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1.
A tyrosinase (Tyr) biosensor was developed based on Fe 3O 4 magnetic nanoparticles (MNPs)-coated carbon nanotubes (CNTs) nanocomposite and further applied to detect the concentration of coliforms with flow injection assay (FIA) system. Negatively charged MNPs were absorbed onto the surface of CNTs which were wrapped with cationic polyelectrolyte poly(dimethyldiallylammonium chloride) (PDDA). The Fe 3O 4 MNPs-coated CNTs nanocomposite was modified on the surface of the glassy carbon electrode (GCE), and Tyr was loaded on the modified electrode by glutaraldehyde. The immobilization matrix provided a good microenvironment for retaining the bioactivity of Tyr, and CNTs incorporated into the nanocomposite led to the improved electrochemical detection of phenol. The Tyr biosensor showed broad linear response of 1.0 × 10 −8-3.9 × 10 −5 M, low detection limit of 5.0 × 10 −9 M and high sensitivity of 516 mA/M for the determination of phenol. Moreover, the biosensor integrated with a FIA system was used to monitor coliforms, represented by Escherichia coli ( E. coli). The detection principle was based on determination of phenol which was produced by enzymatic reaction in the E. coli solution. Under the optimal conditions, the current responses obtained in the FIA system were proportional to the concentration of bacteria ranging from 20 to 1 × 10 5 cfu/mL with detection limit of 10 cfu/mL and the overall assay time of about 4 h. The developed biosensor with the FIA system was well suited for quick and automatic clinical diagnostics and water quality analysis. 相似文献
2.
A colorimetric and ‘‘turn-on” fluorescent chemosensor Rho-Fe 3O 4@SiO 2 for Hg 2+ in which N-(rhodamine-6G)lactam-ethylenediamine (Rho-en) is conjugated with the magnetic core-shell Fe 3O 4@SiO 2 NPs has been strategically designed and synthesized. The final product was characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectra (FTIR) and UV-visible absorption and fluorescence emission. Fluorescence and UV-visible spectra results showed that the resultant multifunctional nanoparticles Rho-Fe 3O 4@SiO 2 exhibited selective ‘turn-on’ type fluorescent enhancements and distinct color changes with Hg 2+. The selectivity of the Rho-Fe 3O 4@SiO 2 for Hg(II) ion is better than that of the Rho-en in the same conditions. In addition, the presence of magnetic Fe 3O 4 nanoparticles in the sensor Rho-Fe 3O 4@SiO 2 NPs would also facilitate the magnetic separation of the Hg(II)-Rho-Fe 3O 4@SiO 2 from the solution. 相似文献
3.
The interforce between the magnetic composite forward osmosis (FO) membranes and the magnetic draw solution was proposed to reduce the internal concentration polarization (ICP) of FO process, and realized the synergetic permeability improvement of resultant FO membranes. The key factor was the successful fabrication of the Fe 3O 4 magnetic nanoparticles (MNPs) with small‐size and narrow distribution via co‐precipitation method. The cellulose triacetate (CTA) magnetic composite FO membranes were fabricated using Fe 3O 4 as additive via in situ interfacial polymerization, and named CTA‐Fe 3O 4. Dynamic light scattering (DLS) and zeta results showed that the coated sodium oleate on the MNPs explained their reducing aggregation and the stability of various pHs. The MNPs' surface segregation during demixing process resulted in the improvement of hydrophilicity, Fe content and roughness of resultant CTA‐Fe 3O 4 composite FO membranes. Furthermore, the in situ interfacial polymerization resulted in the formation of the polyamide selective layer, and the CTA‐Fe 3O 4 membrane's N content was 11.02% to 11.12%. The permeability properties (FO and pressure retarded osmosis modules) were characterized using 1.0 M NaCl and 100 mg/L Fe 3O 4 as draw solutions, respectively. The results indicated that the higher concentration of MNPs supplied more interforce and better FO permeability properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44852. 相似文献
4.
As-synthesized Fe 3O 4 nanoparticles were encapsulated with carbon layers through a simple hydrothermal process. Fe 3O 4/C nanoparticles were coated with YVO 4:Dy 3+ phosphors to form bifunctional Fe 3O 4@C@YVO 4:Dy 3+ composites. Their structure, luminescence and magnetic properties were characterized by XRD, SEM, TEM, HRTEM, PL spectra and VSM. The experimental results indicated that the as-prepared bifunctional composites displayed well-defined core–shell structures. The ∼12 nm diameter YVO 4:Dy 3+ shell exhibited tetragonal structure. Additionally, the composites exhibited a high saturation magnetization (13 emu/g) and excellent luminescence properties, indicating their promising potential as multifunctional biosensors for biomedical applications. 相似文献
5.
