Magnetic Polymer Nanospheres Research Articles

Magnetic Dendritic Polymer Nanospheres for High-Performance Separation of Histidine-Rich Proteins.

Magnetic nanospheres are becoming a promising platform for a wide range of applications in pharmacy, life science, and immunodiagnostics due to their high surface area, ease of synthesis and manipulation, fast separation, good biocompatibility, and recyclable performance. In this work, an innovative and efficient method is developed by in situ reducing and growing Ni(OH)2 for the preparation of dendritic mesoporous nanocomposites of silica@Fe3O4/tannic acid@nickel hydroxide (dSiO2@Fe3O4/TA@Ni(OH)2). The flower-like nanospheres have good magnetic response, large surface area, and high histidine-rich protein (His-protein) purification performance. The dSiO2@Fe3O4/TA@Ni(OH)2 nanospheres were synthesized on the basis of a φ(NaSal/CTAB) of 1/1 and a mass of ferrous chloride tetrahydrate of 0.3 g, resulting in a saturation magnetization value of 48.21 emu/g, which means it can be collected within ∼1 min using a magnetic stand. Also, the BET test showed that the surface area is 92.47 m2/g and the pore size is ∼3.9 nm for dSiO2@Fe3O4/TA@Ni(OH)2 nanocomposites. Notably, the nickel hydroxide with unique flower-like structural features enables the combination of a large number of Ni2+ ions and His-proteins for high performance. The isolation and purification experiments of the synthesized dSiO2@Fe3O4/TA@Ni(OH)2 were performed by separating His-proteins from a matrix composed of bovine hemoglobin (BHb), bovine serum albumin (BSA), and lysozyme (LYZ). The result showed that the nanospheres have a high combination capacity of ∼1880 mg/g in a rapid equilibrium time of 20 min, which was selective for the adsorption of BHb. In addition, the stability and recyclability of BHb are 80% after seven cycles. Furthermore, the nanospheres were also used to isolate His-proteins from fetal bovine serum, proving its utility. Therefore, the strategy of separating and purifying His-proteins using dSiO2@Fe3O4/TA@Ni(OH)2 nanospheres is promising for practical applications.

Preparation of magnetic polymer nanosphere and its profile control

Fe3O4 nanoparticles with a particle size of approximately 16.5 nm were prepared by the chemical coprecipitation method with the raw materials of ferric chloride, ferrous chloride, and sodium hydroxide. The optimum reaction conditions were determined by the single factor control method; then, magnetic polymer nanoparticles were produced by microemulsion polymerization, and the synthesis conditions were optimized by orthogonal experiments with four factors and three levels. As expected, spherical particles of approximately 60 nm were obtained. The morphology, structure, and properties of the product were characterized and analyzed. The results showed that the particles possessed a uniform spherical shape, good thermal stability, and superparamagnetism, which will ensure these particles have a wide application of directional flooding profile control. Average EOR of magnetic polymer nanospheres with magnetic field was 14.41 wt%. The magnetized magnetic polymer nanospheres had better profile control ability, and were less damage to the low permeability layer. Separation experiment showed that magnetized magnetic polymer nanospheres can be effectively separated due to the low viscosity and the good magnetism. Furthermore, the separated polymer nanospheres can be reused again.

Synthesis of core–shell magnetic ion-imprinted polymer nanospheres for selective solid-phase extraction of Pb2+ from biological, food, and wastewater samples

ABSTRACTMagnetic ion-imprinted polymer nanospheres, which have core–shell structures, have been synthesized as an adsorbent for extraction of Pb2+ from real samples prior to its flame atomic absorption spectrometric determination. The prepared adsorbent has been characterized using XRD, VSM, TEM, and FTIR measurements. The optimization results revealed that the adsorbent exhibited high selectivity toward Pb2+ over other cations such as Cu2+ and Zn2+. In addition, the removal efficiency of synthesized adsorbent was considerable (qm = 171.42 mg g−1), its calibration curve was linear (0.5−850.0 ng mL−1), and detection limit was 0.01 ng mL−1. These results suggested that the prepared nanoadsorbent is an ideal candidate for solid-phase extraction of Pb2+ ions.

