Surface modified Fe3O4 nanoparticles as a protein delivery vehicle

We report a one-step synthesis of Fe₃O₄ nanoparticles coated with PEG. The formation of the Fe₃O₄ core and the polymer coating took place simultaneously. Furthermore, these nanoparticles were modified with 3-APTES, providing a -NH₂ functional group, and applied in the immobilization of lysozyme. In this paper, the modified magnetic nanoparticles acting as a general agent to immobilize proteins are around 10 nm in size. The protein immobilization can be adjusted flexibly by changing either the amount of glutaraldehyde or the buffer solution.     

Ultrasonic synthesis of polyaniline nanotubes containing Fe3O4 nanoparticles

Polyaniline (PANI) nanotubes containing Fe₃O₄ nanoparticles were synthesized under ultrasonic irradiation of the aqueous solutions of aniline, ammonium peroxydisulfate (APS), phosphoric acid (H₃PO₄), and the quantitative amount of Fe₃O₄. It was found that the obtained samples had the morphologies of nanotubes. TEM images and selected area electronic diffractions showed that Fe₃O₄ nanoparticles were embedded in PANI nanotubes. We thought that the mechanism of the formation of PANI/Fe₃O₄ nanotubes could be attributed to the ultrasonic irradiation and the H₃PO₄-aniline salt template. The molecular structure of PANI/Fe₃O₄ nanotubes were characterized by Fourier transform infrared spectroscopy (FTIR), UV-vis absorption spectra and X-ray diffraction (XRD). The conductivity and magnetic properties of the PANI nanotubes containing Fe₃O₄ nanoparticles were also investigated.     

Synthesis of pyranopyrazoles using magnetic Fe3O4 nanoparticles as efficient and reusable catalyst

Magnetic Fe₃O₄ nanoparticles as a heterogeneous catalyst, were found to be efficient for the synthesis of a series of pyranopyrazoles by a four component reaction of a mixture of hydrazine hydrate, ethyl acetoacetate, aldehydes/ketones and malononitrile in water at room temperature. The products were attributed to the nanosize of about 16 nm in which the catalyst could act as a nanoreactor. The present protocol offers the advantages of clean reaction, short reaction time, high yield, easy purification and economic availability of the catalyst.     

超声法制备Au/Fe_3O_4及其催化还原4-硝基苯酚性能

通过简易的超声法以及原位还原法成功制备出了负载型可再生Au/Fe_3O_4催化剂。利用3-氨丙基三乙氧基硅烷(APTES)作为有机桥键,将Au固定在Fe_3O_4的表面,得到单分散磁性Au/Fe_3O_4。Au0在氨基的作用下不会团聚,因此具有较高的催化活性及稳定性。XRD、HRTEM、EDS和XPS等测试结果表明Au/Fe_3O_4已被成功制备。将其用于催化还原4-硝基苯酚得到4-氨基苯酚,表现出较高的催化活性,速率常数可达0.225 6 min~(-1)。重复性实验表明该催化剂具有良好的稳定性,反应9个循环之后,催化还原反应的转化率仍可达到94%。     

超声法制备Au/Fe3O4及其催化还原4-硝基苯酚性能

通过简易的超声法以及原位还原法成功制备出了负载型可再生Au/Fe₃O₄催化剂。利用3-氨丙基三乙氧基硅烷（APTES）作为有机桥键,将Au固定在Fe₃O₄的表面,得到单分散磁性Au/Fe₃O₄。Au⁰在氨基的作用下不会团聚,因此具有较高的催化活性及稳定性。XRD、HRTEM、EDS和XPS等测试结果表明Au/Fe₃O₄已被成功制备。将其用于催化还原4-硝基苯酚得到4-氨基苯酚,表现出较高的催化活性,速率常数可达0.225 6 min^-1。重复性实验表明该催化剂具有良好的稳定性,反应9个循环之后,催化还原反应的转化率仍可达到94%。     

Sensitive electrochemical immunoassay for chlorpyrifos by using flake-like Fe3O4 modified carbon nanotubes as the enhanced multienzyme label

