A facile method for synthesis of the magnetic Fe_3O_4 nanoparticles was introduced.Magnetic nanoparticles were prepared via co-precipitation method with(PMF) and without(AMF) 0.15 T static magnetic field.The effects o...A facile method for synthesis of the magnetic Fe_3O_4 nanoparticles was introduced.Magnetic nanoparticles were prepared via co-precipitation method with(PMF) and without(AMF) 0.15 T static magnetic field.The effects of magnetic field on the properties of magnetic nanoparticles were studied by XRD,TEM,SEM,VSM and BET.The results showed that the magnetic field in the co-precipitation reaction process did not result in the phase change of the Fe_3O_4 nanoparticles but improved the crystallinity.The morphology of Fe_3O_4 nanoparticles was varied from random spherical particles to rod-like cluster structure.The VSM results indicated that the saturation magnetization value of the Fe_3O_4 nanoparticles was significantly improved by the magnetic field.The BET of Fe_3O_4nanoparticles prepared with the magnetic field was larger than the control by 23.5%.The batch adsorption experiments of Mn(Ⅱ) on the PMF and AMF Fe_3O_4 nanoparticles showed that the Mn(II) equilibrium capacity was increased with the pH value increased.At pH 8,the Mn(Ⅱ) adsorption capacity for the PMF and AMF Fe_3O_4 was reached at 36.81 and 28.36 mg·g^(-1),respectively.The pseudo-second-order model fitted better the kinetic models and the Freundlich model fitted isotherm model well for both PMF and AMF Fe_3O_4.The results suggested that magnetic nanoparticles prepared by the magnetic field presented a fairly good potential as an adsorbent for an efficient removal of Mn(Ⅱ) from aqueous solution.展开更多
Novel hollow Fe3O4 nanoparticles for drug delivery were synthesized via a one-step template- free approach. These nanoparticles were obtained by modifing the Fe3O4 nanoparticles with 3-aminopropyltrimethoxy silane, an...Novel hollow Fe3O4 nanoparticles for drug delivery were synthesized via a one-step template- free approach. These nanoparticles were obtained by modifing the Fe3O4 nanoparticles with 3-aminopropyltrimethoxy silane, and then grafting alginate onto the surface of amine magnetic. The hollow structure of Fe3O4 spheres was characterized by TEM, XRD, and XPS. The M-H hysteresis loop indicated that the magnetic spheres exhibit snperparamagnetic characteristics at room temperature. Daunorubicin acting as a model drug was loaded into the carrier, and the maximum percent of envelop and load were 28.4% and 14.2% respectively. The drug controlled releasing behaviors of the carriers were compared in different pH media.展开更多
A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B（RB） was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized...A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B（RB） was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane（MPTS）. To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe3O4@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe3O4@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance（SPR） band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon（LSP） and the gap plasmon near-field coupling with the Fe3O4@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10^（-7） mol/L, and the Fe3O4@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe3O4@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.展开更多
Highly biocompatible superparamagnetic Fe3O4 nanoparticles were synthesized by amide of folic acid （FA） ligands and the NH2-group onto the surface of Fe3O4 nanoparticles. The as-synthesized folate-conjugated Fe3O4 n...Highly biocompatible superparamagnetic Fe3O4 nanoparticles were synthesized by amide of folic acid （FA） ligands and the NH2-group onto the surface of Fe3O4 nanoparticles. The as-synthesized folate-conjugated Fe3O4 nanoparticles were characterized by X-ray diffraction diffractometer, transmission electron microscope, FT-IR spectrometer, vibrating sample magnetometer, and dynamic light scattering instrument. The in vivo labeling effect of folate-conjugated Fe3O4 nanoparticles on the hepatoma cells was investigated in tumor-bearing rat. The results demonstrate that the as-prepared nanoparticles have cubic structure of Fe3O4 with a particle size of about 8 nm and hydrated diameter of 25.7 nm at a saturation magnetization of 51 A·m2/kg. These nanoparticles possess good physiological stability, low cytotoxicity on human skin fibroblasts and negligible effect on Wistar rats at the concentration as high as 3 mg/kg body mass. The folate-conjugated Fe3O4 nanoparticles could be effectively mediated into the human hepatoma Bel 7402 cells through the binding of folate and folic acid receptor, enhancing the signal contrast of tumor tissue and surrounding normal tissue in MRI imaging. It is in favor of the tumor cells labeling, tracing, magnetic resonance imaging （MRI） target detection and magnetic hyperthermia.展开更多
Peroxidase-like catalytic properties of Fe3O4 nanoparficles （NPs） with three different sizes, synthesized by chemical coprecipitation and sol-gel methods, were investigated by UV-vis spectrum analysis. By comparing ...Peroxidase-like catalytic properties of Fe3O4 nanoparficles （NPs） with three different sizes, synthesized by chemical coprecipitation and sol-gel methods, were investigated by UV-vis spectrum analysis. By comparing Fe3O4 NPs with average diameters of 11, 20, and 150 nm, we found that the catalytic activity increases with the reduced nanoparticle size. The electrochemical method to characterize the catalytic activity of Fe3O4 NPs using the response currents of the reaction product and substrate was also developed.展开更多
