cell death, respectively, compared to untreated control cells.ConclusionThe preliminary analysis of this study shows significant cell death due to hyperthermia, wherein MFWI revealed higher cytotoxicity compared to MFWL. Additional analysis into the role of the outer stabilizing layer on nanoparticle’s surface, concentration of nanoparticles, and hyperthermic duration is desirable to utilize MFH as a futuristic anti-cancer therapeutic tool.

INFLUENCE OF MAGNETIC NANOPARTICLES ON ACOUSTIC ATTENUATION IN LIQUIDS

Magnetic fluids with nanoparticles dispersed in water or oils offer attractive applications in biomedicine and industry. Biocompatible magnetic fluids are used for diagnostics and therapy in medical applications, in pharmacy, and biosensors. Application of ferrofluids is expanding into energy conservation, faster and efficient cooling, and hence better performance in a wide variety of practical applications (in heat exchangers, mainly in micro-cooling systems). For the study of the influence of an external magnetic field on the aggregation processes of magnetic nanoparticles in magnetic fluids, acoustic spectroscopy was used. The jump changes of the magnetic flux density at various temperatures influenced the acoustic attenuation. The measured changes were results of nanoparticle aggregations into new structures.

Correlation between effects of the particle size and magnetic field strength on the magnetic hyperthermia efficiency of dextran-coated magnetite nanoparticles

A precise control of the particle size of dextran-coated magnetite nanoparticles (Dex-M NPs) was successfully performed by combination of co-precipitation and hydrothermal synthesis methods. The Dex-M NPs, in the size range 3.1-18.9nm, were used to fabricate biocompatible magnetic fluids for application in magnetic hyperthermia therapy (MHT). The effects of the carrier fluid viscosity, particle size, and applied magnetic field strength (Happl) on the specific loss power (SLP) of the Dex-M NPs were investigated at a fixed magnetic field frequency (f). The experimental results show that SLP of the larger Dex-M NPs significantly decreases for a highly viscous carrier fluid. Moreover, regardless of the carrier fluid viscosity, the particle size strongly affects the heating efficiency of the Dex-M NPs. SLP ranges from zero for the smallest Dex-M NPs (with particle size d=3.1 nm) to 55.21 W/g for the largest ones (d=18.9 nm) at Happl=28 kA/m and f=120 kHz. The most important finding in our research is that, at a fixed frequency, the optimal size of the Dex-M NPs (the size that maximizes SLP) shows a rising trend by enhancing Happl. In fact, the highest values of SLP at Happl=11 kA/m, 13-17.5 kA/m, and 19-28 kA/m are obtained for the Dex-M NPs with d=11.5 nm, 15 nm, and 18.9 nm, respectively. The shift of optimal size to the higher values by increasing Happl could shed light on the correlated effects of the particle size and Happl on the heating efficiency of magnetic nanoparticles (MNPs) and pave a new way toward the better tuning of them for an effective and biologically safe treatment.

Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic Properties.

Magnetite (Fe3O4) particles with a diameter around 10 nm have a very low coercivity (Hc) and relative remnant magnetization (Mr/Ms), which is unfavorable for magnetic fluid hyperthermia. In contrast, cobalt ferrite (CoFe2O4) particles of the same size have a very high Hc and Mr/Ms, which is magnetically too hard to obtain suitable specific heating power (SHP) in hyperthermia. For the optimization of the magnetic properties, the Fe2+ ions of magnetite were substituted by Co2+ step by step, which results in a Co doped iron oxide inverse spinel with an adjustable Fe2+ substitution degree in the full range of pure iron oxide up to pure cobalt ferrite. The obtained magnetic nanoparticles were characterized regarding their structural and magnetic properties as well as their cell toxicity. The pure iron oxide particles showed an average size of 8 nm, which increased up to 12 nm for the cobalt ferrite. For ferrofluids containing the prepared particles, only a limited dependence of Hc and Mr/Ms on the Co content in the particles was found, which confirms a stable dispersion of the particles within the ferrofluid. For dry particles, a strong correlation between the Co content and the resulting Hc and Mr/Ms was detected. For small substitution degrees, only a slight increase in Hc was found for the increasing Co content, whereas for a substitution of more than 10% of the Fe atoms by Co, a strong linear increase in Hc and Mr/Ms was obtained. Mössbauer spectroscopy revealed predominantly Fe3+ in all samples, while also verifying an ordered magnetic structure with a low to moderate surface spin canting. Relative spectral areas of Mössbauer subspectra indicated a mainly random distribution of Co2+ ions rather than the more pronounced octahedral site-preference of bulk CoFe2O4. Cell vitality studies confirmed no increased toxicity of the Co-doped iron oxide nanoparticles compared to the pure iron oxide ones. Magnetic heating performance was confirmed to be a function of coercivity as well. The here presented non-toxic magnetic nanoparticle system enables the tuning of the magnetic properties of the particles without a remarkable change in particles size. The found heating performance is suitable for magnetic hyperthermia application.

