Magnetic Carbon Nanotubes Research Articles

Microfluidic fabrication of magnetic porous multi-walled carbon nanotube beads for oil and organic solvent adsorption

Three-dimensional (3D) magnetic porous multi-walled carbon nanotube beads (MCNTBs) with obvious hierarchical pores were fabricated by using a microfluidic device for oil and organic solvent adsorption.

Heterogenization of an imidazolium ionic liquid based on magnetic carbon nanotubes as a novel organocatalyst for the synthesis of 2-amino-chromenes via a microwave-assisted multicomponent strategy

The microwave-assisted synthesis of the first ionic liquid stabilized CNTs–Fe3O4as a novel nanocatalyst for the synthesis of 2-amino-chromenesviaa multicomponent reaction is reported.

A chemiluminescence sensor for determination of lysozyme using magnetic graphene oxide multi-walled carbon nanotube surface molecularly imprinted polymers

In this paper, a new chemiluminescence sensor possessing high selectivity and sensitivity was established for determination of lysozyme using magnetic graphene oxide–multi-walled carbon nanotube surface molecularly imprinted polymer.

Ionic liquid-based carbon nanotube coated magnetic nanoparticles as adsorbent for the magnetic solid phase extraction of triazole fungicides from environmental water

Ionic liquid-based magnetic carbon nanotubes (IL-Fe3O4@MWCNTs) were synthesized as a novel adsorbent in MSPE for determination of six triazole fungicides in environmental water.

Analysis of sulfonylurea herbicides in grain samples using molecularly imprinted polymers on the surface of magnetic carbon nanotubes by extraction coupled with HPLC

A polymerization process for magnetic molecularly imprinted polymers.

A facile controlled in-situ synthesis of monodisperse magnetic carbon nanotubes nanocomposites using water-ethylene glycol mixed solvents

Abstract In this paper, a facile and controllable method for in-situ synthesis of the magnetic carbon nanotubes nanocomposites (Fe/CNTs) in water-ethylene glycol (EG) mixed solvents is reported by the deposition–precipitation method following annealing. The effect of water/EG ratio on the physico-chemical properties of magnetic Fe/CNTs is investigated by X-ray diffraction, transmission electron microscope, scanning electron microscopy, thermogravimetric analysis and physical property measurement system. The results indicate that the iron particle size distribution and grain size can be well-tuned by adjusting the water/EG ratio. With the variation of EG fraction in the mixed solvent, the nucleation, growth and crystallization of magnetic iron oxides with a controllable morphologies and particle sizes attached on the exterior surface of CNTs can be achieved. The as-prepared Fe/CNTs nanocomposites display superparamagnetic property at room temperature and the water/EG ratio determines the magnetization of the sample. Possible formation mechanism for magnetic Fe/CNTs is proposed based on the characterization results.

Fast determination of 24 steroid hormones in river water using magnetic dispersive solid phase extraction followed by liquid chromatography-tandem mass spectrometry.

The easiness-to-handle of the magnetic dispersive solid phase extraction (Mag-dSPE) procedure was developed for preconcentration of 24 steroid hormones in river water. Ethylenediamine-functionalized magnetic carbon nanotubes (EDA@Mag-CNTs) were synthesised by a simple one-pot reaction and were used as sorbent in Mag-dSPE procedure. The properties of the EDA@Mag-CNTs were characterized by transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). An ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) method for determination of 24 steroid hormones in river water at nanograms per liter had been developed with pretreatment of the samples by Mag-dSPE. The obtained results demonstrated the higher extraction capacity of EDA@Mag-CNT Mag-dSPE with recoveries between 82.1 and 113%. The limits of quantification (LOQs) for the steroid hormone were between 0.020 and 1.00 ng/L. The developed method had been successfully applied to 60 river water samples, and it was confirmed that EDA@Mag-CNT Mag-dSPE was a highly effective extraction method for the steroid hormone analyses.

