Influence of ferrous iron incorporation on the structure of hydroxyapatite

Iron is a vital element of cellular function within the body. High concentrations of iron can be found in the kidneys and the circulatory system. In bones and teeth it is present as a trace element. The use of iron-based compounds in combination with hydroxyapatite offers a new alternative for prosthetic devices. This work investigates the synthesis and processing of iron containing apatites as a possible new type of ceramic for biomedical devices. Stoichiometric and calcium deficient iron containing apatites were synthesized by a wet chemical reaction with di-ammonium-hydrogen-phosphate, calcium nitrate and a ferrous iron nitrate solution. A secondary phase of tri-calcium-phosphate (TCP) was observed after heat treatment of iron containing, calcium deficient, hydroxyapatite. The apatite structure was maintained after heat treatment of stoichiometric apatite, synthesized in the presence of iron. Sintering in air produced oxidation of Fe²⁺ to Fe³⁺, resulting in the formation of hematite as a secondary phase. The introduction of iron into the synthesis of hydroxyapatite causes: (i) an increase of the a-lattice parameter after synthesis and heat treatment in air; (ii) an increase in the c-lattice parameter after sintering in air.     

Compact zwitterion-coated iron oxide nanoparticles for biological applications

The potential of superparamagnetic iron oxide nanoparticles (SPIONs) in various biomedical applications, including magnetic resonance imaging (MRI), sensing, and drug delivery, requires that their surface be derivatized to be hydrophilic and biocompatible. We report here the design and synthesis of a compact and water-soluble zwitterionic dopamine sulfonate (ZDS) ligand with strong binding affinity to SPIONs. After ligand exchange, the ZDS-coated SPIONs exhibit small hydrodynamic diameters, and stability with respect to time, pH, and salinity. Furthermore, small ZDS coated SPIONs were found to have a reduced nonspecific affinity (compared to negatively charged SPIONs) toward serum proteins; streptavidin/dye functionalized SPIONs were bioactive and thus specifically targeted biotin receptors.     

SERS-active silver nanoparticle aggregates produced in high-iron float glass by ion exchange process

Silver nanoparticles were produced in iron containing float glasses by silver-sodium ion exchange and post-annealing. In particular, the effect of the concentration and the oxidation state of iron in the host glass on the nanoparticle formation was studied. After the nanoparticle fabrication process, the samples were characterized by optical absorption measurements. The samples were etched to expose nanoparticle aggregates on the surface, which were studied by optical microscopy and scanning electron microscopy. The SERS-activity of these glass samples was demonstrated and compared using a dye molecule Rhodamine 6G (R6G) as an analyte. The importance of the iron oxidation level for reduction process is discussed. The glass with high concentration of Fe²⁺ ions was found to be superior in SERS applications of silver nanoparticles. The optimal surface features in terms of SERS enhancement are also discussed.     

Surface modification of CdSe quantum dots for biosensing applications: Role of ligands

For an optimum performance of colloidal nanocrystal devices for a variety of applications such as photonic devices, solar cells and biological labelling, the determining factors are the nanocrystal surface and size. In this work, these two factors have been tuned via wet chemistry to tailor the material properties: The absorption and emission spectra have been tailored by choice of the nanocrystal size; nanocrystal shape by surface modification and photoluminescence (PL) efficiency determined by surface traps, has been tuned via appropriate selection of the nanocrystal capping ligands. Here, we have shown that through ligand-exchange process, the surface of the CdSe quantum dots (QDs) can be modified by replacing the longer-chain ligands of conventional trioctyl phosphine oxide (TOPO) or oleic acid (OA) with shorter-chain ligand of butyl amine. This imparts colloidal stability and water solubility to CdSe QDs for its potential applications in biosensors and biological imaging. It is conjectured that crystallite sizes, oxidation potential of CdSe QDs and stereochemical compatibility of ligands (TOPO, oleic acid and butyl amine) greatly influences the photophysics and photochemistry of CdSe QDs.     

