Iron oxide hydroxide
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New surface-modified iron oxide nanoparticles were developed by precipitation of Fe(II) and Fe(III) salts with ammonium hydroxide and oxidation of the resulting magnetite with sodium hypochlorite, followed by the addition of poly( L-lysine) (PLL) solution. PLL of several molecular weights ranging from 146 ( L-lysine) to 579 000 was tested as a coating to boost the intracellular uptake of the nanoparticles. The nanoparticles were characterized by TEM, dynamic light scattering, FTIR, and ultrasonic spectrometry. TEM revealed that the particles were ca. 6 nm in diameter, while FTIR showed that their surfaces were well-coated with PLL. The interaction of PLL-modified iron oxide nanoparticles with DMEM culture medium was verified by UV-vis spectroscopy. Rat bone marrow stromal cells (rMSCs) and human mesenchymal stem cells (hMSC) were labeled with PLL-modified iron oxide nanoparticles or with Endorem (control). Optical microscopy and TEM confirmed the presence of PLL-modified iron oxide nanoparticles inside the cells. Cellular uptake was very high (more than 92%) for PLL-modified nanoparticles that were coated with PLL (molecular weight 388 00) at a concentration of 0.02 mg PLL per milliliter of colloid. The cellular uptake of PLL-modified iron oxide was facilitated by its interaction with the negatively charged cell surface and subsequent endosomolytic uptake. The relaxivity of rMSCs labeled with PLL-modified iron oxide and the amount of iron in the cells were determined. PLL-modified iron oxide-labeled rMSCs were imaged in vitro and in vivo after intracerebral grafting into the contralateral hemisphere of the adult rat brain. The implanted cells were visible on magnetic resonance (MR) images as a hypointense area at the injection site and in the lesion. In comparison with Endorem, nanoparticles modified with PLL of an optimum molecular weight demonstrated a higher efficiency of intracellular uptake by MSC cells.
- MeSH
- adsorpce MeSH
- chemické jevy MeSH
- endocytóza účinky léků MeSH
- financování organizované MeSH
- fyzikální chemie MeSH
- krysa rodu rattus MeSH
- kultivační média MeSH
- kultivované buňky MeSH
- lidé MeSH
- lysin chemie MeSH
- magnetická rezonanční tomografie MeSH
- magnetismus MeSH
- mezenchymální kmenové buňky účinky léků ultrastruktura MeSH
- mikroskopie elektronová rastrovací MeSH
- molekulová hmotnost MeSH
- nanočástice MeSH
- oxid železnato-železitý MeSH
- oxidy chemie MeSH
- polylysin chemie MeSH
- proteiny MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- transmisní elektronová mikroskopie MeSH
- transplantace kmenových buněk MeSH
- ultrazvuk MeSH
- velikost částic MeSH
- železité sloučeniny chemie MeSH
- železo chemie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
In this study, the importance of Sb behavior under different pH conditions has been addressed with respect to its stabilization in aqueous solutions using Mg-Fe layered double hydroxides (LDHs). The Sb(V) adsorption onto Mg-Fe LDHs was performed at different initial Sb(V) concentrations and pH values (pH 5.5, 6.5 and 7.5). The removal rate and the maximal adsorbed amount increased with decreasing pH values. Moreover, the surface complexation modeling (SCM) predicted preferable formation of monodentate mononuclear and bidentate binuclear complexes on the Mg-Fe LDH surface. Spectroscopic (X-ray diffraction analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy) and microscopic (scanning electron microscopy and energy-dispersive X-ray spectroscopy) techniques were used to further specify the adsorption mechanisms. The influence of chemical adsorption, surface-induced precipitation of brandholzite Mg[Sb(OH)6]2·6H2O, formation of brandholzite-like phases and/or anion exchange was observed. Moreover, Sb(V) was nonhomogeneously distributed on the Mg-Fe LDH surface at all pH values. The surface complexation modeling supported by solid-state analyses provided a strong tool to investigate the binding arrangements of Sb(V) on the Mg-Fe LDH surface. Such a complex mechanistic/modeling approach has not previously been presented and enables prediction of the Sb(V) adsorption behavior onto Mg-Fe LDHs under different conditions, evaluating their possible use in actual applications.
