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1.
In this study, we compared FeNi alloy magnetic nanoparticles (MNPs) prepared by either combustion or chemical precipitation methods. We found that the FeNi MNPs generated by combustion method have a rather high saturation magnetization Ms of~180 emu/g and a coercivity field Hc of near zero. However, the alloy nanoparticles are easily aggregated and are not well dispersive such that size distribution of the nanoparticle clusters is wide and clusters are rather big (around 50~700 nm). To prepare a better quality and well dispersed Fe-Ni MNPs, we also developed a thermal reflux chemical precipitation method to synthesize FeNi3 alloy MNPs. The precursor chemicals of Fe(acac)3 and Ni(acac)2 in a molecular ratio 1,2-hexadecandiol and tri-n-octylphosphine oxide (TOPO) were used as reducer and surfactant, respectively. The chemically precipitated FeNi3 MNPs are well dispersed and have well-controlled particle sizes around 10~20 nm with a very narrow size distribution (±1.2 nm). The highly monodispersive FeNi3 MNPs present good uniformity in particle shape and crystallinity on particle surfaces. The MNPs exhibit well soft magnetism with saturation magnetization of ~61 emu/g and Hc~0. The biomedically compatible FeNi MNPs which were coated with biocompatible polyethyleneimine (PEI) polymer were also synthesized. We demonstrated that the PEI coated FeNi MNPs can enter the mammalian cells in vitro and can be used as a magnetic resonance imagine (MRI) contrast agent. The results demonstrated that FeNi MNPs potentially could be applied in the biomedical field. The functionalized magnetic beads with biocompatible polymer coated on MNPs are also completed for biomedical applications.  相似文献   

2.
《Ceramics International》2023,49(10):15183-15199
AC induction heating properties of colloidal nano-aggregates of ferrimagnetic cobalt ferrite magnetic nanoparticles (MNPs) are reported in this study. Bio-compatible chitosan polymer-coated CoFe2O4 MNPs are synthesized using a co-precipitation method. Powder X-ray diffraction indicates the formation of mixed spinel structures for the uncoated (CP) and chitosan-coated (CP–CHN) MNPs, which is also supported by the cation distributions obtained from the Mössbauer spectra. The presence of chitosan coating on the surface of the CP-CHN MNPs is confirmed using X-ray photoelectron and Fourier transform infrared spectroscopy studies. Transmission electron microscopy shows primary particle sizes of ∼13 nm, which is larger than the superparamagnetic size limit of the CoFe2O4 MNPs. Hence, the CP and CP-CHN MNPs exhibit ferrimagnetic behaviour at room temperature with estimated saturation magnetization values of ∼77.4 emu/g and ∼74.4 emu/g, respectively. The average hydrodynamic diameter is found to be ∼90 ± 8 nm for an aqueous dispersion of the CP-CHN MNPs, which indicate the formation of colloidal nano-aggregates due to the ferrimagnetic interaction of the primary MNPs. The CP-CHN sample exhibits a significantly high AC induction heating efficiency of ∼267.2 ± 4.0 W/gFe, where the higher heating efficiency is attributed to the combination of hysteresis and relaxation-mediated magneto-thermal energy conversion, as confirmed using Stoner-Wohlfarth model-based dynamic hysteresis loop calculations. Further, the heating efficiency decreases with increasing sample concentration due to an increase in dipolar interaction, which is confirmed using semi-empirical calculations, where a lowering of the initial susceptibility is observed at higher concentrations. The higher AC induction heating efficiency, coupled with the demonstrated significant bio-compatibility during in vitro cytotoxicity studies, make the cobalt ferrite nano-aggregates potential candidates for magnetic hyperthermia.  相似文献   

3.
This paper describes the investigation and development of a novel magnetic drug delivery nanosystem (labeled as MO-20) for cancer therapy. The drug employed was oncocalyxone A (onco A), which was isolated from Auxemma oncocalyx, an endemic Brazilian plant. It has a series of pharmacological properties: antioxidant, cytotoxic, analgesic, anti-inflammatory, antitumor and antiplatelet. Onco A was associated with magnetite nanoparticles in order to obtain magnetic properties. The components of MO-20 were characterized by XRD, FTIR, TGA, TEM and Magnetization curves. The MO-20 presented a size of about 30 nm and globular morphology. In addition, drug releasing experiments were performed, where it was observed the presence of the anomalous transport. The results found in this work showed the potential of onco A for future applications of the MO-20 as a new magnetic drug release nanosystem for cancer treatment.  相似文献   