Characterization of a magnetic fluid exposed to a shear flow and external magnetic field using small angle laser scattering

The paper demonstrates a possibility to use Small Angle Light Scattering (SALS) method realized in a conventional laboratory to investigate structuring processes in a magnetic fluid simultaneously exposed to a shear flow and an external magnetic field. We have used a custom made SALS-setup with a laser source combined with a microfluidic chip, an electromagnet and a magnetic circuit to obtain scattering images of a low concentrated biocompatible magnetic fluid with clustered iron oxide nanoparticles. The application of an external magnetic field drastically influences the physical behaviour of the fluid and this effect is directly related to aggregation of particles resulting in chains with a dimension of several micrometers. These chains lead to an anisotropy of the scattering patterns. We have observed an influence of the field and flow on the intensity gradient of the obtained scattering patterns. The presented method opens broad perspectives to obtain microstructural information as well to evaluate structuring kinetics of the diluted magnetic suspensions using conventional laboratory conditions. The SALS measurements are accomplished with a full characterization of the fluid using magneto-rheometry, vibrating sample magnetometry, microscopy as well as dynamic light scattering.

Chondroitin-Sulfate-A-Coated Magnetite Nanoparticles: Synthesis, Characterization and Testing to Predict Their Colloidal Behavior in Biological Milieu.

Biopolymer coated magnetite nanoparticles (MNPs) are suitable to fabricate biocompatible magnetic fluid (MF). Their comprehensive characterization, however, is a necessary step to assess whether bioapplications are feasible before expensive in vitro and in vivo tests. The MNPs were prepared by co-precipitation, and after careful purification, they were coated by chondroitin-sulfate-A (CSA). CSA exhibits high affinity adsorption to MNPs (H-type isotherm). We could only make stable MF of CSA coated MNPs (CSA@MNPs) under accurate conditions. The CSA@MNP was characterized by TEM (size ~10 nm) and VSM (saturation magnetization ~57 emu/g). Inner-sphere metal–carboxylate complex formation between CSA and MNP was proved by FTIR-ATR and XPS. Electrophoresis and DLS measurements show that the CSA@MNPs at CSA-loading > 0.2 mmol/g were stable at pH > 4. The salt tolerance of the product improved up to ~0.5 M NaCl at pH~6.3. Under favorable redox conditions, no iron leaching from the magnetic core was detected by ICP measurements. Thus, the characterization predicts both chemical and colloidal stability of CSA@MNPs in biological milieu regarding its pH and salt concentration. MTT assays showed no significant impact of CSA@MNP on the proliferation of A431 cells. According to these facts, the CSA@MNPs have a great potential in biocompatible MF preparation for medical applications.

Obtaining and Characterizing a Water-Based Magnetic Fluid

A way of obtaining a biocompatible magnetic fluid and its parameters are described. It is proposed that depolarized dynamic light scattering be used to determine the size of nanoparticles in the fluid phase, and to estimate the aggregative and sedimentation stability of a magnetic fluid upon dilution. It is established that upon the dilution of the magnetic fluid, ellipsoidal aggregates consisting of 20 or more single nanoparticles form in it.