Selective extraction of gallic acid in pomegranate rind using surface imprinting polymers over magnetic carbon nanotubes.

A novel surface imprinting polymer based on magnetic carbon nanotubes was prepared using dendritic polyethyleneimine as functional monomer to amplify the number of imprinted cavities. The characteristics of resulting polymers were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM). Results suggest that magnetic nanoparticles are deposited onto the surface of multiwalled carbon nanotubes and the imprinted shell is coated on the surface of magnetic carbon nanotubes with a thickness of approximately 8 nm. Magnetic imprinted polymers are sensitive to magnetic fields and can be easily separated within 3 s using an external magnet. The adsorption results indicate that the obtained imprinted polymers have fast kinetics, an ultrahigh adsorption capacity of 479.9 mg g(-1), and satisfactory selectivity towards the template molecule. The prepared materials have excellent stability with no obvious deterioration after six adsorption-regeneration cycles. In addition, a method for determination of gallic acid (GA) in pomegranate rind was developed, using a combination of the prepared polymers used as solid-phase extraction (SPE) sorbents and high-performance liquid chromatography (HPLC) for rapid isolation and determination of GA. The limit of detection of the proposed method is 0.001 μg mL(-1), and the intra and inter-day relative standard deviations (RSDs) are lower than 3.8% and 5.3%, respectively. The recoveries of GA from pomegranate rind extract are in the range 98.2-103.6% with RSDs lower than 4.3%.

A novel sandwich electrochemiluminescence immunosensor for ultrasensitive detection of carbohydrate antigen 19-9 based on immobilizing luminol on Ag@BSA core/shell microspheres.

A novel sandwich-type electrochemiluminescence immunosensor based on immobilizing luminol on Ag@BSA core/shell microspheres (Ag@BSA-luminol) for ultrasensitive detection of tumor marker carbohydrate antigen 19-9 (CA19-9) has been developed. Herein, magnetic carbon nanotubes (MAGCNTs) decorated with polyethylenimine (PEI) was used to construct the base of the immunosensor. MAGCNTs with prominent electrical conductivity and high surface area could be beneficial for promoting the electron transfer and loading plenty of primary antibodies (Ab1) via glutaraldehyde (GA). Meanwhile, the magnetic property of MAGCNTs makes it easy to be attached to the surface of magnetic glass carbon electrode (MGCE) through magnetism interaction, which provides an outstanding platform for this immunosensor. Moreover, Ag@BSA microspheres with large surface area, good stability, and excellent biocompatibility were desirable candidates for effective cross-link of CA19-9 detection antibodies (Ab2). A more interesting thing was that ELISA color reaction was used as an ultrasensitive strategy for identifying Ab2 was successfully coated on Ag@BSA with the naked eye. Additionally, we immobilized the luminol on the surface of Ag@BSA to prepare the target immunosensor. Immobilization of luminol on the surface of Ag@BSA could decrease the distance between luminophores and the electrode surface, leading to great enhancement of the ECL intensity of luminol in the present of hydrogen peroxide (H2O2). Under the optimal conditions, the intensity of the ECL immunosensor increased linearly with the logarithm of CA19-9 concentration in a wide linear range from 0.0005 to 150UmL(-1) with a detection limit of 0.0002UmL(-1) (S/N=3). All the results suggested the prepared CA19-9 immunosensor displayed high sensitivity, excellent stability and good specificity. The developed method opened a new avenue to clinical bioassay.

Cationic Dye Removal Ability from Multicomponent System by Magnetic Carbon Nanotubes

In this paper, magnetic carbon nanotubes (MCNT; CNT-CoFe2O4) were synthesized and characterized. MCNT was used to remove cationic dyes from single and multicomponent (ternary) colored systems. Basic Blue 41 (BB41), Basic Red 18 (BR18) and Basic Violet 16 (BV16) were used as cationic dyes. The effects of operational parameters (MCNT dosage, dye concentration and salt) on dye removal were investigated. The adsorption kinetic and isotherm were studied. Dye adsorption kinetics in single and ternary systems followed a pseudo-second order kinetics model. The isotherm data in single and ternary systems followed the Langmuir isotherm. The maximum adsorption capacity (Q0) of BB41, BR18 and BV16 was 95, 94 and 106 mg·g−1, respectively. The results showed MCNT is an effective adsorbent to remove cationic dyes from ternary systems.