CoFe 2O 4 nanowire arrays were fabricated by electrodeposition of Fe 2+ and Co 2+ into anodic aluminum oxide (AAO) templates and further oxidization. The phase structure of the nanowires is cubic spinel-type, and the XRD result exhibits perfect preferred crystallite orientation along the nanowire axes. Compared with CoFe 2O 4 nanowire arrays synthesized by other methods, the magnetic hysteresis loops demonstrate that the arrays of nanowires exhibit uniaxial magnetic anisotropy with easy magnetization direction along the nanowire axes owing to the large shape anisotropy. This approach provides a facile technology to fabricate oxide nanowires with uniaxial magnetic anisotropy. 相似文献
6.
In this paper, a free radical polymerization system consisting of DPE was used to prepare magnetic composite microspheres. Fe 3O 4/P(AA-MMA-St) core-shell magnetic composite microspheres have been synthesized by copolymerization of acrylic acid, methyl methacrylate and styrene using DPE as radical control agent in the presence of Fe 3O 4 nanoparticles. The structure and properties of the magnetic composite microspheres were analyzed by FTIR, 1H NMR, SEC-MALLS, TEM, TGA, VSM and other instruments, and the formation mechanism of composite microspheres was supposed by those results. It was found that the Fe 3O 4/P(AA-MMA-St) microspheres were nano-size with relatively homogeneous particle size distribution, perfect sphere-shaped morphologies, superparamagnetism with a saturation magnetization of 18.430 emu/g, and high magnetic content with a value of 40%. 1H NMR and TEM analysis indicated that at the first stage of polymerization, a DPE-containing copolymer of acrylic acid, methyl methacrylate formed and was then absorbed on the surface of Fe 3O 4 nanoparticles. Contact angle analysis indicated that the DPE-containing copolymer improved hydrophobicity of Fe 3O 4 nanoparticles through chemical absorption. In the second step polymerization, certain amount of monomers of styrene and residue methacrylate were initiated by the DPE-containing copolymer on the Fe 3O 4 nanoparticles' surface and resulted in the formation of Fe 3O 4/P(AA-MMA-St) composite microspheres. 相似文献
7.
In this work, a series of Fe 3−xTi xO 4 (0 ≤ x ≤ 0.78) was synthesized using a new soft chemical method. The synthetic Fe 3−xTi xO 4 were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Mössbauer spectroscopy, thermogravimetric and differential scanning calorimetry (TG–DSC) analyses. The results showed that they were spinel structures and Ti was introduced into their structures.Then, decolorization of methylene blue (MB) by Fe 3−xTi xO 4 in the presence of H 2O 2 at neutral pH values was studied using UV–vis spectra, dissolved organic carbon (DOC) and element C analyses. Furthermore, the degradation products remained in reaction solution after the decolorization were identified using ionic chromatography (IC), 13C nuclear magnetic resonance spectra (NMR), liquid chromatography and mass spectrometry (LC–MS). Although small amounts of MB were mineralized, the aromatic rings in MB were destroyed completely after the decolorization. Decolorization of MB by Fe 3−xTi xO 4 in the presence of H 2O 2 was promoted remarkably with the increase of Ti content in Fe 3−xTi xO 4 due to the enhancement of both adsorption and degradation of MB on Fe 3−xTi xO 4. 相似文献
8.
A low-cost magnetic composite (gelatin/Fe 3O 4) is prepared by Fe 3O 4 nanoparticles treated with gelatin using an environmentally-friendly plasma technique, and is applied for the removal of toxic Pb(II) ions from aqueous solutions. Not only that it originates from cheap and abundant raw materials, the gelatin/Fe 3O 4 composite also has advantages in convenient magnetic separation from aqueous solution, which can hopefully reduce water treatment expenses. The batch experimenta results indicate that the maximum adsorption capacity (q max) of Pb(II) on this gelatin/Fe 3O 4 composite is ~115 mg/g, higher than most of the other bare and modified magnetic materials, which is considered to be attributed to the strong interaction between Pb(II) and the abundant functional groups introduced by gelatin. When exposed to acidic solutions, the dissolution of the gelatin/Fe 3O 4 nanoparticles is minimal due to the protective character of the grafted gelatin layer on the Fe 3O 4 nanoparticles. The utilization of the plasma technique in the synthesis of magnetic composite agrees well with the tenet of green chemistry. It is promising that this gelatin/Fe 3O 4 composite would become an efficient and economic material for heavy metal ion removal in the practical environmental remediation. 相似文献
9.
