Efficient purification of His-tagged protein by superparamagnetic Fe3O4/Au–ANTA–Co2 + nanoparticles

Superparamagnetic Fe₃O₄/Au nanoparticles were synthesized and surface modified with mercaptopropionic acid (MPA), followed by conjugating Nα,Nα-Bis(carboxymethyl)-l-lysine hydrate (ANTA) and subsequently chelating Co^2 +. The resulting Fe₃O₄/Au–ANTA–Co^2 + nanoparticles have an average size of 210 nm in aqueous solution, and a magnetization of 36 emu/g, endowing the magnetic nanoparticles with excellent magnetic responsivity and dispersity. The Co^2 + ions in the magnetic nanoparticle shell provide docking site for histidine, and the Fe₃O₄/Au–ANTA–Co^2 + nanoparticles exhibit excellent performance in binding of a His-tagged protein with a binding capacity of 74 μg/mg. The magnetic nanoparticles show highly selective purification of the His-tagged protein from Escherichia coli lysate. Therefore, the obtained Fe₃O₄/Au–ANTA–Co^2 + nanoparticles exhibited excellent performance in the direct separation of His-tagged protein from cell lysate.     

Magnetic 99mTc- core-shell of polyethylene glycol/polyhydroxyethyl methacrylate based on Fe3O4 nanoparticles: Radiation synthesis,characterization and biodistribution study in tumor bearing mice

Magnetic nanoparticles (Fe₃O₄) coated with polyethylene glycol (PEG), (Fe₃O₄/PEG), were synthesized by chemical co-precipitation of Fe²⁺/Fe³⁺ salts by aqueous ammonia in PEG solution. Radiation polymerization of 2-hydroxyethyl methacrylate (HEMA) monomer solution onto Fe₃O₄/PEG was performed at different doses to synthesize (Fe₃O₄/PEG)-pHEMA, namely FPH, nanocomposites. Properties of FPH nanocomposites were characterized by FT-IR, XRD, SEM, TEM, DLS, ESR and TGA techniques. The XRD of FPH nanocomposites showed all the peaks of Fe₃O₄ nanoparticles. SEM was used to assess the surface morphology of FPH. TEM showed that the average diameter of FPH nanocomposites was in the range of 9–40 nm. The thermal stability of FPH nanocomposites was higher than that of Fe₃O₄ and Fe₃O₄/PEG. Radio-labeling of (Fe₃O₄/PEG)-pHEMA nanocomposite irradiated at 10 kGy (FPH10) with ^99mTc was performed using stannous chloride as reducing agent. Factors affecting the labeling yield (%) such as the substrate amount, the amount of reducing agent, the pH of reaction medium, the reaction time and the reaction temperature were investigated. The maximum labeling yield was 93% using 0.25 mg of FPH10 at pH 6 and 20 min reaction time. The biodistribution study of ^99mTc-FPH10 was examined on two groups of ascites and solid tumor bearing mice. The biodistribution results referred that ^99mTc-FPH10 was rapidly uptake in tumor sites ascites or solid tumors. The results indicated that FPH nanocomposites could be potentially used for tumor imaging and therapy.     

Preparation of Fe3O4–chitosan nanoparticles used for hyperthermia

The Fe₃O₄–chitosan nanoparticles with core-shell structure have been prepared by crosslinking method. Oleic acid modified Fe₃O₄ nanoparticles were firstly prepared by co-precipitation then chitosan was added to coat on the surface of the Fe₃O₄ nanoparticles by physical absorption. The Fe₃O₄–chitosan nanoparticles were obtained by crosslinking the amino groups on the chitosan using glutaraldehyde. Transmission electron microscopy showed that the Fe₃O₄–chitosan nanoparticles were quasi-spherical with a mean diameter of 10.5 nm. X-ray diffraction pattern and X-ray photoelectron spectra indicated that the magnetic nanoparticles were pure Fe₃O₄ with a cubic inverse spinel structure. The modification using chitosan did not result in a phase change. The binding of chitosan to the Fe₃O₄ nanoparticles was also demonstrated by the measurement of fourier transform infrared spectra and thermogravimetric analysis. Magnetic measurement revealed that the saturation magnetization of the composite nanoparticles was 30.7 emu/g and the nanoparticles were superparamagnetic at room temperature. Furthermore, the inductive heating property of the composite nanoparticles in an alternating current magnetic field was investigated and the results indicated that the heating effect was significant. The Fe₃O₄–chitosan nanoparticles prepared have great potential in hyperthermia.     