A highly sensitive electrochemical immunoassay of chlorpyrifos (CPF) was developed by using a biocompatible quinone-rich polydopamine nanospheres modified glass carbon electrode as the sensor platform and multi-horseradish peroxidase-flake like Fe₃O₄ coated carbon nanotube nanocomposites as the signal label. Due to the quinone-rich polydopamine nanospheres, the platform exhibited excellent fixing capacity by simple coating of sticky polydopamine nanospheres and subsequent oxidization. By coprecipitation of Fe³⁺ and Fe²⁺ on polydopamine modified carbon nanotubes (CNTs) with the aid of ethylene glycol (EG), the flake-like Fe₃O₄ coated CNTs (CNTs@f-Fe₃O₄) were synthesized and chosen as the carrier of multi-enzyme label due to the high loading of secondary antibody (Ab₂) and horseradish peroxidase (HRP) and also the peroxidase-mimic activity of Fe₃O₄. Under the optimum conditions, the immunosensor can detect CPF over a wide range with a detection limit of 6.3 pg/mL. Besides, the high specificity, reproducibility and stability of the proposed immunosensor were also proved. The preliminary application in real sample showed good recoveries, indicating it holds promise for fast analysis of CPF in aquatic environment.     

Magnetically separable Fe3O4 nanoparticles: an efficient catalyst for the synthesis of propargylamines

Magnetically separable Fe₃O₄ nanoparticles endow with an efficient and economic route for the synthesis of propargylamines by the three-component coupling of aldehyde, amine, and alkyne through C-H activation. The reaction is especially effective for reactions involving aliphatic aldehydes and no additional co-catalyst or activator is required. High catalytic activity and ease of recovery using an external magnetic field are additional eco-friendly attributes of this catalytic system. The catalyst was recycled for five times without a significant loss of catalytic activity.     

一维纳米Co_3O_4,Ag/Co_3O_4及CuO/Co_3O_4的合成与电催化性能(英文)

采用水热合成法制备了Co3O4及复合Ag/Co3O4、CuO/Co3O4一维纳米产品。用XRD,FE-SEM和TEM手段对产品进行了表征。采用循环伏安法研究了合成产品修饰的玻碳电极在碱性溶液中对对硝基苯酚的电催化还原性能。与裸玻碳电极相比,1mmol·L-1的对硝基苯酚在用Co3O4、特别是CuO/Co3O4修饰的玻碳电极上还原的峰电流明显增大,用Ag/Co3O4(Ag/Co原子比分别为1∶5和2∶5)修饰的玻碳电极催化还原对硝基苯酚时,尽管还原峰电流增大不是太大,但其峰电位明显降低(分别降低0.265和0.371V)。     

Preparation of Fe3O4 nanoparticle enclosure hydroxylated multi-walled carbon nanotubes for the determination of aconitines in human serum samples

A magnetic carbon nanomaterial for Fe₃O₄ enclosure hydroxylated multi-walled carbon nanotubes (Fe₃O₄-EC-MWCNTs-OH) was prepared by the aggregating effect of Fe₃O₄ nanoparticle on MWCNTs-OH, and combined with high-performance liquid chromatography (HPLC)/diode array detection (DAD) to determine the aconitines (aconitine, hypaconitine and mesaconitine) in human serum samples. Compared with other extraction modes investigated in experiment, Fe₃O₄-EC-MWCNTs-OH sorbents showed a good affinity to target analytes. Some important parameters that could influence extraction efficiency of aconitines, including the extraction mode, amounts of Fe₃O₄-EC-MWCNTs-OH, pH of sample solution, extraction time, desorption solvent and desorption time, were optimized. Under optimal conditions, the recoveries of spiked serum samples were between 98.0% and 103.0%; relative standard deviations (RSDs) ranged from 0.9% to 6.2%. The correlation coefficients varied from 0.9996 to 0.9998. The limits of detection ranged from 3.1 ng mL⁻¹ to 4.1 ng mL⁻¹ at a signal-to-noise ratio of 3. The experimental results showed that the proposed method was feasible for the analysis of aconitines in serum samples.     

