Preparation of surface plasmon resonance biosensor based on magnetic core/shell Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles

In this paper, surface plasmon resonance biosensors based on magnetic core/shell Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were developed for immunoassay. With Fe(3)O(4) and Fe(3)O(4)/Ag nanoparticles being used as seeding materials, Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were formed by hydrolysis of tetraethyl orthosilicate. The aldehyde group functionalized magnetic nanoparticles provide organic functionality for bioconjugation. The products were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), FTIR and UV-vis absorption spectrometry. The magnetic nanoparticles possess the unique superparamagnetism property, exceptional optical properties and good compatibilities, and could be used as immobilization matrix for goat anti-rabbit IgG. The magnetic nanoparticles can be easily immobilized on the surface of SPR biosensor chip by a magnetic pillar. The effects of Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles on the sensitivity of SPR biosensors were also investigated. As a result, the SPR biosensors based on Fe(3)O(4)/SiO(2) nanoparticles and Fe(3)O(4)/Ag/SiO(2) nanoparticles exhibit a response for rabbit IgG in the concentration range of 1.25-20.00 μg ml(-1) and 0.30-20.00 μg ml(-1), respectively.     

Features of doxorubicin adsorption on Fe3O4 magnetic nanoparticles coated with SiO2 or SiO2/aminopropylsilane

New nanocomposites based on Fe₃O₄ magnetic nanoparticles coated with SiO₂ or SiO₂/aminopropylsilane (APS), including those using N-(phosphonomethyl)iminodiacetic acid (PMIDA), were obtained, and the immobilization of the antitumor agent doxorubicin (Dox) on nanocomposites was examined. It has been shown that the binding of Dox to the negatively charged surface of SiO₂ particles occurs more efficiently than that to the APS-modified surface with positively charged amino groups; the presence of PMIDA molecules on the surface significantly increased the loading content. Based on DFT calculations, a mechanism for Dox binding to the surface of the synthesized nanocomposites was proposed.     

Fe3O4/ZnMg(Al)O magnetic nanoparticles for efficient biodiesel production

Fe₃O₄/ZnMg(Al)O solid base catalyst was prepared by calcining ZnMgAl‐LDHs grown on the surface of magnetic Fe₃O₄ synthesized by chemical coprecipitation. The magnetic property of the catalyst was studied by vibrating sample magnetometer. The results showed that the catalyst possessed excellent magnetic responsivity, and it could be recovered by external magnetic field. The magnetic catalyst was also characterized by ICP, TG‐DTG, XRD, SEM, EDS, TEM and N₂ absorption‐desorption. It was found that the catalyst showed a unique porous structure. The reaction conditions affecting biodiesel yield were investigated, the biodiesel yield reached 94% was obtained under the optimal conditions. The biodiesel yield was still above 82% after 7 times of regeneration, and the catalyst can be easily separated and recycled.     

Fe3O4/SiO2 nanoparticles: an efficient and magnetically recoverable nanocatalyst for the one-pot multicomponent synthesis of diazepines

In this research, a new protocol for the one-pot multicomponent synthesis of diazepine derivatives using a 1,2-diamine, a linear or cyclic ketone, and an isocyanide in the presence of a catalytic amount of silica-supported iron oxide (Fe₃O₄/SiO₂) nanoparticles at ambient temperature in excellent yields is described.     

