Photoirradiation surface molecularly imprinted polymers for the separation of 6‐O‐α‐d‐maltosyl‐β‐cyclodextrin

Photoirradiation surface molecularly imprinted polymers for the separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin were synthesized using functionalized silica as a matrix, 4‐(phenyldiazenyl)phenol as a light‐sensitive monomer, and 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin as a template. Fourier transform infrared spectroscopy results indicated that 4‐(phenyldiazenyl)phenol was grafted onto the surface of functionalized silica. The obtained imprinted polymers exhibited specific recognition toward 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin. Equilibrium binding experiments showed that the photoirradiation surface molecularly imprinted polymers obtained the maximum adsorption amount of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin at 20.5 mg/g. In binding kinetic experiments, the adsorption reached saturation within 2 h with binding capacity of 72.8%. The experimental results showed that the adsorption capacity and selectivity of imprinted polymers were effective for the separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin, indicating that imprinted polymers could be used to isolate 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin from a conversion mixture containing β‐cyclodextrin and maltose. The results showed that the imprinted polymers prepared by this method were very promising for the selective separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin.     

6‐TIPS‐β‐Cyclodextrin‐Modified Fe3O4 for Facile Enantioseparation of 1‐(1‐Naphthyl)ethylamine

A new type of chiral magnetic nanoparticle was prepared from covalently linked magnetic nanoparticles (Fe₃O₄) and heptakis‐(6‐O‐triisopropylsilyl)‐β‐cyclodextrin (6‐TIPS‐β‐CD). The resulting selectors (TIPS‐β‐CD‐MNPs) combined the good magnetic properties Fe₃O₄ and efficient chiral recognition ability of 6‐TIPS‐β‐CD. The enantioselectivity of TIPS‐β‐CD‐MNPs towards 1‐(1‐naphthyl)ethylamine was six times higher than that of the parent β‐CD modified Fe₃O₄ particles.     

The Synthesis of Magnetic Lysozyme‐Imprinted Polymers by Means of Distillation–Precipitation Polymerization for Selective Protein Enrichment

A protein imprinting approach for the synthesis of core–shell structure nanoparticles with a magnetic core and molecularly imprinted polymer (MIP) shell was developed using a simple distillation–precipitation polymerization method. In this work, Fe₃O₄ magnetic nanoparticles were first synthesized through a solvothermal method and then were conveniently surface‐modified with 3‐(methacryloyloxy)propyltrimethoxylsilane as anchor molecules to donate vinyl groups. Next a high‐density MIP shell was coated onto the surface of the magnetic nanoparticles by the copolymerization of functional monomer acrylamide (AAm), cross‐linking agent N,N′‐methylenebisacrylamide (MBA), the initiator azodiisobutyronitrile (AIBN), and protein in acetonitrile heated at reflux. The morphology, adsorption, and recognition properties of the magnetic molecularly imprinted nanoparticles were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and rebinding experiments. The resulting MIP showed a high adsorption capacity (104.8 mg g^?1) and specific recognition (imprinting factor=7.6) to lysozyme (Lyz). The as‐prepared Fe₃O₄@Lyz‐MIP nanoparticles with a mean diameter of 320 nm were coated with an MIP shell that was 20 nm thick, which enabled Fe₃O₄@Lyz‐MIP to easily reach adsorption equilibrium. The high magnetization saturation (40.35 emu g^?1) endows the materials with the convenience of magnetic separation under an external magnetic field and allows them to be subsequently reused. Furthermore, Fe₃O₄@Lyz‐MIP could selectively extract a target protein from real egg‐white samples under an external magnetic field.     

Cu (II)‐β‐cyclodextrin complex stabilized on magnetic nanoparticles: A retrievable hybrid promoter for green synthesis of spiropyrans

The magnetic core of manganese ferrite (MnFe₂O₄) nanoparticles has a significant stability in comparison with ferrite (Fe₃O₄) nanoparticles. The unique supramolecular properties of β‐cyclodextrin (β‐CD), such as hydrophobic cavity, hydrophilic exterior and ‐OH functional groups, make it a good candidate for functionalization and catalytic application. So, a surface‐modified magnetic solid support with the Cu (II)‐β‐CD complex was prepared. The structure of nanoparticles was characterized by Fourier transform‐infrared spectroscopy, X‐ray powder diffraction, thermogravimetric analysis, vibrating‐sample magnetometry, inductively coupled plasma‐optical emission spectrometry and scanning electron microscope analyses. The catalytic activity of these nanoparticles was investigated in the synthesis of spiropyrans and high yields of desired products obtained under green media. Some advantages of this novel catalyst for this reaction are high yields, short reaction times, green solvent and conditions, easy workup procedure, negligible copper leaching, reusability without a significant diminish in catalytic efficiency, and simple separation of nanocatalyst by using an external magnet alongside the environmental compatibility and sustainability.     