Polymer-coated magnetic nanospheres for preconcentration of organochlorine and pyrethroid pesticides prior to their determination by gas chromatography with electron capture detection

Magnetic polymer nanospheres were prepared and used as adsorbents for the extraction of organochlorine and pyrethroid pesticides from water samples. The adsorbents were synthesized by miniemulsion polymerization of N-vinylimidazole and divinylbenzene and simultaneous encapsulation of oleic acid-coated Fe3O4 nanoparticles. Following desorption with ethyl acetate, the target analytes β-hexachlorocyclohexane, δ-hexachlorocyclohexane, p,p’-DDE, heptachlor, trans-chlordan, cis-chlordan, bifenthrin, β-cypermethrin, δ-methrin, λ-cyhalothrin and esfenvalerate were determined by gas chromatography with electron capture detection. Desorption conditions, extraction times and sample volume were screened by Plackett-Burman design and optimized by Box-Behnken design. Under the optimum conditions, the organochlorines can be quantified in the 20 to 400 ng L−1 concentration range, and the pyrethroids in the 400 to 4000 ng L−1 concentration range. The recoveries of organochlorines and pyrethroids from spiked real water samples are between 77.6 and 97.3 %, with relative standard deviations between 0.9 and 10.0 %. The method for magnetic solid phase extraction described here is fast, simple and friendly to the environment.

Miniemulsion-based assembly of iron oxide nanoparticles and synthesis of magnetic polymer nanospheres

A facile method to synthesize core-shell iron oxide/polymer nanospheres has been developed. Oleic acid-modified iron oxide nanoparticles were first prepared by the coprecipitation method. The iron oxide nanoparticles were then assembled into colloidal magnetic nanoparticle clusters (MNCs) by a miniemulsion-based assembly approach. The size of the MNCs can be tuned from about 50 nm to about 93 nm by rationally designing the experimental conditions. Magnetic iron oxide/poly(methyl methacrylate-co-divinylbenzene) (P(MMA-co-DVB)) nanospheres with well-defined core-shell structure and uniform size were finally prepared by seeded emulsion polymerization with the MNCs as the seeds. By the same procedure, core-shell iron oxide/poly(styrene-co-divinylbenzene) (P(St-co-DVB)) nanospheres were also successfully fabricated, demonstrating the versatility of the preparation method. The prepared composite nanospheres have uniform size, high saturation magnetization, and easily functionalized surface, promising for further biomedical applications and liquid phase catalysis.

Preparation of Epoxy-Functionalized Magnetic Polymer Nanospheres for Magnetically Targeted Radiotherapy

Magnetic poly(styrene−methyl methacrylate-glycidyl methacrylate)/Fe3O4 nanospheres with epoxy groups were prepared by modified one-step mini-emulsion polymerization in the presence of Fe3O4 ferrofluids. The products were characterized by fourier-transform infrared spectrum, transmission electron microscopy, thermogravimetric analysis and vibrating sample magnetometer. After surface modification with diaminopropane, histidine was covalently linked to the amine group of magentic nanospheres using glutaraldehyde as crosslinker. Finally, the preliminary labeling study based on non-radioactive rhenium was carried out and the labeling efficiency reached 80.4%. Such magnetic nanospheres had promising potential in magnetically targeted radiotherapy of cancer.

Magnetic nanoparticle-loaded polymer nanospheres as magnetic hyperthermia agents.

Uniform magnetic nanoparticle-loaded polymer nanospheres with different loading contents of manganese ferrite nanoparticles were successfully synthesized using a flexible emulsion process. The MnFe2O4-loaded polymer nanospheres displayed an excellent dispersibility in both water and phosphate buffer saline. The effect of loading ratio and size of MnFe2O4 nanoparticles within the nanospheres on the specific absorption rate (SAR) under an alternating magnetic field was investigated. Our results indicate that a large size (here 18 nm) and a low loading ratio are preferable for a high SAR. For a smaller particle size (6 nm), the low loading ratio did not result in an enhancement of the SAR value, while a very low SAR value is expected for 6 nm. In addition, the SAR of low-content MnFe2O4 (18 nm)-loaded polymer nanospheres in the agarose gel which is simulated for in vivo environment is the highest among the samples and does not change substantially in physiological environments. This differs largely from the behaviour of singly dispersed nanoparticles. Our results have paved the way for the design of MnFe2O4-loaded polymer nanospheres as magnetic hyperthermia agents for in vivo bio-applications.

