Magnetic Nanofibers Research Articles

Mussel‐Inspired Electrospun Smart Magnetic Nanofibers for Hyperthermic Chemotherapy

A method for the versatile synthesis of novel, mussel‐inspired, electrospun nanofibers with catechol moieties is reported. These mussel‐inspired nanofibers are used to bind iron oxide nanoparticles (IONPs) and the borate‐containing anticancer drug Bortezomib (BTZ) through a catechol metal binding mechanism adapted from nature. These smart nanofibers exhibit a unique conjugation of Bortezomib to their 1, 2‐benzenediol (catechol) moieties for enabling a pH‐dependent drug delivery towards the cancer cells and the IONPs via strong coordination bonds for exploiting the repeated application of hyperthermia. Thus the synergistic anticancer effect of these mussel‐inspired magnetic nanofibers were tested in vitro for the repeated application of hyperthermia along with the chemotherapy and found that the drug‐bound catecholic magnetic nanofibers exhibited excellent therapeutic efficacy for potential anticancer treatment.

Removal of oil from water using magnetic bicomponent composite nanofibers fabricated by electrospinning

In the present study, a magnetic nanofibrous composite mat composed of polystyrene (PS)/polyvinylidene fluoride (PVDF) nanofibers with selective incorporation of iron oxide (Fe3O4) nanoparticles (NPs) on/in PS was successfully prepared via a facile two-nozzle electrospinning process for oil-in-water separation. Field emission scanning electron microscopy and infrared spectroscopy showed the mats to be highly-porous in structure and confirmed the presence of the Fe3O4 NPs on/in the nanofibers. Both PS and PVDF nanofibers exhibited oleophilic and hydrophobic properties. The results showed improved mechanical properties when PVDF was added to the composite mat compared to the pristine PS mat. In addition, the incorporation of magnetic Fe3O4 NPs in the composite mat helps in the easy recovery of the mats after the oil-in-water sorption process. The composite mats showed good oil sorption capacity (35–46 g/g) and improved mechanical property. The present electrospun magnetic PVDF/Fe3O4@PS nanofibers could be potentially useful for the efficient removal of oil in water and recovery of sorbent material.

A novel method to fabricate CoFe2O4/SrFe12O19 composite ferrite nanofibers with enhanced exchange coupling effect.

Nanocomposite of CoFe2O4/SrFe12O19 has been synthesized by the electrospinning and calcination process. A novel method that cobalt powder was used to replace traditional cobalt salt in the precursor sol-gel for electrospinning was proposed. The crystal structures, morphologies, and magnetic properties of these samples have been characterized in detail. Moreover, when the average crystallite size of the hard/soft phases reached up to an optimal value, the CoFe2O4 have an enhanced saturation magnetization of 62.8 emu/g and a coercivity of 2,290 Oe. Significantly, the hysteresis loops for the nanocomposites show a single-phase magnetization behavior, and it has been found that the exchange coupling interaction strongly exists in the CoFe2O4/SrFe12O19 magnetic nanocomposite nanofibers.

Application of response surface methodology in optimization of electrospinning process to fabricate (ferrofluid/polyvinyl alcohol) magnetic nanofibers.

Magnetic nanofibers are composed of good dispersion of magnetic nanoparticles along an organic material. Magnetic nanofibers are potentially useful for composite reinforcement, bio-medical and tissue engineering. Nanofibers with the thinner diameter have to result in higher rigidity and tensile strength due to better alignments of lamellae along the fiber axis. In this study, the performance of electrospinning process was explained using response surface methodology (RSM) during fabrication of magnetic nanofibers using polyvinyl alcohol (PVA) as a shelter for (γ-Fe2O3) nanoparticles where the parameters investigated were flow rate, applied voltage, distance between needle and collector and collector rotating speed. The response variable was diameter distribution. The two parameters flow rate and applied voltage in primary evaluation were distinguished as significant factors. Central composite design was applied to optimize the variable of diameter distribution. Quadratic estimated model developed for diameter distribution indicated the optimum conditions to be flow rate of 0.25 ml/h at voltage of 45 kV while the distance and rotating speed are at 8 cm and 1500 rps respectively. The obtained model was verified successfully by the confirmation experiments.