Fe3O4 nanoparticles coated with polyhedral oligomeric silsesquioxanes and β‐cyclodextrin for magnetic solid‐phase extraction of carbaryl and carbofuran

In this study, porous sandwich structure Fe₃O₄ nanoparticles coated by polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were prepared by surface polymerization and were used as the magnetic solid phase extraction adsorbent for the extraction and determination of carbaryl and carbofuran. The Fe₃O₄ nanoparticles coated with polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, and scanning electron microscopy. After optimizing the extraction conditions, a method that combined magnetic solid phase extraction with high‐performance liquid chromatography was developed for the determination of carbaryl and carbofuran in apple. The method exhibited a good linearity in the range of 2–400 μg/kg for carbaryl and carbofuran (R² = 0.9995), respectively. The limits of detection were 0.5 μg/kg of carbaryl and 0.7 μg/kg for carbofuran in apple, respectively. Extraction recoveries ranged from 94.2 to 103.1% with the preconcentration factor of 300 and the relative standard deviations were less than 5.9%. These results indicated that the method combined magnetic solid phase extraction with high‐performance liquid chromatography and was promising for the determination of carbaryl and carbofuran at trace amounts.     

Facile and versatile strategy to prepare magnetic molecularly imprinted particles based on the coassembly of magnetic nanoparticles and amphiphilic random copolymers

Magnetic molecularly imprinted polymer nanoparticles for bisphenol A were prepared by coassembling magnetic nanoparticles and amphiphilic random copolymers. Under optimized conditions, bisphenol A as template molecules, magnetic molecularly imprinted polymer particles with regular morphology, small size, good monodispersity, and high content of OA‐Fe₃O₄ were prepared by the coassembly method using P(MMA‐co‐MAA) with monomer ratio of 9:1. These magnetic molecularly imprinted polymer particles could be rapidly collected by an external magnet within 1 min. The saturated adsorption capacity of the magnetic molecularly imprinted polymer for bisphenol A was 201.5 mg/g, and the imprinting factor was 2.5. The separation factors for bisphenol A to β‐estradiol, estriol, and diethylstilbestrol was 3.1, 2.9, and 3.7, respectively. Unlike assembling amphiphilic copolymer in the selective solvent, the coassembly process was simple and rapid. Therefore, the present work provided a facile and versatile approach to construct magnetic molecularly imprinted polymer nanoparticles under mild conditions.     

Molecularly imprinted polymer functionalized magnetic Fe3O4 for the highly selective extraction of triclosan

We present a facile strategy to prepare the molecularly imprinted polymers layer on the surface of Fe₃O₄ nanoparticles with core‐shell structure via sol–gel condensation for recognition and enrichment of triclosan. The Fe₃O₄ nanoparticles were first synthesized by a solvothermal method. Then, template triclosan was self‐assembled with the functional monomer 3‐aminopropyltriethoxysilane on the silica‐coated Fe₃O₄ nanoparticles in the presence of ethanol and water. Finally, the molecularly imprinted polymers were formed on the surface of silica‐coated Fe₃O₄ nanoparticles to obtain the product. The morphology, magnetic susceptibility, adsorption, and recognition property of magnetic molecularly imprinted polymers were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffractometry, vibrating sample magnetometry, and re‐binding experiments. The magnetic molecularly imprinted polymers showed binding sites with good accessibility, fast adsorption rate, and high adsorption capacity (218.34 μg/g) to triclosan. The selectivity of magnetic molecularly imprinted polymers was evaluated by the rebinding capability of triclosan and two other structural analogues (phenol and p‐chlorophenol) in a mixed solution and good selectivity with an imprinting factor of 2.46 was obtained. The application of triclosan removal in environmental samples was demonstrated.     

