Human nigral and liver iron – comparison by Mössbauer spectroscopy, electron microscopy and ELISA

The properties of iron present in human liver and human substantia nigra (SN) were compared. Mössbauer measurements have shown that iron is present in similar concentrations in SN and in the liver, mainly as ferritin-like iron. The size of the iron cores of ferritin, as obtained from electron microscopy, is much smaller in SN (3.6?±?0.4 nm) than in liver (5.7?±?0.5 nm). The small size in SN is in agreement with the low blocking temperature (about 10 K), determined by temperature dependent Mössbauer studies on whole tissues. ELISA studies have shown differences between SN and liver in the structures of the protein shells of ferritin. The H/L ratio (concentration of heavy to light chains) in liver is 0.40?±?0.02, while in SN it is 4.3?±?0.3. Another possible iron binding compound in SN is neuromelanin (NM). Mössbauer studies of neuromelanin, isolated from 22 SNs, demonstrated that this iron is superparamagnetic. The blocking temperature found for this neuromelanin iron is however much higher than that for ferritin.     

Iron in Parkinson's Disease Revisited

Hyperfine Interactions - Mössbauer studies of fresh frozen samples taken at autopsy from different parts of the human brain (globus pallidus (GP), substantia nigra (NS), and hippocamp (Hip))...     

Magnetic and Mössbauer spectroscopic studies of NiZn ferrite nanoparticles synthesized by a combustion method

The properties of nanocrystalline Ni_0.5Zn_0.5Fe₂O₄ synthesized by an auto-combustion method have been investigated by magnetic measurements and Mössbauer spectroscopy. The as-synthesized single phase nanosized ferrite powder is annealed at different temperatures in the range 673–1,273 K to obtain nanoparticles of different sizes. The powders are characterized by powder X-ray diffraction, vibrating sample magnetometer, transmission electron microscopy and Mössbauer spectroscopy. The as-synthesized powder with average particle size of ~9 nm is superparamagnetic. Magnetic transition temperature increases up to 665 K for the nanosized powder as compared to the transition temperature of 548 K for the bulk ferrite. This has been confirmed as due to the abnormal cation distribution, as evidenced from room temperature Mössbauer spectroscopic studies.     

Iron in typical and atypical parkinsonism – Mössbauer spectroscopy and MRI studies

Iron may play important role in neurodegeneration. The results of comparative studies of human brain areas (control and pathological) performed by Mössbauer spectroscopy (MS) and magnetic resonance imaging (MRI) techniques are presented. Mössbauer spectroscopy demonstrated a higher concentration of iron in atypical parkinsonism (progressive supranuclear palsy PSP) in the brain areas Substantia Nigra (SN) and Globus Pallidus (GP) involved in this pathological process, compared to control, while the concentration of iron in pathological tissues in typical parkinsonism (Parkinson’s disease - PD) did not differ from that in control. These results were compared with the changes in 1/T1 and 1/T2 (T1 and T2 being the relaxation times determined by MRI). A good linear correlation curve was found between the concentration of iron as determined by MS in different areas of control human brains and between 1/T1 and 1/T2. Whereas the finding in PSP-GP (the brain area involved in PSP) also fitted to such a correlation, this was not so for the correlation between pathological SN – the brain area involved in both diseases – and 1/T2, indicating a dependence of T2 on other factors than just the concentration of iron.     

Formation of graphite encapsulated iron nanoparticles during mechanical activation and annealing analyzed by Mössbauer spectroscopy

The investigation performed by means of Mössbauer spectroscopy, X-ray diffraction and transmission electron microscopy demonstrated that the interaction in the system iron-amorphous carbon proceeds via the formation of nano-sized iron particles (10–40 nm) and the carbide nano- phases distributed over amorphous carbon matrix. The annealing of these samples causes a crystallization of the amorphous carbon, decomposition of nano-sized carbide phases and formation of iron nanoparticles (50–100 nm) encapsulated by graphite.     

Mössbauer effect phase determination in iron oxide–polyaniline nanocomposites

Mössbauer effect spectroscopy and thermal analysis techniques were applied to characterize polyaniline composites successfully synthesized by embedding Fe oxide nanoparticles (about 10–13 nm) in a polymeric matrix in the presence of dodecyl benzene sulfonic acid and HCl (dopant). Thermal techniques provided quantitative information on iron oxide content and on polyaniline stability and transformations. Mössbauer results indicated that for the whole studied composition range, 3.4 to 100 iron oxide wt.%, composites hold maghemite particles. A preliminary study of the conductivity of the nanocomposites was performed. The largest conductivity was observed for a 8 wt.% maghemite composite where all particles are magnetically unblocked at room temperature within the Mössbauer time window.     