ChemInform Abstract: Magnetically Active Carbon Nanotubes at Work

AbstractReview: [preparation and application of hybrid materials of magnetic nanoparticles and carbon nanotubes; 125 refs.

Novel polydopamine imprinting layers coated magnetic carbon nanotubes for specific separation of lysozyme from egg white

Novel core–shell nanocomposites, consisting of magnetic carbon nanotubes (MCNTs) core surrounded by a thin polydopamine (PDA) imprinting shell for specific recognition of lysozyme (Lyz), were fabricated for the first time. The obtained products were characterized and the results showed that the PDA layer was successfully attached onto the surface of MCNTs and the corresponding thickness of imprinting layer was just about 10nm which could enable the template access the recognition cavities easily. The polymerization conditions and adsorption performance of the resultant nanomaterials were investigated in detail. The results indicated that the obtained imprinted polymers showed fast kinetic and high affinity towards Lyz and could be used to specifically separate Lyz from real egg white. In addition, the prepared materials had excellent stability and no obvious deterioration after five adsorption–regeneration cycles. Easy preparation, rapid separation, high binding capacity, and satisfactory selectivity for the template protein make this polymer attractive in biotechnology and biosensors.

Evaluation of Diazinon Adsorption from Water Solutions Using Magnetic Carbon Nano-Tubes with Fe3O4

Background and objective: Insecticides are one of the most important pollutants in water. Diazinon is one of the phosphorus pesticides that can be found in aquatic ecosystems in Iran. The toxic effect of diazinon is inhibition of the enzyme acetyl cholinesterase (Ache). In this study, MWCNT/ Fe3O4 efficiency was investigated. Materials and Methods: In this study, co-precipitation method was used for the Fe3O4 synthesis on multiwall carbon nanotube. The pH, contact time, adsorbent dose, pollutant concentrations and temperature parameters were investigated. Diazinon was measured by Gas chromatography method. Results: The results showed that the optimum conditions for diazinon removal were pH 6, contact time of 15 minutes, andn adsorption dose of 0.6 g/l. So, the absorption efficiency increases with increasing of temperature and decresing of pollutant concentration. The diazinon adsorption corresponded with Freundlich isotherm (R2> 0.99) more than Langmuir isotherm model (R2> 0.90). Conclusion: The results show that the magnetic carbon nanotubes with Fe3O4 can be suitable adsorbent for diazinon removal from aquatic environment.n

Magnetically Active Carbon Nanotubes at Work.

Endohedral and exohedral assembly of magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) recently gave birth to a large body of new hybrid nanomaterials (MNPs-CNTs) featuring properties that are otherwise not in reach with only the graphitic or metallic cores themselves. These materials feature enhanced magnetically guided motions (rotation and translation), magnetic saturation and coercivity, large surface area, and thermal stability. By guiding the reader through the most significant examples in this Concept paper, we describe how researchers in the field engineered and exploited the synergistic combination of these two types of nanoparticles in a large variety of current and potential applications, such as magnetic fluid hyperthermia therapeutics and in magnetic resonance imaging to name a few.