MCM-41-supported nanoscale zero-valent iron (nZVI) was sytnhesized by impregnating the mesoporous silica martix with ferric chloride, followed by chemical reduction with NaHB4. The samples were studied with a combination of characterization techniques such as powder X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and Mössbauer spectroscopy, N2 adsorption measurements, transmission electron microscopy (TEM), magnetization measurements, and thermal analysis methods. The experimental data revealed development of nanoscale zero-valent iron particles with an elliptical shape and a maximum size of ∼80 nm, which were randomly distributed and immobilized on the mesoporous silica surface. Surface area measurements showed that the porous MCM-41 host matrix maintains its hexagonal mesoporous order structure and exhibits a considerable high surface area (609 m(2)/g). Mössbauer and magnetization measurements confirmed the presence of core-shell iron nanoparticles composed of a ferromagnetic metallic core and an oxide/hydroxide shell. The kinetic studies demonstrated a rapid removal of Cr(VI) ions from the aqueous solutions in the presence of these stabilized nZVI particles on MCM-41, and a considerably increased reduction capacity per unit mass of material in comparison to that of unsupported nZVI. The results also indicate a highly pH-dependent reduction efficiency of the material, whereas their kinetics was described by a pseudo-first order kinetic model.
The remediation of a soil contaminated with Zn, Pb and Cd was tested by using biochar (BC), nano zero-valent iron (nZVI) and a combination of these two (BC + nZVI). Each amendment was individually applied to the soil at 2 wt%. We tested the influence of (i) the used amendments, (ii) time, and (iii) soil moisture conditions on the metal availability and soil physico-chemical parameters using various extraction methods, as well as soil pore water samplings. We found that metal availability was mainly affected by pH under the influence of time and water content. Among the tested treatments, BC was the most successful, resulting in the lowest amounts of the target metals in the pore water and the smallest temporal changes in metal concentrations and pH in the soil. The use of nZVI efficiently decreased water-extractable Pb in the short- and long-term. The BC + nZVI treatment also yielded promising results regarding the immobilisation of the studied metals. Time provoked a general decrease in pH, which occasionally increased the available metal concentrations. Raising the soil water content increased the pH and subsequently lowered the available metal concentrations in the pore water. The mechanisms of metal stabilisation were further investigated by SEM/EDS. The results indicated that the used soil amendments enhanced the binding of Zn, Pb, and Cd on Fe/Mn/Al oxides/hydroxides, which in turn resulted in the stabilisation of the target metals.
- MeSH
- dřevěné a živočišné uhlí chemie MeSH
- kadmium analýza MeSH
- látky znečišťující půdu analýza chemie MeSH
- olovo MeSH
- oxidy chemie MeSH
- půda chemie MeSH
- regenerace a remediace životního prostředí metody MeSH
- těžké kovy analýza chemie MeSH
- železo chemie MeSH
- zinek analýza MeSH
- Publikační typ
- časopisecké články MeSH
Separations of bare superparamagnetic magnetite nanoparticles (BSPMNPs, approx. 11 nm diameter) was performed using non-complexing (nitrate) and complexing (chloride, citrate and phosphate) electrolyte ions with additions of tetramethylammonium hydroxide (TMAOH), which is commonly applied to control the synthesis of stable iron oxides. The use of TMAOH as a background electrolyte (BGE) additive for capillary electrophoresis (CE) separations provided for the first time electropherograms of BSPMNPs exhibiting symmetrical and highly reproducible peaks, free of spurious spikes characteristic of nanoparticle clusters. Consequently, accurate determination of the electrophoretic effective mobility of BSPMNPs was possible, yielding a value of -3.345E-08 m2 V-1 s-1 (relative standard deviation (RSD) of 0.500%). The obtained mobilities of BSPMNPs in the presence of various electrolyte ions show that the degree of complexation with the surface of BSPMNPs follows the order chloride < citrate < phosphate, correlating with the stabilities of Fe(III) complexes with the respective anions. Finally, bare and carboxylated iron oxide nanoparticles were successfully separated in only 10 min using 10 mM Tris-nitrate containing 20 mM of TMAOH as electrolyte. Our findings show that simple and rapid CE experiments are an excellent tool to characterise and monitor properties and interactions of iron oxide nanoparticles with other molecules for surface modification purposes.
