In this work, superparamagnetic Fe3O4 nanoparticles were synthesized by chemical co-precipitation using ionic liquid of 1-Butyl-3-methylimidazolium tetrafluoroborate (BMINBF4) as templates. Then, the ...magnetic Fe3O4 nanoparticles were treated with 3-aminopropyltriethoxysilane (APTES) and obtain the surface amino-functionalized magnetic nanoparticles (APTES-Fe3O4) were used as immobilization material. Lipase was covalently bound to the APTES-Fe3O4 magnetic nanoparticles by using glutaraldehyde as a coupling reagent. A fatty acid methyl ester (FAME) conversion of 89.4% could be achieved by lipase immobilized on APTES-Fe3O4 magnetic nanoparticles under optimized conditions of methanol-oil molar ratio of 6:1, with a catalyst dose of 20%, 2% water content and 250 rpm agitation speed at 45 °C for 24 h. The FAME conversion remained greater than 70% even after reusing the catalyst for 5 reactions. In addition, the lipases immobilized on APTES-Fe3O4 magnetic nanoparticles could be recovered easily by external magnetic field for further use.
The redox cycle of iron is a well-known rate-determining step for hydroxyl radical generation in photo-Fenton system. In this study, oxalate was employed as regulator to enhance the degradation of ...Orange II in Fe3O4 magnetic nanoparticles (NPs)-catalyzed heterogeneous UV-Fenton system. Results showed that the oxalate could interact with the surface ≡FeIII species of catalyst, which weakened the bond of ≡FeIII–O and promoted the leaching of iron ions. Then the redox cycle of iron and generation of HO· would be accelerated via the homogeneous UV-Fenton reaction. The degradation rate constant of Orange II reached 0.220 min−1 when additional oxalate concentration was 0.4 mM, which was 2.5 times as high as that without oxalate in heterogeneous UV-Fenton system. In this case, the removal efficiencies of color and TOC were 99.3% and 92.0% after 30 and 120 min treatment, respectively. In addition, based on the results of XRD and XPS characterization, it could be deduced that the crystal structure and elemental configuration of Fe3O4 magnetic nanoparticles could be maintained after reaction. Besides, the results of FTIR and magnetization characterization indicated that the C2O42− on surface of catalyst could be degraded and the catalyst could be easily separated from aqueous by applying an external magnetic field. The Fe3O4 magnetic nanoparticles showed high catalytic stability and reusability under the regulation of oxalate due to the fact that the leached iron ions could be re-adsorbed on the catalyst after treatment.
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•Oxalate enhanced Orange II degradation in heterogeneous UV-Fenton system.•Oxalate interact with surface ≡FeIII species result in abundant iron leaching.•HO· generation was facilitated due to fast redox cycle of iron.•Fe3O4 NPs showed high catalytic stability and reusability under modification of oxalate.
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•Magnetic porous biochar supported La(OH)3 was synthesized via a hydrothermal process.•La3-MPBC had high adsorption capacity (116.08 mg P/g) and fast adsorption kinetics.•La3-MPBC was ...easily separated by magnet force with negligible La and Fe leakages.•La3-MPBC had excellent reusability and selectivity to P among competing anions.•Efficient low-concentration P removal from nature water and wastewater was achieved.
Herein, La(OH)3 decorated magnetic porous biochar (MPBC) was synthesized via KHCO3 activation and hydrothermal processes. The La-to-MPBC mass ratio of 3:1 described as La3-MPBC possessed a monolayer phosphate adsorption capacity of 116.08 mg/g across a pH range of 3.0–6.0 with fast attainment of adsorption equilibrium in 150 min. Moreover, the phosphate adsorption was substantially stable during the interference of various co-existing ions with over 92% of phosphate removal and 77% of desorption efficiency maintained after four recycles. And La3-MPBC was easily separated by magnet force with negligible La and Fe leakages within the pH range of 3.0–10.0. Furthermore, La3-MPBC was supported to achieve phosphate binding through the synergistic actions of electrostatic attraction, ligand exchange, inner-sphere complexation and weak precipitation. Significantly, La3-MPBC exhibited a high performance for decontaminating low-concentration phosphate to meet regulatory requirements. All these results suggested La3-MPBC to be an ideal candidate for phosphate removal in real applications.
Adsorption isotherm of OPP–Cd
2+, MNP–Cd
2+ and MNP–OPP–Cd
2+.
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► A novel low cost MNP–OPP was developed for cadmium removal from aqueous solutions. ► Superior efficiency and kinetics ...were demonstrated as compared to parent adsorbents. ► Cadmium removal result from simulated electroplating industry effluent is promising. ► Desorption and reusability without loss of efficiency showed its practical utility. ► Additional benefits like easy synthesis, recovery, and environmental friendliness.
