Synthesis of Fe3O4@SiO2@polymer nanoparticles for controlled drug release

Novel multifunctional nanoparticles containing a magnetic Fe₃O₄@SiO₂ sphere and a biocompatible block copolymer poly(ethylene glycol)-b-poly(aspartate) (PEG-b-PAsp) were prepared. The silica coated on the superparamagnetic core was able to achieve a magnetic dispersivity, as well as to protect Fe₃O₄ against oxidation and acid corrosion. The PAsp block was grafted to the surface of Fe₃O₄@SiO₂ nanoparticles by amido bonds, and the PEG block formed the outermost shell. The anticancer agent doxorubicin (DOX) was loaded into the hybrid nanoparticles via an electrostatic interaction between DOX and PAsp. The release rate of DOX could be adjusted by the pH value.     

Synthesis of a highly active amino‐functionalized Fe3O4@SiO2/APTS/Ru magnetic nanocomposite catalyst for hydrogenation reactions

An amino‐functionalized silica‐coated Fe₃O₄ nanocomposite (Fe₃O₄@SiO₂/APTS) was synthesized. The Fe₃O₄@SiO₂ microspheres possessed a well‐defined core–shell structure, uniform sizes and high magnetization. An immobilized ruthenium nanoparticle catalyst (Fe₃O₄@SiO₂/APTS/Ru) was obtained after coordination and reduction of Ru³⁺ on the Fe₃O₄@SiO₂/APTS nanocomposite. The Ru nanoparticles were not only ultra‐small with nearly monodisperse sizes but also had strong affinity with the surface of Fe₃O₄@SiO₂/APTS. The obtained catalyst exhibited excellent catalytic performance for the hydrogenation of a variety of aromatic nitro compounds, even at room temperature. Moreover, Fe₃O₄@SiO₂/APTS/Ru was easily recovered using a magnetic field and directly reused for at least five cycles without significant loss of its activity.     

Synthesis of Fe3O4@SiO2-Au/Cu magnetic nanoparticles and its efficient catalytic performance for the Ullmann coupling reaction of bromamine acid

Over bimetallic Au/Cu catalyst supported on magnetic Fe₃O₄ nanoparticles, water-mediated bromamine acid could be selectively converted into 4,4'-diamino-1,1'-dianthraquinonyl-3,3'-disulfonic acid (DAS) with a yield of 88.67%. The magnetic catalyst could be readily separated and reused.     

Ferrocene-modified Fe3O4@SiO2 magnetic nanoparticles as building blocks for construction of reagentless enzyme-based biosensors

A novel amperometric glucose biosensor was developed by entrapping glucose oxidase (GOD) in chitosan (CS) composite doped with ferrocene monocarboxylic acid-modified magnetic core-shell Fe₃O₄@SiO₂ nanoparticles (FMC-AFSNPs). It is shown that the obtained magnetic bio-nanoparticles attached to the surface of a carbon paste electrode (CPE) with the employment of a permanent magnet showed excellent electrochemical characteristics and at the same time acted as mediator to transfer electrons between the enzyme and the electrode. Under optimal conditions, this biosensor was able to detect glucose in the linear range from 1.0 × 10⁻⁵ to 4.0 × 10⁻³ M with a detection limit of 3.2 μM (S/N = 3). This immobilization approach effectively improved the stability of the electron transfer mediator and is promising for construction of biosensor and bioelectronic devices.     

Enhanced catalytic performance on the thermal decomposition of TKX-50 by Fe3O4 nanoparticles highly dispersed on rGO

Journal of Thermal Analysis and Calorimetry - Fe3O4/reduced graphene oxide (Fe3O4/rGO) nanocomposite has been successfully fabricated using a modified interface solvothermal method and...     

Myoglobin immobilized on Fe3O4@SiO2 magnetic nanoparticles: Direct electron transfer,enhanced thermostability and electroactivity

Myoglobin (Mb) has been successfully immobilized in alternation with oppositely charged poly(dimethyldiallylammonium chloride) via the sequential layering approach on the biocompatible Fe₃O₄@SiO₂ nanoparticles. The bound Mb could be easily separated by an external magnetic field and used as less costly, more stable, and reusable alternatives to the soluble ones. Direct electron transfer between the immobilized Mb and the electrode was observed. Moreover, the immobilized Mb provided remarkable thermostability up to 70 °C and high electroactivity with the apparent Michaelis–Menten constant (k_M) of 45 μM.     