The iron distribution among the sulfoaluminate clinker phases and its ability to enter the calcium sulfoaluminate lattice in solid solution can have a significant influence on manufacturing process and reactivity of calcium sulfoaluminate (CSA) cements. X-ray diffraction (XRD) analysis, Mössbauer spectroscopy, scanning electron microscopy (SEM) equipped with an energy dispersive X-ray analysis system (EDAX) and infrared spectroscopy were used to identify the mineralogical conditions of iron inclusion during the formation of calcium sulfoaluminate (C 4A 3S) phase from different mixtures in the CaO-Al 2O 3-Fe 2O 3-SO 3 system. The mixtures, heated in a laboratory electric oven, contained stoichiometric amounts of reagent grade CaCO 3, Al 2O 3, Fe 2O 3 and CaSO 4·2H 2O for the synthesis of Ca 4Al (6 − 2x)Fe 2xSO 16, where x, comprised between 0 and 3, is the mole number of Al 2O 3 substituted by Fe 2O 3. With x increasing from 0 to 1.5, both the iron content of C 4A 3S phase and the amounts of side components such as C 2F and CS increased. For x values included in the range of 1.5-3.0, at temperatures higher than 1200 °C, melting phenomena were observed and, instead of the C 4A 3S solid solution, ferritic phases and anhydrite were formed. 相似文献
10.
Fe3O4 magnetic nanoparticles were prepared by the aqueous co-precipitation of FeCl3-6H2O and FeCl2-4H2O with addition of ammonium hydroxide. The conditions for the preparation of Fe3O4 magnetic nanoparticles were optimized, and Fe3O4 magnetic nanoparticles obtained were characterized systematically by means of transmission electron microscope (TEM), dynamic laser scattering analyzer (DLS) and X-ray diffraction (XRD). The results revealed that the magnetic nanoparticles were cubic shaped and dispersive, with narrow size distribution and average diameter of 11.4 nm. It was found that the homogeneous variation of pH value in the solution via the control on the dropping rate of aqueous ammonia played a critical role in size distribution. The magnetic response of the product in the magnetic field was also analyzed and evaluated carefully. A 32.6 mT magnetic field which is produced by four ferromagnets was found to be sufficient to excite the dipole moments of 0.05 g Fe3O4 powder 2 cm far away from the ferromagnets. In conclusion, the Fe3O4 magnetic nanoparticles with excellent properties were competent for the magnetic carders of targeted-drug in future application. 相似文献
11.
Ag(II)O–Fe 3O 4 hybrids with good magnetic and bactericidal activity were synthesized via mechano-chemistry. The resulted products were characterized by transmission electronic microscope, X-ray diffraction, X-ray photoelectron and Fourier transform infrared spectroscopy, atomic absorption spectrophotometer, vibrating sample magnetometry and the shake-flask method. The results indicated that magnetite nanoparticles were effectively grafted onto the surface of Ag(II)O submicron particles. The functionalized particles remained dispersed and superparamagnetic. The saturation magnetization increased with the amount of magnetite in the hybrids. Element Ag was released from Ag(II)O–Fe 3O 4 hybrids with a slow dissolution speed. Ag(II)O–Fe 3O 4 hybrids had strong antibacterial properties. When the concentrations of the two hybrids with the mass ratio of Ag(II)O to Fe 3O 4 of 1:2 and 2:1 were 10 mg/L, more than 99.9% of the Staphylococcus aureus or Escherichia coli bacteria were killed. 相似文献
12.
Composite ceramics of CoFe 2O 4/Fe 3O 4 with different weight ratios were synthesized by Spark Plasma Sintering (SPS) at a sintering temperature of 500 °C. The X-ray diffraction patterns demonstrate that all samples are composed of CoFe 2O 4 and Fe 3O 4 phases. The magnetization curves for all the composite ceramic are single-step loops indicating the existence of exchange spring effect. Due to the competition between the exchange interaction and the dipolar interaction, magnetic properties like coercivity ( Hc) and remanence ( Mr) are sensitive to the weight ratio of the soft phase. 相似文献
13.