Amino‐polyvinyl Alcohol Coated Superparamagnetic Iron Oxide Nanoparticles are Suitable for Monitoring of Human Mesenchymal Stromal Cells In Vivo

Mesenchymal stromal cells (MSCs) are promising candidates in regenerative cell‐therapies. However, optimizing their number and route of delivery remains a critical issue, which can be addressed by monitoring the MSCs’ bio‐distribution in vivo using super‐paramagnetic iron‐oxide nanoparticles (SPIONs). In this study, amino‐polyvinyl alcohol coated (A‐PVA) SPIONs are introduced for cell‐labeling and visualization by magnetic resonance imaging (MRI) of human MSCs. Size and surface charge of A‐PVA‐SPIONs differ depending on their solvent. Under MSC‐labeling conditions, A‐PVA‐SPIONs have a hydrodynamic diameter of 42 ± 2 nm and a negative Zeta potential of 25 ± 5 mV, which enable efficient internalization by MSCs without the need to use transfection agents. Transmission X‐ray microscopy localizes A‐PVA‐SPIONs in intracellular vesicles and as cytosolic single particles. After identifying non‐interfering cell‐assays and determining the delivered and cellular dose, in addition to the administered dose, A‐PVA‐SPIONs are found to be non‐toxic to MSCs and non‐destructive towards their multi‐lineage differentiation potential. Surprisingly, MSC migration is increased. In MRI, A‐PVA‐SPION‐labeled MSCs are successfully visualized in vitro and in vivo. In conclusion, A‐PVA‐SPIONs have no unfavorable influences on MSCs, although it becomes evident how sensitive their functional behavior is towards SPION‐labeling. And A‐PVA‐SPIONs allow MSC‐monitoring in vivo.     

Cytotoxicity and Cell Cycle Effects of Bare and Poly(vinyl alcohol)‐Coated Iron Oxide Nanoparticles in Mouse Fibroblasts

Super‐paramagnetic iron oxide nanoparticles (SPIONs) are recognized as powerful biocompatible materials for use in various biomedical applications, such as drug delivery, magnetic‐resonance imaging, cell/protein separation, hyperthermia and transfection. This study investigates the impact of high concentrations of SPIONs on cytotoxicity and cell‐cycle effects. The interactions of surface‐saturated (via interactions with cell medium) bare SPIONs and those coated with poly(vinyl alcohol) (PVA) with adhesive mouse fibroblast cells (L929) are investigated using an MTT assay. The two SPION formulations are synthesized using a co‐precipitation method. The bare and coated magnetic nanoparticles with passivated surfaces both result in changes in cell morphology, possibly due to clustering through their magnetostatic effect. At concentrations ranging up to 80 × 10^?3 M , cells exposed to the PVA‐coated nanoparticles demonstrate high cell viability without necrosis and apoptosis. In contrast, significant apoptosis is observed in cells exposed to bare SPIONs at a concentration of 80 × 10^?3 M . Nanoparticle exposure (20–80 × 10^?3 M ) leads to variations in both apoptosis and cell cycle, possibly due to irreversible DNA damage and repair of oxidative DNA lesions, respectively. Additionally, the formation of vacuoles within the cells and granular cells indicates autophagy cell death rather than either apoptosis or necrosis.     

Effect of iron state on crystallization and dissolution in Fe2O3-CaO-SiO2 glasses

The possibility of iron-containing glasses as thermoseeds for hyperthermia of bone tumor was reported previously. There is, however, no report about the effect of iron state on the crystallization of magnetite and the resultant properties. The iron states were determined by Mo¨ssbauer spectroscopy in Fe₂O₃-CaO-SiO₂ system. It was found that the higher CaO content interrupts the crystallization of magnetite crystallites as well as the oxidation of iron, that is, the transformation from Fe³⁺ to Fe²⁺. A sample containing large amounts of Fe²⁺ showed the faster increment of temperature when the alternating magnetic field was applied. In order to use the thermoseed for a hyperthermia, we can say that the composition with low CaO content is most useful.     

One-pot synthesis of oleic acid modified monodispersed mesoporous TiO2 nanospheres with enhanced visible light photocatalytic performance

Herein, we report a facile one-pot solvothermal method to prepare unique oleic acid (OA) modified monodispersed mesoporous TiO₂ nanospheres with carboxylate ligands from the oleic acid in the bidentate chelating linkage mode. The mesoporous OA-TiO₂ nanospheres have a very large specific surface of nearly 510?m²/g. The oleic acid cannot only act as a binding ligand to control the shape of mesoporous TiO₂ nanospheres, but also be benefit to enhance the visible-light absorption. The mesoporous OA-TiO₂ nanospheres exhibit an excellent photocatalytic performance in the degradation of Rhodamine B and phenol under the visible light irradiation and show almost no attenuation after four cycles.     