多功能Fe3O4@SiO2 Janus颗粒

采用溶剂热法和溶胶-凝胶法制备了顺磁性Fe₃O₄@SiO₂颗粒,以Pickering乳液界面保护法实现颗粒表面分区获得Fe₃O₄@SiO₂ Janus颗粒,进一步选区复合生长Pt或Ag纳米颗粒制备Fe₃O₄@SiO₂-Pt和Fe₃O₄@SiO₂-Ag Janus颗粒.Fe₃O₄@SiO₂-Pt Janus颗粒的Pt一侧进行催化过氧化氢的反应,具有自驱动功能.因其顺磁性和两亲性,Fe₃O₄@SiO₂-Ag Janus颗粒能够作为磁响应颗粒乳化剂稳定油水乳液,并将Ag的催化功能引入界面.     

超声合成Fe3O4@SiO2复合纳米磁性粒子用于质粒DNA的提纯

用超声合成了Fe3O4@SiO2复合纳米磁性粒子, 并用于质粒DNA的提取. 用透射电镜(TEM)、红外光谱(FT-IR)、震动样品磁场计(VSM)、X光电子能谱仪(XPS)等方法对合成的复合磁性粒子的表面形貌、结构、磁性质等进行了表征, 合成的复合磁微粒粒径分布均匀, 在15～20 nm, 磁响应性好. 用该复合磁微粒提取DNA的纯度能达到A260/A280＝ 1.8±0.1, 琼脂糖电泳证明质粒DNA结构基本没有被破坏, 主要为超螺旋结构, 能满足PCR等后续分子生物学操作的要求.     

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.     

Size-dependent peroxidase-like catalytic activity of Fe3O4 nanoparticles

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.     

A highly sensitive method for detection of bisphenol A in water samples based on functionalised Fe3O4@SiO2@nylon66

A simple and sensitive method was developed for preconcentration and determination of bisphenol A (BPA) in environmental samples by high performance liquid chromatography (HPLC). The hydrophilic silicon-dioxide- and nylon66-functionalised magnetic material (Fe₃O₄@SiO₂@nylon66) was used as a sorbent for magnetic solid-phase extraction (MSPE). With the anhydrous microemulsion reaction, the Fe₃O₄@SiO₂@nylon66 had shown great characteristics such as good magnetic responsivity, water dispersibility and stability. Based on the materials, various extraction parameters including pH, extraction time, elution time, the number of sorbents, sample volume and elution times were optimised. The whole extraction procedure could be accomplished within 20 min and the materials could be used more than 10 times after regeneration. Under the optimised conditions, different types of water samples (Tap water, river water, sea water and underground water) were successfully analysed to verify the applicability of the proposed method. The recoveries of different samples ranged from 88.54% to 104.46%. An enrichment factor of 250 was achieved with 0.05 μg/L detection limit. Thus, the developed MSPE is a potential technique that can be used for water samples preconcentration or combined with other analytical methods for determination of BPA.     

Adsorption of light green and brilliant yellow anionic dyes using amino functionalized magnetic silica (Fe3O4@SiO2@NH2) nanocomposite

Abstract

Fe₃O₄@SiO₂@NH₂ nanocomposite was prepared for highly effective adsorption of two anionic dyes one of which is triarylmethane dye (light green, LG) and the other is azo dye (brilliant yellow, BY). The characterization results demonstrated that superparamagnetic Fe₃O₄ nanoparticles were covered with silica and functionalized with amino groups successfully without losing magnetic character. The effects of adsorbent dosage, contact time, pH, temperature, and dye molecular structure on the adsorption were investigated. Acidic pH was better for both LG and BY, on the other hand, alkaline pH was favorable to some extent for LG in comparison with BY due to the contribution of stacking effect in addition to electrostatic attraction. Kinetic data demonstrated that the driving force for adsorption process could be explained by pseudo-second order mechanism in both systems. The equilibrium data were more compatible with Langmuir isotherm than those of Freundlich isotherm and the maximum adsorption capacities of Fe₃O₄@SiO₂@NH₂ calculated from Langmuir isotherm model for LG and BY at 30?°C and natural pH of the solution were 40.2 and 35.5?mg g^?1. Thermodynamic calculations related to temperature dependence demonstrated that the adsorption process was spontaneous and exothermic.     