4.
Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEONLA-BSA, which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEONLA-BSA particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v). Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEONLA-BSA changed only marginally. The specific absorption rate (SAR) was not greatly affected by concentration. In contrast, the maximum temperature Tmax in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment.  相似文献   

5.
One of the most challenging efforts in drug delivery is the targeting of the eye. The eye structure and barriers render this organ poorly permeable to drugs. Quite recently the entrance of nanoscience in ocular drug delivery has improved the penetration and half-life of drugs, especially in the anterior eye chamber, while targeting the posterior chamber is still an open issue. The retina and the retinal pigment epithelium/choroid tissues, located in the posterior eye chamber, are responsible for the majority of blindness both in childhood and adulthood. In the present study, we used magnetic nanoparticles (MNPs) as a nanotool for ocular drug delivery that is capable of specific localization in the retinal pigmented epithelium (RPE) layer. We demonstrate that, following intraocular injection in Xenopus embryos, MNPs localize specifically in RPE where they are retained for several days. The specificity of the localization did not depend on particle size and surface properties of the MNPs used in this work. Moreover, through similar experiments in zebrafish, we demonstrated that the targeting of RPE by the nanoparticles is not specific for the Xenopus species.  相似文献   

6.
Size and magnetic properties of magnetic nanoparticles (MNPs) in fluids allow special remote control of fluid flow using appropriate externally applied magnetic fields, especially when submicronic mixing is critical, inter alia, for catalytic reactions, separation and drug delivery. This work explores MNPs as nanoscale devices to control mixing at microscale by submitting the system of interest to a rotating magnetic field (RMF). Magnetic nanoparticles are harnessed by RMF and converted into nanostirrers thereby generating MNP-pinned localized agitation in the liquid phase. Using this technique, self-diffusion coefficient of water in a static diffusion cell was intensified up to 200 folds. Also, axial dispersion of capillary Poiseuille flows under RMF underwent a reduction prompted by MNP-mediated intensification of lateral mixing relative to that in absence of magnetic field. Finally a multiphase flow case concerned gas–liquid mass transfer from oxygen Taylor bubbles to the liquid in capillaries where dilute MNP solutions led to measurable enhancement of kLa under RMF.  相似文献   

7.

The magnetic relaxation of magnetic nanoparticles (MNPs) has been used as a potential heating agent for magnetic hyperthermia treatment (MHT). This requires an understanding of the heating mechanism of MNPs, such as Néel relaxation; however, few studies about magnetic relaxation using a low-frequency AC magnetic field have been reported. This study attempts to clarify the correlation between the dominance of Néel relaxation in low-frequency AC fields and the magnetic properties. Nanoparticles of Ni0.8Zn0.2Fe2O4 coated with poly(ethylene glycol) (PEG) were synthesized in various sizes (d?=?12, 15, and 19 nm), and were subjected to structural analysis, PEG modification, and magnetic measurements. The PEG400 coating results in a hydrodynamic diameter ten times smaller than that of our previous sample. The heat generation experiment was conducted on samples suspended in solvents of different viscosities in the presence of an AC field (h?=?3.2 kAm?1, f?=?90 kHz). The specific absorption rate (SAR) as a function of the viscosity of the 15-nm NP sample is consistent with the theoretically calculated value in cases where the Néel relaxation is dominant. Therefore, we conclude that the Néel relaxation dominates the heating mechanism of the 15 nm sample. Rather than being fully superparamagnetic, this sample was partly superparamagnetic and slightly ferromagnetic, with the dominance of the Néel relaxation to a certain degree affected by spin blocking. Detailed analysis of the magnetic relaxation is crucial to improve the heating efficiency of MNPs for MHT.

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8.
A simple colorimetric immunoassay system, based on the peroxidase mimicking activity of Fe3O4 magnetic nanoparticles (MNPs), has been developed to detect clinically important antigenic molecules. MNPs with ca. 10 nm in diameter were synthesized and conjugated with specific antibodies against target molecules, such as rotaviruses and breast cancer cells. Conjugation of the MNPs with antibodies (MNP-Abs) enabled specific recognition of the corresponding target antigenic molecules through the generation of color signals arising from the colorimetric reaction between the selected peroxidase substrate, 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2. Based on the MNP-promoted colorimetric reaction, the target molecules were detected and quantified by measuring absorbance intensities corresponding to the oxidized form of TMB. Owing to the higher stabilities and economic feasibilities of MNPs as compared to horseradish peroxidase (HRP), the new colorimetric system employing MNP-Abs has the potential of serving as a potent immunoassay that should substitute for conventional HRP-based immunoassays. The strategy employed to develop the new methodology has the potential of being extended to the construction of simple diagnostic systems for a variety of biomolecules related to human cancers and infectious diseases, particularly in the realm of point-of-care applications.  相似文献   