Preparation,characterization and application of Fe3O4/ZnO core/shell magnetic nanoparticles

Fe₃O₄ magnetic nanoparticles (MNPs) were synthesized by a co-precipitation method. The phase purity was confirmed by X-ray powder diffraction (XRD) analysis. The crystal size was found to be 10 nm from transmission electron microscopy (TEM). It is evidenced that the surface of Fe₃O₄ MNPs was modified by sodium citrate. The Fe₃O₄/ZnO core/shell MNPs were obtained by coating the MNPs with direct precipitation using zinc acetate and ammonium carbonate. The precursor was firstly dried and then calcined at 350 °C. The antioxidation tests indicated that the core/shell MNPs give better antioxidation than that of the Fe₃O₄ MNPs. The photocatalytic degradation of methyl orange revealed that the core/shell MNPs have higher photocatalytic activity than that of the ZnO nanoparticles. Separation of the core/shell MNPs from the aqueous suspension using a magnet provides an easy way to recycle the core/shell MNPs. After four-time recycling, the photocatalytic degradation percentage of the core/shell MNPs is about 70%.     

Synthesis and characterization of PEG-iron oxide core-shell composite nanoparticles for thermal therapy

In this study, core-shell nanoparticles were developed to achieve thermal therapy that can ablate cancer cells in a remotely controlled manner. The core-shell nanoparticles were prepared using atomic transfer radical polymerization (ATRP) to coat iron oxide (Fe₃O₄) nanoparticles with a poly(ethylene glycol) (PEG) based polymer shell. The iron oxide core allows for the remote heating of the particles in an alternating magnetic field (AMF). The coating of iron oxide with PEG was verified through Fourier transform infrared spectroscopy and thermal gravimetric analysis. A thermoablation (55 °C) study was performed on A549 lung carcinoma cells exposed to nanoparticles and over a 10 min AMF exposure. The successful thermoablation of A549 demonstrates the potential use of polymer coated particles for thermal therapy.     

Synthesis and functionalization of SiO2 coated Fe3O4 nanoparticles with amine groups based on self-assembly

The purpose of this research was to synthesize amino modified Fe₃O₄/SiO₂ nanoshells for biomedical applications. Magnetic iron-oxide nanoparticles (NPs) were prepared via co-precipitation. The NPs were then modified with a thin layer of amorphous silica. The particle surface was then terminated with amine groups. The results showed that smaller particles can be synthesized by decreasing the NaOH concentration, which in our case this corresponded to 35 nm using 0.9 M of NaOH at 750 rpm with a specific surface area of 41 m² g^? 1 for uncoated Fe₃O₄ NPs and it increased to about 208 m² g^?1 for 3-aminopropyltriethoxysilane (APTS) coated Fe₃O₄/SiO₂ NPs. The total thickness and the structure of core-shell was measured and studied by transmission electron microscopy (TEM). For uncoated Fe₃O₄ NPs, the results showed an octahedral geometry with saturation magnetization range of (80–100) emu g^?1 and coercivity of (80–120) Oe for particles between (35–96) nm, respectively. The Fe₃O₄/SiO₂ NPs with 50 nm as particle size, demonstrated a magnetization value of 30 emu g^?1. The stable magnetic fluid contained well-dispersed Fe₃O₄/SiO₂/APTS nanoshells which indicated monodispersity and fast magnetic response.     