Fe3O4 nanoparticles were prepared by chemistry co-precipitation and the mean crystal size was 17.9 nm measured by XRD. After it had been treated by silane-coupling agents KH570, magnetic micro-spheres dispersed in org...Fe3O4 nanoparticles were prepared by chemistry co-precipitation and the mean crystal size was 17.9 nm measured by XRD. After it had been treated by silane-coupling agents KH570, magnetic micro-spheres dispersed in organic medium glycol were gained and the mean size of Fe3O4 nanopowders was 33.7 nm. So it can be concluded that magnetic micro-sphere is made of a few Fe3O4 crystals. Many factors of modification were researched, such as the time of ball milling, the content of Fe3O4 and the content of KH570. The modification of Fe3O4 is relative to the time of ball milling, but the dominant function is affected by the content of Fe3O4 and KH570. When the content of Fe3O4 is known, there is a suitable content of KH570. Different content of Fe3O4 will make the different suitable content of KH570, but the range of latter is less than former, which is relative to the distribution of KH570 on Fe3O4 surface or in the solution.展开更多
The surface organic modification of Fe3O4 nanoparticles with silane coupling reagent KH570 was studied. The modified and unmodified nanoparticles were characterized by FT-IR, XPS and TEM. The spectra of FT-IR and XPS ...The surface organic modification of Fe3O4 nanoparticles with silane coupling reagent KH570 was studied. The modified and unmodified nanoparticles were characterized by FT-IR, XPS and TEM. The spectra of FT-IR and XPS revealed that KH570 was coated onto the surface of Fe3O4 nanoparticles to get Fe-O- Si bond and an organic coating layer also was formed. Fe3O4 nanoparticles were spheres partly with mean size of 18,8 nm studied by TEM, which was consistent with the result 17.9 nm calculated by Scherrer＇s equation. KH570 was adsorbed on surface and formed chemistry bond to be steric hindrance repulsion which prevented nanoparticles from reuniting. Then glycol-based Fe3O4 magnetic liquids dispersed stably was gained.展开更多
Fe3O4 magnetic nanoparticles(MNPs) were synthesised, characterised, and used as a peroxidase mimetic to accelerate levofloxacin sono-degradation in an ultrasound(US)/H2O2 system. The Fe3O4 MNPs were in nanometre scale...Fe3O4 magnetic nanoparticles(MNPs) were synthesised, characterised, and used as a peroxidase mimetic to accelerate levofloxacin sono-degradation in an ultrasound(US)/H2O2 system. The Fe3O4 MNPs were in nanometre scale with an average diameter of approximately 12 to 18 nm. The introduction of Fe3O4 MNPs increased levofloxacin sono-degradation in the US/H2O2 system. Experimental parameters, such as Fe3O4 MNP dose, initial solution p H, and H2O2 concentration, were investigated by a one-factor-at-a-time approach. The results showed that Fe3O4 MNPs enhanced levofloxacin removal in the p H range from 4.0 to 9.0. Levofloxacin removal ratio increased with Fe3O4 MNP dose up to 1.0 g·L-1and with H2O2 concentration until reaching the maximum. Moreover, three main intermediate compounds were identified by HPLC with electrospray ionisation tandem mass spectrometry, and a possible degradation pathway was proposed. This study suggests that combination of H2O2, Fe3O4 MNPs and US is a good way to improve the degradation efficiency of antibiotics.展开更多
Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin...Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin（HSA） for magnetic resonance imaging as contrast agent. Characteristics of magnetic particles coated or uncoated were carried out using scanning electron microscopy and X-ray diffraction. Zeta potentials, package effects and distributions of colloid particles were measured to confirm the attachment of HSA on magnetic particles. Effects of Fe3O4 nanoparticles coated with HSA on magnetic resonance imaging were investigated with rats. The experimental results show that the adsorption of HSA on magnetic particles is very favorable to dispersing of magnetic Fe3O4 particles, while the sizes of Fe3O4 particles coated are related to the molar ratio of Fe3O4 to HSA. The diameters of the majority of particles coated are less than 100 nm. Fe3O4 nanoparticle coated with HSA has a good biocompatibility and low toxicity. This new contrast agent has some effects on the nuclear magnetic resonance imaging of liver and the lowest dosage is 20μmol/kg for the demands of diagnosis.展开更多
A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-...A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-PDMAEMA-grafted-Fe3O4 magnetic nanoparticles with amino and epoxy groups were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermo-gravimetric analysis, and scanning electron microscopy. Lipase from Burkholderia cepacia was successfully immobilized onto the magnetic nanoparticles by physical adsorption and covalent bonding. The immobilization capacity of the magnetic particles is 0.5 mg lipase per mg support, with an activity recovery of up to 43.1% under the optimum immobilization condition. Biochemical characterization shows that the immobilized lipase exhibits improved thermal stability, good tolerance to organic solvents with high lg P, and higher p H stability than the free lipase at p H 9.0. After six consecutive cycles, the residual activity of the immobilized lipase is still over55% of its initial activity.展开更多