9.
The size fractionation of magnetic nanoparticles is a technical problem, which until today can only be solved with great effort. Nevertheless, there is an important demand for nanoparticles with sharp size distributions, for example for medical technology or sensor technology. Using magnetic chromatography, we show a promising method for fractionation of magnetic nanoparticles with respect to their size and/or magnetic properties. This was achieved by passing magnetic nanoparticles through a packed bed of fine steel spheres with which they interact magnetically because single domain ferro-/ferrimagnetic nanoparticles show a spontaneous magnetization. Since the strength of this interaction is related to particle size, the principle is suitable for size fractionation. This concept was transferred into a continuous process in this work using a so-called simulated moving bed chromatography. Applying a suspension of magnetic nanoparticles within a size range from 20 to 120 nm, the process showed a separation sharpness of up to 0.52 with recovery rates of 100%. The continuous feed stream of magnetic nanoparticles could be fractionated with a space-time-yield of up to 5 mg/(L∙min). Due to the easy scalability of continuous chromatography, the process is a promising approach for the efficient fractionation of industrially relevant amounts of magnetic nanoparticles.  相似文献   

10.
Forced oscillation of spherical and rod-shaped iron oxide magnetic nanoparticles (MNPs) via low-power and low-frequency alternating magnetic field (AMF) was firstly used to kill cancer cells in vitro. After being loaded by human cervical cancer cells line (HeLa) and then exposed to a 35-kHz AMF, MNPs mechanically damaged cell membranes and cytoplasm, decreasing the cell viability. It was found that the concentration and morphology of the MNPs significantly influenced the cell-killing efficiency of oscillating MNPs. In this preliminary study, when HeLa cells were pre-incubated with 100 μg/mL rod-shaped MNPs (rMNP, length of 200 ± 50 nm and diameter of 50 to 120 nm) for 20 h, MTT assay proved that the cell viability decreased by 30.9% after being exposed to AMF for 2 h, while the cell viability decreased by 11.7% if spherical MNPs (sMNP, diameter of 200 ± 50 nm) were used for investigation. Furthermore, the morphological effect of MNPs on cell viability was confirmed by trypan blue assay: 39.5% rMNP-loaded cells and 15.1% sMNP-loaded cells were stained after being exposed to AMF for 2 h. It was also interesting to find that killing tumor cells at either higher (500 μg/mL) or lower (20 μg/mL) concentration of MNPs was less efficient than that achieved at 100 μg/mL concentration. In conclusion, the relatively asymmetric morphological rod-shaped MNPs can kill cancer cells more effectively than spherical MNPs when being exposed to AMF by virtue of their mechanical oscillations.  相似文献   

11.
Despite the large efforts to prepare super paramagnetic iron oxide nanoparticles (MNPs) for biomedical applications, the number of FDA or EMA approved formulations is few. It is not known commonly that the approved formulations in many instances have already been withdrawn or discontinued by the producers; at present, hardly any approved formulations are produced and marketed. Literature survey reveals that there is a lack for a commonly accepted physicochemical practice in designing and qualifying formulations before they enter in vitro and in vivo biological testing. Such a standard procedure would exclude inadequate formulations from clinical trials thus improving their outcome. Here we present a straightforward route to assess eligibility of carboxylated MNPs for biomedical tests applied for a series of our core-shell products, i.e., citric acid, gallic acid, poly(acrylic acid) and poly(acrylic acid-co-maleic acid) coated MNPs. The discussion is based on physicochemical studies (carboxylate adsorption/desorption, FTIR-ATR, iron dissolution, zeta potential, particle size, coagulation kinetics and magnetization measurements) and involves in vitro and in vivo tests. Our procedure can serve as an example to construct adequate physico-chemical selection strategies for preparation of other types of core-shell nanoparticles as well.  相似文献   