Synthesis of nanocrystalline GaN from Ga2O3 nanoparticles derived from salt-assisted spray pyrolysis

Gallium nitride (GaN) nanoparticles were successfully produced from nano-sized gallium oxide (Ga₂O₃) particles under a flow of ammonia gas. The gallium oxide nanoparticles were prepared by salt-assisted spray pyrolysis (SASP). Highly crystalline Ga₂O₃ nanoparticles with an average diameter of approximately 10 nm were obtained at various temperatures when a flux salt (LiCl, 5 mol/l) was added to the precursor solution. The effects of the crystallinity of the Ga₂O₃ particles and nitridation time on transformation to GaN were characterized using X-ray diffraction and scanning/transmission electron microscopy. Highly crystalline GaN nanoparticles with a mean size of 23.4 nm and a geometric standard deviation of 1.68 nm were obtained when Ga₂O₃ nanoparticles with relatively low crystallinity were used as the starting material. The resulting GaN nanoparticles showed a photoluminescence peak at 364 nm under UV excitation at 254 nm.     

Synthesis and magnetic characterization of magnetite obtained by monowavelength visible light irradiation

Magnetite (Fe₃O₄) nanoparticles were controllably synthesized by aerial oxidation Fe^IIEDTA solution under different monowavelength light-emitting diode (LED) lamps irradiation at room temperature. The results of the X-ray diffraction (XRD) spectra show the formation of magnetite nanoparticle further confirmed by Fourier transform infrared spectroscope (FTIR) and the difference in crystallinity of as-prepared samples. Fe₃O₄ particles are nearly spherical in shape based on transmission electron microscopy (TEM). Average crystallite sizes of magnetite can be controlled by different irradiation light wavelengths from XRD and TEM: 50.1, 41.2, and 20.3 nm for red, green, and blue light irradiation, respectively. The magnetic properties of Fe₃O₄ samples were investigated. Saturation magnetization values of magnetic nanoparticles were 70.1 (sample M-625), 65.3 (sample M-525), and 58.2 (sample M-460) emu/g, respectively.     

High T2-relaxation and biocompatible magnetic nanofluids with poly(amino acid) coating

A facile one-pot method has been developed to prepare poly(amino acid) functionalized, water-stable, biocompatible, and superparamagnetic iron oxide nanoparticles (NPs) with small diameters of ∼10 nm. The obtained biocompatible magnetic nanoparticles capped with polyaspartic acid (PASP) exhibit a relatively high saturation magnetization (57.1 emu/g) and a much strong magnetic resonance (MR) T₂ relaxation effect with the transverse relaxivity coefficient (r₂) as high as 302.6 s⁻¹ mM⁻¹. Interestingly, the as-prepared Fe₃O₄@PASP NPs are highly stable in aqueous solution and demonstrate the property of magnetic nanofluids. The high T₂ effect, good water-stability, superparamagnetization, biocompatibility and bioconjugatability render the as-synthesized Fe₃O₄@PASP NPs great desirable for bioapplications such as magnetic resonance imaging (MRI), bioseparation, targeted drug delivery, and so on.     

Folate targeted PEGylated titanium dioxide nanoparticles as a nanocarrier for targeted paclitaxel drug delivery