单分散Fe_3O_4亚微米球的合成与表征

采用溶剂热法制备出具有尺寸可调、分散性好、亲水性和超顺磁性的亚微米Fe3O4磁球,并考察了不同表面活性剂、反应时间和反应温度的影响。分别采用XRD、FE-SEM、FTIR、超导量子干涉仪(SQUID)对其结构、形貌、表面性质及磁性进行了表征。结果表明,产物为立方结构、具有单分散性的Fe3O4亚微米球,粒径在140~360nm可调。所得Fe3O4亚微米球在室温条件下的磁滞回线表现出超顺磁性,矫顽力为零。不同表面活性剂对粒径大小和磁饱和强度有一定的影响,但对其形貌和晶相结构无影响。随着反应时间的延长和反应温度的提高,颗粒粒径有逐渐减小的趋势。     

叶酸对磁性Fe_3O_4纳米粒子的表面修饰

以FeCl3·6H2O作为单一铁源,1,6-己二胺作为胺化试剂,利用无模板的溶剂热方法制备了胺基功能化的磁性Fe3O4纳米粒子,并利用其键合叶酸分子,制备出表面修饰了叶酸的磁性Fe3O4复合纳米粒子。利用傅里叶变换红外光谱仪、X-射线衍射仪、透射电镜、差热-热重分析仪和振动样品磁强计对所得纳米粒子的形貌、粒径、化学组成和磁性能进行了表征。结果表明,叶酸分子通过化学键牢固键合在磁性纳米Fe3O4粒子表面,叶酸修饰的复合纳米粒子仍然具有良好的磁性能。     

球形纳米Fe3O4的制备及超级电容性能研究

采用双氧水氧化水热法制备Fe₃O₄,通过IR、XRD和SEM对样品的结构和性能进行表征。结果表明,产物为形貌规整的球形,平均粒径为25 nm。通过恒流充放电、循环伏安和交流阻抗等方法研究Fe₃O₄电极的电容性能。电化学测试表明,在1 mol·L^-1 Na₂SO₃溶液中,-1.2～0.2 V(vs SCE)电位范围内,Fe₃O相似文献   

多孔朵状Fe_3O_4纳米微球的制备及其性能研究

<正>众所周知,纳米材料的尺寸大小、晶型、形貌构型等结构特征对材料的化学物理性能有重要的影响[1],由于特殊形貌的新材料所具有独特、新颖、高效的化学物理等方面的性质以及在众多领域中的潜在应用[2],特别是3D花状空心纳米结构新物质[3-4],新形貌物质的纳米材料的制备方法和应用特性已经吸引了世界上材料领域的广泛兴趣和关注[5]。目前为止,合成3D纳米结构的方法有自组装法、三维导向连接法以及水热法等,即通过使用有     

磁性Fe3O4 /壳聚糖的化学修饰及包覆机理研究

Nano-sized Fe₃O₄ powder was prepared through an Oxygenation-Hydrothermal method. The chitosan magnetic complex was prepared by coating chitosan on the surface of Fe₃O₄ powders through Microlatex-Crosslinking Method. The product was characterized by IR， XRD， TEM， Vibrating Sample Magnetometer (VSM)， TG methods. Results show that the as-prepared powder is 25 nm in size and shows supermagnetism. The content of magnetite in microspheres is 37.8%. The mechanism for the coating reaction of chitosan to Fe₃O₄ nanoparticles is also suggested.     

Hydrothermal synthesis of monodisperse Fe3O4 nanoparticles based on modulation of tartaric acid

In this paper, monodisperse Fe₃O₄ nanoparticles with single crystalline structure were synthesized via a facile environment-friendly method. And the size of the nanoparticles ranges from 10 nm to 15 nm. As-synthesized Fe₃O₄ were characterized by X-ray diffraction instrument (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectrometer and field emission transmission electron microscope (FE-TEM). The effect of tartaric acid (TA) amount on products was investigated by XRD and TEM. The results indicated that TA could commendably modulate the crystalline phase, morphology and size of nanometer Fe₃O_4. A possible generated mechanism of Fe₃O₄ crystals was proposed in virtue of UV–vis absorption spectra. Besides, the magnetic properties of as-synthesized Fe₃O₄ were detected.     