A magnetic bar carbon paste electrode （MBCPE） modified with Fe3O4 magnetic nanoparticles （Fe3O4NPs） and 2‐（3,4‐dihydroxyphenyl） benzothiazole （DPB） for the electrochemical determina‐tion of hydrazine was de...A magnetic bar carbon paste electrode （MBCPE） modified with Fe3O4 magnetic nanoparticles （Fe3O4NPs） and 2‐（3,4‐dihydroxyphenyl） benzothiazole （DPB） for the electrochemical determina‐tion of hydrazine was developed. The DPB was firstly self‐assembled on the Fe3O4NPs, and the re‐sulting Fe3O4NPs/DPB composite was then absorbed on the designed MBCPE. The MBCPE was used to attract the magnetic nanoparticles to the electrode surface. Owing to its high conductivity and large effective surface area, the novel electrode had a very large current response for the electrocat‐alytic oxidation of hydrazine. The modified electrode was characterized by voltammetry, scanning electron microscopy, electrochemical impedance spectroscopy, infrared spectroscopy, and UV‐visible spectroscopy. Voltammetric methods were used to study the electrochemical behaviour of hydrazine on MBCPE/Fe3O4NPs/DPB in phosphate buffer solution （pH = 7.0）. The MBCPE/Fe3O4NPs/DPB, acting as an electrochemical sensor, exhibited very high electrocatalytic activity for the oxidation of hydrazine. The presence of DPB was found to reduce the oxidation potential of hydrazine and increase the catalytic current. The dependence of the electrocatalytic current on the hydrazine concentration exhibited two linear ranges, 0.1–0.4 μmol/L and 0.7–12.0 μmol/L, with a detection limit of 18.0 nmol/L. Additionally, the simultaneous determination of hydrazine and phe‐nol was investigated using the MBCPE/Fe3O4NPs/DPB electrode. Voltammetric experiments showed a linear range of 100–470 μmol/L and a detection limit of 24.3 μmol/L for phenol, and the proposed electrode was applied to the determination of hydrazine and phenol in water samples.展开更多
A novel type of Fe3O4 nanoparticles modified glass carbon electrode（Fe3O4/GCE） was constructed and the electrochemical properties of N-（4-nitro-2-phenoxyphenyl）methanesulfonamide（nimesulide） were studied on the ...A novel type of Fe3O4 nanoparticles modified glass carbon electrode（Fe3O4/GCE） was constructed and the electrochemical properties of N-（4-nitro-2-phenoxyphenyl）methanesulfonamide（nimesulide） were studied on the Fe3O4/GCE.In 0.4mol/L HAc-NaAc buffer solution（pH=5.0）,the electrode process of nimesulide was irreversible at bare GCE and Fe3O4/GCE.The Fe3O4/GCE exhibited a remarkable catalytic and enhancement effect on the reduction of nimesulide.The reduction peak potential of nimesulide shifted positively from-0.683 V at bare GCE to-0.625 V at Fe3O4/GCE,and the sensitivity was increased by ca.3 times.Some experimental conditions were optimized.The linear range between the peak current and the concentration of nimesulide was 2.6×10-6 ＂1.0×10-4mol/L（R=0.993） with a detection limit of 1.3×10-7mol/L.This method has been used to determine the content of nimesulide in medical tablets.The recovery was determined to be 96.9% ＂101.9% by means of standard addition method.The method is comparable to UV-Vis spectrometry.展开更多
Fe3O4 magnetic nanoparticles were prepared by co-precipitation of Fe^2＋ and Fe^3＋ in an ammonia solution, and its size was about 36 nm measured by an atomic force microscope. Fe3O4 magnetic nanoparticles were modifi...Fe3O4 magnetic nanoparticles were prepared by co-precipitation of Fe^2＋ and Fe^3＋ in an ammonia solution, and its size was about 36 nm measured by an atomic force microscope. Fe3O4 magnetic nanoparticles were modified by L-dopa or dopamine using sonication method. The analysis of FTIR clearly indicated the formation of Fe-O-C bond. Direct immobilization of trypsin （EC： 3.4.21.4） on Fe3O4 magnetic nanoparticles with L-dopa and dopamine spacer was investigated using glutaraldehyde as a coupling agent. No significant changes in the size and magnetic property of the three kinds of magnetic nanoparticles linked with or without trypsin were observed. The existence of the spacer molecule on magnetic nanoparticles could greatly improve the activity and the storage stability of bound trypsin through increasing the flexibility of enzyme and changing the microenvironment on nanoparticles surface compared to the naked magnetic nanoparticles.展开更多
A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sampl...A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sample was typical of superparamagnetic material.The samples were characterized by transmission electron microscope,and it is found that the particles are of small size.The Fe_3O_4/GO MNPs were further used as an adsorbent to remove Rhodamine B.The effects of initial pH of the solution,the dosage of adsorbent,temperature,contact time and the presence of interfering dyes on adsorption performance were investigated as well.The adsorption equilibrium and kinetics data were fitted well with the Freundlich isotherm and the pseudosecond-order kinetic model respectively.The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption of Rhodamine B.And the adsorption process was endothermic in nature.Furthermore,the magnetic composite with a high adsorption capacity of Rhodamine B could be effectively and simply separated using an external magnetic field.And the used particles could be regenerated and recycled easily.The magnetic composite could find potential applications for the removal of dye pollutants.展开更多
Magnetite （Fe3O4） nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the g...Magnetite （Fe3O4） nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the growth mechanism in detail. It is found that the size and shape of nanoparticles are determined by adjusting the precursor concentration and duration time, which can be well explained by the mechanism based on the LaMer model in our synthetic system. The monodisperse Fe3O4 nanoparticles have a mean diameter from 5nm to 16nm, and shape evolution from spherical to triangular and cubic. The magnetic properties are size-dependent, and Fe3O4 nanoparticles in small size about 5 nm exhibit superparamagnetie properties at room temperature and maximum saturation magnetization approaches to 78 emu/g, whereas Fe3O4 nanoparticles develop ferromagnetic properties when the diameter increases to about 16nm.展开更多