In vivo study of anti‐epidermal growth factor receptor antibody‐based iron oxide nanoparticles (anti‐EGFR‐SPIONs) as a novel MR imaging contrast agent for lung cancer (LLC1) cells detection

Superparamagnetic iron oxide nanoparticles (SPIONs) conjugated with anti‐epidermal growth factor receptor monoclonal antibody (anti‐EGFR‐SPIONs) were characterised, and its cytotoxicity effects, ex vivo and in vivo studies on Lewis lung carcinoma (LLC1) cells in C57BL/6 mice were investigated. The broadband at 679.96 cm⁻¹ relates to Fe–O, which verified the formation of the anti‐EGFR‐Mab with SPIONs was obtained by the FTIR. The TEM images showed spherical shape 20 and 80 nm‐sized for nanoparticles and the anti‐EGFR‐SPIONs, respectively. Results of cell viability at 24 h after incubation with different concentrations of nanoprobe showed it has only a 20% reduction in cell viabilities. The synthesised nanoprobe administered by systemic injection into C57BL/6 mice showed good Fe tumour uptake and satisfied image signal intensity under ex vivo and in vivo conditions. A higher concentration of nanoprobe was achieved compared to non‐specific and control, indicating selective delivery of nanoprobe to the tumour. It is concluded that the anti‐EGFR‐SPIONs was found to be as an MR imaging contrast nanoagent for lung cancer (LLC1) cells detection.Inspec keywords: toxicology, biomedical MRI, lung, magnetic particles, biomedical materials, nanofabrication, nanomagnetics, transmission electron microscopy, nanomedicine, superparamagnetism, nanoparticles, iron compounds, proteins, cellular biophysics, molecular biophysics, cancer, tumours, Fourier transform infrared spectraOther keywords: MR imaging contrast agent, LLC1, superparamagnetic iron oxide nanoparticles, Lewis lung carcinoma cells, ex vivo conditions, cell viability, antiepidermal growth factor receptor antibody‐based iron oxide nanoparticles, antiEGFR‐SPION, lung cancer cell detection, antiepidermal growth factor receptor monoclonal antibody, cytotoxicity effects, C57BL‐6 mice, antiEGFR‐Mab, FTIR spectra, TEM, spherical shape, incubation, nanoprobe concentrations, systemic injection, Fe tumour uptake, image signal intensity, in vivo conditions, time 24.0 hour, Fe₃ O₄      

Fe2+ oxidation rate drastically affect the formation and phase of secondary iron hydroxysulfate mineral occurred in acid mine drainage

During the processes of secondary iron hydroxysulfate mineral formation, Fe²⁺ ion was oxidized by the following three methods: (1) biooxidation treatment by Acidithiobacillus ferrooxidans (A. ferrooxidans); (2) rapid abiotic oxidation of Fe²⁺ with H₂O₂ (rapid oxidation treatment); (3) slow abiotic oxidation of Fe²⁺ with H₂O₂ (slow oxidation treatment). X-ray diffraction (XRD) patterns, element composition, precipitate weight and total Fe removal efficiency were analyzed. The XRD patterns and element composition of precipitates synthesized through the biooxidation and the slow oxidation treatments well coincide with those of potassium jarosite, while precipitates formed at the initial stage of incubation in the rapid oxidation treatment showed a similar XRD pattern to schwertmannite. With the ongoing incubation, XRD patterns and element composition of the precipitates that occurred in the rapid oxidation treatment were gradually close to those in the biooxidation and the slow oxidation treatments. Due to the inhibition of A. ferrooxidans itself and its extracellular polymeric substances (EPS) in aggregation of precipitates, the amount of precipitates and soluble Fe removal efficiency were lower in the biooxidation treatment than in the slow oxidation treatment. Therefore, it is concluded that Fe²⁺ oxidation rate can greatly affect the mineral phase of precipitates, and slow oxidation of Fe²⁺ is helpful in improving jarosite formation.     

LHRH-functionalized superparamagnetic iron oxide nanoparticles for breast cancer targeting and contrast enhancement in MRI

This paper shows that superparamagnetic iron oxide nanoparticles (SPIONs) conjugated to luteinizing hormone releasing hormone (LHRH) (LHRH–SPIONs), can be used to target breast cancer cells. They also act as contrast enhancement agents during the magnetic resonance imaging of breast cancer xenografts. A combination of transmission electron microscopy (TEM) and spectrophotometric analysis was used in our experiments, to investigate the specific accumulation of the functionalized superparamagnetic iron oxide nanoparticles (SPIONs) in cancer cells. The contrast enhancement of conventional T2 images obtained from the tumor tissue and of breast cancer xenograft bearing mice is shown to be much greater than that in saline controls, when the tissues were injected with LHRH–SPIONs. Magnetic anisotropy multi-CRAZED images of tissues extracted from mice injected with SPIONs were also found to have enhanced MRI contrast in breast cancer xenografts and metastases in the lungs.     