Kinetics of adsorption of Saccharomyces cerevisiae mandelated dehydrogenase on magnetic Fe3O4–chitosan nanoparticles

The adsorption of Saccharomyces cerevisiae mandelated dehydrogenase (SCMD) protein on the surface-modified magnetic nanoparticles coated with chitosan was studied in a batch adsorption system. Functionalization of surface-modified magnetic particles was performed by the covalent binding of chitosan onto the surface of magnetic Fe₃O₄ nanoparticles. Characterization of these particles was carried out using FTIR spectra, transmission electron micrography (TEM), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). Magnetic measurement revealed that the magnetic Fe₃O₄–chitosan nanoparticles were superparamagnetic and the saturation magnetization was about 37.3 emu g⁻¹. The adsorption capacities and rates of SCMD protein onto the magnetic Fe₃O₄–chitosan nanoparticles were evaluated. The adsorption capacity was influenced by pH, and it reached a maximum value around pH 8.0. The adsorption capacity increased with the increase in temperature. The adsorption isothermal data could be well interpreted by the Freundlich isotherm model. The kinetic experimental data properly correlated with the first-order kinetic model, which indicated that the reaction is the adsorption control step. The apparent adsorption activation energy was 27.62 kJ mol⁻¹ and the first-order constant for SCMD protein was 0.01254 min⁻¹ at 293 K.     

钛铁矿制备二氧化钛-四氧化三铁复合材料及其光催化应用

TiO_2因具有多种优异的特性被广泛应用在半导体光催化领域,但是纳米结构的TiO_2颗粒细微,在进行光催化反应之后,难以回收再利用。本文以廉价钛铁矿为原料制备光催化剂TiO_2,同时利用副产物铁合成Fe_3O_4,并采用简单温和的浸渍法制备Fe_3O_4/TiO_2磁性复合材料。通过XRD、FT-IR、SEM、EDS等手段对材料形态结构进行表征分析,并以光降解有机污染物若丹明B为探针反应,考察其光催化性能。结果表明,质量比为1∶10的Fe_3O_4/TiO_2复合材料结构稳定、分散均匀,具有最优的光催化活性(波长356nm下反应3h,若丹明B降解率达到64.0%),并表现出良好的重复性。同时,动力学结果显示降解符合一级反应动力学。     

Fe3O4纳米晶的简单调控合成、表征及磁性能

采用醋酸铵作保护剂在200℃下制备了单分散的400 nm粒径的Fe3O4空心纳米球.通过改变实验条件,对产品的形貌、内部结构和粒径进行了调控合成,得到了粒径范围在100～200 nm的实心纳米球和片形结构的Fe3O4纳米材料.采用SEM、TEM和XRD等对样品进行了表征.结果表明,所得尖晶石型Fe3O4纳米晶粒径均匀,分散度好.利用振动样品磁场计检测了不同形貌样品的磁性能.结果显示,Fe3O4纳米空心球的饱和磁化强度和矫顽力均大于Fe3O4纳米片的对应值.     

A one-pot synthesis of 5,5-disubstituted hydantoin derivatives using magnetic Fe3O4 nanoparticles as a reusable heterogeneous catalyst

A facile and rapid method for the one-pot synthesis of 5,5-disubstituted hydantoins in the presence of magnetic Fe₃O₄ nanoparticles has been developed. The multicomponent reactions of carbonyl compounds (aldehydes and ketones), potassium cyanide and ammonium carbonate were carried out under solvent-free conditions to obtain various hydantoin derivatives. The magnetic catalyst could be readily separated by an external magnet from the reaction mixture. This procedure has many advantages, such as the use of a reusable magnetic catalyst, high yields, short reaction times, simplicity and very easiness with implementing the methodology.     

Fe3O4磁液的悬浮率测定及稳定性研究

The paper first reported the preparation of ultrafine Fe₃O₄ powder about 8～10nm by improved chemical pre-cipitation method， then turned it into magnetic fluid. The phase analysis， morphology， ultrafine powder size and magnetic property were measured by XRD， TEM and vibrating sample magnetometer(VSM)，respectively. In ad-dition， a new method ， by analyzed the suspending percentage of Fe₃O₄ powder， was introduced to study the effects of concentration， pH value， centrifugal rate and time on the stability of the magnetic fluid.