A facile method to synthesize magnetic polymer nanospheres with multifunctional groups

Magnetic poly(styrene methyl methacrylate)/Fe 3O 4 nanospheres with ester groups were prepared by a modified one-step mini-emulsion polymerization in the presence of Fe 3O 4 ferrofluids. The effects of monomer dose, surfactant content, ferrofluid concentration and initiator content on the particle characteristics such as the size, morphology and magnetic properties were investigated by Fourier-transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis and vibrating sample magnetometer. The results indicated that magnetic nanospheres were superparamagnetic with high saturation magnetization of 51.0 emu/g and corresponding magnetite content of 61.5 wt%. Subsequently, magnetic nanospheres with carboxyl and amino groups were also obtained by hydrolysis and ammonolysis reaction. These magnetic nanospheres with multifunctional groups have biomedical applications.

Thermal Analysis of Magnetic Polymer Nanospheres for Drug Targeting

Poly(D,L-lactic-co-glycolic) acid (PLGA) polymer nanospheres loaded with different input amounts of anticancer drug taxol were prepared by the modified nanoprecipitation method. Magnetite was incorporated into the polymer nanospheres to impart them superparamagnetic properties. Thermal properties of the drug loaded magnetic polymer nanospheres were characterized using differential scanning calorimetry and thermogravimetric analysis. The solid state solubility of taxol in PLGA nanospheres and the influence of external magnetic field on their thermal stability were estimated. The investigations have revealed that the samples of dried taxol loaded magnetic PLGA nanospheres undergo mass loss at three stages during heating.

Magnetic polymer nanospheres for anticancer drug targeting

Poly(D,L-lactide-co-glycolide) polymer (PLGA) nanospheres loaded with biocom-patible magnetic fluid as a magnetic carrier and anticancer drug Taxol were prepared by the modified nanoprecipitation method with size of 200–250 nm in diameter. The PLGA polymer was utilized as a capsulation material due to its biodegradability and biocompatibility. Taxol as an important anticancer drug was chosen for its significant role against a wide range of tumours. Thermal properties of the drug-polymer system were characterized using thermal analysis methods. It was determined the solubility of Taxol in PLGA nanospheres. Magnetic properties investigated using SQUID magnetometry showed superparamagnetism of the prepared magnetic polymer nanospheres.

Controllable preparation of magnetic polymer nanospheres with high saturation magnetization by miniemulsion polymerization

Magnetic Fe 3O 4/poly(styrene-co-acrylamide) core/shell nanospheres were prepared by one-step miniemulsion polymerization in the presence of Fe 3O 4 ferrofluids. The functional monomer of acrylamide was used not only to modify the surface of the nanospheres with functional groups, but also to form modified bilayer with SDBS to control the encapsulation and particle size of nanospheres. The properties of magnetic nanospheres were characterized by IR, TEM, TG and VSM. The results indicated that the superparamagnetic nanopsheres had small particle size of 60 nm, high saturation magnetization of 27.1 emu/g, high magnetic content and abundant functional groups. The possible formation mechanism of magnetic nanospheres was discussed in detail.

The efficient and specific isolation of the antibodies from human serum by thiophilic paramagnetic polymer nanospheres

A rapid and effective method to specifically isolate the antibodies from human serum was presented based on the fast magnetic separation and specific adsorption of the novel thiophilic magnetic polymer nanospheres, which were synthesized by using miniemulsion copolymerization. After the thiophilic heterocyclic ligands of 2-mercaptonicotinic acid were first activated via divinyl sulfone, they were immobilized on the surface of these magnetic nanospheres, through which the strong specificity to immunoglobulin G was evidently expressed in the isolation of antibodies from human serum. The mild conditions used in the process, including the physiological pH range, low temperature, and low ion strength, were so favorable for keeping the biological activity of antibodies, which resulted in their bioactivity purity to exceed 99%. The efficient isolation, simplicity process, mild conditions, and the conventional equipments required make this technology so attractive to purify antibodies from human serum.