Room temperature ferromagnetism in Co-doped CuAlO2 nanofibers fabricated by electrospinning

One-dimensional, diluted magnetic semiconductor nanofibers have attracted increasing attention for their unique magnetic properties, large specific surface area, and high porosity. These qualities lead to excellent performance in magneto-optical devices, magnetic resonance imaging, ferrofluids and magnetic separation. The purpose of this study is to fabricate P-type one dimensional CuAlO2-based diluted magnetic semiconductor nanofibers. First, we fabricated CuAl0.95Co0.05O2 nanofibers with an average diameter of 1 μm with the electrospinning method. The annealed nanofibers were thermally treated at a temperature of 1 100 °C and then shrunk to a diameter of about 650 nm. We used X-ray diffraction measurements and Raman spectra to confirm that the CuAl0.95Co0.05O2 nanofibers had a single impurity free delafossite phase. The X-ray photoelectron spectroscopy analysis indicates that Co was present in the +2 oxidation state, resulting in an room temperature ferromagnetism in the CuAl0.95Co0.05O2 fiber. This contrasts with nonmagnetism in pristine CuAlO2 fiber. The coercivity (H c) value of 65.26 Oe and approximate saturation magnetization (M s) of 0.012 emu/g demonstrate good evidence of ferromagnetism at room temperature for CuAl0.95Co0.05O2 nanofibers.

Visualization of Magnetic Nanofibers Using Magnetic Particle Imaging

Purpose: Magnetic nanofibers (MNFs) are nanofibers impregnated with magnetic nanoparticles (MNPs). Magnetic particle imaging (MPI) is a recently introduced imaging method that allows im-aging of the spatial distribution of MNPs. The purpose of this study was to develop MNFs and to investigate the feasibility of visualizing them using MPI and of heating them using an alternating magnetic field (AMF). Materials and Methods: First, chitosan nanofibers were cross-linked with glu-taraldehyde vapor in a sealed vial for 24 hours. Next, they were mixed with various concentrations of MNPs and the mixture was stirred for 1 hour using a magnetic stirrer. After the mixture was re-frigerated at –80℃ for 24 hours, it was freeze-dried for 24 hours. The morphology of the resultant MNFs was characterized by scanning electron microscopy, and the magnetic properties were meas-ured using a vibrating sample magnetometer. After these measurements, we imaged the MNFs us-ing our MPI scanner, and investigated the correlation between the pixel values of the MPI image and the concentration of MNPs or the number of MNF sheets. We also heated the MNFs using AMF, and measured the temperature rise using an infrared thermometer. Results: The MNFs were suc-cessfully visualized using our MPI scanner, and the pixel values of the MPI image showed excellent correlation with the concentration of MNPs (r = 0.992) and the number of MNF sheets (r = 0.997). A significant temperature rise was observed under AMF, and the initial slope of the time-dependent temperature rise showed excellent correlation with the concentration of MNPs (r = 0.994) and the number of MNF sheets (r = 0.979). Conclusion: The MNFs developed in this study can be visualized using MPI and can be applied to magnetic hyperthermia. They will be useful in biomedicine including cancer therapy and tissue regeneration.

Synthesis and characterization of vinyl-functionalized magnetic nanofibers for protein imprinting.

One kind of surface protein imprinting method was developed by a more convenient, simpler and cheaper approach based on vinyl-functionalized magnetic nanofibers (NFs).

Magnetic BaFe12O19 nanofiber filter for effective separation of Fe3O4 nanoparticles and removal of arsenic

Magnetic nanoparticles are promising in applications where magnetic separation is intended, although material losses via leaching mechanisms are often inevitable. Magnetic separations with widely available permanent magnets can effectively trap particles, leading to a complete removal of used or waste particles. In this report, we first demonstrate the synthesis of the thinnest (112.7 ± 16.4 nm) and most magnetic (71.96 emu g−1) barium hexaferrite (BaFe12O19, BHF—fridge magnet) via an organic solvent-free electrospinning procedure. When the fibers are then packed into a column, they clearly remove 12 nm magnetite (Fe3O4) nanoparticles quantitatively. The same BHF cartridge also removes more than 99.9 % As-treated magnetite nanoparticles at capacities up to 70 times of its weight. As a result, one liter of 150 μg L−1 As-contaminated water can be purified rapidly at a material cost of less than 2 US cents.