12.
Silica-coated magnetic nanoparticles (MNPs) have great potential for use in field of biotechnology owing to their unique properties, which can be manipulated by an external magnetic field gradient. Herein, we describe a method for facile synthesis of monodispersed silica-coated MNPs (MNP@SiO2 NPs). Commercially available oleate-MNPs were successfully converted to polyvinylpyrrolidone-MNPs (PVP-MNPs), and then coated with silica by the modified Stöber method. More than 95% of MNPs were individually coated with a silica shell; non-magnetic core silica nanoparticles (NPs) were not detected. Notably, the MNP@SiO2 NPs are highly monodispersed in size (size distribution < 2.5%) and synthesis at the scale of grams was easily obtained by a simple scale up process. Moreover, aggregation was not detected upon storage of over three months.  相似文献   

13.
A magnetic nanocomposite of citric‐acid‐functionalized graphene oxide was prepared by an easy method. First, citric acid (CA) was covalently attached to acyl‐chloride‐functionalized graphene oxide (GO). Then, Fe3O4 magnetic nanoparticles (MNPs) were chemically deposited onto the resulting adsorbent. CA, as a good stabilizer for MNPs, was covalently attached to the GO; thus MNPs were adsorbed much more strongly to this framework and subsequent leaching decreased and less agglomeration occurred. The attachment of CA onto GO and the formation of the hybrid were confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction spectrometry and transmission electron microscopy. The specific saturation magnetization of the magnetic CA‐grafted GO (GO‐CA‐Fe3O4) was 57.8 emu g?1 and the average size of the nanoparticles was found to be 25 nm by transmission electron microscopy. The magnetic nanocomposite was employed as an adsorbent of methylene blue from contaminated water. The adsorption tests demonstrated that it took only 30 min to attain equilibrium. The adsorption capacity in the concentration range studied was 112 mg g?1. The GO‐CA‐Fe3O4 nanocomposite was easily manipulated in an external magnetic field which eases the separation and leads to the removal of dyes. Thus the prepared nanocomposite has great potential in removing organic dyes. © 2014 Society of Chemical Industry  相似文献   

14.
This work is aimed to evaluate a method to detect the residual magnetic nanoparticles (MNPs) in animal tissues. Ferric ions released from MNPs through acidification with hydrochloric acid can be measured by complexation with potassium thiocyanate. MNPs in saline could be well detected by this chemical colorimetric method, whereas the detected sensitivity decreased significantly when MNPs were mixed with mouse tissue homogenates. In order to check the MNPs in animal tissues accurately, three improvements have been made. Firstly, proteinase K was used to digest the proteins that might bind with iron, and secondly, ferrosoferric oxide (Fe3O4) was collected by a magnetic field which could capture MNPs and leave the bio-iron in the supernatant. Finally, the collected MNPs were carbonized in the muffle furnace at 420°C before acidification to ruin the groups that might bind with ferric ions such as porphyrin. Using this method, MNPs in animal tissues could be well measured while avoiding the disturbance of endogenous iron and iron-binding groups.  相似文献   

15.
The tremendous interest in magnetic nanoparticles (MNPs) is reflected in published research that ranges from novel methods of synthesis of unique nanoparticle shapes and composite structures to a large number of MNP characterization techniques, and finally to their use in many biomedical and nanotechnology-based applications. The knowledge gained from this vast body of research can be made more useful if we organize the associated results to correlate key magnetic properties with the parameters that influence them. Tuning these properties of MNPs will allow us to tailor nanoparticles for specific applications, thus increasing their effectiveness. The complex magnetic behavior exhibited by MNPs is governed by many factors; these factors can either improve or adversely affect the desired magnetic properties. In this report, we have outlined a matrix of parameters that can be varied to tune the magnetic properties of nanoparticles. For practical utility, this review focuses on the effect of size, shape, composition, and shell-core structure on saturation magnetization, coercivity, blocking temperature, and relaxation time.  相似文献   

16.
In this study, poly(y-glutamic acid)-coated Fe3O4 magnetic nanoparticles (y-PGA/Fe304 MNPs) were successfully fabricated using the co-precipitation method. Fe3O4 MNPs were also prepared for comparison. The av erage size and specific surface area results reveal that 7-PGA/Fe304 MNPs (52.4 nm, 88.41 m2.g-1) have smaller particle size and larger specific surface area_ than Fe3O4 MNPs (62.0 nm, 76.83 mLg-1). The y-PGA/Fe3O4 MNPs  相似文献   