Poly(caprolactone; PCL)—poly( N‐isopropylacrylamie; PNIPAAm)—Fe 3O 4 fiber, that can be magnetically actuated, is reported. Here, a structure is engineered that can be utilized as a smart carrier for the release of chemotherapeutic drug via magneto‐thermal activation, with the aid of magnetic nanoparticles (MNPs). The magnetic measurement of the fibers revealed saturation magnetization values within the range of 1.2–2.2 emu g ?1. The magnetic PCL‐PNIPAAm‐Fe 3O 4 scaffold shows a specific loss power value of 4.19 W g ?1 at 20 wt% MNPs. A temperature increase of 40 °C led to a 600% swelling after only 3 h. Doxorubicin (DOX) as a model drug, demonstrates a controllable drug release profile. 39% ± 0.92 of the total drug loaded is released after 96 h at 37 °C, while 25% drug release in 3 h at 40 °C is detected. Cytotoxicity results show no significant difference in cell attachment efficiency between the MNP‐loaded fibers and control while the DOX‐loaded fibers effectively inhibited cell proliferation at 24 h matching the drug release profile. The noncytotoxic effect, coupled with the magneto‐thermal property and controlled drug release, renders excellent potential for these fibers to be used as a smart drug‐release agent for localized cancer therapy. 相似文献
14.
Different phosphates and phosphonates have shown excellent coating ability toward magnetic nanoparticles, improving their stability and biocompatibility which enables their biomedical application. The magnetic hyperthermia efficiency of phosphates (IDP and IHP) and phosphonates (MDP and HEDP) coated Fe3O4 magnetic nanoparticles (MNPs) were evaluated in an alternating magnetic field. For a deeper understanding of hyperthermia, the behavior of investigated MNPs in the non-alternating magnetic field was monitored by measuring the transparency of the sample. To investigate their theranostic potential coated Fe3O4-MNPs were radiolabeled with radionuclide 177Lu. Phosphate coated MNPs were radiolabeled in high radiolabeling yield (>?99%) while phosphonate coated MNPs reached maximum radiolabeling yield of 78%. Regardless lower radiolabeling yield both radiolabeled phosphonate MNPs may be further purified reaching radiochemical purity of more than 95%. In vitro stabile radiolabeled nanoparticles in saline and HSA were obtained. The high heating ability of phosphates and phosphonates coated MNPs as sine qua non for efficient in vivo hyperthermia treatment and satisfactory radiolabeling yield justifies their further research in order to develop new theranostic agents. 相似文献
15.
L-cysteine functionalized Fe 3O 4 magnetic nanoparticles (Cys–Fe 3O 4 MNPs) were continuously fabricated by a simple high-gravity reactive precipitation method combined with surface modification through a novel impinging stream-rotating packed bed with the assistance of sonication. The obtained Cys–Fe 3O 4 MNPs was characterized by XRD, TEM, FTIR, TGA and VSM, and further used for the removal of heavy metal ions from aqueous solution. The influence of pH values, contact time and initial metal concentration on the adsorption efficiency were investigated. The results revealed that the adsorption of Pb(II) and Cd(II) were pH dependent process, and the pH 6.0 was found to be optimum condition. Moreover, the adsorption kinetic for Cys–Fe 3O 4 MNPs followed the mechanism of the pseudo-second order kinetic model, and their equilibrium data were fitted with the Langmuir isothermal model well. The maximum adsorption capacities calculated from Langmuir equation were 183.5 and 64.35 mg g −1 for Pb(II) and Cd(II) at pH 6.0, respectively. Furthermore, the adsorption and regeneration experiment showed there was about 10% loss in the adsorption capacity of the as-prepared Cys–Fe 3O 4 MNPs for heavy metal ions after 5 times reuse. All the above results provided a potential method for continuously preparing recyclable adsorbent applied in removing toxic metal ions from wastewater through the technology of process intensification. 相似文献
16.