Coaxial nanofibers to help achieve tunable and enhanced simultaneous magnetic-luminescent bifunctionality

A new nanostructure of CoFe2O4@Y2O3:5 %Tb3+ magnetic-luminescent bifunctional coaxial nanofibers has been successfully fabricated via electrospinning technology using a homemade coaxial spinneret. The morphologies, structures, magnetic and luminescent properties of the final products were investigated in detail by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, and fluorescence spectroscopy. The results show the CoFe2O4@Y2O3:5 %Tb3+ magnetic-luminescent bifunctional coaxial nanofibers simultaneously possess superior magnetic and luminescent properties due to isolating Y2O3:5 %Tb3+ luminescence center from CoFe2O4 magnetic nanofibers. Furthermore, the luminescent intensity and color of the coaxial nanofibers can be tuned via adjusting the concentrations of rare earth ions. The bifunctional magnetic-luminescent CoFe2O4@Y2O3:5 %Tb3+ coaxial nanofibers have potential applications in biomedical area, such as drug-delivery systems, cell labeling and separation, enhancement for magnetic resonance imaging, and subsequent optical identification. More importantly, the design conception and construction technology are of universal significance to fabricate other bifunctional coaxial nanofibers.

Iron oxide nanofibers: A new magnetic catalyst for azo dyes degradation in aqueous solution

In this study, a simple and novel magnetic α-Fe2O3 nanofibers were successfully synthesized by electrospinning of a solution of polyvinyl alcohol (PVA) and Fe(NO3)3·9H2O composite nanofibers followed by calcinations. These nanostructures were used as heterogeneous iron Fenton catalyst for the effective degradation and decolorization of methyl orange (MO) in aqueous solution. The initial and final concentrations of MO were determined using a UV–visible spectrophotometer. The morphologies and structures of the nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The average diameter of magnetic α-Fe2O3 nanofibers was between 50 and 90nm. The effect of different variables on the decolorization efficiency was studied simultaneously using an experimental design. The variables of interest were as concentration of methyl orange, and H2O2, amount of catalyst, pH, temperature and time of decolorization. A Plackett–Burman design was performed for screening in order to determine the significant variables affecting the decolorization efficiency. Then, the significant factors were optimized by a Box–Behnken design (BBD) and the response surface equations were derived. Under the optimum conditions, the decolorization efficiency of methyl orange using α-Fe2O3 nanofibers was >99% in a short period time of 10min. Finally, the developed process was successfully applied for degradation and decolorization of MO using magnetic α-Fe2O3 nanofibers as a catalyst in waste water samples.

Magnetorheology of dimorphic magnetorheological fluids based on nanofibers

We report a systematic experimental investigation on the use of nanofibers to enhance the magnetorheological (MR) effect in conventional (microsphere-based) MR fluids formulated in polyalphaolefin oil/1-octanol. Two kinds of nanofibers are employed that have very similar morphology but very different magnetic properties. On the one hand we use non-magnetic goethite nanofibers. On the other hand we employ magnetic chromium dioxide nanofibers. For appropriate concentrations the on-state relative yield stress increases up to 80% when incorporating the nanofibers in the formulation. A similar yield stress enhancement is found for both nanofibers investigated (magnetic and non-magnetic) suggesting that the main factor behind this MR enhancement is the particle shape anisotropy. The relative yield stresses obtained by partial substitution of carbonyl iron particles with nanofibers are significantly larger than those measured in previous works on MR fluids formulated by partial substitution with non-magnetic micronsized spherical particles. We also demonstrate that these dimorphic MR fluids also exhibit remarkably larger long-term sedimentation stability while keeping the same penetration and redispersibility characteristics.