Fe3O4 magnetic nanoparticles with diameters varying from 10 to 426 nm were synthesized and characterized.Heating effects of Fe3O4 magnetic nanoparticles under radiofrequency capacitive field(RCF) with frequency of 27....Fe3O4 magnetic nanoparticles with diameters varying from 10 to 426 nm were synthesized and characterized.Heating effects of Fe3O4 magnetic nanoparticles under radiofrequency capacitive field(RCF) with frequency of 27.12 MHz and power of 60-150 W were investigated.When the power of RCF is lower than 90 W,temperatures of Fe3O4 magnetic nanoparticles(75-150 mg/mL) can be raised and maximal temperatures are all lower than 50 ℃.When the power of RCF is 90-150 W,temperatures of Fe3O4 magnetic nanoparticles can be quickly raised and are all obviously higher than those of normal saline and distilled water under the same conditions.Temperature of Fe3O4 magnetic nanoparticles can even reach 70.2 ℃ under 150 W RCF.Heating effects of Fe3O4 magnetic nanoparticles are related to RCF power,particle size and particle concentration.展开更多
Nanometer particles are important portion of magnetic fluid. Fe3O4 magnetic nanoparticles were studied in this paper and the surface modification of Fe3O4 nanoparticles was investigated by a series of experiments. Fe3...Nanometer particles are important portion of magnetic fluid. Fe3O4 magnetic nanoparticles were studied in this paper and the surface modification of Fe3O4 nanoparticles was investigated by a series of experiments. Fe3O4 magnetic nanoparticles were synthesized with pH value, temperature, and the dosage of surfactant. The phase, structure, size and magnetism of nanoparticles were tested by X-ray diffration （XRD）, transmission electron microscopy （TEM） and magnetic balance. On the basis of the surface modification coating mechanism, the experimental phenomena and the effects on the variation of size, magnetism and stability of Fe3O4 nanoparticles were theoretically analyzed. X-Ray diffraction spectrum and TEM photograph show that 1） the nanoparticles structure is perfect, 2） the diameter of narnoparticles is small and have good deliquescence, and 3） Sodium oleate is the anion surfactant. Therefore 1） the good condition of surface modification is in an acidic solution, 2） the best temperature of surface modification is at 80 ℃, and 3） the dosage of surfactant should be about 0.6 times of that of Fe^2＋.展开更多
In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of S...In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of SDS （sodium dodeci[ sulfate）. The temperature of the nanoparticles and the SDS solution was evaluated by a novel method based on measuring the Q-factor （quality-factor） of a resonant circuit. The Q-factor of the investigated system as a function of the frequency of the EM field was obtained. The nanoparticles-SDS liquid system exhibited a resonance-like behavior of the absorption, where the resonance frequency was about 170 MHz, and the absorption rise up to the resonance frequency was rather slow. The observed absorption of EM energy was accompanied by a small temperature increasing of the system. Measurements of the ESR （electron spin resonance） spectrum of the Fe3O4 nanoparticles have presented a slightly asymmetric singlet with the proportionality factor g = 2 and a line-width of the magnetic field strength △H = 0.1 mT. It was shown that the observed absorption spectrum corresponds to paramagnetic behavior of the investigated nanoparticles.展开更多
[ Objective] The study aims at developing a novel fluorescence enhancement method to determine anionic surfactants. [ Method] Based on Fe3O4 @ PAA-RB fluorescent nanoparticles as fluorescent probes, we have developed ...[ Objective] The study aims at developing a novel fluorescence enhancement method to determine anionic surfactants. [ Method] Based on Fe3O4 @ PAA-RB fluorescent nanoparticles as fluorescent probes, we have developed a novel fluorescence enhancement method for the determi- nation of an anionic surfactant sodium dodecyl sulfate （SDS） through the gradual optimization of experiment conditions. [ Result] Under the opti- mum conditions, the extent of fluorescence enhancement is directly proportional to SDS concentration varying from 0.5 to 16.0 μmol/L, and the de- tection limit reaches 0.051 μmol/L. The relative standard deviation （RSD） for 4.0 μmol/L SDS is 3.3% （ n =6）. The proposed method has been successfully applied to the determination of SDS in environmental water samples, with recovery of 96.3% -105.5%. E Conclusion] The novel fluo- rescence enhancement method is not only simple and rapid, but also has avoided using tedious solvent-extraction and toxic organic solvents.展开更多
Enhancement of Fe3O4/Au nanoparticles （Fe3O4/Au NPs） catalyst was observed in the oxidative degradation of methyl orange by employing H2O2 as oxidant. To evaluate the catalytic activity of Fe3O4/Au nanoparticles, di...Enhancement of Fe3O4/Au nanoparticles （Fe3O4/Au NPs） catalyst was observed in the oxidative degradation of methyl orange by employing H2O2 as oxidant. To evaluate the catalytic activity of Fe3O4/Au nanoparticles, different degradation conditions were investigated such as the amounts of catalyst, H2O2 concentration and pH value. Based on our data, methyl orange was degraded completely in a short time. The enhanced catalytic activity and increased oxidation rate constant may be ascribed to synergistic catalyst-activated decomposition of H2O2 to ,OH radical, which was one of the strong oxidizing species. Besides, Fe3O4/Au nanoparticles have exhibited satisfying recycle performance for potential industrial application.展开更多