A novel biodegradable magnetic‐sensitive shape memory poly(?‐caprolactone) nanocomposites, which were crosslinked with functionalized Fe 3O 4 magnetic nanoparticles (MNPs), were synthesized via in situ polymerization method. Fe 3O 4 MNPs pretreated with γ‐(methacryloyloxy) propyl trimethoxy silane (KH570) were used as crosslinking agents. Because of the crosslinking of functionalized Fe 3O 4 MNPs with poly(?‐caprolactone) prepolymer, the properties of the nanocomposites with different content of functionalized Fe 3O 4 MNPs, especially the mechanical properties, were significantly improved. The nanocomposites also showed excellent shape memory properties in both 60 °C hot water and alternating magnetic field ( f = 60, 90 kHz, H = 38.7, 59.8 kA m ?1). In hot water bath, all the samples had shape recovery rate ( Rr) higher than 98% and shape fixed rate ( Rf) nearly 100%. In alternating magnetic field, the Rr of composites was over 85% with the highest at 95.3%. In addition, the nanocomposites also have good biodegradability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45652. 相似文献
17.
Herein, the authors report the synthesis of electro-magnetic polyfuran/Fe 3O 4 nanocomposites using Fe 3O 4 magnetic nanoparticles of different content as nucleation sites via in situ chemical oxidation polymerization method. Surface, structural, morphological, thermal, electrical and magnetic properties of the nanocomposites were studied by FT-IR, UV-visible spectroscopies, XRD, FESEM, TGA, four probe, and VSM, respectively. The effect of Fe 3O 4 nanoparticles content on the electrical conductivity and magnetization of nanocomposites was studied. The obtained polyfuran and polyfuran/Fe 3O 4 nanocomposites were analyzed for their antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. In addition, polyfuran/Fe 3O 4 nanocomposites have been investigated for application as electrochemical biosensor. 相似文献
18.
Fe 3O 4-graphene nanocomposite was prepared by a gas/liquid interface reaction. The structure and morphology of the Fe 3O 4-graphene nanocomposite were characterized by X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. The electrochemical performances were evaluated in coin-type cells. Electrochemical tests show that the Fe 3O 4-22.7 wt.% graphene nanocomposite exhibits much higher capacity retention with a large reversible specific capacity of 1048 mAh g −1 (99% of the initial reversible specific capacity) at the 90th cycle in comparison with that of the bare Fe 3O 4 nanoparticles (only 226 mAh g −1 at the 34th cycle). The enhanced cycling performance can be attributed to the facts that the graphene sheets distributed between the Fe 3O 4 nanoparticles can prevent the aggregation of the Fe 3O 4 nanoparticles, and the Fe 3O 4-graphene nanocomposite can provide buffering spaces against the volume changes of Fe 3O 4 nanoparticles during electrochemical cycling. 相似文献
19.
β-Galactosidase was immobilized on chitosan-coated magnetic Fe 3O 4 nanoparticles and was used to produce galactooligosaccharides (GOS) from lactose. Immobilized enzyme was prepared with or without the coupling agent, tris(hydroxymethyl)phosphine (THP). The two immobilized systems and the free enzyme achieved their maximum activity at pH 6.0 with an optimal temperature of 50 °C. The immobilized enzymes showed higher activities at a wider range of temperatures and pH. Furthermore, the immobilized enzyme coupled with THP showed higher thermal stability than that without THP. However, activity retention of batchwise reactions was similar for both immobilized systems. All the three enzyme systems produced GOS compound with similar concentration profiles, with a maximum GOS yield of 50.5% from 36% (w·v −1) lactose on a dry weight basis. The chitosan-coated magnetic Fe 3O 4 nanoparticles can be regenerated using a desorption/re-adsorption process described in this study. 相似文献
20.
Polyvinyl alcohol (PVA) was used as a hydrogen bond functionalizing agent to modify multi-walled carbon nanotubes (CNTs). Nanoparticles of Fe 3O 4 were then formed along the sidewalls of the as-modified CNTs by the chemical coprecipitation of Fe 2+ and Fe 3+ in the presence of CNTs in an alkaline solution. The structure and electrochemical performance of the Fe 3O 4/CNTs nanocomposite electrodes have been investigated in detail. Electrochemical tests indicated that at the 145th cycle, the CNTs-66.7 wt.%Fe 3O 4 nanocomposite electrode can deliver a high discharge capacity of 656 mAh g −1 and stable cyclic retention. The improvement of reversible capacity and cyclic performance of the Fe 3O 4/CNTs nanocomposite could be attributed to the nanosized Fe 3O 4 particles and the network of CNTs. 相似文献
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