Magnetic composite nanofibers fabricated by electrospinning of Fe 3 O 4 /gelatin aqueous solutions

We have fabricated magnetic composite nanofibers containing superparamagnetic Fe3O4 nanoparticles by the electrospinning method. Highly dispersed Fe3O4 magnetic nanoparticles were synthesized by one-step co-precipitation of Fe2+/Fe3+ under an alkaline condition with 4 wt% poly(vinyl alcohol) (PVA) aqueous solution as the stabilizer. Gelatin (GE) was used as a polymeric matrix for fabricating the nanocomposites. The prepared Fe3O4/GE composite nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. These composite nanofibers show uniform and continuous morphology with the Fe3O4 nanoparticles embedded in the nanofibers. By studying the magnetic properties of the Fe3O4/GE composite nanofibers, we confirm that the composite nanofibers possess superparamagnetic properties with a high saturated magnetization (Ms = 12.87 emμ g−1) at room temperature. The features of this approach for getting one-dimensional magnetic nanostructure are its simplicity, effectiveness and safety. The Fe3O4/GE nanofibers with superparamagnetic properties would be potentially applied in biomedical field.

Coaxial-electrospun magnetic core-shell Fe@TiSi nanofibers for the rapid purification of typical dye wastewater.

Magnetic mesoporous γ-Fe2O3@Ti0.9Si0.1O2 (abbreviated as Fe@TiSi) core-shell nanofibers were prepared using sol-gel chemistry combined with coaxial-electrospinning technology by adjusting the inner and outer feed ratios. The properties of these novel core-shell nanofibers were characterized by SEM, HRTEM, XRD, FTIR, BET, XPS, and UV-vis spectra. To evaluate the chemical properties of the nanofibers for cleaning typical organic wastewater, methylene blue (MB) was used as a target organic pollutant and was cleaned under irradiation with sunlight and visible light. The Fe@TiSi hierarchical nanofibers composed of a 1:10 feed ratio displayed a mesoporous structure and showed the highest photocatalytic activity for the degradation of MB in water. Furthermore, 86.8% and 71.1% of the MB, which was added at an original concentration of 1 mg/L, was removed after 60 min of irradiation with sunlight and visible light in the presence of Fe@TiSi at a concentration of 0.2 g/L, and 100% of the MB was removed after 75 min. It is very important that the magnetic nanofibers could be recycled rapidly with an outside magnet, and the actual water treatment process was easy to achieve. Moreover, the mechanism of MB degradation by Fe@TiSi core-shell nanofibers was proposed.

Influence of Process Factors on Diameter of Core (γ-Fe2O3)/Shell (Polyvinyl Alcohol) Structure Magnetic Nanofibers During Co-Axial Electrospinning

In this study, magnetic nanofibers were fabricated using polyvinyl alcohol (PVA) as a shelter for (γ-Fe2O3) magnetic nanoparticles suspension. Two-level full factorial experiments with center and augmented axial points were performed where process parameters studied were flow rate, applied voltage, distance between needle and collector, and collector rotating speed. The response variables analyzed were morphology and fiber diameter distribution. The model obtained from the experimental design revealed that the flow rate, voltage, the two-way interaction of these factors and the second order effect of flow rate-A2 were significant in determining nanofiber diameters. Nanofibers with smaller diameters tend to have higher tensile strength contributed by the better alignment of lamellae along the fibers axis and molecular orientation. The fabricated (γ-Fe2O3)/PVA nanofibers were ultra-fine with nano size diameter within the range of approximately 280–500 nm.

Flexible Coaxial Nanofibers: A Strategy to Realize Tunable and Enhanced Magnetic‐Luminescent Bifunctionality

AbstractA new flexible nanostructure of [CoFe2O4/PVP]@[YAG:7 %Tb3+/PVP] magnetic‐luminescent bifunctional coaxial nanofibers is fabricated successfully by electrospinning technology using a homemade coaxial spinneret. The morphologies, structures, and magnetic and luminescent properties of the final products are investigated by modern determination techniques. The results show that the coaxial nanofibers simultaneously provide better magnetic and luminescent properties than CoFe2O4/YAG:7 %Tb3+/PVP composite nanofibers owing to the isolation of the YAG:7 %Tb3+ luminescent nanofibers from the CoFe2O4 magnetic nanofibers. Furthermore, the luminescent characteristics and saturation magnetizations of the coaxial nanofibers can be tuned by adjusting the contents of luminescent and magnetic compounds. The formation mechanism of coaxial nanofibers is also presented. More importantly, the design concept and construction technology are of universal significance for the fabrication of other bifunctional coaxial nanofibers.