Carbon Nano Tubes Analysis for Blood Flow in Stenosed Tapered Arteries

Blood flow model is recycled to study the influence of magnetic field and carbon nanotubes in stenosed arteries. The carbon nanotubes for the blood flow with water as base fluid is not explored so far. The representation for the blood flow is through an axially nonsymmetrical but radially symmetric stenosis. Symmetry of the distribution of the wall shearing stress and resistive impedance and their growth with the developing stenosis is another important feature of our analysis. Exact solutions have been evaluated for velocity, resistance impedance, wall shear stress and shearing stress at the stenosis throat. The graphical results of different type of tapered arteries (i.e., converging tapering, diverging tapering, nontapered artery) have been examined for different parameters of interest for single wall carbon nanotubes and multiwall carbon nanotubes.

Bioconjugated Iron-Filled Carbon Nanotubes As Cancer Theranostics Agents

Magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) have emerged as two new classes of nanomaterials for simultaneous diagnostics and treatment (theranostics) of cancer. On one hand, MNPs can act as magnetic resonance imaging (MRI) contrast agents, magnetically-driven drug delivery cargoes, filtrations and selective separations of biological entities agents and magnetic fluid hyperthermia (MFH) treatments.[1] On the other hand, CNTs have been used against cancer as intracellular carriers for biologically relevant species[2] thanks to their large surface area and their faculty to penetrate cells or as infrared hyperthermia agents[3], among other possibilities.[4] In order to combine the advantages of both parts, we synthesized in our group a hybrid composed of metallic iron nanoparticles filled in multiwall carbon nanotubes (Fe@CNTs) bioconjugated to the monoclonal antibody (mAb) Cetuximab. CNTs graphitic layers offers a protection against oxidation of iron nanoparticles, keeping them in more magnetically active phases whereas mAb targets epidermal growth factor receptor (EGFR) overexpressing A431 cancer cells. In a pilot study, we showed the in vitro efficiency of Fe@CNTs in selective targeting and elimination of A431 cells over control cell lines via magnetic filtration and hyperthermia.[5] We then studied in detail various Fe@CNTs possessing different phases of iron, in order to correlate their structural and magnetic properties onto their biological performances.[6] In parallel we developed seminal work[7]led by our team about H-bonded supramolecular polymer (SMP) able to wrap around CNTs to exploit the potential of our Fe@CNTs as a non-covalent scaffold. We thus synthesized new pegylated H-bonded supramolecular polymers able to solubilize Fe@CNTs in aqueous media. Moreover, this polymer-CNTs nano-assembly shows interesting properties of reversible wrapping and un-wrapping under thermal stimulus, and is envisaged to be used for simultaneous MFH and triggered drug delivery treatments.

Thermoresponsive and magnetic molecularly imprinted polymers based on iron oxide encapsulated carbon nanotubes as a matrix for the selective adsorption and controlled release of 2,4,5‐trichlorophenol

ABSTRACTThermoresponsive and magnetic molecularly imprinted polymers (TMMIPs) based on magnetic carbon nanotubes (MCNTs) were prepared and applied to the switched recognition and controlled release of 2,4,5‐trichlorophenol (2,4,5‐TCP) from aqueous solution. In this study, MCNTs were first synthesized via the encapsulation of Fe3O4 nanoparticles into the tunnel of carbon nanotubes by a wet impregnation technology. Then, the TMMIPs were synthesized with N‐isopropyl acrylamide as a thermal functional monomer by free‐radical polymerization. The magnetic sensitivity and stability of the prepared materials were tested with a vibrating sample magnetometer (saturation magnetization = 1.4 emu/g) and atomic absorption spectrophotometer (in the pH range 3.0–8.0), respectively. The thermoresponsive properties of the TMMIPs were evaluated by two means, including the results of ultraviolet–visible spectroscopy and the controlled release of 2,4,5‐TCP at 30 and 40°C, respectively. The effects of the pH, initial concentration, and contact time on adsorption were examined with batch mode experiments, and several other compounds were selected as model analytes to evaluate the selective recognition performance of the TMMIPs. This demonstrated that the TMMIPs had a higher affinity for 2,4,5‐TCP than did the thermoresponsive and magnetic nonimprinted polymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42087.

