Science.gov

Sample records for acidophilic iron-oxidizing bacterium

  1. Cobalamin Protection against Oxidative Stress in the Acidophilic Iron-oxidizing Bacterium Leptospirillum Group II CF-1

    PubMed Central

    Ferrer, Alonso; Rivera, Javier; Zapata, Claudia; Norambuena, Javiera; Sandoval, Álvaro; Chávez, Renato; Orellana, Omar; Levicán, Gloria

    2016-01-01

    Members of the genus Leptospirillum are aerobic iron-oxidizing bacteria belonging to the phylum Nitrospira. They are important members of microbial communities that catalyze the biomining of sulfidic ores, thereby solubilizing metal ions. These microorganisms live under extremely acidic and metal-loaded environments and thus must tolerate high concentrations of reactive oxygen species (ROS). Cobalamin (vitamin B12) is a cobalt-containing tetrapyrrole cofactor involved in intramolecular rearrangement reactions and has recently been suggested to be an intracellular antioxidant. In this work, we investigated the effect of the exogenous addition of cobalamin on oxidative stress parameters in Leptospirillum group II strain CF-1. Our results revealed that the external supplementation of cobalamin reduces the levels of intracellular ROSs and the damage to biomolecules, and also stimulates the growth and survival of cells exposed to oxidative stress exerted by ferric ion, hydrogen peroxide, chromate and diamide. Furthermore, exposure of strain CF-1 to oxidative stress elicitors resulted in the transcriptional activation of the cbiA gene encoding CbiA of the cobalamin biosynthetic pathway. Altogether, these data suggest that cobalamin plays an important role in redox protection of Leptospirillum strain CF-1, supporting survival of this microorganism under extremely oxidative environmental conditions. Understanding the mechanisms underlying the protective effect of cobalamin against oxidative stress may help to develop strategies to make biomining processes more effective. PMID:27242761

  2. Uncovering a Microbial Enigma: Isolation and Characterization of the Streamer-Generating, Iron-Oxidizing, Acidophilic Bacterium “Ferrovum myxofaciens”

    PubMed Central

    Hallberg, Kevin B.; Hedrich, Sabrina

    2014-01-01

    A betaproteobacterium, shown by molecular techniques to have widespread global distribution in extremely acidic (pH 2 to 4) ferruginous mine waters and also to be a major component of “acid streamer” growths in mine-impacted water bodies, has proven to be recalcitrant to enrichment and isolation. A modified “overlay” solid medium was devised and used to isolate this bacterium from a number of mine water samples. The physiological and phylogenetic characteristics of a pure culture of an isolate from an abandoned copper mine (“Ferrovum myxofaciens” strain P3G) have been elucidated. “F. myxofaciens” is an extremely acidophilic, psychrotolerant obligate autotroph that appears to use only ferrous iron as an electron donor and oxygen as an electron acceptor. It appears to use the Calvin-Benson-Bassham pathway to fix CO2 and is diazotrophic. It also produces copious amounts of extracellular polymeric materials that cause cells to attach to each other (and to form small streamer-like growth in vitro) and to different solid surfaces. “F. myxofaciens” can catalyze the oxidative dissolution of pyrite and, like many other acidophiles, is tolerant of many (cationic) transition metals. “F. myxofaciens” and related clone sequences form a monophyletic group within the Betaproteobacteria distantly related to classified orders, with genera of the family Nitrosomonadaceae (lithoautotrophic, ammonium-oxidizing neutrophiles) as the closest relatives. On the basis of the phylogenetic and phenotypic differences of “F. myxofaciens” and other Betaproteobacteria, a new family, “Ferrovaceae,” and order, “Ferrovales,” within the class Betaproteobacteria are proposed. “F. myxofaciens” is the first extreme acidophile to be described in the class Betaproteobacteria. PMID:24242243

  3. Genome Sequence of the Acidophilic Iron Oxidizer Ferrimicrobium acidiphilum Strain T23T.

    PubMed

    Eisen, Sebastian; Poehlein, Anja; Johnson, D Barrie; Daniel, Rolf; Schlömann, Michael; Mühling, Martin

    2015-04-30

    Extremely acidophilic iron-oxidizing bacteria have largely been characterized for the phyla Proteobacteria and Nitrospira. Here, we report the draft genome of an iron-oxidizing and -reducing heterotrophic mesophile of the Actinobacteria, Ferrimicrobium acidiphilum, which was isolated from an abandoned pyrite mine. The genome sequence comprises 3.08 Mb.

  4. Leaching of pyrite by acidophilic heterotrophic iron-oxidizing bacteria in pure and mixed cultures

    SciTech Connect

    Bacelar-Nicolau, P.; Johnson, D.B.