CS@Cu2O and magnetic Fe3O4@SiO2-pAMBA-CS-Cu2O as heterogeneous catalysts for CuAAC click reaction

The recovery of agricultural and food wastes are one of the main areas of current research for optimal biowaste management to reduce greenhouse gas (GHG) emissions that are generated when it is not properly treated. Corn silk (CS) as biowaste from the agricultural sector is a rich source of natural compounds especially polysaccharides. We present here a chemical activation method to convert CS to values added heterogeneous catalyst for the synthesis of triazoles compounds via copper catalyzed azide–alkyne cycloaddition (CuAAC) reaction. For this purpose, cuprous oxide coated CS (CS@Cu₂O) and multifunctional Fe₃O₄@SiO₂–para-aminomethyl benzoic acid–CS–Cu₂O composite (denoted as Fe₃O₄@SiO₂‐pAMBA-CS‐Cu₂O) were fabricated. Different analytical techniques have been used to describe the size, crystal structure, elemental composition and other physical properties of the fabricated catalysts. These heterogeneous catalysts showed excellent catalytic activities for the synthesis of 1,4-disubstituted-1,2,3-triazoles via click reaction in H₂O at 70 °C under base and external-reductant-free conditions. The magnetic properties of the catalyst allowed easy separation after reaction by simply applying an external magnet. Other advantages of this work are the recyclability of the catalyst, the absence of reducing agent and base, besides utilisation of bio wastes for the production of heterogeneous catalyst.     

Preparation of Fe3O4@SiO2@layered double hydroxide core-shell microspheres for magnetic separation of proteins

Three-component microspheres containing an SiO(2)-coated Fe(3)O(4) magnetite core and a layered double hydroxide (LDH) nanoplatelet shell have been synthesized via an in situ growth method. The resulting Fe(3)O(4)@SiO(2)@NiAl-LDH microspheres display three-dimensional core-shell architecture with flowerlike morphology, large surface area (83 m(2)/g), and uniform mesochannels (4.3 nm). The Ni(2+) cations in the NiAl-LDH shell provide docking sites for histidine and the materials exhibit excellent performance in the separation of a histidine (His)-tagged green fluorescent protein, with a binding capacity as high as 239 μg/mg. The microspheres show highly selective adsorption of the His-tagged protein from Escherichia coli lysate, demonstrating their practical applicability. Moreover, the microspheres possess superparamagnetism and high saturation magnetization (36.8 emu/g), which allows them to be easily separated from solution by means of an external magnetic field and subsequently reused. The high stability and selectivity of the Fe(3)O(4)@SiO(2)@NiAl-LDH microspheres for the His-tagged protein were retained over several separation cycles. Therefore, this work provides a promising approach for the design and synthesis of multifunctional LDH microspheres, which can be used for the practical purification of recombinant proteins, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors.     

Gold nanoparticles/carbon nanotubes composite microspheres for catalytic reduction of 4-nitrophenol

The layer-by-layer assembly of polyethyleneimine and carbon nanotubes is carried out through the electrostatic interactions on colloidal polystyrene templates. The successful spherical growth of polyethyleneimine/carbon nanotube multilayers could be investigated by SEM. The subsequent in situ preparation and deposition of gold nanoparticles on the core–shell composites could yield novel microsphere complexes, which are characterized by SEM, TEM, EDX and XRD. The functional hierarchical microspheres with gold nanoparticles exhibit good catalytic activity in the reaction of reducing 4-nitrophenol to 4-aminophenol.     

Preparation for Magnetic Nanoparticles Fe3O4 and Fe3O4@SiO2 and Heterogeneous Fenton Catalytic Degradation of Methylene Blue

Dyestuff textile wastewater treatment has become a research hotspot due to its high chroma, poor biodegradability, and low toxicity characteristics. In this paper, we have synthesized magnetic Fe₃O₄ and core‐shell Fe₃O₄@SiO₂ materials by hydrothermal methods. These materials were characterized by XRD, TEM, N₂ adsorption‐desorption and so on. These materials’ heterogeneous Fenton has been applied to dye wastewater treatment. Methylene blue was used as a typical target of dye wastewater. Decolorization ratios of methylene blue were determined by different nanostructure composites catalysts. A serious of results of study showed that decolorization ratios of magnetic nanoparticles and core‐shell composites arrived at above 90 % under the weakly acidic or neutral conditions and room temperature. When these catalysts were reused, the results show that Fe₃O₄@SiO₂ materials were possessed with good cycle performance.     

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.     

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...     

Biogenic synthesis of Fe2O3@SiO2 nanoparticles for ipso-hydroxylation of boronic acid in water

Here, biogenic synthesis of Fe₂O₃@SiO₂ nanoparticles using fruit extract of Zanthoxylum rhetsa is reported. The SiO₂ nanoparticles was synthesized using paddy straw which is a byproduct obtained in cultivation of rice. The composite was characterised by spectroscopic method like XRD, SEM, TEM and EDX analysis. The ipso-hydroxylation reactions were carried out with excellent yield within a moderate time period with mild reaction condition in all cases. Therefore, this approach may be considered as simple, easy, cheap and greener, environment friendly protocol for ipso-hydroxylation of arylboronic acids at 50 °C temperature.