Magnetic and quadrupolar studies of the iron storage overload in livers

Absorption⁵⁷Fe Mössbauer spectra, performed directly on tissues of liver with iron overload due to an excessive intestinal iron absorption or induced by hypertransfusional therapeutics, have pointed out a new high spin ferric storage iron besides the ferritin and hemosiderin. Mössbauer studies, carried out on ferritin and hemosiderin fractions isolated from normal and overloaded livers, show that this compound, only present in the secondary iron overload (transfusional pathway), seems characteristic of the physiological process which induces the iron overload.     

Mössbauer study of iron uptake in cucumber root

⁵⁷Fe Mössbauer spectroscopy was used to study the uptake and distribution of iron in the root of cucumber plants grown in iron-deficient modified Hoagland nutrient solution and put into iron-containing solution with 10 μM Fe citrate enriched with ⁵⁷Fe (90%) only before harvesting. The Mössbauer spectra of the frozen roots exhibited two Fe³⁺ components with typical average Mössbauer parameters of δ?=?0.5 mm s^?1, Δ?=?0.46 mm s^?1 and δ?=?0.5 mm s^?1, Δ?=?1.2 mm s^?1 at 78 K and the presence of an Fe²⁺ doublet, assigned to the ferrous hexaaqua complex. This finding gives a direct evidence for the existence of Fe²⁺ ions produced via root-associated reduction according to the mechanism proposed for iron uptake for dicotyledonous plants. Monotonous changes in the relative content of the components were found with the time period of iron supply. The Mössbauer results are interpreted in terms of iron uptake and transport through the cell wall and membranes.     

Magnetism in plant and mammalian ferritin

A rich variety of magnetic phenomena is observed in Mössbauer studies of ferritin. Depending on the amount of iron in the horse spleen ferritin core, a paramagnetic relaxation spectrum, or quadrupole split doublet or a magnetically split sextet showing superpara-magnetism, are obtained a 4.1 K. Mössbauer studies of the recently prepared iron loaded concanavalin A yield hyperfine parameters identical to those found previously in mammalian ferritin, yet show the existence of larger iron aggregates. Due to the larger particle size it is possible to follow the magnetic hyperfine field and to obtain the magnetic ordering temperature as 240 K. This is exactly the Neél temperature of ferrihydrite, thus establishing that this is indeed the iron compound in the ferritin core.     

Surface oxidation control of nanosized magnetite and Mössbauer measurements

Selected highly homogeneous powders of Fe₃O₄ with different particle size on the nanometer scale (10?±?2 and 3?±?2 nm) obtained by soft-chemical methods were studied by Mössbauer spectroscopy. The study shows clearly the powerful possibilities of Mössbauer spectroscopy to analyze the surface oxidation of nanostructured powders of magnetite. On the other hand, it is shown that for very small superparamagnetic particles the spectrum of magnetite might be quite similar to that of maghemite, making it difficult to distinguish between both phases.     

A Mössbauer study of iron and iron–cobalt nanotubes in polymer ion-track membranes

Iron and iron–cobalt nanostructures that were synthesized in polymer ion-track membranes have been studied via Mössbauer spectroscopy combined with raster electron microscopy, energy-dispersion analysis, and X-ray diffraction data. The obtained nanostructures are single-phase bcc Fe_1–xCo_x nanotubes with a high degree of polycrystallinity, whose length is 12 μm; their diameter is 110 ± 3 nm and the wall thickness is 21 ± 2 nm. Fe²⁺ and Fe³⁺ cations were detected in the nanotubes, which belong to iron salts that were used and formed in the electrochemical deposition. The Fe nanotubes exhibit eventual magnetic moment direction distributions of Fe atoms, whereas Fe/Co nanotubes have a partial magnetic structure along the nanotube axis with a mean value of the angle between the magnetic moment and nanotube axis of 34° ± 2°. Substituting the Fe atom with Co in the nearest environment of the Fe atom within the Fe/Co structure of nanotubes leads to a noticeable increase in the hyperfine magnetic field at the ⁵⁷Fe nuclei (by 8.7 ± 0.4 kOe) and to a slight decrease in the shift of the Mössbauer line (by 0.005 ± 0.004 mm/s).     

Mössbauer studies of iron uptake,ferritin and hemoglobin synthesis and denaturation in erythroid cell cultures

Mössbauer studies in murine (MEL) and human K-562 erythroleukemia cell lines have been utilized to study the fate of iron during intracellular Hb synthesis and denaturation. The results showed that ferritin can serve as an intermediate iron pool for Hb synthesis and for storage of iron released during intracellular Hb denaturation.     