A novel titanium dioxide nanocarrier was synthesized for targeted delivery of the anticancer drug, paclitaxel, by grafting folic acid (FA) onto the PEGylated titanium dioxide nanoparticles. Titanium dioxide is used in biomedical field for its stability and no toxicity characteristics. Titanium dioxide is one of the most promising nanoparticles (NPs) capable of a wide variety of applications in medicine and life science. Polyethylene glycol (PEG), when attached to the surface of the nanoparticles, increases the biocompatibility of the nanoparticles. PEGylated nanocarriers evade the reticuloendothelial system (RES). Folic acid (FA) is used as the ligand to target folate receptors, which are found abundant in cancer cells. FA–PEG–TiO₂ nanoparticles when used as drug carriers have the ability to target cancer cells and also capable of evading the reticuloendothelial system. Titanium dioxide nanoparticles were synthesized by wet chemical method. It was annealed at 450° for 3 h. XRD analysis confirms the formation of anatase titanium dioxide. Analyses by transmission electron microscopy (TEM) and dynamic light scattering (DLS) revealed that the nanoparticles had an average size of 12 nm and uniform size distribution. The PEGylation and folic acid grafting was confirmed by UV spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The study on the loading of anticancer drug paclitaxel revealed that the titanium dioxide nanocarrier possessed a considerably higher adsorption capability. In addition, the in vitro release profile of paclitaxel from FA–PEG–TiO₂ nanoparticles was characterized by an initial fast release followed by a sustained release phase.     

Capture and release of genomic DNA by PEI modified Fe3O4/Au nanoparticles

Polyethylenimine (PEI) modified Fe₃O₄/Au nanoparticles were synthesized in aqueous solution and characterized by photo correlation spectroscopy (PCS) and vibrating sample magnetometer (VSM). The so-obtained Fe₃O₄/Au-PEI nanoparticles were capable of efficient electrostatic capture of DNA. The maximum amount of genomic DNA captured on 1.0 mg Fe₃O₄/Au-PEI nanoparticles was 90 μg. The DNA release behavior was studied and the DNA recovery from Fe₃O₄/Au-PEI nanoparticles approached 100% under optimal conditions. DNA extraction from mammalian cells using Fe₃O₄/Au-PEI nanoparticles was successfully performed. Up to approximately 43.1 μg of high-purity (OD₂₆₀/OD₂₈₀ ratio = 1.81) genomic DNA was extracted from 10 mg of liver tissue. The results indicated that the prepared Fe₃O₄/Au-PEI nanoparticles could be successfully used for DNA capture and release.     

Synthesis,characterization and microwave absorption properties of Fe3O4/Co core/shell-type nanoparticles

Co coated Fe₃O₄ core/shell-type nanoparticles were fabricated by hydrothermal technique and electroless plating process. X-ray powder diffraction (XRD), X-ray fluorescence spectrometer (XRF) and transmission electron microscope (TEM) were employed to investigate the crystal structure, element composition and morphology of the prepared nanoparticles. Vibrating sample magnetometer (VSM) and vector network analyzer were used to measure the magnetic properties and electromagnetic parameters of pure Fe₃O₄ and Fe₃O₄/Co core/shell-type nanoparticles, then reflection losses (RL(dB)) were calculated in the frequency range of 2–18 GHz. Magnetic studies revealed typical ferromagnetic behavior for the pure Fe₃O₄ and Fe₃O₄/Co core/shell-type nanoparticles with their saturation magnetization (M_s = 63.1 and 72.4 emu/g) and coercivity (H_c = 99.5, and 165.4 Oe), respectively. Due to the existence of the core/shell structure, the electromagnetic characteristic of the Fe₃O₄/Co nanoparticles exhibit better microwave absorption performance than the pure Fe₃O₄ in the range of 2–18 GHz, such as more powerful absorbing property and wider frequency band of microwave absorption.     

Simple and low-temperature preparation of Co3O4 sphere-like nanoparticles via solid-state thermolysis of the [Co(NH3)6](NO3)3 complex

In this work, spinel-type Co₃O₄ spherical nanoparticles were easily prepared via decomposition of the hexamminecobalt(III) nitrate complex, [Co(NH₃)₆](NO₃)₃, at low temperature (200 °C). The product was characterized by thermal analysis (TGA/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV–vis spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) specific surface area measurement and magnetic measurements. The results confirmed that pure single-phase Co₃O₄ nanoparticles with weak ferromagnetic behavior were obtained by this method. TEM images showed that the Co₃O₄ nanoparticles are sphere-like with an average diameter size of around 15 nm. The optical spectrum indicated two direct band gaps at 2.15 and 3.56 eV which are blue-shifted relative to reported values for the bulk sample. Using this fast and simple method, Co₃O₄ nanoparticles can be produced without expensive and toxic solvents or complicated equipment.     