Flexible Janus nanofiber to acquire tuned and enhanced simultaneous magnetism-luminescence bifunctionality

A novel nanostructure of [CoFe2O4/PVP]//[YAG:7 % Tb3+/PVP] magnetic-luminescent bifunctional Janus nanofibers has been successfully fabricated via electrospinning technology using a homemade parallel spinneret. Electrospun YAG:7 % Tb3+ luminescent nanofibers and CoFe2O4 magnetic nanofibers were respectively incorporated into polyvinyl pyrrolidone (PVP) matrix and electrospun into Janus nanofibers with CoFe2O4 magnetic nanofibers/PVP as one strand nanofiber and YAG:7 % Tb3+ luminescent nanofibers/PVP as another strand nanofiber. [CoFe2O4/PVP]//[YAG:7 % Tb3+/PVP] magnetic-luminescent bifunctional Janus nanofibers possess superior magnetic and luminescent properties due to their peculiar nanostructure, and the luminescent characteristics and saturation magnetizations of the Janus nanofibers can be tuned by adding various amounts of YAG:7 % Tb3+ luminescent nanofibers and CoFe2O4 magnetic nanofibers. Compared with CoFe2O4/YAG:7 % Tb3+/PVP composite nanofibers, the magnetic-luminescent bifunctional Janus nanofibers provide higher performances due to isolating YAG:7 %Tb3+ luminescent nanofibers from CoFe2O4 magnetic nanofibers. Formation mechanism of [CoFe2O4/PVP]//[YAG:7 % Tb3+/PVP] Janus nanofibers is also presented. The design conception and construction technology are of universal significance to fabricate other bifunctional Janus nanofibers.

Potential of Magnetic Nanofiber Scaffolds with Mechanical and Biological Properties Applicable for Bone Regeneration

Magnetic nanofibrous scaffolds of poly(caprolactone) (PCL) incorporating magnetic nanoparticles (MNP) were produced, and their effects on physico-chemical, mechanical and biological properties were extensively addressed to find efficacy for bone regeneration purpose. MNPs 12 nm in diameter were citrated and evenly distributed in PCL solutions up to 20% and then were electrospun into nonwoven nanofibrous webs. Incorporation of MNPs greatly improved the hydrophilicity of the nanofibers. Tensile mechanical properties of the nanofibers (tensile strength, yield strength, elastic modulus and elongation) were significantly enhanced with the addition of MNPs up to 15%. In particular, the tensile strength increase was as high as ∼25 MPa at 15% MNPs vs. ∼10 MPa in pure PCL. PCL-MNP nanofibers exhibited magnetic behaviors, with a high saturation point and hysteresis loop area, which increased gradually with MNP content. The incorporation of MNPs substantially increased the degradation of the nanofibers, with a weight loss of ∼20% in pure PCL, ∼45% in 10% MNPs and ∼60% in 20% MNPs. Apatite forming ability of the nanofibers tested in vitro in simulated body fluid confirmed the substantial improvement gained by the addition of MNPs. Osteoblastic cells favored the MNPs-incorporated nanofibers with significantly improved initial cell adhesion and subsequent penetration through the nanofibers, compared to pure PCL. Alkaline phosphatase activity and expression of genes associated with bone (collagen I, osteopontin and bone sialoprotein) were significantly up-regulated in cells cultured on PCL-MNP nanofibers than those on pure PCL. PCL-MNP nanofibers subcutaneously implanted in rats exhibited minimal adverse tissue reactions, while inducing substantial neoblood vessel formation, which however, greatly limited in pure PCL. In vivo study in radial segmental defects also signified the bone regeneration ability of the PCL-MNP nanofibrous scaffolds. The magnetic, bone-bioactive, mechanical, cellular and tissue attributes of MNP-incorporated PCL nanofibers make them promising candidate scaffolds for bone regeneration.