亚微米级Cu0/Fe3O4复合物多相催化过一硫酸盐降解有机污染物

过一硫酸盐催化活化技术因其可产生强氧化性活性氧化物种,可快速氧化降解并矿化有机污染物的优异性能而备受关注.本文成功制备了亚微米级Cu0/Fe3O4复合物,发现其能多相催化过一硫酸盐产生单线态氧降解有机污染物.首先,以CuCl2·2H2O,FeCl2·4H2O和FeCl3·6H2O为铜源和铁源,水合肼为还原剂,采用水热法在180oC反应24 h制备了亚微米级磁性Cu0/Fe3O4复合物.表征结果显示,所制材料为Cu0和Fe3O4的复合物,颗粒大小约为220 nm;单一相Cu0和Fe3O4晶体粒径分别为33.8和106.2 nm,而Cu0/Fe3O4复合物中Cu0和Fe3O4晶体粒径分别减为20.8和31.9 nm.这表明Cu0和Fe3O4复合降低了Cu0和Fe3O4晶体粒径,有利于Cu0和Fe3O4的分散.BET测试结果表明,Cu0/Fe3O4复合物比表面积为4.6 m2/g,与Cu0颗粒的(4.2 m2/g)相当,但远小于Fe3O4的(15.6 m2/g).制备的Cu0/Fe3O4复合物可有效催化过一硫酸盐产生单线态氧降解罗丹明B、亚甲基蓝、金橙II、苯酚和对氯酚.当Cu0/Fe3O4复合物的用量为0.1 g/L,过一硫酸盐浓度为0.5 mmol/L和初始pH为7时,Cu0/Fe3O4复合物可在30 min内完全降解20μmol/L的罗丹明B、亚甲基蓝、金橙II以及0.1 mmol/L的苯酚和对氯酚.对比试验显示,在相同条件下,Cu0和Fe3O4颗粒分别可以降解28%和20%的罗丹明B.这表明Cu0/Fe3O4复合物中的Cu0和Fe3O4晶体在催化过一硫酸盐降解污染物的反应中具有协同作用,这主要来源于Cu0/Fe3O4复合物中Cu0和Fe3O4的晶体粒径变小和更好的分散.采用分光光度法测定了降解反应液中铜和铁离子的溶出量.当Cu0/Fe3O4复合物的用量为0.1 g/L,过一硫酸盐浓度为0.5 mmol/L和初始pH为7时,反应60 min后,降解液中铜和铁离子的浓度分别为0.22和0.1 mg/L,仅占复合物中总铜和总铁量的1.1%和0.2%,表明Cu0/Fe3O4复合物具有较强的化学稳定性.所制Cu0/Fe3O4复合物具有超顺磁性,借助磁场实现快速分离回收,可循环利用五次,表明其优越的催化稳定性.通过加入乙醇和叠氮化钠,考察了Cu0/Fe3O4复合物催化活化过一硫酸盐体系中的活性氧化物种.发现100 mmol/L乙醇的加入对污染物的降解无明显影响,而加入同等量的叠氮化钠可完全抑制污染物的降解,表明Cu0/Fe3O4复合物催化活化过一硫酸盐产生的主要活性氧物种为单线态氧.采用电子顺磁共振谱进一步证实了单线态氧的生成.基于以上研究,Cu0/Fe3O4复合物催化活化过一硫酸盐的机理为Cu0/Fe3O4作为一个电子媒介加速过一硫酸盐和污染物之间的电子转移,从而导致污染物被快速降解.该反应机理不同于常见的金属催化过一硫酸盐产生硫酸根和羟自由基的反应机理.我们推测,电导性优良的Cu0在此催化反应中起着关键性作用.本催化方法可作为一种绿色的氧化技术用于环境污染物的氧化降解处理.     

Synthesis of Fe3O4, Fe2O3, Ag/Fe3O4 and Ag/Fe2O3 nanoparticles and their electrocatalytic properties

Two important iron oxides:Fe3O4 and Fe2O3,as well as Fe3O4 and Fe2O3 nanoparticles mingling with Ag were successfully synthesized via a hydrothermal procedure.The samples were confirmed and characterized by X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The morphology of the samples was observed by transmission electron microscopy(TEM).The results indicated Fe3O4,Fe2O3,Ag/Fe3O4 and Ag/Fe2O3 samples all were nanoparticles with smaller sizes.The samples were modified on a glassy carbon electrode and their elctrocatalytic properties for p-nitrophenol in a basic solution were investigated.The results revealed all the samples showed enhanced catalytic performances by comparison with a bare glassy carbon electrode.Furthermore,p-nitrophenol could be reduced at a lower peak potential or a higher peak current on a glassy carbon electrode modified with Ag/Fe3O4 or Ag/Fe2O3 composite nanoparticles.     