Preparation and characterization of ω-functionalized polystyrene–magnetite nanocomposites

Magnetite (Fe₃O₄) nanoparticles were prepared by in situ precipitation and oxidation of ferrous ions in the presence of ω-functionalized polystyrenes having carboxylate, sulfonate, thiol, and thiolated groups. Based on the results for the orthogonal experimental design, both the ratio of the concentration of iron precursor to polymer and the reaction temperature were the major factors controlling the particle size and its shape morphology. By adjusting the reaction conditions, the iron oxide particle size can be effectively controlled in the range between 2 and 20 nm. The magnetite-based polymer composite was characterized by UV–vis spectroscopy, thermogravimetric analysis, transmission electron microscopy, and X-ray diffraction. Magnetization measurements revealed that the nanocomposite materials exhibit superparamagnetic behavior at room temperature.     

Synthesis of flexible magnetic nanohybrid based on bacterial cellulose under ultrasonic irradiation

Flexible magnetic membrane based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of the Fe₃O₄ nanoparticles under different conditions and its properties were characterized. The results demonstrated that the Fe₃O₄ nanoparticles coated with PEG were well homogeneously dispersed in the BC matrix under ultrasonic irradiation with the saturation magnetization of 40.58 emu/g. Besides that, the membranes exhibited the striking flexibility and mechanical properties. This study provided a green and facile method to inhibit magnetic nanoparticle aggregation without compromising the mechanical properties of the nanocomposites. Magnetically responsive BC membrane would have potential applications in electronic actuators, information storage, electromagnetic shielding coating and anti-counterfeit.     

Low temperature synthesis of nanocrystalline calcium aluminate compounds with surfactant-assisted precipitation method

Nanocrystalline calcium aluminates with different CaO:Al₂O₃ and surfactant/metal ion molar ratios were prepared by wet chemical synthesis method using Poly (ethylene glycol)-block-poly(propylene glycol)-block poly(ethylene glycol) (PEG–PPG–PEG, MW:5800) as surfactant. X-ray diffraction (XRD) and N₂ adsorption–desorption results showed that the increase in CaO:Al₂O₃ ratio decreased the specific surface area and increased the particle sizes of prepared samples while the surfactant/metal ion molar ratios were kept constant. These analyses also declared that for the sample with CaO:Al₂O₃ = 1:2 (CA2) addition of polymeric surfactant increased the specific surface area and decreased the crystallite size. Scanning electron microscopy (SEM) results confirmed that size of particles for CaO:Al₂O₃ = 1:6 (CA6) sample are smaller than CA2. Transmission electron microscopy (TEM) revealed no particular particle shape for the CA2 sample but it showed the high degree of crystallinity and single phase for the prepared sample at 1100 °C.     

Doxorubicin loaded PVA coated iron oxide nanoparticles for targeted drug delivery

Magnetic drug targeting is a drug delivery system that can be used in locoregional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by coprecipitation of iron oxide followed by coating with polyvinyl alcohol (PVA). Characterization was carried out using X-ray diffraction, TEM, TGA, FTIR and VSM techniques. The magnetic core of the carriers was magnetite (Fe₃O₄), with average size of 10 nm. The room temperature VSM measurements showed that magnetic particles were superparamagnetic. The amount of PVA bound to the iron oxide nanoparticles were estimated by thermogravimetric analysis (TGA) and the attachment of PVA to the iron oxide nanoparticles was confirmed by FTIR analysis. Doxorubicin (DOX) drug loading and release profiles of PVA coated iron oxide nanoparticles showed that up to 45% of adsorbed drug was released in 80 h, the drug release followed the Fickian diffusion-controlled process. The binding of DOX to the PVA was confirmed by FTIR analysis. The present findings show that DOX loaded PVA coated iron oxide nanoparticles are promising for magnetically targeted drug delivery.     