Correct identification of P forms together with their main Fe and Al binding partners in non-calcareous sediments is of crucial importance for evaluation of P cycling in water bodies. In this paper, we assess extraction methods frequently used for this purpose, i.e., a sequential five-step fractionation (water, bicarbonate buffered dithionite solution (BD), NaOH, HCl, nitric-perchloric acid), ascorbate extraction (pH ~7.5), and oxalate extraction (pH ~3), directly on a range of laboratory prepared Fe and Al minerals enriched with adsorbed P. Extraction selectivity and efficiency for particular P, Fe and Al forms were also verified by specific combinations of these extraction methods applied on freshwater sediment samples. In the sequential fractionation, BD was highly effective in dissolving both amorphous and crystalline Fe (hydr)oxides and the associated P, while neither FeS nor Al (hydr)oxides were dissolved. The following NaOH extraction effectively dissolved both amorphous and crystalline Al (hydr)oxides. The high solubilizing power of BD and NaOH to dissolve crystalline Fe and Al oxides that have only a small P-sorption ability prevents the use of resulting Fe/P and Al/P ratios as simple predictors of total P sorption capacity of sediments and soils. Ascorbate non-selectively extracted small proportions of FeS and amorphous Fe and Al (hydr)oxides, but significant amounts of adsorbed P, which hinders its use for the characterization of P forms in non-calcareous sediments. Similar nonselective characteristics were found for oxalate extractions. As oxalate extracts most of the adsorbed phosphate, it is not possible to use it unambiguously to determine specific Fe/P and Al/P ratios of active complexes. However, this method is convenient (and more selective than NaOH step in the sequential fractionation) for the determination of amorphous Al (hydr)oxides.
- MeSH
- adsorpce MeSH
- chemická frakcionace metody MeSH
- fosfor analýza chemie izolace a purifikace MeSH
- geologické sedimenty chemie MeSH
- hydroxid sodný chemie MeSH
- indikátory a reagencie chemie MeSH
- kvalita vody MeSH
- kyselina oxalová chemie MeSH
- minerály analýza chemie izolace a purifikace MeSH
- reprodukovatelnost výsledků MeSH
- rozpustnost MeSH
- sladká voda chemie MeSH
- sloučeniny hliníku analýza chemie izolace a purifikace MeSH
- sloučeniny železa analýza chemie izolace a purifikace MeSH
- vodní zdroje analýza MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Geografické názvy
- Česká republika MeSH
Maghemite (gamma-Fe2O3) nanoparticles, 12 nm in size, were prepared by co-precipitation of Fe(II) and Fe(III) chlorides with ammonium hydroxide and oxidation with hydrogen peroxide. To achieve stability and biocompatibility, obtained particles were coated with silica, to which glucose and ascorbic acid were bound by different mechanisms. The composite particles were thoroughly characterized by transmission electron microscopy, dynamic light scattering, elemental analysis, and FT-Raman and fluorescence spectroscopy to determine composition, morphology, size and its distribution, zeta-potential, and scavenging of peroxyl and hydroxyl radicals. As the particles showed promising antioxidative properties, they may have a possible application as a stable magnetically controlled scavenger of reactive oxygen species.
Cell wall envelopes treated with sodium hydroxide and spray-dried were used as mercury sorbents. The sorbent having sorption capacity 17.7 ± 0.1 μmol/g determined was employed for preconcentration of mercury containing 1-10 ng/L. After preconcentration, bioavailable mercury was detected in samples of soil, stream, and tap water via induction of bioluminescence of E. coli ARL1. Iron and manganese at concentrations of tenth microgram per liter interfered bioluminescence detection of mercury. In tap water was detected semiquantitatively 0.127 ± 0.1 nmol/L by the induction of bioluminescence of E. coli ARL1 in medium with tryptone after preconcentration using a method of standard addition.