17.
A supermagnetic polysaccharide‐based nanocomposite gel has been developed as a potential drug delivery system. The gel was made via graft copolymerization of 2‐acrylamido‐2‐methylpropanesulfonic acid on pectin using ammonium peroxodisulfate as an initiator and N,N‐methylenebisacrylamide as a crosslinker under microwave irradiation. The magnetic nanoparticles (MNPs) were incorporated within the gel network via an in situ method of diffusion of Fe2+/Fe3+ followed by reduction with ammonia solution. The graft copolymer gel and its nanocomposite were characterized using attenuated total reflection Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X‐ray diffraction, field‐emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and transmission electron microscopy. The magnetic properties of the nanocomposite were measured using a vibrating sample magnetometer and mechanical properties using a tensile compressive tester. The gel was evaluated for adsorption and release of the drug diclofenac sodium. The presence of MNPs is observed to enhance significantly the mechanical properties, swelling capacity, drug loading and release ability of the graft polymer gel. The increased porosity of the gel network and higher surface area of MNPs allowed for 20% higher adsorption of diclofenac sodium molecules compared to the parent nonmagnetic gel. About 95% of the loaded drug was released from the MNP‐containing gel. The drug release pattern followed first‐order kinetic model and the Higuchi square root model, indicating swelling‐controlled diffusion to be the mode of drug release. © 2018 Society of Chemical Industry  相似文献   

18.
Magnetic nanoparticle (MNP)-based magnetic resonance imaging (MRI) contrast agents (CAs) have been the subject of extensive research over recent decades. The particle size of MNPs varies widely and is known to influence their physicochemical and pharmacokinetic properties. There are two commonly used methods for synthesizing MNPs, organometallic and aqueous solution coprecipitation. The former has the advantage of being able to control the particle size more effectively; however, the resulting particles require a hydrophilic coating in order to be rendered water soluble. The MNPs produced using the latter method are intrinsically water soluble, but they have a relatively wide particle size distribution. Size-controlled water-soluble MNPs have great potential as MRI CAs and in cell sorting and labeling applications. In the present study, we synthesized CoFe2O4 MNPs using an aqueous solution coprecipitation method. The MNPs were subsequently separated into four groups depending on size, by the use of centrifugation at different speeds. The crystal shapes and size distributions of the particles in the four groups were measured and confirmed by transmission electron microscopy and dynamic light scattering. Using X-ray diffraction analysis, the MNPs were found to have an inverse spinel structure. Four MNP groups with well-selected semi-Gaussian-like diameter distributions were obtained, with measured T2 relaxivities (r2) at 4.7 T and room temperature in the range of 60 to 300 mM−1s−1, depending on the particle size. This size regulation method has great promise for applications that require homogeneous-sized MNPs made by an aqueous solution coprecipitation method. Any group of the CoFe2O4 MNPs could be used as initial base cores of MRI T2 CAs, with almost unique T2 relaxivity owing to size regulation. The methodology reported here opens up many possibilities for biosensing applications and disease diagnosis.

PACS

75.75.Fk, 78.67.Bf, 61.46.Df  相似文献   

19.
The preparation of chitosan‐coated magnetic nanoparticles (MNPs) and covalent immobilization of α‐amylase for starch hydrolysis was investigated. Surface morphology, chemical composition, and structural characteristics of the MNPs were analyzed by scanning electron microscopy, energy dispersion spectrometry, and X‐ray diffractometry, respectively. Surface functional groups of MNPs, chitosan‐coated MNPs, and α‐amylase‐immobilized MNPs were characterized by Fourier transform infrared spectroscopy. Response surface methodology based on three levels was implemented to optimize three immobilization conditions and a regression model was developed. α‐Amylase‐immobilized MNPs provided better stability towards pH and temperature. The prepared thermostable nanobiocatalyst is well‐suited for industrial processes involving starch hydrolysis.  相似文献   

20.
This study determines the effect of bare and heparin (HP)-based magnetic iron oxide (Fe3O4) nanoparticles (MNPs) on the human ovarian cancer cells of CP70 type. Cisplatin (CP) was used as the anticancer drug, entrapped in MNPs. The nanoparticles containing the anticancer drug, CP, were prepared by a solvent evaporation and emulsification cross-linking method. The physicochemical properties of the nanoparticles were characterized by various techniques, and uniform particles of bare and HP coated MNPs, with average particle sizes of 25 and 45 ± 15 nm, having high encapsulation efficiencies, were obtained. Additionally, a sustained release of CP from the MNPs was successful in vitro. Cytotoxicity tests showed that the MNP–HP–CP had higher cell toxicity than the individual HP; and confocal microscopic analysis confirmed excellent cellular uptake efficiency of CP70 cells for MNP–HP–CP. These results indicate that HP based MNPs have potential uses as anticancer drug carriers and have also proved to have enhanced anti-neoplastic effects.  相似文献   

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