An agricultural waste-orange peel powder (OPP) was successfully modified into a novel magnetic nano-adsorbent (MNP–OPP) by co-precipitating it with Fe
3O
4 nanoparticles (MNP) for cadmium ion removal from aqueous solutions. Characterization of MNP–OPP by FTIR, SEM, XRD, TEM and VSM revealed the covalent binding of hydroxyl groups of MNP with the carboxyl groups of OPP, and further confirmed its physico-chemical properties favorable for metal binding. The cadmium adsorption onto MNP–OPP, MNP and OPP was tested under different pH, ionic strength, natural organic matter, adsorbate concentration, contact time and temperature conditions. Results revealed a faster kinetics and efficiency of MNP–OPP in comparison to those of MNP and OPP and further confirmed a complexation and ion exchange mechanism to be operative in metal binding. The adsorption equilibrium data obeyed the Langmuir model and the kinetic data were well described by the pseudo-second-order model. Thermodynamic studies revealed the feasibility and endothermic nature of the system. Breakthrough capacity from column experiments, adequate desorption as well as reusability without significant loss of efficiency established the practicality of the developed system. Cadmium removal was achieved at 82% from a simulated electroplating industry wastewater. The experimental results reveal the technical feasibility of MNP–OPP, its easy synthesis, recovery, economic, eco-friendly and a promising advanced adsorbent in environmental pollution cleanup.
Peripheral nerve injury is a common clinical problem bringing heavy burden to patients, due to its high incidence and unsatisfactory treatment. Nerve guidance conduit (NGC) is a promising scaffold ...for peripheral nerve repair, and bioactive agents are applied for great functional recovery. Melatonin (MLT) and Fe3O4 magnetic nanoparticles (Fe3O4‐MNPs) are proven to inhibit oxidative stress, inflammation, and induce nerve regeneration. Herein, a multilayered composite NGC loaded with MLT and Fe3O4‐MNPs is designed for sequential and sustainable drug release, creating an appropriate microenvironment for nerve regeneration. The composite scaffold shows sufficient mechanical strength and biocompatibility in vitro, and evidently promotes morphological, functional, and electrophysiological recovery of regenerated sciatic nerves in vivo. This work proves that the multilayered conduits show great prospect in the long‐term nerve defects treatment due to easy manufacture and desired efficacy.
A multilayered composite scaffold loaded with melatonin (MLT) and Fe3O4‐MNPs is fabricated by electrospinning, which possesses good biocompatibility and proper stiffness. MLT inhibits oxidative stress and inflammation, while Fe3O4‐MNPs induces neurite regrowth. Sequential and sustainable release of bioactive agents provides an appropriate microenvironment for the long‐term treatment of nerve transections, showing great performance in nerve regeneration and functional recovery.
Magnetic nanoparticle-based drug delivery systems (MDDSs) are gaining popularity over other known systems due to their superior biocompatibility and versatile loading capabilities. MDDSs are ...generally made up of iron oxide (Fe3O4, Fe2O3, etc.) superparamagnetic nanoparticles. Organic or inorganic alterations can be used to functionalize their surface for effective control over and drug delivery to the targeted place. The mechanism of MDDSs is more advanced than other drug delivery systems due to their strong targeting power and lesser side effects. MDDSs can be created by targeted ligand assembling, magnetic nanoparticle assemblage and loading of drugs. Magnetic nanoparticles (MNPs) and associated assemblages are reported as one of the innovative delivery methods due to their sensitive responsiveness to external magnetic fields. This paper is focused on magnetic and physicochemical properties of the ideal systems designed for drug delivery that fit in the criteria of unique medical applications. The surface alterations and functionalization concerns that come up when building complicated MDDSs for future clinical application are also discussed in this article. Finally, this discussion includes surface coating of magnetic nanoparticles with polymers, liposomes, silica etc. for their use as MDDSs in cancer detection and therapy. This study also highlights the challenges and latest developments in MDDSs delivery systems.
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CuFe2O4 MNPs possess excellent catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 with the bleaching of the yellow color of the reaction solution. Display ...omitted
► CuFe2O4 MNPs is an outstanding catalyst for the reduction of nitrophenol. ► CuFe2O4 MNPs possess higher catalytic activity than other nanocatalysts. ► The rate constant kapp for the reduction of 4-NP by CuFe2O4 MNPs is 0.12s−1.