Magnetic Polymer Nanospheres Immobilizing Metalloporphyrins. Catalysis and Reuse to Hydroxylate Cyclohexane with Molecular Oxygen

Magnetic polymer nanospheres immobilizing Co(II) porphyrin or Mn(III) porphyrin were synthesized and their catalytic activities in hydroxylating cyclohexane were comparably investigated. The catalytic results have shown that these magnetic nanospheres are highly efficient and recyclable catalysts and the nanospheres with Mn(III) porphyrin are more active than those with Co(II) porphyrin.

Mn(III) porphyrins immobilized on magnetic polymer nanospheres as biomimetic catalysts hydroxylating cyclohexane with molecular oxygen

Three types of magnetic polymer nanospheres immobilizing Mn(III) porphyrins appending p-OCH 3, p-H and p-Cl phenyl substituents (designated as MPNSs(MnMP), MPNSs(MnPP) and MPNSs(MnCP), respectively) were synthesized and their catalytic activities as biomimetic catalysts to hydroxylate cyclohexane with molecular oxygen were investigated. The catalytic efficiencies of these magnetic nanospheres are much higher than those of the non-supported Mn(III) porphyrin analogues and follow the order of MPNSs(MnMP) > MPNSs(MnPP) > MPNSs(MnCP). It is also found that these nanospheres have good magnetic responsiveness and thus can be completely recovered by applying an external magnetic field. Furthermore, they can maintain their catalytic activities after being recycled several times. These results may be helpful in designing new, highly efficient metalloporphyrin catalysts.

Preparation and characterization of magnetic polymer nanospheres with high protein binding capacity

A novel magnetic support with high protein binding capacity was prepared by mini-emulsion polymerization. The magnetic poly(methacrylate-divinylbenzene) nanospheres prepared are 390 nm in diameter with narrow size distribution and star-like external morphology which leads to a large increase in specific surface area. Experimental results indicate that the maximum protein binding capacity is 316 mg bovine hemoglobin (BHb)/g support.

Magnetic polymer nanospheres with high and uniform magnetite content

Magnetic polymer nanospheres with high and uniform magnetite content were synthesized using a new process based on miniemulsion polymerization, where a stable water-based dispersion of sodium dodecyl sulfate (SDS)/oleic acid bilayer coated magnetite aggregates was first synthesized and mixed with monomer styrene miniemulsion. Then another miniemulsification was performed for the full encapsulation of magnetite into monomer droplets. Subsequent polymerization generated magnetic polymer nanospheres. Extensive characterization of magnetic polymer particles by transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA) and Vibrating Sample Magnetometer (VSM) showed that up to 40 wt% of 8 nm superparamagnetic magnetite particles could be uniformly encapsulated into polystyrene nanospheres with an average diameter of 80 nm.

Surface Modification and Characterization of Magnetic Polymer Nanospheres Prepared by Miniemulsion Polymerization

A novel and effective protocol for the surface modification and quantitative characterization of magnetic polymeric nanospheres prepared by miniemulsion polymerization is reported. Composite nanospheres consisting of polymer-coated iron oxide nanoparticles were prepared by the miniemulsion polymerization of methyl methacrylate and divinylbenzene in the presence of magnetic fluid. Surface modification reaction of the magnetic polymer with poly(ethylene glycol) (PEG) was employed to obtain a hydrophilic hydroxyl-group-functionalized magnetic nanospheres. An affinity dye, Cibacron blue F3G-A (CB), was then coupled covalently to prepare a magnetic nonporous affinity adsorbent. The morphology and magnetic property of the polymer nanospheres obtained were examined by transmission electron microscopy and a vibrating sample magnetometer. The contents of surface groups modified were quantitatively measured by using diffusive reflectance Fourier transform infrared spectroscopy on the basis of a linear relationship between the intensity ratio of IC-O-C/IC=O and the content of PEG. X-ray photoelectron spectroscopy (XPS) was used to examine the surface of magnetic nanospheres. It was confirmed by the comparison of XPS spectra of both dye-coated and uncoated magnetic nanospheres to which the CB ligand was coupled, and the surface of the PEG-modified nanospheres had an exact 3:7 atomic ratio of sulfur to nitrogen.