Comparative Efficacy of a Biocompatible Citrate-Functionalized Magnetic Fluid Mediating Radiofrequency Hyperthermia and Magnetohyperthermia to Treat Ectopic Ehrlich-Solid-Tumor-Bearing Elderly Mice

Objective: We aimed to evaluate the efficacy of a biocompatible citrate-functionalized magnetic fluid (NPCit) sample in mediating hyperthermia, using two types of alternated (AC) magnetic field equipment operating in two different ways: a portable apparatus, generating an electromagnetic field in MHz range (radiofrequency range; radiofrequency hyperthermia-RFHT) developed by our research group (CMagMHG), and a commercial one working in kHz range (magnetohyperthermia-MHT) (Magnetherm, NanoTherics Ltd, Newcastle, United Kingdom), to treat ectopic Ehrlich-solid-tumor-bearing elderly mice. Methods: Females intraperitoneally anesthetized with ketamine (80 mg/kg) and xylazine (10 mg/Kg) were subcutaneously inoculated with Ehrlich ascitic tumor cell suspension (1.03 × 106 viable cells) in the upper head region for solid form implantation. After 48 hours, mice received one of four treatments: (a) filtered water and no tumor implantation (negative control); (b) tumor inoculation and no treatment (tumor control); (c) intratumoral injection of NPCit (40 µL) containing 18 × 1018 particles/mL and 13 minutes’ exposure to CMagMHG, operating at 1MHz, 40 Oe field amplitude; (d) intratumoral injection of NPCit and 13 minutes’ exposure to Magnetherm, assembled with 17-turn coil, capacitive box B22, operating under 330 kHz, 4.9 A, 25 V and maximum field strength 170 Oe. Treatments occurred once daily for three consecutive days. Tumor histopathology and semi-quantitative analysis of necrosis area served to assess tumor aggressiveness and regression. Possible acute side effects were assessed by animals’ body and spleen weight and hemogram. Results: NPcit showed adequate biocompatibility and was effective in mediating RFHT and MHT, which promoted significant increases in necrosis area using both equipment types. Conclusion: Our findings evidence the potential use of NPcit mediating hyperthermia for future use as an adjuvant in breast cancer therapy.

Radiation Stability of the BSA Modified Biocompatible Magnetic Fluid

The aim of the presented work was to investigate the stability of biocompatible magnetic uid, i.e. water-based magnetic uid containing magnetite nanoparticles stabilized by surfactant sodium oleate and modi ed by bovine serum albumin (BSA) after electron irradiation. Samples with the same concentration of Fe3O4 but di erent mass ratio BSA/Fe3O4 (w/w= 0.25, 1.0 and 2.5) were studied. The electron irradiation caused about 10% reduction of the saturation magnetization in the samples with w/w BSA/Fe3O4 ratio of 0.25 and less than 5% in the samples with w/w BSA/Fe3O4 ratio of 1 and 2.5.

Thermal Properties of Magnetic Nanoparticles Modified With Polyethylene Glycol

Magnetic fluids used in biomedicine have to be biocompatible and therefore the magnetic nanoparticles are modified by different biocompatible materials. In this work the magnetic nanoparticles Fe3O4 sterically stabilized by sodium oleate were prepared by coprecipitation method. Consequently they were modified with polyethylene glycol (PEG) of different molecular weights and different PEG to magnetite Fe3O4 feed weight ratios varying from 0.01 to 30 to produce biocompatible magnetic fluids (MFPEG). The morphology was observed by scanning electron microscopy. The magnetic nanoparticles coated with PEG showed almost spherical shape for all studied systems of MFPEG. Differential scanning calorimetry (DSC) was used to study the adsorption of PEG on magnetic nanoparticles and to determine the maximal amount of PEG adsorbed on the magnetic nanoparticles. The increasing PEG molecular weight leads to the decrease in maximal PEG/Fe3O4 feed weight ratio. In vitro toxicity of the magnetic fluids using cells of skin cancer of mice B16 was tested with the aim to confirm the biocompatibility of the prepared magnetic fluids.

Diagnostic and analysis of aggregation stability of magnetic fluids for biomedical applications by small-angle neutron scattering

Diagnostics of aggregation and determination of the aggregation regimes and their control in biocompatible magnetic fluids are necessary for their development in biomedical applications. Small-angle neutron scattering (SANS) method was applied in the structure analysis of various types of magnetic fluids for biomedical applications. Additionally the interaction characteristics between surfactant/polymer molecules used in stabilization of magnetic fluids were investigated, which is very important for understanding the synthesis procedure of highly stable magnetic fluids with controllable properties.