Rapid microwave-assisted regeneration of magnetic carbon nanotubes loaded with p-nitrophenol

A novel magnetic carbon nanotubes (CNTs) adsorbent with good sorption, magnetic separability, and microwave (MW) regeneration properties was prepared successfully using thermal decomposition. The magnetic CNTs were characterized using transmission electron microscopy, energy dispersive X-ray, nitrogen adsorption (Brunauer–Emmett–Teller surface area), and X-ray diffraction and their magnetic properties were measured using a vibrating sample magnetometer. Magnetic nanoparticles (≈10nm diameter) were dispersed uniformly on the CNTs with a magnetic CNTs surface area of 146.7m2g−1 and a saturation magnetization of 21.11emug−1. When the magnetic CNTs were used in the sorption of p-nitrophenol, the equilibrium time was 20min and the sorption isotherms fit the Freundlich isotherm well. The spent magnetic CNTs could be separated magnetically and be regenerated by MW irradiation. After six adsorption and MW regeneration cycles (at 850W for 180s), the adsorption capacity of the magnetic CNTs was higher than that of the virgin magnetic CNTs with a low carbon loss.

Magnetic N-doped carbon nanotubes: A versatile and efficient material for the determination of polycyclic aromatic hydrocarbons in environmental water samples

This paper describes a new, efficient and versatile method for the sampling and preconcentration of PAH in environmental water matrices using special hybrid magnetic carbon nanotubes. These N-doped amphiphilic CNT can be easily dispersed in any aqueous matrix due to the N containing hydrophilic part and at the same time show high efficiency for the adsorption of different PAH contaminants due to the very hydrophobic surface. After adsorption, the CNT can be easily removed from the medium by a simple magnetic separation. GC/MS analyses showed that the CNT method is more efficient than the use of polydimethylsiloxane (PDMS) with much lower solvent consumption, technical simplicity and time, showing good linearity (range 0.18–80.00μgL−1) and determination coefficient (R2>0.9810). The limit of detection ranged from 0.05 to 0.42μgL−1 with limit of quantification from 0.18 to 1.40μgL−1. Recovery (n=9) ranged from 80.50±10 to 105.40±12%. Intraday precision (RSD, n=9) ranged from 1.91 to 9.01%, whereas inter day precision (RSD, n=9) ranged from 7.02 to 17.94%. The method was applied to the analyses of PAH in four lake water samples collected in Belo Horizonte City, Brazil.

Applications of magnetic surface imprinted materials for solid phase extraction of levofloxacin in serum samples.

In this work, molecularly imprinted magnetic carbon nanotubes (MCNTs@MIPs) was prepared with surface imprinting technique for extraction of levofloxacin in serum samples. The preparation of molecularly imprinted polymers (MIPs) used levofloxacin as template, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross-linker, and the magnetic carbon nanotubes (MCNTs) was synthesized by solvothermal method. The prepared polymers not only can be separated and collected easily by an external magnetic, but also exhibited high specific surface area and high selectivity to template molecules. Kinetic adsorption and static adsorption capacity investigations indicated that the synthesized MCNTs@MIPs had excellent recognition towards levofloxacin. Furthermore, magnetic solid phase extraction (MSPE) using the prepared MCNTs@MIPs as sorbent was then investigated, and an efficient sample cleanup was obtained with recoveries ranged from 78.7 ± 4.8 % to 83.4 ± 4.1%. In addition, several parameters, including the pH of samples, the amount of MCNTs@MIPs, the adsorption and desorption times, and the eluent, were investigated to obtain optimal extraction efficiency. Under the optimal extraction conditions, the stability of the polymer was also evaluated, and the average recovery reduced less than 7.6% after 5 cycles. MCNTs@MIPs successfully applied in the preconcentration and determination of levofloxacin in serum sample suggested that the MSPE method based on the novel polymers could be a promising alternative for selective and efficient extraction of trace amounts of pharmaceutical substances in bio-matrix samples.