基金Supported by the National Natural Science Foundation of China(No.41201487)the Natural Science Foundation of Hebei Province(No.2014202074)
文摘A facile method for synthesis of the magnetic Fe_3O_4 nanoparticles was introduced.Magnetic nanoparticles were prepared via co-precipitation method with(PMF) and without(AMF) 0.15 T static magnetic field.The effects of magnetic field on the properties of magnetic nanoparticles were studied by XRD,TEM,SEM,VSM and BET.The results showed that the magnetic field in the co-precipitation reaction process did not result in the phase change of the Fe_3O_4 nanoparticles but improved the crystallinity.The morphology of Fe_3O_4 nanoparticles was varied from random spherical particles to rod-like cluster structure.The VSM results indicated that the saturation magnetization value of the Fe_3O_4 nanoparticles was significantly improved by the magnetic field.The BET of Fe_3O_4nanoparticles prepared with the magnetic field was larger than the control by 23.5%.The batch adsorption experiments of Mn(Ⅱ) on the PMF and AMF Fe_3O_4 nanoparticles showed that the Mn(II) equilibrium capacity was increased with the pH value increased.At pH 8,the Mn(Ⅱ) adsorption capacity for the PMF and AMF Fe_3O_4 was reached at 36.81 and 28.36 mg·g^(-1),respectively.The pseudo-second-order model fitted better the kinetic models and the Freundlich model fitted isotherm model well for both PMF and AMF Fe_3O_4.The results suggested that magnetic nanoparticles prepared by the magnetic field presented a fairly good potential as an adsorbent for an efficient removal of Mn(Ⅱ) from aqueous solution.
文摘Novel hollow Fe3O4 nanoparticles for drug delivery were synthesized via a one-step template- free approach. These nanoparticles were obtained by modifing the Fe3O4 nanoparticles with 3-aminopropyltrimethoxy silane, and then grafting alginate onto the surface of amine magnetic. The hollow structure of Fe3O4 spheres was characterized by TEM, XRD, and XPS. The M-H hysteresis loop indicated that the magnetic spheres exhibit snperparamagnetic characteristics at room temperature. Daunorubicin acting as a model drug was loaded into the carrier, and the maximum percent of envelop and load were 28.4% and 14.2% respectively. The drug controlled releasing behaviors of the carriers were compared in different pH media.
基金Funded by the National Natural Science Foundation of China(NSFC)(Nos.51273048 and 51203025)the Natural Science Foundation of Guangdong Province(No.S2012040007725)
文摘A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B（RB） was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane（MPTS）. To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe3O4@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe3O4@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance（SPR） band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon（LSP） and the gap plasmon near-field coupling with the Fe3O4@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10^（-7） mol/L, and the Fe3O4@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe3O4@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.
基金Project(2011JQ028)supported by the Fundamental Research Funds for the Central Universities,ChinaProjects(2008SK3114,2010SK3113)supported by Hunan Provincial Science&Technology Plan,China+2 种基金Project(B2007086)supported by Science&Research Funds of Hunan Health Department,ChinaProject(12JJ5057)supported by Natural Science Foundation of Hunan Province,ChinaProjects(XCX1119,XCX12073)supported by University Students Innovative Experiment Plan Project of Hunan Agricultural University,China
文摘Highly biocompatible superparamagnetic Fe3O4 nanoparticles were synthesized by amide of folic acid （FA） ligands and the NH2-group onto the surface of Fe3O4 nanoparticles. The as-synthesized folate-conjugated Fe3O4 nanoparticles were characterized by X-ray diffraction diffractometer, transmission electron microscope, FT-IR spectrometer, vibrating sample magnetometer, and dynamic light scattering instrument. The in vivo labeling effect of folate-conjugated Fe3O4 nanoparticles on the hepatoma cells was investigated in tumor-bearing rat. The results demonstrate that the as-prepared nanoparticles have cubic structure of Fe3O4 with a particle size of about 8 nm and hydrated diameter of 25.7 nm at a saturation magnetization of 51 A·m2/kg. These nanoparticles possess good physiological stability, low cytotoxicity on human skin fibroblasts and negligible effect on Wistar rats at the concentration as high as 3 mg/kg body mass. The folate-conjugated Fe3O4 nanoparticles could be effectively mediated into the human hepatoma Bel 7402 cells through the binding of folate and folic acid receptor, enhancing the signal contrast of tumor tissue and surrounding normal tissue in MRI imaging. It is in favor of the tumor cells labeling, tracing, magnetic resonance imaging （MRI） target detection and magnetic hyperthermia.
基金This work was supported by the National Natural Science Foundation of China （Nos. 90406023 and 60571031）；National Important Science Research Program of China （Nos. 2006CB933206 and 2006CB705606）.
文摘Peroxidase-like catalytic properties of Fe3O4 nanoparficles （NPs） with three different sizes, synthesized by chemical coprecipitation and sol-gel methods, were investigated by UV-vis spectrum analysis. By comparing Fe3O4 NPs with average diameters of 11, 20, and 150 nm, we found that the catalytic activity increases with the reduced nanoparticle size. The electrochemical method to characterize the catalytic activity of Fe3O4 NPs using the response currents of the reaction product and substrate was also developed.