Fabrication of Fe3O4/SiO2 core/shell nanoparticles attached to graphene oxide and its use as an adsorbent

Thermoresponsive gelling behavior of concentrated alumina suspensions with poly(acrylic acid) (PAA) and triblock copolymer (PEO(101)-PPO(56)-PEO(101), Pluronic F127) was investigated as a function of PAA concentration (0.4-1.2 mass%) for ceramic solid free forming. The copolymer species assemble into micelles at temperatures above 15°C, yielding aqueous physical gel. In this study, the concentrated alumina aqueous suspensions (φ=35 vol%) were first prepared using the anionic dispersant of PAA, and then the copolymer species (10 mass%) were dissolved at a cooled temperature at 10°C. The addition of the copolymer species had a negligible influence on the adsorption state of PAA onto the alumina surfaces. The PAA concentration needed for the saturation adsorption on the alumina surfaces was ~0.6 mass%. When the PAA concentration was this value or slightly less, the suspension became gel state at 30°C from low viscous state at 10°C. The thermally induced alumina gel had excellent viscoelastic properties, and thereby the three dimensional periodic ceramic structures were successfully fabricated by a direct colloidal printing method that using the gels as "solid" inks at the room temperature. On the other hand, when it exceeded the saturation adsorption limit, the gelling behavior was not observed, indicating that the non-adsorbing PAA species may partly suppress the micellization of the copolymer on the heating.     

Functionalization of Fe3O4 magnetic nanoparticles with RGD peptide derivatives

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Characterization and application of Fe3O4/SiO2 nanocomposites

A sol-gel procedure was used to cover Fe₃O₄ nanoparticles with SiO₂ shell, forming a core/shell structure. The core/shell nanocomposites were synthesized by a two-step process. First, Fe₃O₄ nanoparticles were obtained through co-precipitation and dispersed in aqueous solution through electrostatic interactions in the presence of tetramethylammonium hydroxide (TMAOH). In the second step, Fe₃O₄ was capped with SiO₂ generated from the hydrolyzation of tetraethyl orthosilicate (TEOS). The structure and properties of the formed Fe₃O₄/SiO₂ nanocomposites were characterized and the results indicate that the Fe₃O₄/SiO₂ nanocomposites are superparamagnetic and are about 30 nm in size. Bioconjugation to IgG was also studied. Finally, the mechanism of depositing SiO₂ on magnetic nanoparticles was discussed.     

Chemical effects of51Cr-neutron capture recoils in K3Cr/C2O4/3−K3Fe/C2O4/3 mixed crystals

The chemical effects of⁵¹Cr-neutron capture recoils produced in a series of mixed crystals of the type K₃Cr/C₂O₄/₃–K₃Fe/C₂O₄/₃ were investigated. Analysis of the neutron irradiated samples was performed making use of synergetic solvent extraction and gamma ray scintillation spectroscopy. It was found that the initial chromium parent retentions vary linearly with mole fraction in the mixed crystals. The results are discussed in terms of retention and non-retention reactions and in view of a kinetic model and a mechanism involving elementary impacts, metal- and ligand-vacancy exchange, substitution and transfer reactions.     

Magnetic Fe3O4/SiO2/NH2 As the Recyclable Heterogeneous Nanocatalyst on Bisphenol-A Recovery from Polycarbonate Wastes

Polycarbonate (PC) wastes received from optical (CDs) and digital optical discs (DVDs) were chemical recycled by using diethylene glycol (DEG) and water as an alternative green solvents and magnetite nanomaterials coated with amine modified silica nanoshell (Fe₃O₄/SiO₂/NH₂) as the recyclable heterogeneous catalyst to recover bisphenol-A (BPA) as a valuable material in 100% yield and without using harmful reagent and environmental problems. The nano-magnetic heterogeneous catalyst can be recycled for four cycles and used next reaction. The recovered BPA and nanomaterials were examined with transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and spectroscopic methods (¹H NMR, ¹³C NMR, FTIR).