In this paper, we discovered that CuFe2O4 magnetic nanoparticles (MNPs) possessed high catalytic performance in the reduction of nitrophenol for the first time. The as-prepared CuFe2O4 MNPs exhibited several advantages such as stability, monodispersity, low-cost, simplicity and rapid separation performance over other catalysts for the reduction of nitrophenol. The CuFe2O4 MNPs showed high efficiency in the catalytic reduction of 4-nitrophenol to 4-aminophenol with the conversion of 95% within 40s in the presence of NaBH4. The pseudo-first-order kinetic equation could describe the reduction of 4-nitrophenol with the excess amount of NaBH4.
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•The magnetic COFs was prepared by ball milling method.•The magnetic COFs showed high superparamagnetic properties.•Fenton-like catalytic activity of magnetic COFs was higher than ...other catalysts.•The heterogeneous and homogeneous Fenton reaction mechanism was also explored.•It provides a new strategy for magnetic COFs prepared by ball milling method.
The practical application of covalent organic frameworks (COFs) is limited because of the difficulties in rapid separation. This issue is expected to be solved with the emergence of magnetic nanoparticles. However, it remains challenging to quickly prepare magnetic COFs with high catalytic activity. In this study, a magnetic COF material (Fe3O4@TpMA) was prepared using a ball milling method based on grinding amino-functionalized magnetic nanoparticles (Fe3O4-NH2) and COFs (TpMA). The -C = N bond were as a bridge between Fe3O4 and COFs. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) characterizations showed that the doping of Fe3O4 nanoparticles did not destroy the structure of the COFs. In addition, Fe3O4@TpMA exhibited excellent superparamagnetic properties that were conducive to the magnetic separation of pollutants and catalysts. In the Fe3O4@TpMA + H2O2 system, 88.1% of methyl orange (MO) was degraded within 40 min. The degradation rate of MO in the Fe3O4@TpMA + H2O2 system was 4.2, 8.0, and 11.8 times that in the Fe3O4-NH2 + H2O2, TpMA + H2O2, and mixed material (Fe3O4-NH2/TpMA) + H2O2 systems, respectively. Furthermore, experimental parameters such as pollutant concentration, and catalyst dosage played an important role in the degradation of MO. The Fe3O4@TpMA catalyst also achieved highly efficient degradation of MO under weakly acidic conditions (pH = 6.38). The degradation mechanism is complex, involving the heterogeneous Fenton mechanism as the main step, and the homogeneous Fenton mechanism as the auxiliary step. This study aims to provide a new strategy for the preparation of magnetic COFs via mechanical grinding.
Because of the serological cross-reactivity among the flaviviruses, molecular detection methods, such as reverse-transcription polymerase chain reaction (RT-PCR), play an important role in the recent ...Zika outbreak. However, due to the limited sensitivity, the detection window of RT-PCR for Zika viremia is only about one week after symptom onset. By combining loop-mediated isothermal amplification (LAMP) and AC susceptometry, we demonstrate a rapid and homogeneous detection system for the Zika virus oligonucleotide. Streptavidin-magnetic nanoparticles (streptavidin-MNPs) are premixed with LAMP reagents including the analyte and biotinylated primers, and their hydrodynamic volumes are dramatically increased after a successful LAMP reaction. Analyzed by a portable AC susceptometer, the changes of the hydrodynamic volume are probed as Brownian relaxation frequency shifts, which can be used to quantify the Zika virus oligonucleotide. The proposed detection system can recognize 1 aM synthetic Zika virus oligonucleotide in 20% serum with a total assay time of 27min, which can hopefully widen the detection window for Zika viremia and is therefore promising in worldwide Zika fever control.
•Synthetic Zika virus oligonucleotide is quantified by an AC susceptometer.•Amplicons of the LAMP reaction are attached to the magnetic nanoparticles.•Mg2P2O7 deposits onto the nanoparticles and further improves the signal.•An LOD of 1 aM oligos can be achieved with a total assay time of 27min.
Abstract It is becoming progressively more understandable that sensitivity and versatility of magnetic biosensors provides unique platform for high performance diagnostics in clinical settings. ...Confluence of information suggested that magnetic biosensors required well-tailored magnetic particles as probes for detection that generate large and specific biological signal with minimum possible nonspecific binding. However, there are visible knowledge gaps in our understanding of the strategies to overcome existing challenges related to even smaller size of intracellular targets and lower signal-to-noise ratio than that in whole-cell studies, therefore tool designing and development for intracellular measurement and manipulation is problematic. In this review we describe magnetic nanoparticles, synthesis and sensing principles of magnetic nanoparticles as well as surface functionalization and modification and finally magnetic nanoparticles for medical diagnostics. This review gathers important and up-to-date information and may help to develop the method of obtaining magnetic materials especially for medical application.
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