基金This work was financially supported by the Graduate Innovation Plan Projects of Jiangsu Province in 2005.
文摘Fe3O4 nanoparticles were prepared by chemistry co-precipitation and the mean crystal size was 17.9 nm measured by XRD. After it had been treated by silane-coupling agents KH570, magnetic micro-spheres dispersed in organic medium glycol were gained and the mean size of Fe3O4 nanopowders was 33.7 nm. So it can be concluded that magnetic micro-sphere is made of a few Fe3O4 crystals. Many factors of modification were researched, such as the time of ball milling, the content of Fe3O4 and the content of KH570. The modification of Fe3O4 is relative to the time of ball milling, but the dominant function is affected by the content of Fe3O4 and KH570. When the content of Fe3O4 is known, there is a suitable content of KH570. Different content of Fe3O4 will make the different suitable content of KH570, but the range of latter is less than former, which is relative to the distribution of KH570 on Fe3O4 surface or in the solution.
基金the Natural Science Fund of Jiangsu province (No.BK2007586)Jiangsu Planned Projects(No.0701012B)for Postdoctoral Research Funds
文摘The surface organic modification of Fe3O4 nanoparticles with silane coupling reagent KH570 was studied. The modified and unmodified nanoparticles were characterized by FT-IR, XPS and TEM. The spectra of FT-IR and XPS revealed that KH570 was coated onto the surface of Fe3O4 nanoparticles to get Fe-O- Si bond and an organic coating layer also was formed. Fe3O4 nanoparticles were spheres partly with mean size of 18,8 nm studied by TEM, which was consistent with the result 17.9 nm calculated by Scherrer＇s equation. KH570 was adsorbed on surface and formed chemistry bond to be steric hindrance repulsion which prevented nanoparticles from reuniting. Then glycol-based Fe3O4 magnetic liquids dispersed stably was gained.
基金Supported by the National Natural Science Foundation of China(51009115)Shaanxi Provincial Department of Education Key Laboratory Project(13JS067)+2 种基金the Hall of Shaanxi Province Science and Technology(2013JK0881)the Research Plan Project of Water Resources Department of Shaanxi Province(2013slkj-07)the Innovation of Science and Technology Fund of Xi'an University of Technology(211302)
文摘Fe3O4 magnetic nanoparticles(MNPs) were synthesised, characterised, and used as a peroxidase mimetic to accelerate levofloxacin sono-degradation in an ultrasound(US)/H2O2 system. The Fe3O4 MNPs were in nanometre scale with an average diameter of approximately 12 to 18 nm. The introduction of Fe3O4 MNPs increased levofloxacin sono-degradation in the US/H2O2 system. Experimental parameters, such as Fe3O4 MNP dose, initial solution p H, and H2O2 concentration, were investigated by a one-factor-at-a-time approach. The results showed that Fe3O4 MNPs enhanced levofloxacin removal in the p H range from 4.0 to 9.0. Levofloxacin removal ratio increased with Fe3O4 MNP dose up to 1.0 g·L-1and with H2O2 concentration until reaching the maximum. Moreover, three main intermediate compounds were identified by HPLC with electrospray ionisation tandem mass spectrometry, and a possible degradation pathway was proposed. This study suggests that combination of H2O2, Fe3O4 MNPs and US is a good way to improve the degradation efficiency of antibiotics.
文摘Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin（HSA） for magnetic resonance imaging as contrast agent. Characteristics of magnetic particles coated or uncoated were carried out using scanning electron microscopy and X-ray diffraction. Zeta potentials, package effects and distributions of colloid particles were measured to confirm the attachment of HSA on magnetic particles. Effects of Fe3O4 nanoparticles coated with HSA on magnetic resonance imaging were investigated with rats. The experimental results show that the adsorption of HSA on magnetic particles is very favorable to dispersing of magnetic Fe3O4 particles, while the sizes of Fe3O4 particles coated are related to the molar ratio of Fe3O4 to HSA. The diameters of the majority of particles coated are less than 100 nm. Fe3O4 nanoparticle coated with HSA has a good biocompatibility and low toxicity. This new contrast agent has some effects on the nuclear magnetic resonance imaging of liver and the lowest dosage is 20μmol/kg for the demands of diagnosis.
基金Supported by the National Basic Research Program of China(2009CB724706)
文摘A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-PDMAEMA-grafted-Fe3O4 magnetic nanoparticles with amino and epoxy groups were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermo-gravimetric analysis, and scanning electron microscopy. Lipase from Burkholderia cepacia was successfully immobilized onto the magnetic nanoparticles by physical adsorption and covalent bonding. The immobilization capacity of the magnetic particles is 0.5 mg lipase per mg support, with an activity recovery of up to 43.1% under the optimum immobilization condition. Biochemical characterization shows that the immobilized lipase exhibits improved thermal stability, good tolerance to organic solvents with high lg P, and higher p H stability than the free lipase at p H 9.0. After six consecutive cycles, the residual activity of the immobilized lipase is still over55% of its initial activity.
