Use of PEI-coated Magnetic Iron Oxide Nanoparticles as Gene Vectors

Summary: To evaluate the feasibility of using polyethyleneimine (PEI) coated magnetic iron oxide nanoparticles (polyMAG-1000) as gene vectors. The surface characteristics of the nanoparticles were observed with scanning electron microscopy. The ability of the nanoparticles to combine with and protect DNA was investigated at different PH values after polyMAG-1000 and DNA were combined in different ratios. The nanoparticles were tested as gene vectors with in vitro transfection models. Under the scanning electron microscope the nanoparticles were about 100 nm in diameter. The nanoparticles could bind and condense DNA under acid, neutral and alkaline conditions, and they could transfer genes into cells and express green fluorescent proteins (GFP). The transfection efficiency was highest (51 %) when the ratio of nanoparticles to DNA was 1:1 (v:w). In that ratio, the difference in transfection efficiency was marked depending on whether a magnetic field was present or not: about 10 % when it was absent but 51 % when it was present. The magnetic iron oxide nanoparticles coated with PEI may potentially be used as gene vectors.

Efficient degradation of dye pollutants in wastewater via photocatalysis using a magnetic zinc oxide/graphene/iron oxide-based catalyst

In this paper, we present a proof-of-concept study of the enhancement of photocatalytic activity via a combined strategy of fabricating a visible-light responsive ternary heterostructure and improving overall photostability by incorporating magnetic zinc oxide/graphene/iron oxide (ZGF). A solvothermal approach was used to synthesize the catalyst. X-ray diffraction (XRD), scanning electron microscopic, energy dispersive X-ray, transmission electron microscopic, vibrating sample magnetometric, and ultraviolet–visible diffuse reflectance spectroscopic techniques were used to characterize the synthesized samples. The obtained optimal Zn(NO_(3))_(2) concentration, temperature, and heating duration were 0.10 mol/L, 600℃, and 1 h, respectively. The XRD pattern revealed the presence of peaks corresponding to zinc oxide, graphene, and iron oxide, indicating that the ZGF catalyst was effectively synthesized. Furthermore, when the developed ZGF was used for methylene blue dye degradation, the optimum irradiation time, dye concentration, catalyst dosage, irradiation intensity, and solution pH were 90 min, 10 mg/L, 0.03 g/L, 100 W, and 8.0, respectively. Therefore, the synthesized ZGF system could be used as a catalyst to degrade dyes in wastewater samples. This hybrid nanocomposite consisting of zinc oxide, graphene, and iron oxide could also be used as an effective photocatalytic degrader for various dye pollutants.

Rapid determination of iron oxide content in magnetically modified particulate materials

Magnetically responsive composite materials have been used in interesting applications in various areas of bioscience, biotechnology, and environmental technology. In this work, a simple method to determine the amount of magnetic iron oxide nano- and microparticles attached to magnetically-modified partic- ulate diamagnetic materials has been developed using a commercially available magnetic permeability meter, The procedure is fast and enables dry particulate magnetically modified materials to be analysed without any modification or pretreatment. We show that the magnetic permeability can be measured for materials containing up to 20% magnetic iron oxide, The magnetic permeability measurements are highly reproducible.

Synthesis and application of bilayer-surfactant-enveloped Fe_3O_4 nanoparticles: water-based bilayer-surfactant-enveloped ferrofluids

Superparamagnetic carbon-coated Fe3O4 nanoparticles with high magnetization（85 emu·g-（-1）） and high crystallinity were synthesized using polyethylene glycol-4000（PEG（4000）） as a carbon source.Fe3O4 water-based bilayer-surfactant-enveloped ferrofluids were subsequently prepared using sodium oleate and PEG（4000） as dispersants.Analyses using X-ray photoelectron spectroscopy,X-ray diffraction,and Fourier-transform infrared spectroscopy indicate that the Fe3O4 nanoparticles with a bilayer surfactant coating retain the inverse spinel-type structure and are successfully coated with sodium oleate and PEG（4000）.Transmission electron microscopy,vibrating sample magnetometry,and particle-size analysis results indicate that the coated Fe3O4 nanoparticles also retain the good saturation magnetization of Fe3O4（79.6 emu·g^-1） and that the particle size of the bilayer-surfactant-enveloped Fe3O4 nanoparticles is 42.97 nm,which is substantially smaller than that of the unmodified Fe3O4 nanoparticles（486.2 nm）.UV-vis and zeta-potential analyses reveal that the ferrofluids does not agglomerate for 120 h at a concentration of 4 g·L^-1,which indicates that the ferrofluids are highly stable.