Investigation of microwave absorbing properties for magnetic nanofiber of polystyrene–polyvinylpyrrolidone

Aligned magnetic blend of polystyrene–polyvinylpyrrolidone (PS–PVP) nanofibers were prepared by this method. First, polystyrene–polyvinylpyrrolidone (PS–PVP) blend solution in THF was synthesized. Then magnetic of PS–PVP–Fe3O4–polyethylene glycol (PEG) was prepared by masking method. Finally, magnetic nanofiber of PS–PVP–Fe3O4–PEG was prepared by electrospinning method, too. An electric potential difference of 25 kV was applied between the collector and a syringe tip, and the distance between the collector and the tip was 13 cm. Fe3O4 is exhibit various magnetic properties of which the complex permeability and the permittivity, in particular, are important in determining their high frequency characteristics. The magnetic oxide particles and nanofiber of nanometer size were characterized by TEM and SEM respectively. The thermal properties of nanofibers were determined by TGA and DSC. The magnetic characterization of the fibers was also performed by VSM and AFM techniques. On the other hand, nanofiber with diameters ranging from 30 to 40 nm, showing at room temperature, coercive field values of around 25 kV and saturation magnetization was 1.1 emu/g. Microwave reflection loss of the sample was tested at 8–12 GHz microwave frequencies and the results showed that magnetic nanofiber possessed the microwave absorbing properties.

Study of polyvinyl alcohol nanofibrous membrane by electrospinning as a magnetic nanoparticle delivery approach

Electrospinning technique was used to fabricate polyvinyl alcohol (PVA)-based magnetic biodegradable nanofibers. PVA solution was mixed with ferrofluid or magnetic nanoparticles (MNPs) powder and formed two individual nanofibrous membranes (PVA/ferrofluid and PVA/MNPs powder) by electrospinning. The surface morphology of the nanofibrous membrane was characterized by scanning electron microscopy and the magnetic properties were measured by vibrating sample magnetometer. Macrophages (RAW 264.7) were co-cultured with the nanofibrous membranes for 12, 24, and 48 h and exhibited good cell viability (>95%). Results showed that the PVA fibers would be degraded and the embedded Fe3O4 nanoparticles would be released and delivered to cells.

Flexible Janus Nanofibers: Facile Electrospinning Construction and Enhanced Luminescent–Electrical–Magnetic Trifunctionality

AbstractFlexible luminescent–electrical–magnetic trifunctional Janus nanofibers have been successfully fabricated through electrospinning technology by using specially designed parallel spinnerets. The terbium complex [Tb(ba)3(phen)] (BA=benzoic acid, phen=1,10‐phenanthroline), polyaniline (PANI), and Fe3O4 nanoparticles (NPs) were incorporated into polyvinyl pyrrolidone (PVP) and electrospun into Janus nanofibers with [Tb(ba)3(phen)]/PVP as one strand of the nanofiber and PANI/Fe3O4/PVP as another. The morphologies and properties of the final products were investigated in detail by XRD, SEM, TEM, fluorescence spectroscopy, Hall effect measurement system, and vibrating sample magnetometry. The [[Tb(ba)3(phen)]/PVP]//[PANI/Fe3O4/PVP] Janus nanofibers, with an average diameter of 180 nm, simultaneously possess enhanced luminescent performance, electrical conduction, and magnetism. Fluorescence emission peaks of Tb3+ are observed in the [[Tb(ba)3(phen)]/PVP]//[PANI/Fe3O4/PVP] Janus nanofibers and assigned to the 5D4→5F6 (λ=491 nm), 5D4→5F5 (λ=544 nm), 7D4→5F4 (λ=585 nm), and 5D4→7F3 (λ=620 nm) energy‐level transitions of Tb3+ ions; the 5D4→5F5 hypersensitive transition at λ=544 nm is the predominant emission peak. The electrical conductivity of Janus nanofibers reaches up to the order of 10−3 S cm−1. The luminescent intensity, electrical conductivity, and magnetic properties of Janus nanofibers can be tunable by adjusting the amounts of rare‐earth complex, PANI, and Fe3O4 NPs present. This new type of luminescent–electrical–magnetic trifunctional Janus nanofiber holds potential for a variety of applications, including molecular electronics, microwave absorption, and future nanodevices, owing to their excellent fluorescence, electrical conduction, and magnetism.