文摘A magnetic bar carbon paste electrode （MBCPE） modified with Fe3O4 magnetic nanoparticles （Fe3O4NPs） and 2‐（3,4‐dihydroxyphenyl） benzothiazole （DPB） for the electrochemical determina‐tion of hydrazine was developed. The DPB was firstly self‐assembled on the Fe3O4NPs, and the re‐sulting Fe3O4NPs/DPB composite was then absorbed on the designed MBCPE. The MBCPE was used to attract the magnetic nanoparticles to the electrode surface. Owing to its high conductivity and large effective surface area, the novel electrode had a very large current response for the electrocat‐alytic oxidation of hydrazine. The modified electrode was characterized by voltammetry, scanning electron microscopy, electrochemical impedance spectroscopy, infrared spectroscopy, and UV‐visible spectroscopy. Voltammetric methods were used to study the electrochemical behaviour of hydrazine on MBCPE/Fe3O4NPs/DPB in phosphate buffer solution （pH = 7.0）. The MBCPE/Fe3O4NPs/DPB, acting as an electrochemical sensor, exhibited very high electrocatalytic activity for the oxidation of hydrazine. The presence of DPB was found to reduce the oxidation potential of hydrazine and increase the catalytic current. The dependence of the electrocatalytic current on the hydrazine concentration exhibited two linear ranges, 0.1–0.4 μmol/L and 0.7–12.0 μmol/L, with a detection limit of 18.0 nmol/L. Additionally, the simultaneous determination of hydrazine and phe‐nol was investigated using the MBCPE/Fe3O4NPs/DPB electrode. Voltammetric experiments showed a linear range of 100–470 μmol/L and a detection limit of 24.3 μmol/L for phenol, and the proposed electrode was applied to the determination of hydrazine and phenol in water samples.
基金Supported by the National Natural Science Foundation of China(No.21065001)the Natural Science Foundation of Guangxi Province,China(Nos.0639025,0991084)+2 种基金the Support Program for 100 Young and Middle-aged Disciplinary Leaders in Higher Education Institutions of Guangxi Province,China(No.RC20060703005)the Project of Key Laboratory of Development and Application of Forest Chemicals of Guangxi Province,China(No.GXFC08-06)the Fund of Education Department of Guangxi Province,China(No.200812MS074)
文摘A novel type of Fe3O4 nanoparticles modified glass carbon electrode（Fe3O4/GCE） was constructed and the electrochemical properties of N-（4-nitro-2-phenoxyphenyl）methanesulfonamide（nimesulide） were studied on the Fe3O4/GCE.In 0.4mol/L HAc-NaAc buffer solution（pH=5.0）,the electrode process of nimesulide was irreversible at bare GCE and Fe3O4/GCE.The Fe3O4/GCE exhibited a remarkable catalytic and enhancement effect on the reduction of nimesulide.The reduction peak potential of nimesulide shifted positively from-0.683 V at bare GCE to-0.625 V at Fe3O4/GCE,and the sensitivity was increased by ca.3 times.Some experimental conditions were optimized.The linear range between the peak current and the concentration of nimesulide was 2.6×10-6 ＂1.0×10-4mol/L（R=0.993） with a detection limit of 1.3×10-7mol/L.This method has been used to determine the content of nimesulide in medical tablets.The recovery was determined to be 96.9% ＂101.9% by means of standard addition method.The method is comparable to UV-Vis spectrometry.
基金the Key Technologies R&D Program of Hubei Province(No.2005AA301B14)
文摘Fe3O4 magnetic nanoparticles were prepared by co-precipitation of Fe^2＋ and Fe^3＋ in an ammonia solution, and its size was about 36 nm measured by an atomic force microscope. Fe3O4 magnetic nanoparticles were modified by L-dopa or dopamine using sonication method. The analysis of FTIR clearly indicated the formation of Fe-O-C bond. Direct immobilization of trypsin （EC： 3.4.21.4） on Fe3O4 magnetic nanoparticles with L-dopa and dopamine spacer was investigated using glutaraldehyde as a coupling agent. No significant changes in the size and magnetic property of the three kinds of magnetic nanoparticles linked with or without trypsin were observed. The existence of the spacer molecule on magnetic nanoparticles could greatly improve the activity and the storage stability of bound trypsin through increasing the flexibility of enzyme and changing the microenvironment on nanoparticles surface compared to the naked magnetic nanoparticles.
基金Supported by the National Natural Science Foundation of China(21107143,21207033)the Fundamental Research Funds for the Central Universities,South-Central University for Nationalities(CZY15003)
文摘A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sample was typical of superparamagnetic material.The samples were characterized by transmission electron microscope,and it is found that the particles are of small size.The Fe_3O_4/GO MNPs were further used as an adsorbent to remove Rhodamine B.The effects of initial pH of the solution,the dosage of adsorbent,temperature,contact time and the presence of interfering dyes on adsorption performance were investigated as well.The adsorption equilibrium and kinetics data were fitted well with the Freundlich isotherm and the pseudosecond-order kinetic model respectively.The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption of Rhodamine B.And the adsorption process was endothermic in nature.Furthermore,the magnetic composite with a high adsorption capacity of Rhodamine B could be effectively and simply separated using an external magnetic field.And the used particles could be regenerated and recycled easily.The magnetic composite could find potential applications for the removal of dye pollutants.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51571135,11274214 and 61434002the Special Funds of Shanxi Scholars Program under Grant No IRT1156+1 种基金Collaborative Innovation Center for Shanxi Advanced Permanent Materials and Technologythe Special Funds of the Ministry of Education of China under Grant No 20121404130001
文摘Magnetite （Fe3O4） nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the growth mechanism in detail. It is found that the size and shape of nanoparticles are determined by adjusting the precursor concentration and duration time, which can be well explained by the mechanism based on the LaMer model in our synthetic system. The monodisperse Fe3O4 nanoparticles have a mean diameter from 5nm to 16nm, and shape evolution from spherical to triangular and cubic. The magnetic properties are size-dependent, and Fe3O4 nanoparticles in small size about 5 nm exhibit superparamagnetie properties at room temperature and maximum saturation magnetization approaches to 78 emu/g, whereas Fe3O4 nanoparticles develop ferromagnetic properties when the diameter increases to about 16nm.