Owing to their high surface area, stability, and functional groups on the surface, iron oxide hydroxide nanoparticles have attracted attention as enzymatic support. In this work, a chemometric approach was performed, aiming at the optimization of the horseradish peroxidase (HRP) immobilization process on Δ-FeOOH nanoparticles (NPs). The enzyme/NPs ratio (X1), pH (X2), temperature (X3), and time (X4) were the independent variables analyzed, and immobilized enzyme activity was the response variable (Y). The effects of the factors were studied using a factorial design at two levels (-1 and 1). The biocatalyst obtained was evaluated for the ferulic acid (FA) removal, a pollutant model. The materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The SEM images indicated changes in material morphology. The independent variables X1 (-0.57), X2 (0.71), and X4 (0.42) presented the significance effects estimate. The variable combinations resulted in two significance effects estimates, X1*X2 (-0.57) and X2*X4 (0.39). The immobilized HRP by optimized conditions (X1 = 1/63 (enzyme/NPs ratio, X2 = pH 8, X4 = 60 °C, and 30 min) showed high efficiency for FA oxidation (82%).
- MeSH
- biokatalýza MeSH
- difrakce rentgenového záření MeSH
- enzymy imobilizované metabolismus MeSH
- křenová peroxidasa metabolismus ultrastruktura MeSH
- kyseliny kumarové chemie metabolismus MeSH
- nanočástice chemie MeSH
- oxidace-redukce MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- železité sloučeniny chemie MeSH
- Publikační typ
- časopisecké články MeSH
Maghemite (gamma-Fe2O3) nanoparticles were obtained by the coprecipitation of Fe(II) and Fe (III) salts with ammonium hydroxide followed by oxidation with sodium hypochlorite. Solution radical polymerization of N,N-dimethylacrylamide(DMAAm) in the presence of maghemite nanoparticles yielded poly(N,N-dimethylacrylamide)(PDMAAm)-coated maghemite nanoparticles. The presence of PDMAAm on the maghemite particle surface was confirmed by elemental analysis and ATR FTIR spectroscopy. Other methods of nanoparticle characterization involved scanning and transmission electron microscopy, atomic adsorption spectroscopy (AAS), and dynamic light scattering (DLS). The conversion of DMAAm during polymerization and the molecular weight of PDMAAmbound to maghemite were determined by using gas and size-exclusion chromatography, respectively. The effect of ionic 4,4'-azobis(4-cyanovaleric acid) (ACVA) initiator on nanoparticle morphology was elucidated. The nanoparticles exhibited long-term colloidal stability in water or physiological buffer. Rat and human bone marrow mesenchymal stem cells (MSCs) were labeled with uncoated and PDMAAm-coated maghemite nanoparticles and with Endorem as a control. Uptake of the nanoparticles was evaluated by Prussian Blue staining, transmission electron microscopy, T(2)-MR relaxometry, and iron content analysis. Significant differences in labeling efficiency were found for human and rat cells. PDMAAm-modified nanoparticles demonstrated a higher efficiency of intracellular uptake into human cells in comparison with that of dextran-modified (Endorem) and unmodified nanoparticles. In gelatin, even a small number of labeled cells changed the contrast in MR images. PDMAAmcoatednanoparticles provided the highest T(2) relaxivity of all the investigated particles. In vivo MR imaging ofPDMAAm-modified iron oxide-labeled rMSCs implanted in a rat brain confirmed their better resolution compared with Endorem-labeled cells.
- MeSH
- akrylamidy chemie MeSH
- barvení a značení metody MeSH
- financování organizované MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- magnetická rezonanční spektroskopie MeSH
- magnetická rezonanční tomografie MeSH
- mezenchymální kmenové buňky cytologie metabolismus ultrastruktura MeSH
- nanočástice chemie MeSH
- radiační rozptyl MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- transmisní elektronová mikroskopie MeSH
- viabilita buněk MeSH
- želatina metabolismus MeSH
- železité sloučeniny chemická syntéza chemie metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