Anti-CEA loaded maghemite nanoparticles as a theragnostic device for colorectal cancer

Nanosized maghemite particles were synthesized, precoated (with dimercaptosuccinic acid) and surface-functionalized with anticarcinoembryonic antigen (anti-CEA) and successfully used to target cell lines expressing the CEA, characteristic of colorectal cancer (CRC) cells. The as-developed nanosized material device, consisting of surface decorated maghemite nanoparticles suspended as a biocompatible magnetic fluid (MF) sample, labeled MF-anti-CEA, was characterized and tested against two cell lines: a high-CEA expressing cell line (LS174T) and a low-CEA expressing cell line (HCT116). Whereas X-ray diffraction was used to assess the average core size of the as-synthesized maghemite particles (average 8.3 nm in diameter), dynamic light scattering and electrophoretic mobility measurements were used to obtain the average hydrodynamic diameter (550 nm) and the zeta-potential (−38 mV) of the as-prepared and maghemite-based nanosized device, respectively. Additionally, surface-enhanced Raman spectroscopy (SERS) was used to track the surface decoration of the nanosized maghemite particles from the very first precoating up to the attachment of the anti-CEA moiety. The Raman peak at 1655 cm−1, absent in the free anti-CEA spectrum, is the signature of the anti-CEA binding onto the precoated magnetic nanoparticles. Whereas MTT assay was used to confirm the low cell toxicity of the MF-anti-CEA device, ELISA and Prussian blue iron staining tests performed with both cell lines (LS174T and HCT116) confirm that the as-prepared MF-anti- CEA is highly specific for CEA-expressing cells. Finally, transmission electron microscopy analyses show that the association with anti-CEA seems to increase the number of LS174T cells with internalized maghemite nanoparticles, whereas no such increase seems to occur in the HCT116 cell line. In conclusion, the MF-anti-CEA sample is a biocompatible device that can specifically target CEA, suggesting its potential use as a theragnostic tool for CEA-expressing tumors, micrometastasis, and cancer-circulating cells.

Novel ferrofluids coated with a renewable material obtained from cashew nut shell liquid

In this work, we present the synthesis and characterization of a new surfactant molecule obtained from a byproduct of the cashew nut processing (diphosphorylated cardol, DPC). It is herein used to overcoat magnetic nanoparticles showing spinel structures in order to create new ferrofluids. The nanoparticle structure and magnetic properties have been deeply investigated. DPC-functionalized Fe3O4 and NiFe2O4 samples exhibit higher magnetic saturation than DPC–CoFe2O4. These new ferrofluids reveal appealing as possible nanoparticle stabilizing molecules, magnetic resonance imaging agents, storage systems or in any material science field that requires the employment of biocompatible magnetic stable fluids.

Preparation and Characterization of Biocompatible Magnetic Fluids

Nano-Fe3O4magnetic particles were prepared by ultrasonic emulsion method and then were dispersed into water with chitosan or folate as surfactants for biocompatible water-based Fe3O4magnetic fluid. The cubic inverse spinel structure of Fe3O4nanoparticles were analyzed by X-ray diffraction technique (XRD). The saturation magnetizations of different magnetic particles were tested by a vibrating sample magnetometer (VSM). The morphologies of nanoparticles were observed by transmission electron microscope (TEM). The particle size was about uniform 10-20 nm, and their shape was approximately spherical. Meanwhile, dispersity was improved markedly after the surface modification. Comparing to magnetic fluid with chitosan modification, magnetic fluid was coated with chitosan and folate gets higher dispersity and stability when both of them have same saturation magnetizations.

Absorption and translocation to the aerial part of magnetic carbon-coated nanoparticles through the root of different crop plants

The development of nanodevices for agriculture and plant research will allow several new applications, ranging from treatments with agrochemicals to delivery of nucleic acids for genetic transformation. But a long way for research is still in front of us until such nanodevices could be widely used. Their behaviour inside the plants is not yet well known and the putative toxic effects for both, the plants directly exposed and/or the animals and humans, if the nanodevices reach the food chain, remain uncertain. In this work we show that magnetic carbon-coated nanoparticles forming a biocompatible magnetic fluid (bioferrofluid) can easily penetrate through the root in four different crop plants (pea, sunflower, tomato and wheat). They reach the vascular cylinder, move using the transpiration stream in the xylem vessels and spread through the aerial part of the plants in less than 24 hours. Accumulation of nanoparticles was detected in wheat leaf trichomes, suggesting a way for excretion/detoxification. This kind of studies is of great interest in order to unveil the movement and accumulation of nanoparticles in plant tissues for assessing further applications in the field or laboratory.