基金Projects(30571779,10775085) supported by the National Natural Science Foundation of ChinaProject(Z07000200540704) supported by Beijing Municipal Science and Technology Commission,China
文摘Fe3O4 magnetic nanoparticles with diameters varying from 10 to 426 nm were synthesized and characterized.Heating effects of Fe3O4 magnetic nanoparticles under radiofrequency capacitive field(RCF) with frequency of 27.12 MHz and power of 60-150 W were investigated.When the power of RCF is lower than 90 W,temperatures of Fe3O4 magnetic nanoparticles(75-150 mg/mL) can be raised and maximal temperatures are all lower than 50 ℃.When the power of RCF is 90-150 W,temperatures of Fe3O4 magnetic nanoparticles can be quickly raised and are all obviously higher than those of normal saline and distilled water under the same conditions.Temperature of Fe3O4 magnetic nanoparticles can even reach 70.2 ℃ under 150 W RCF.Heating effects of Fe3O4 magnetic nanoparticles are related to RCF power,particle size and particle concentration.
文摘Nanometer particles are important portion of magnetic fluid. Fe3O4 magnetic nanoparticles were studied in this paper and the surface modification of Fe3O4 nanoparticles was investigated by a series of experiments. Fe3O4 magnetic nanoparticles were synthesized with pH value, temperature, and the dosage of surfactant. The phase, structure, size and magnetism of nanoparticles were tested by X-ray diffration （XRD）, transmission electron microscopy （TEM） and magnetic balance. On the basis of the surface modification coating mechanism, the experimental phenomena and the effects on the variation of size, magnetism and stability of Fe3O4 nanoparticles were theoretically analyzed. X-Ray diffraction spectrum and TEM photograph show that 1） the nanoparticles structure is perfect, 2） the diameter of narnoparticles is small and have good deliquescence, and 3） Sodium oleate is the anion surfactant. Therefore 1） the good condition of surface modification is in an acidic solution, 2） the best temperature of surface modification is at 80 ℃, and 3） the dosage of surfactant should be about 0.6 times of that of Fe^2＋.
文摘In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of SDS （sodium dodeci[ sulfate）. The temperature of the nanoparticles and the SDS solution was evaluated by a novel method based on measuring the Q-factor （quality-factor） of a resonant circuit. The Q-factor of the investigated system as a function of the frequency of the EM field was obtained. The nanoparticles-SDS liquid system exhibited a resonance-like behavior of the absorption, where the resonance frequency was about 170 MHz, and the absorption rise up to the resonance frequency was rather slow. The observed absorption of EM energy was accompanied by a small temperature increasing of the system. Measurements of the ESR （electron spin resonance） spectrum of the Fe3O4 nanoparticles have presented a slightly asymmetric singlet with the proportionality factor g = 2 and a line-width of the magnetic field strength △H = 0.1 mT. It was shown that the observed absorption spectrum corresponds to paramagnetic behavior of the investigated nanoparticles.
基金Supported by the Project of Chongqing Municipal Education Commis-sion(KJ101101)Project of Innovation Team for"Water Quality Vari-ation and Water Environmental Security of Three Gorge Reservoir"of Higher Education in Chongqing City(201024)
文摘[ Objective] The study aims at developing a novel fluorescence enhancement method to determine anionic surfactants. [ Method] Based on Fe3O4 @ PAA-RB fluorescent nanoparticles as fluorescent probes, we have developed a novel fluorescence enhancement method for the determi- nation of an anionic surfactant sodium dodecyl sulfate （SDS） through the gradual optimization of experiment conditions. [ Result] Under the opti- mum conditions, the extent of fluorescence enhancement is directly proportional to SDS concentration varying from 0.5 to 16.0 μmol/L, and the de- tection limit reaches 0.051 μmol/L. The relative standard deviation （RSD） for 4.0 μmol/L SDS is 3.3% （ n =6）. The proposed method has been successfully applied to the determination of SDS in environmental water samples, with recovery of 96.3% -105.5%. E Conclusion] The novel fluo- rescence enhancement method is not only simple and rapid, but also has avoided using tedious solvent-extraction and toxic organic solvents.
基金This work was supported by the National Natural Science Foundation of China （No. 21303136）.
文摘Enhancement of Fe3O4/Au nanoparticles （Fe3O4/Au NPs） catalyst was observed in the oxidative degradation of methyl orange by employing H2O2 as oxidant. To evaluate the catalytic activity of Fe3O4/Au nanoparticles, different degradation conditions were investigated such as the amounts of catalyst, H2O2 concentration and pH value. Based on our data, methyl orange was degraded completely in a short time. The enhanced catalytic activity and increased oxidation rate constant may be ascribed to synergistic catalyst-activated decomposition of H2O2 to ,OH radical, which was one of the strong oxidizing species. Besides, Fe3O4/Au nanoparticles have exhibited satisfying recycle performance for potential industrial application.