Synthesis of well‐defined 7‐arm and 21‐arm poly(N‐isopropylacrylamide) star polymers with β‐cyclodextrin cores via click chemistry and their thermal phase transition behavior in aqueous solution

The syntheses of well‐defined 7‐arm and 21‐arm poly(N‐isopropylacrylamide) (PNIPAM) star polymers possessing β‐cyclodextrin (β‐CD) cores were achieved via the combination of atom transfer radical polymerization (ATRP) and click reactions. Heptakis(6‐deoxy‐6‐azido)‐β‐cyclodextrin and heptakis[2,3,6‐tri‐O‐(2‐azidopropionyl)]‐β‐cyclodextrin, β‐CD‐(N₃)₇ and β‐CD‐(N₃)₂₁, precursors were prepared and thoroughly characterized by nuclear magnetic resonance and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. A series of alkynyl terminally functionalized PNIPAM (alkyne‐PNIPAM) linear precursors with varying degrees of polymerization (DP) were synthesized via atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide using propargyl 2‐chloropropionate as the initiator. The subsequent click reactions of alkyne‐PNIPAM with β‐CD‐(N₃)₇ and β‐CD‐(N₃)₂₁ led to the facile preparation of well‐defined 7‐arm and 21‐arm star polymers, namely β‐CD‐(PNIPAM)₇ and β‐CD‐(PNIPAM)₂₁. The thermal phase transition behavior of 7‐arm and 21‐arm star polymers with varying molecular weights were examined by temperature‐dependent turbidity and micro‐differential scanning calorimetry, and the results were compared to those of linear PNIPAM precursors. The anchoring of PNIPAM chain terminal to β‐CD cores and high local chain density for star polymers contributed to their considerably lower critical phase separation temperatures (T_c) and enthalpy changes during phase transition as compared with that of linear precursors. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 404–419, 2009     

Functionalized superparamagnetic nanoparticles with a polymer containing β‐cyclodextrin for the extraction of sertraline hydrochloride in biological samples

In this study, a novel magnetic nanoadsorbent was synthesized by grafting β‐cyclodextrin onto the modified surface of Fe₃O₄ nanoparticles for the sorption and extraction of sertraline hydrochloride from human biological fluids. The extracted sertraline hydrochloride was measured by high‐performance liquid chromatography. The grafted nanosorbent was confirmed by Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, and elemental analysis. The kinetic sorption of sertraline hydrochloride by magnetic nanosorbent was 1 h. The best temperature for sorption of sertraline hydrochloride was at 25°C at an optimum pH of 5. The adsorbed sertraline hydrochloride can be desorbed by using methanol solution containing acetic acid (5%) and trifluoroacetic acid (1%).     

Synthesis of magnetic,reactive, and thermoresponsive Fe3O4 nanoparticles via surface‐initiated RAFT copolymerization of N‐isopropylacrylamide and acrolein

A reversible addition‐fragmentation chain transfer (RAFT) agent was directly anchored onto Fe₃O₄ nanoparticles in a simple procedure using a ligand exchange reaction of S‐1‐dodecyl‐S′‐(α,α′‐dimethyl‐α″‐acetic acid)trithiocarbonate with oleic acid initially present on the surface of pristine Fe₃O₄ nanoparticles. The RAFT agent‐functionalized Fe₃O₄ nanoparticles were then used for the surface‐initiated RAFT copolymerization of N‐isopropylacrylamide and acrolein to fabricate structurally well‐defined hybrid nanoparticles with reactive and thermoresponsive poly(N‐isopropylacrylamide‐co‐acrolein) shell and magnetic Fe₃O₄ core. Evidence of a well‐controlled surface‐initiated RAFT copolymerization was gained from a linear increase of number‐average molecular weight with overall monomer conversions and relatively narrow molecular weight distributions of the copolymers grown from the nanoparticles. The resulting novel magnetic, reactive, and thermoresponsive core‐shell nanoparticles exhibited temperature‐trigged magnetic separation behavior and high ability to immobilize model protein BSA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 542–550, 2010     

Multi‐walled carbon nanotube modified dummy‐template magnetic molecularly imprinted microspheres as solid‐phase extraction material for the determination of polychlorinated biphenyls in fish