Characterization of Maghsail meteorite from Oman by Mössbauer spectroscopy, X-ray diffraction and petrographic microscopy

The meteorite found at Maghsail (16 55 70 N–53 46 69 E) west of Salalah Oman, has been studied by ⁵⁷Fe Mössbauer spectroscopy, X-diffractometry and petrographic microscopy. In the polished section the meteorite exhibits a porphyritic texture consisting of pyroxene and olivine phenocrysts in a fine to medium grained ground mass in addition to minor phases possibly skeletal chromite, troilite and minute amount of iron oxides. X-ray diffraction supports the existence of these compounds. The Mössbauer spectra of powdered material from the core of the rock at 298 K and 78 K exhibit a mixture of magnetic and paramagnetic components. The paramagnetic components are assigned to the silicate minerals olivine and pyroxene. On the other hand, the magnetic spectra reveal the presence of troilite and iron oxides. The petrographic analyses indicate that the iron oxides are terrestrial alteration products.     

Comparative study of nanosized iron cores in human liver ferritin and its pharmaceutically important models Maltofer® and Ferrum Lek using Mössbauer spectroscopy

Studies of human liver ferritin and its pharmaceutically important models Maltofer® and Ferrum Lek were carried out using Mössbauer spectroscopy with a high velocity resolution at 295 and 90 K and Mössbauer spectroscopy with a low velocity resolution at 40 and 20 K. The Mössbauer spectra fits using a multi-component model confirm the hypothesis of the complicated heterogeneous structure of nanosized iron cores in the investigated samples.     

Mössbauer investigation of iron uptake in wheat

Iron uptake and distribution in wheat roots were studied with ⁵⁷Fe Mössbauer spectroscopy. Plants were grown both in iron sufficient and in iron deficient nutrient solutions. Mössbauer spectra of the frozen iron sufficient roots exhibited three iron(III) components with the typical average Mössbauer parameters of δ?= 0.50 mm s^???1, Δ?= 0.43 mm s^???1, δ?= 0.50 mm s^???1, Δ?= 0.75 mm s^???1 and δ?= 0.50 mm s^???1, Δ?= 1.20 mm s^???1 at 80 K. These doublets are very similar to those obtained earlier for cucumber [0], which allows us to suppose that iron is stored in a very similar way in different plants. No ferrous iron could be identified in any case, not even in the iron deficient roots, which confirms the mechanism proposed for iron uptake in the graminaceous plants.     

Crystal chemistry and Mössbauer spectroscopic analysis of clays around Riyadh for brick industry

A total of 30 clay samples were collected from the area around Riyadh city, Saudi Arabia. A complete chemical analysis was carried out using different techniques. X-ray diffraction studies showed that the clay samples were mainly of the smectite group with traces of the kaolinite one. The samples studied were classified as nontronite clay minerals. One of the clay fraction has been studied by Mössbauer spectroscopy as raw clay fraction and after being fired at 950–1,000 °C. The Mössbauer spectra showed accessory iron compounds in the form of hematite and goethite. The structural iron contents disintegrate on firing transforming into magnetic iron oxide and a paramagnetic small particles iron oxide.     

A study of the sump beaver's dental enamel

The nature of the iron-containing phase in the dental enamel of sump beaver incisors has been studied by use of Mössbauer spectroscopy. All iron atoms are found to be trivalent and to be present in particles exhibiting superparamagnetic relaxation. The iron-containing phase has Mössbauer parameters similar to those of ferritin.     

Magnetic and Mössbauer studies of fucan-coated magnetite nanoparticles for application on antitumoral activity

Fucan-coated magnetite (Fe₃O₄) nanoparticles were synthesized by the co-precipitation method and studied by Mössbauer spectroscopy and magnetic measurements. The sizes of the nanoparticles were 8–9 nm. Magnetization measurements and Mössbauer spectroscopy at 300 K revealed superparamagnetic behavior. The magnetic moment of the Fe₃O₄ is partly screened by the Fucan coating aggregation. When the magnetite nanoparticles are capped with oleic acid or fucan, reduced particle-particle interaction is observed by Mössbauer and TEM studies. The antitumoral activity of the fucan-coated nanoparticles were tested in Sarcoma 180, showing an effective reduction of the tumor size.     

Mössbauer studies of impactites from Huamalies province in Huanuco Region

This report is about the X-ray diffraction and Mössbauer studies of three impactite samples denominated PMe-8, PMe-9 and PMe-11 from Huamalies Province in Huánuco Region, Peru. When terrestrial rocks are submitted to pressures higher than 60 GP, the majority is completely melted, forming a kind of glass called impactites. X-ray diffraction indicates the presence of quartz as the principal mineralogical phase in all samples. The ⁵⁷Fe Mössbauer spectra at room temperature of samples PMe-8 and PMe-9 show broadened spectra that were fitted using a distribution model. The most probable field of the magnetic component is 34 T, corresponding to the presence of small particles of goethite, confirmed by the 4.2 K spectrum. For the sample PMe-11, the MS showed the presence of well crystallized hematite.