     

Polyaniline-coated Fe(3) O(4) nanoparticles: An anion exchange magnetic sorbent for solid-phase extraction

In this study, the capability of the prepared polyaniline-coated Fe(3) O(4) nanoparticles for magnetic solid-phase extraction of three parabens from environmental wastewater, cream, and toothpaste samples is presented. Synthesized Fe(3) O(4) nanoparticles were coated with sulfate-doped polyaniline via polymerization of aniline in the presence of Fe(3) O(4) nanoparticles and sulfuric acid. Here, polyaniline-coated Fe(3) O(4) nanoparticles are presented as anion exchange sorbent, which extract anionic form of parabens via anion exchange with dopant of polyaniline. The experimental conditions affecting extraction efficiency were further studied and optimized. The experimental results showed that maximum extraction efficiency can be obtained at 70 mL sample solution of pH 8, extraction and desorption times of 2 and 1 min, respectively, 100 μL of 3% (v/v) acetic acid in acetonitrile as eluent, and 100 mg of the adsorbent. Under these conditions, the linear dynamic ranges were 0.5-100 μg/L with good correlation coefficients (0.998-0.999). The detection limits were in the range of 0.3-0.4 μg/L and the relative standard deviations were less than 2.4 (n = 5) for the three parabens. Finally, this fast and efficient method was further employed for determination of target analytes in cream, toothpaste, and environmental wastewater samples and satisfactory results were obtained.     

Bifunctional aminosilane-functionalized Fe3O4 nanoparticles as efficient sorbent for preconcentration of cobalt ions from food and water samples

Research on Chemical Intermediates - Magnetic Fe3O4 nanoparticles were synthesized by a coprecipitation method, then their surface was covered and modified by...     

TiO2/SiO2/Fe3O4的制备及其光催化性能

TiO2/SiO2/Fe3O4的制备及其光催化性能;磁栽;光催化;脱色作用;Oraange     

Immobilization of fluorescent protein TagGFP2 on Fe3O4-based magnetic nanoparticles

Russian Chemical Bulletin - The immobilization of fluorescent protein TagGFP2 on Fe3O4-based magnetic nano particles (MNPs), preliminarily functionalized with 3-aminopropylsilane and...     

Fe2O3/ZnO/ZnFe2O4 composites for the efficient photocatalytic degradation of organic dyes under visible light

In this study, novel ternary Fe₂O₃/ZnO/ZnFe₂O₄ (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B.     

Encapsulation of superparamagnetic Fe3O4@SiO2 core/shell nanoparticles in MnO2 microflowers with high surface areas

Microflowers made of interconnected MnO₂ nanosheets have been successfully synthesized in a microwave reactor through a hydrothermal reduction of KMnO₄ with aqueous HCI at elevated temperatures in the presence of superparamagnetic Fe₃O₄SiO₂ core-shell nanoparticles.Due to the chemical compatibility between SiO₂ and MnO₂,the heterogeneous reaction leads to the spontaneous encapsulation of the Fe₃O₄@SiO₂ core-shell nanoparticles in the MnO₂ microflowers.The resulting hybrid particles exhibit multiple properties including high surface area associated with the MnO₂nanosheets and superparamagnetism originated from the Fe₃O₄@SiO₂ core-shell nanoparticles.which are beneficial for applications requiring both high surface area and magnetic separation.     

Photoluminescent Fe3O4/carbon nanocomposite with magnetic property

Fe(3)O(4)/carbon nanocomposite has been prepared by a facile chemical method, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, fourier transform infrared spectroscopy and scanning electron microscopy. The fluorescent and magnetic properties of the sample were investigated by fluorescence spectroscopy and vibrating-sample magnetometer, respectively. The results indicate that the Fe(3)O(4)/carbon nanocomposite exhibit good photoluminescent (emission ranging from 425 to 550 nm) and strong magnetic (saturation magnetization of 44.2 emu/g) properties.