Novel multi‐walled carbon nanotube modified dummy‐template molecularly imprinted microspheres (MWCNTs@DMMIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs). MWCNTs@DMMIPs were prepared by a surface molecular imprinting technique. Core–shell Fe₃O₄@SiO₂ nanoparticles were employed as magnetic support. 3,4‐Dichlorobenzene acetic acid was used as a dummy template instead of PCBs, methacrylic acid was used as functional monomer and ethylene glycol dimethacrylate was used as the cross‐linker. The resulting absorbent was characterized by various methods. The adsorbent was employed for extracting PCBs and exhibited good selectivity and high adsorption efficiency. Furthermore, it was reusable and capable of magnetic separation. Adsorption kinetics fit well with a pseudo‐second‐order kinetic equation and also exhibited a three‐stage intra‐particle diffusion model. The Freundlich model was used to describe the adsorption isotherms. The materials were successfully applied to the magnetic dispersive solid‐phase extraction of six kinds of PCBs followed by gas chromatography with mass spectrometry determination in fish samples, the limit of detection of six kinds of PCBs were 0.0028–0.0068 μg/L and spiked recoveries ranged between 73.41 and 114.21%. The prepared adsorbent was expected to be a new material for the removal and recovery of PCBs from contaminated foods.     

Synthesis of polymers by template polymerization. I. Template polymerization of poly(methacrylic acid) with β‐cyclodextrin

A novel template monomer with multiple methacryloyl groups was synthesized with β‐cyclodextrin by the acetylation of primary hydroxyl groups and the esterification of secondary hydroxyl groups with methacrylic acid anhydride. The average number of methacryloyl groups in the monomer was 11. The radical polymerization of the monomer was carried out with the following initiators: α,α′‐azobisisobutylonitrile, H₂O₂? Fe²⁺ redox initiator, p‐xylyl‐N,N‐dimethyldithiocarbamate (XDC), and α‐bromo‐p‐xylyl‐N,N‐dimethyldithiocarbamate (BXDC). When the concentration of the monomer was less than 4.12 × 10^?3 M, polymerization was limited inside the molecule, and gelation of the system was hindered. For controlled radical photopolymerization with XDC and BXDC, the methacryloyl groups of the monomer were homogeneously polymerized, and poly(methacrylic acid) with a narrow molecular weight distribution was obtained by the hydrolysis of the polymerized products. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3539–3546, 2001     

Synthesis of multiresponsive β‐cyclodextrin nanocomposite through surface RAFT polymerization for controlled drug delivery

In this study, a unique magnetic, pH, and thermo‐responsive hydrogel nanocomposite was synthesized via surface reversible addition fragmentation chain transfer (RAFT) copolymerization of acrylic acid (AA) and N‐isopropyl acrylamide (NIPAM) in the presence of magnetic β‐cyclodextrin (β‐CD). The nanocomposite demonstrated a pH‐responsiveness behavior at pHs 3 and 9. Moreover, swelling behaviors of nanocomposite were measured in solutions with various temperatures. Furthermore, the nanocomposites exhibited high swelling capacity by applying an external magnetic field because of the presence of Fe₃O₄ nanoparticles in the polymer structure. Besides, the doxorubicin (DOX) loading and releasing behaviors of the hydrogel nanocomposites were studied because of the stimuli‐responsive properties of the synthesized carriers. The adsorption of DOX obeyed a pseudo‐second‐order model and fitted well to the Langmuir isotherm model with the maximum adsorption capacity uptake of 291 mg g^?1. In conclusion, the hydrogel nanocomposites were found to be as potential nanocarriers for use in controlled release applications.     

A sensitive and selective sensor‐coated molecularly imprinted sol–gel film incorporating β‐cyclodextrin‐multi‐walled carbon nanotubes and cobalt nanoparticles‐chitosan for oxacillin determination

A sensitive and selective imprinted electrochemical sensor for the determination of oxacillin was developed based on indium tin oxide electrode. The proposed sensor was decorated with imprinted sol–gel film and cobalt nanoparticles‐chitosan/β‐cyclodextrin‐multiwalled carbon nanotubes nanocomposites. The surface morphologies of the modified electrodes were characterized by scanning electron microscopy and transmission electron microscope. The stepwise assembly process and electrochemical behavior of the novel sensor were characterized by differential pulse voltammetry, cyclic voltammetry and Amperometric i‐t response. The imprinted sensor displayed excellent selectivity toward oxacillin. Meanwhile, the introduced cobalt nanoparticles‐chitosan and β‐cyclodextrin‐multi‐walled carbon nanotubes exhibited noticeable amplified electrochemical response signal. The differential voltammetric anodic peak current was linear to oxacillin concentration in the range from 2.0 × 10^?7 to 1.0 × 10^?4 mol·l^?1, and the detection limit was 6.9 × 10^?9 mol·l^?1. The proposed imprinted sensor was applied to the determination of oxacillin in human blood serum samples successfully. Copyright © 2011 John Wiley & Sons, Ltd.     