Fenton-like oxidation of Rhodamine B in the presence of two types of iron (II,III) oxide

The catalytic efficiency of iron (II, III) oxide to promote Fenton-like reaction was examined by employing Rhodamine B (RhB) as a model compound at neutral pH. Two types of iron (II, III) oxides were used as heterogeneous catalysts and characterized by XRD, Mössbauer spectroscopy, BET surface area, particle size and chemical analyses. The adsorption to the catalyst changed significantly with the pH value and the sorption isotherm was fitted using the Langmuir model for both solids. Both sorption and FTIR results indicated that surface complexation reaction may take place in the system. The variation of oxidation efficiency against H₂O₂ dosage and amount of exposed surface area per unit volume was evaluated and correlated with the adsorption behavior in the absence of oxidant. The occurrence of optimum amount of H₂O₂ or of exposed surface area for the effective degradation of RhB could be explained by the scavenging effect of hydroxyl radical by H₂O₂ or by iron oxide surface. Sorption and decolourization rate of RhB as well as H₂O₂ decomposition rate were found to be dependent on the surface characteristics of iron oxide. The kinetic oxidation experiments showed that structural Fe^II content strongly affects the reactivity towards H₂O₂ decomposition and therefore RhB decolourization. The site density and sorption ability of RhB on surface may also influence the oxidation performance in iron oxide/H₂O₂ system. The iron (II, III) oxide catalysts exhibited low iron leaching, good structural stability and no loss of performance in second reaction cycle. The sorption on the surface of iron oxide with catalytic oxidation using hydrogen peroxide would be an effective oxidation process for the contaminants.     

Magnetically responsive,sorafenib loaded alginate microspheres for hepatocellular carcinoma treatment

This study aimed to develop sorafenib loaded magnetic microspheres for the treatment of hepatocellular carcinoma. To achieve this goal, superparamagnetic iron oxide nanoparticles (SPIONs) were synthesised and encapsulated in alginate microspheres together with an antineoplastic agent, sorafenib. In the study, firstly SPIONs were synthesised and characterised by dynamic light scattering, energy‐dispersive X‐ray spectroscopy, and scanning electron microscopy. Then, alginate‐SPIONs microspheres were developed, and further characterised by electron spin resonance spectrometer and vibrating sample magnetometer. Besides the magnetic properties of SPIONs, alginate microspheres with SPIONs were also found to have magnetic properties. The potential use of microspheres in hyperthermia treatment was then investigated and an increase of about 4°C in the environment was found out. Drug release studies and cytotoxicity tests were performed after sorafenib was encapsulated into the magnetic microspheres. According to release studies, sorafenib has been released from microspheres for 8 h. Cytotoxicity tests showed that alginate‐SPION‐sorafenib microspheres were highly effective against cancerous cells and promising for cancer therapy.Inspec keywords: drug delivery systems, drugs, nanofabrication, magnetic particles, iron compounds, scanning electron microscopy, hyperthermia, biomedical materials, encapsulation, nanoparticles, light scattering, nanomagnetics, cellular biophysics, toxicology, cancer, nanomedicine, superparamagnetism, nanocomposites, magnetometry, paramagnetic resonance, X‐ray chemical analysisOther keywords: sorafenib loaded alginate microspheres, hepatocellular carcinoma treatment, sorafenib loaded magnetic microspheres, superparamagnetic iron oxide nanoparticles, dynamic light scattering, energy‐dispersive X‐ray spectroscopy, scanning electron microscopy, electron spin resonance spectrometer, vibrating sample magnetometer, hyperthermia treatment, drug release, alginate‐SPION‐sorafenib microspheres, antineoplastic agent, cytotoxicity tests, cancerous cells, time 8.0 hour, Fe₃ O₄      

Facile conversion of bulk metal surface to metal oxide single-crystalline nanostructures by microwave irradiation: Formation of pure or Cr-doped hematite nanostructure arrays