Synthesis of Bio-Compatible SPION-based Aqueous Ferrofluids and Evaluation of RadioFrequency Power Loss for Magnetic Hyperthermia.

Bio-compatible magnetic fluids having high saturation magnetization find immense applications in various biomedical fields. Aqueous ferrofluids of superparamagnetic iron oxide nanoparticles with narrow size distribution, high shelf life and good stability is realized by controlled chemical co-precipitation process. The crystal structure is verified by X-ray diffraction technique. Particle sizes are evaluated by employing Transmission electron microscopy. Room temperature and low-temperature magnetic measurements were carried out with Superconducting Quantum Interference Device. The fluid exhibits good magnetic response even at very high dilution (6.28 mg/cc). This is an advantage for biomedical applications, since only a small amount of iron is to be metabolised by body organs. Magnetic field induced transmission measurements carried out at photon energy of diode laser (670 nm) exhibited excellent linear dichroism. Based on the structural and magnetic measurements, the power loss for the magnetic nanoparticles under study is evaluated over a range of radiofrequencies.

Magnetic fluid: Comparative study of nanosized Fe3O4 and Fe3O4 suspended in Copaiba oil using Mössbauer spectroscopy with a high velocity resolution

Comparative study of nanosized magnetite and magnetite suspended in Copaiba oil (biocompatible magnetic fluid) was made using Mössbauer spectroscopy with a high velocity resolution (spectra were measured in 4096 channels). The better fit of room temperature spectra was done using 15 sextets and 1 doublet employing different parameters while spectra measured at 90 K were better fitted using 15 sextets with different parameters. These component numbers were related to multi-domain structure and non-stoichiometry of magnetite. Observed differences of magnetic hyperfine fields and relative areas of spectral components for nanosized Fe3O4 and Fe3O4 suspended in Copaiba oil may be related to the effect of surface interactions of Fe3O4 and polar molecules of Copaiba oil.

Magnetic polymer nanospheres for anticancer drug targeting

Poly(D,L-lactide-co-glycolide) polymer (PLGA) nanospheres loaded with biocom-patible magnetic fluid as a magnetic carrier and anticancer drug Taxol were prepared by the modified nanoprecipitation method with size of 200–250 nm in diameter. The PLGA polymer was utilized as a capsulation material due to its biodegradability and biocompatibility. Taxol as an important anticancer drug was chosen for its significant role against a wide range of tumours. Thermal properties of the drug-polymer system were characterized using thermal analysis methods. It was determined the solubility of Taxol in PLGA nanospheres. Magnetic properties investigated using SQUID magnetometry showed superparamagnetism of the prepared magnetic polymer nanospheres.

Time-modulation of surface functionalization in biocompatible magnetic fluids

Photoacoustic spectroscopy (300–1000 nm wavelength range) was used to investigate the aging of dimercaptosuccinic acid-coated maghemite nanoparticles suspended as biocompatible magnetic fluids. The three samples investigated presented increasing surface-grafting coefficient and were water-diluted at day-0. The time evolution (from day-0 to day-40) of the areas under band-L and band-S photoacoustic features was used to draw conclusions on the changes on the relative populations of carboxyl ( N L ) and hydroxyl ( N S ) groups adsorbed onto the nanoparticle surface. We found the time-dependence of the relative populations of molecular species ( N L / N S ) peaking at band-L and band-S following a sigmoid-like curve with characteristic times of 2.7, 3.7 and 4.1 days for samples presenting increasing molecular surface-grafting coefficient ( N).

Effect of Poly(Ethylene Glycol) Coating on the Acoustic Properties of Biocompatible Magnetic Fluid

The aim of this study was to investigate the influence of a poly(ethylene glycol) surface-active coating on the mechanical properties of biocompatible magnetic fluids. The coating of long-chain polymer molecules on ferrite particles serves as a protective layer that prevents agglomeration of the particles and minimizes the direct exposure of the ferrite surface to the biological environment. A useful method of studying mechanical properties of magnetic fluids is based on using ultrasound.