Separation of chiral compounds using magnetic molecularly imprinted polymer nanoparticles as stationary phase by microchip capillary electrochromatography

In this work, a simple and rapid approach was developed for separation and detection of chiral compounds based on a magnetic molecularly imprinted polymer modified poly(dimethylsiloxane) (PDMS) microchip coupled with electrochemical detection. Molecularly imprinted polymers were prepared employing Fe₃O₄ nanoparticles (NPs) as the supporting substrate and norepinephrine as the functional monomer in the presence of template molecule in a weak alkaline solution. After extracting the embedded template molecules, Fe₃O₄@polynorepinephrine NPs (MIP–Fe₃O₄@PNE NPs) showed specific molecular recognition selectivity and high affinity towards the template molecule, which were then used as stationary phase of microchip capillary electrochromatography for chiral compounds separation. Mandelic acid and histidine enantiomers were used as model compounds to test the chiral stationary phase. By using R‐mandelic acid as the template molecule, mandelic acid enantiomer was effectively separated and detected on the MIP‐Fe₃O₄@PNE NPs modified PDMS microchip. Moreover, the successful separation of histidine enantiomers on the MIP–Fe₃O₄@PNE NPs modified microchip using L‐histidine as template molecule was also achieved.     

Synthesis and characterization of photo‐responsive magnetic molecularly imprinted microspheres for the detection of sulfonamides in aqueous solution

A dual responsive molecularly imprinted polymer sensitive to both photonic and magnetic stimuli was successfully prepared for the detection of four sulfonamides in aqueous media. The photoresponsive magnetic molecularly imprinted polymer was prepared by surface imprinting polymerization using superparamagnetic Fe₃O₄ nanoparticles functionalized with a silica layer as a support, water‐soluble 4‐[(4‐methacryloyloxy)phenylazo]benzenesulfonic acid as the functional monomer, and sulfadiazine as the template. The magnetic molecularly imprinted polymers showed specific affinity to sulfadiazine and its structural analogs in aqueous media. Upon alternate irradiation at 365 and 440 nm, the quantitative bind and release of the four sulfonamides by magnetic molecularly imprinted polymers occurred. Furthermore, the prepared magnetic molecularly imprinted polymers were used as solid‐phase extraction material selectively extracted the four sulfonamides from water samples with good recoveries. Thus, a simple, convenient, and reliable detection method for sulfonamides in the environment based on responsive magnetic molecularly imprinted polymers was successfully established.     

Protease Immobilization on γ‐Fe2O3/Fe3O4 Magnetic Nanoparticles for the Synthesis of Oligopeptides in Organic Solvents

The use of nanobiocatalysts, with the combination of nanotechnology and biotechnology, is considered as an exciting and rapidly emerging area. The use of iron oxide magnetic nanoparticles, as enzyme immobilization carriers, has drawn great attention because of their unique properties, such as controllable particle size, large surface area, modifiable surface, and easy recovery. In this study, various γ‐Fe₂O₃/Fe₃O₄ magnetic nanoparticles with immobilized proteases were successfully prepared by three different immobilization strategies including A) direct binding, B) with thiophene as a linker, and C) with triazole as a linker. The oligopeptides syntheses catalyzed by these magnetic nanoparticles (MNPs) with immobilized proteases were systematically studied. Our results show that i) for magnetic nanoparticles immobilized α‐chymotrypsin, both immobilization strategies A and B furnished good reusability for the Z‐Tyr‐Gly‐Gly‐OEt synthesis, the MNPs enzymes can be readily used at least five times without significant loss of its catalytic performance: ii) In the case of Z‐Asp‐Phe‐OMe synthesis catalyzed by magnetic nanoparticles immobilized thermolysin, immobilization Strategy B provided the best recyclability: iii) For the immobilized papain, although Strategy A or B afforded an immobilized enzyme for the first cycle of Z‐Ala‐Leu‐NHNHPh synthesis in good yield, their subsequent catalytic activity decreased rapidly. In general, the γ‐Fe₂O₃ MNPs were better for use as an immobilization matrix, rather than the Fe₃O₄ MNPs, owing to their smaller particle size and higher surface area.     