We report a method for converting the surfaces of bulk metal substrates (pure iron or stainless steel) to metal oxide (hematite or Cr-doped hematite) nanostructures using microwave irradiation. When microwave radiation (2.45 GHz, single-mode) was applied to a metal substrate under the flow of a gas mixture containing O₂ and Ar, metal oxide nanostructures formed and entirely covered the substrate. The nanostructures were single crystalline, and the atomic ratios of the substrate metals were preserved in the nanostructures. When a pure iron sheet was used as a substrate, hematite nanowires (1000 W microwave radiation) or nanosheets (1800 W microwave radiation) formed on the surface of the substrate. When a SUS410 sheet was used as a substrate, slightly curved rod-like nanostructures were synthesized. The oxidation states of Fe and Cr in these nanorods were Fe³⁺ and Cr³⁺. Quantitative analyses revealed an average Fe/Cr atomic ratio of 9.2, nearly identical to the ratio of the metals in the SUS410 substrate.     

Effect of magnetic field on the zero valent iron induced oxidation reaction

The magnetic field (MF) effect on the zero valent iron (ZVI) induced oxidative reaction was investigated for the first time. The degradation of 4-chlorophenol (4-CP) in the ZVI system was employed as the test oxidative reaction. MF markedly enhanced the degradation of 4-CP with the concurrent production of chlorides. The consumption of dissolved O₂ by ZVI reaction was also enhanced in the presence of MF whereas the competing reaction of H₂ production from proton reduction was retarded. Since the ZVI-induced oxidation is mainly driven by the in situ generated hydroxyl radicals, the production of OH radicals was monitored by the spin trap method using electron spin resonance (ESR) spectroscopy. It was confirmed that the concentration of trapped OH radicals was enhanced in the presence of MF. Since both O₂ and Fe⁰ are paramagnetic, the diffusion of O₂ onto the iron surface might be accelerated under MF. The magnetized iron can attract oxygen on itself, which makes the mass transfer process faster. As a result, the surface electrochemical reaction between Fe⁰ and O₂ can be accelerated with the enhanced production of OH radicals. MF might retard the recombination of OH radicals as well.     

Oxidation of polyvinyl alcohol by persulfate activated with heat,Fe, and zero-valent iron

The oxidation of polyvinyl alcohol (PVA) by persulfate (S₂O₈²⁻) activated with heat, Fe²⁺, and zero-valent iron (Fe(0)) was investigated via batch experiments. It was hypothesized that elevated temperature and the addition of Fe²⁺ or Fe(0) into a persulfate-water system could enhance the oxidation of PVA by activated persulfate. Increasing the temperature from 20 to 60 °C or 80 °C accelerated the oxidation rate of PVA, which achieved complete oxidation in 30 and 10 min, respectively. At 20 °C, the addition of Fe²⁺ or Fe(0) to the persulfate-water system significantly enhanced the oxidation of PVA. The optimal persulfate-to-Fe²⁺ or Fe(0) molar ratio was found to be 1:1. Complete oxidation of PVA was obtained by Fe(0)-activated persulfate in 2 h. Synergistic activation of persulfate by heat and Fe²⁺ or Fe(0) was also shown to enhance the oxidation of PVA in the persulfate-water system. By using GC–MS analysis, an oxidation product of PVA was identified as vinyl acetic acid (C₄H₆O₂), which is readily biodegradable. Our results suggest that the oxidative treatment of PVA by activated persulfate is a viable option for the pretreatment of PVA-laden wastewater to enhance its biodegradability.     

Bulk and surface structures of iron doped zirconium oxide systems: Influence of preparation method

Three different Fe-Zr oxide systems were prepared using firstly classical impregnation of iron nitrates on calcined ZrO₂ (Fe_x/ZrO₂, x represents Fe/Zr ratio = 0.01 and 0.11), secondly impregnation of iron nitrates on dried zirconium hydroxide ZrO(OH)₂ (Fe_x/ZrO(OH)₂) and finally hydrolysis of aqueous suspension of iron and zirconium salts to coprecipitate iron and zirconium hydroxides (Fe_x-Zr). Thermal decomposition study of dried samples evidenced a delay in the temperature crystallization of zirconia for Fe_x-Zr and Fe_x/ZrO(OH)₂, the more the iron content in the sample, the more important the delay. For these samples, the formation and the stabilization of different phases were evidenced by several characterization techniques : X-Ray Diffraction (XRD), Raman spectroscopy and Electron Paramagnetic Resonance (EPR).The interaction of iron species with zirconia was different in accordance with different preparations. A bulk dispersion of the coprecipitated sample was observed and as a consequence Zr^{3 +} defects in the solid were not produced. In the case of Fe_x/ZrO₂ sample, production of surface Zr^{3 +} ions was established at low temperature of calcination (up to 600^∘C) and explained by the reaction of NO₃⁻ with Zr^{4 +} on the zirconia surface. However such interaction did not occur for Fe_x/ZrO(OH)₂ since a low dispersion of iron species was observed by X-ray Photoelectron Spectroscopy (XPS), deposited phase (Fe₂O₃) forming preferentially blocks. Temperature Programmed Reduction (TPR) showed that the reduction of small particles of Fe₂O₃ and bulk Fe₂O₃ present in the impregnated samples was easier than that of iron species well dispersed in the bulk of the coprecipitated solid.     