Magnetically modified microbial cells:A new type of magnetic adsorbents

Microbial cells, either in free or immobilized form, can be used for the preconcentration or removal of metal ions, organic and inorganic xenobiotics or biologically active compounds. Magnetic modification of these cells enables to prepare magnetic adsorbents that can be easily manipulated in difficult-to-handle samples, such as suspensions, in the presence of external magnetic field. In this review, typical examples of magnetic modifications of microbial cells are presented, as well as their possible applications for the separation of organic xenobiotics and heavy metal ions.

Biochars and their magnetic derivatives as enzyme-like catalysts mimicking peroxidases

Various materials have been extensively investigated to mimic the structures and functions of natural enzymes.We describe the discovery of a new catalytic property in the group of biochar-based carbonaceous materials,which are usually produced during biowaste thermal processing under specific conditions.The tested biochars exhibited peroxidase-like catalytic activ-ity.Biomaterial feedstock,pyrolysis temperature,size of resulting biochar particles or biochar modification(e.g.,magnetic particles deposition)influenced the peroxidase-like activity.Catalytic activity was measured with the chromogenic organic substrates N,N-diethyl-p-phenylenediamine(DPD)or 3,3′,5,5′-tetramethylbenzidine(TMB),in the presence of hydrogen peroxide.Magnetic biochar composite was studied as a complementary material,in which the presence of iron oxide particles enhances catalytic activity and enables smart magnetic separation of catalyst even from complex mixtures.The activity of the selected biochar had an optimum at pH 4 and temperature 32℃;biochar catalyst can be reused ten times without the loss of activity.Using DPD as a substrate,Km values for native wood chip biochar and its magnetic derivative were 220±5μmol L^(−1)and 690±80μmol L^(−1),respectively,while Vmax values were 10.1±0.3μmol L^(−1)min^(−1)and 16.1±0.4μmol L^(−1)min^(−1),respectively.Biochar catalytic activity enabled the decolorization of crystal violet both in the model solution and the fish pond water containing suspended solids and dissolved organic matter.The observed biochar enzyme mimetic activity can thus find interesting applications in environmental technology for the degradation of selected xenobiotics.In general,this property predestines the low-cost biochar to be a perspective supplement or even substitution of common peroxidases in practical applications.

Magnetic modification of diamagnetic agglomerate forming powder materials

A simple method for the magnetic modification of various types of powdered agglomerate forming dia- magnetic materials was developed. Magnetic iron oxide particles were prepared from ferrous sulfate by microwave assisted synthesis. A suspension of the magnetic particles in water soluble organic solvent （methanol, ethanol, propanol, isopropyl alcohol, or acetone） was mixed with the material to be modified and then completely dried at elevated temperature. The magnetically modified materials were found to be stable in water suspension at least for 2 months.

Fe–EBT Chelate Complex: A Novel Mean for Growth of α-FeOOH and γ-Fe_2O_3 Nanostructures

Acicular goethite（a-Fe OOH） and worm-like maghamite（γ-Fe2O3） nanostructures have been prepared adopting a novel route, using Na2[Fe（HL）2（H2O）2] chelate complex in alkaline medium. It is found that concentration of hydrated Fe（III） ions increased with increasing temperature, which later play a key role in generation of different phases of iron oxide. Phase and morphology of the products are investigated using XRD, FTIR, SEM, and TEM analysis. Using UV–Vis spectra, various electronic transitions of goethite and maghamite particles are examined. Maghamite nanostructures exhibit superparamagnetic property at room temperature. On the basis of experimental observations and analytical data, growth mechanism of the nanostructures is discussed.