Intramolecular Oxidative O‐Demethylation of an Oxoferryl Porphyrin Complexed with a Per‐O‐methylated β‐Cyclodextrin Dimer

The intramolecular oxidation of ROCH₃ to ROCH₂OH, where the latter compound spontaneously decomposed to ROH and HCHO, was observed during the reaction of the supramolecular complex (met‐hemoCD3) with cumene hydroperoxide in aqueous solution. Met‐hemoCD3 is composed of meso‐tetrakis(4‐sulfonatophenyl)porphinatoiron(III) (Fe^IIITPPS) and a per‐O‐methylated β‐cyclodextrin dimer having an ‐OCH₂PyCH₂O‐ linker (Py=pyridine‐3,5‐diyl). The O=Fe^IVTPPS complex was formed by the reaction of met‐hemoCD3 with cumene hydroperoxide, and isolated by gel‐filtration chromatography. Although the isolated O=Fe^IVTPPS complex in the cyclodextrin cage was stable in aqueous solution at 25 °C, it was gradually converted to Fe^IITPPS (t_1/2=7.6 h). This conversion was accompanied by oxidative O‐demethylation of an OCH₃ group in the cyclodextrin dimer. The results indicated that hydrogen abstraction by O=Fe^IVTPPS from ROCH₃ yields HO‐Fe^IIITPPS and ROCH₂^.. This was followed by radical coupling to afford Fe^IITPPS and ROCH₂OH. The hemiacetal (ROCH₂OH) immediately decomposed to ROH and HCHO. This study revealed the ability of oxoferryl porphyrin to induce two‐electron oxidation.     

Graphene‐Based Composite with γ‐Fe2O3 Nanoparticle for the High‐Performance Removal of Endocrine‐Disrupting Compounds from Water

Graphene is a 2D sp²‐hybridized carbon sheet and an ideal material for the adsorption‐based separation of organic pollutants. However, such potential applications of graphene are largely limited, owing to their poor solubility and extensive aggregation properties through graphene? graphene interactions. Herein, we report the synthesis of graphene‐based composites with γ‐Fe₂O₃ nanoparticle for the high‐performance removal of endocrine‐disrupting compounds (EDC) from water. The γ‐Fe₂O₃ nanoparticles partially inhibit these graphene? graphene interactions and offer water dispersibility of the composite without compromising much of the high surface area of graphene. In their dispersed form, the graphene component offers the efficient adsorption of EDC, whilst the magnetic iron‐oxide component offers easier magnetic separation of adsorbed EDC.     

Facile Hydrogen‐Bond‐Assisted Polymerization and Immobilization Method to Synthesize Hierarchical Fe3O4@Poly(4‐vinylpyridine‐co‐divinylbenzene)@Au Nanostructures and Their Catalytic Applications

Hierarchical Fe₃O₄@poly(4‐vinylpyridine‐co‐divinylbenzene)@Au (Fe₃O₄@P(4‐VP–DVB)@Au) nanostructures were fabricated successfully by means of a facile two‐step synthesis process. In this study, well‐defined core–shell Fe₃O₄@P(4‐VP–DVB) microspheres were first prepared with a simple polymerization method, in which 4‐VP was easily polymerized on the surface of Fe₃O₄ nanoparticles by means of strong hydrogen‐bond interactions between ? COOH groups on poly(acrylic acid)‐modified Fe₃O₄ nanoparticles and a 4‐VP monomer. HAuCl₄ was adsorbed on the chains of a P(4‐VP) shell and then reduced to Au nanoparticles by NaBH₄, which were embedded into the P(4‐VP) shell of the composite microspheres to finally form the Fe₃O₄@P(4‐VP–DVB)@Au nanostructures. The obtained Fe₃O₄@P(4‐VP–DVB)@Au catalysts with different Au loadings were applied in the reduction of 4‐nitrophenol (4‐NP) and exhibited excellent catalytic activity (up to 3025 h^?1 of turnover frequency), facile magnetic separation (up to 31.9 emu g^?1 of specific saturation magnetization), and good durability (over 98 % of conversion of 4‐NP after ten runs of recyclable catalysis and almost negligible leaching of Au).