Surface engineered magnetic nanoparticles for removal of toxic metal ions and bacterial pathogens

Surface engineered magnetic nanoparticles (Fe₃O₄) were synthesized by facile soft-chemical approaches. XRD and TEM analyses reveal the formation of single-phase Fe₃O₄ inverse spinel nanostructures. The functionalization of Fe₃O₄ nanoparticles with carboxyl (succinic acid), amine (ethylenediamine) and thiol (2,3-dimercaptosuccinic acid) were evident from FTIR spectra, elemental analysis and zeta-potential measurements. From TEM micrographs, it has been observed that nanoparticles of average sizes about 10 and 6 nm are formed in carboxyl and thiol functionalized Fe₃O₄, respectively. However, each amine functionalized Fe₃O₄ is of size ∼40 nm comprising numerous nanoparticles of average diameter 6 nm. These nanoparticles show superparamagnetic behavior at room temperature with strong field dependent magnetic responsivity. We have explored the efficiency of these nanoparticles for removal of toxic metal ions (Cr³⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺, Pb²⁺ and As³⁺) and bacterial pathogens (Escherichia coli) from water. Depending upon the surface functionality (COOH, NH₂ or SH), magnetic nanoadsorbents capture metal ions either by forming chelate complexes or ion exchange process or electrostatic interaction. It has been observed that the capture efficiency of bacteria is strongly dependent on the concentration of nanoadsorbents and their inoculation time. Furthermore, these nanoadsorbents can be used as highly efficient separable and reusable materials for removal of toxic metal ions.     

Characterizing the discoloration of methylene blue in Fe/H2O systems

Methylene blue (MB) was used as a model molecule to characterize the aqueous reactivity of metallic iron in Fe⁰/H₂O systems. Likely discoloration mechanisms under used experimental conditions are: (i) adsorption onto Fe⁰ and Fe⁰ corrosion products (CP), (ii) co-precipitation with in situ generated iron CP, (iii) reduction to colorless leukomethylene blue (LMB). MB mineralization (oxidation to CO₂) is not expected. The kinetics of MB discoloration by Fe⁰, Fe₂O₃, Fe₃O₄, MnO₂, and granular activated carbon were investigated in assay tubes under mechanically non-disturbed conditions. The evolution of MB discoloration was monitored spectrophotometrically. The effect of availability of CP, Fe⁰ source, shaking rate, initial pH value, and chemical properties of the solution were studied. The results present evidence supporting co-precipitation of MB with in situ generated iron CP as main discoloration mechanism. Under high shaking intensities (>150 min⁻¹), increased CP generation yields a brownish solution which disturbed MB determination, showing that a too high shear stress induced the suspension of in situ generated corrosion products. The present study clearly demonstrates that comparing results from various sources is difficult even when the results are achieved under seemingly similar conditions. The appeal for an unified experimental procedure for the investigation of processes in Fe⁰/H₂O systems is reiterated.     

Preparation of Water-Dispersible and Biocompatible Iron Oxide Nanoparticles for MRI Agent

Highly monodisperse superparamagnetic iron oxide nanoparticles (SPIONs, 7.5 nm gamma- F₂O₃) were synthesized by thermal decomposition of iron pentacarbonyl and consecutive aeration in organic medium. By treating with a small amount of iron pentacarbonyl, Fe-rich surface has been formed on SPION. Water-dispersible SPIONs (SPION-MPA) were prepared by Fe-S covalent conjugation between Fe-rich SPION and mercaptopropionic acid (MPA) and then, transformed to SPION-MPA-dextran composite by physical adsorption of biocompatible polymer dextran. The hydrodynamic diameter of SPION-MPA-dextran was in the range of 225~237 nm in water. MR contrast and spin-spin relaxation intensity of our SPION-MPA-dextran were similar to those of the commercial products, Ferridex and Resovist.