Synthesis of nanocrystalline Ni0.5Zn0.5Fe2O4 ferrite and study of its magnetic behavior at different temperatures

Ni_0.5Zn_0.5Fe₂O₄ ferrite nanocrystals with average diameter in the range of 1–2 nm have been synthesized by reverse microemulsion. X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) are used to characterize the structural, morphological and magnetic properties. X-ray analysis showed that the nanocrystals possess cubic spinel structure. The absence of hysteresis, negligible remanence and coercivity at 300 K indicate the superparamagnetic character and single domain in the nanocrystalline Ni_0.5Zn_0.5Fe₂O₄ ferrite materials. The nanocrystalline Ni_0.5Zn_0.5Fe₂O₄ ferrite were annealed at 600 °C. As a result of heat treatment the average particle size increases from 2 nm to 5 nm and the corresponding magnetization values have increased to 21.69 emu/g at 300 K. However, at low temperature of 100 K, the annealed samples show hysteresis loop which is the characteristic of a superparamagnetic to ferromagnetic transition. In addition, a comparative study of the magnetic properties of Ni_0.5Zn_0.5Fe₂O₄ ferrite nanocrystals obtained from reverse microemulsion has been carried out with those obtained from the general chemical co-precipitation route.     

Encapsulation of superparamagnetic iron oxide nanoparticles in poly-(lactide-co-glycolic acid) microspheres for biomedical applications

Magnetic microspheres were prepared using a single step coaxial electrohydrodynamic atomization technique at ambient temperature and pressure, with poly(lactic-co-glycolic acid) as the coating and iron oxide (Fe₃O₄) nanoparticles dispersed in polyethylene glycol as the encapsulated material. The morphology and particle size distributions of the prepared magnetic microspheres were investigated by scanning electron microscopy. The particles were spherical with mean diameters ranging from ~ 2 μm to 18 μm, depending on the combination of processing parameters (flow rate and applied voltage). Analysis by infrared spectroscopy and focused ion-beam sectioning confirmed incorporation of iron oxide nanoparticles into the microspheres and the prepared samples were shown to be responsive to an applied magnetic field. This study demonstrates a convenient method for the preparation of nanoparticle loaded microspheres, which could be used potentially as transverse relaxation contrast agents in magnetic resonance imaging, as well as for magnetically guided drug delivery.     

Synthesis and characterization of Piperidine-4-carboxylic acid functionalized Fe3O4 nanoparticles as a magnetic catalyst for Knoevenagel reaction

Piperidine-4-carboxylic acid (PPCA) functionalized Fe₃O₄ nanoparticles as a novel organic–inorganic hybrid heterogeneous catalyst was fabricated and characterized by XRD, FT-IR, TGA, TEM and VSM techniques. Composition was determined as Fe₃O₄, while particles were observed to have spherical morphology. Size estimations using X-ray line profile fitting (10 nm), TEM (11 nm) and magnetization fitting (9 nm) agree well, revealing nearly single crystalline character of Fe₃O₄ nanoparticles. Magnetization measurements reveal that PPCA functionalized Fe₃O₄ NPs have superparamagnetic features, namely immeasurable coercivity and absence of saturation. Small coercivity is established at low temperatures. The catalytic activity of Fe₃O₄–PPCA was probed through one-pot synthesis of nitro alkenes through Knoevenagel reaction in CH₂Cl₂ at room temperature. The heterogeneous catalyst showed very high conversion rates (97%) and could be recovered easily and reused many times without significant loss of its catalytic activity.