    1999-02-01

    Seven strains of heterotrophic iron-oxidizing acidophilic bacteria were examined to determine their abilities to promote oxidative dissolution of pyrite (FeS{sub 2}) when they were grown in pure cultures and in mixed cultures with sulfur-oxidizing Thiobacillus spp. Only one of the isolates (strain T-24) oxidized pyrite when it was grown in pyrite-basal salts medium. However, when pyrite-containing cultures were supplemented with 0.02% (wt/vol) yeast extract, most of the isolates oxidized pyrite, and one (strain T-24) promoted rates of mineral dissolution similar to the rates observed with the iron-oxidizing autotroph Thiobacillus ferroxidans. Pyrite oxidation by another isolate (strain T-21) occurred in cultures containing between 0.005 and 0.05% (wt/vol) yeast extract but was completely inhibited in cultures containing 0.5% yeast extract. Ferrous iron was also needed for mineral dissolution by the iron-oxidizing heterotrophs, indicating that these organisms oxidize pyrite via the indirect mechanism. Mixed cultures of three isolates (strains T-21, T-232, and T-24) and the sulfur-oxidizing autotroph Thiobacillus thiooxidans promoted pyrite dissolution; since neither strains T-21 and T-23 nor T. thiooxidans could oxidize this mineral in yeast extract-free media, this was a novel example of bacterial synergism. Mixed cultures of strains T-21 and T-23 and the sulfur-oxidizing mixotroph Thiobacillus acidophilus also oxidized pyrite but to a lesser extent than did mixed cultures containing T. thiooxidans. Pyrite leaching by strain T -23 grown in an organic compound-rich medium and incubated either shaken or unshaken was also assessed. The potential environmental significance of iron-oxidizing heterotrophs in accelerating pyrite oxidation is discussed.

  5. Geochemical niches of iron-oxidizing acidophiles in acidic coal mine drainage.

    PubMed

    Jones, Daniel S; Kohl, Courtney; Grettenberger, Christen; Larson, Lance N; Burgos, William D; Macaladya, Jennifer L

    2015-02-01

    A legacy of coal mining in the Appalachians has provided a unique opportunity to study the ecological niches of iron-oxidizing microorganisms. Mine-impacted, anoxic groundwater with high dissolved-metal concentrations emerges at springs and seeps associated with iron oxide mounds and deposits. These deposits are colonized by iron-oxidizing microorganisms that in some cases efficiently remove most of the dissolved iron at low pH, making subsequent treatment of the polluted stream water less expensive. We used full-cycle rRNA methods to describe the composition of sediment communities at two geochemically similar acidic discharges, Upper and Lower Red Eyes in Somerset County, PA, USA. The dominant microorganisms at both discharges were acidophilic Gallionella-like organisms, “Ferrovum” spp., and Acidithiobacillus spp. Archaea and Leptospirillum spp. accounted for less than 2% of cells. The distribution of microorganisms at the two sites could be best explained by a combination of iron(II) concentration and pH. Populations of the Gallionella-like organisms were restricted to locations with pH>3 and iron(II) concentration of >4 mM, while Acidithiobacillus spp. were restricted to pH<3 and iron(II) concentration of <4 mM. Ferrovum spp. were present at low levels in most samples but dominated sediment communities at pH<3 and iron(II) concentration of >4 mM. Our findings offer a predictive framework that could prove useful for describing the distribution of microorganisms in acid mine drainage, based on readily accessible geochemical parameters.

  6. Geochemical Niches of Iron-Oxidizing Acidophiles in Acidic Coal Mine Drainage

    PubMed Central

    Kohl, Courtney; Grettenberger, Christen; Larson, Lance N.; Burgos, William D.

    2014-01-01

    A legacy of coal mining in the Appalachians has provided a unique opportunity to study the ecological niches of iron-oxidizing microorganisms. Mine-impacted, anoxic groundwater with high dissolved-metal concentrations emerges at springs and seeps associated with iron oxide mounds and deposits. These deposits are colonized by iron-oxidizing microorganisms that in some cases efficiently remove most of the dissolved iron at low pH, making subsequent treatment of the polluted stream water less expensive. We used full-cycle rRNA methods to describe the composition of sediment communities at two geochemically similar acidic discharges, Upper and Lower Red Eyes in Somerset County, PA, USA. The dominant microorganisms at both discharges were acidophilic Gallionella-like organisms, “Ferrovum” spp., and Acidithiobacillus spp. Archaea and Leptospirillum spp. accounted for less than 2% of cells. The distribution of microorganisms at the two sites could be best explained by a combination of iron(II) concentration and pH. Populations of the Gallionella-like organisms were restricted to locations with pH >3 and iron(II) concentration of >4 mM, while Acidithiobacillus spp. were restricted to pH <3 and iron(II) concentration of <4 mM. Ferrovum spp. were present at low levels in most samples but dominated sediment communities at pH <3 and iron(II) concentration of >4 mM. Our findings offer a predictive framework that could prove useful for describing the distribution of microorganisms in acid mine drainage, based on readily accessible geochemical parameters. PMID:25501473

  7. Cytochrome 572 is a conspicuous membrane protein with iron oxidation activity purified directly from a natural acidophilic microbial community

    SciTech Connect

    Verberkmoes, Nathan C; Singer, Steven; Shah, Manesh B; Thelen, Michael P.; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2008-01-01

    We have discovered and characterized a novel membrane cytochrome of an iron oxidizing microbial biofilm obtained from the surface of extremely acidic mine water. This protein was initially identified through proteogenomic analysis as one of many novel gene products of Leptospirillum group II, the dominant bacterium of this community (Ram et al, 2005, Science 308, 1915-20). Extraction of proteins directly from environmental biofilm samples followed by membrane fractionation, detergent solubilization and gel filtration chromatography resulted in the purification of an abundant yellow-red protein. Covalently bound to heme, the purified cytochrome has a unique spectral signature at 572 nm and is thus called Cyt572. It readily oxidizes Fe2+ even in the presence of Fe3+ over a pH range from 0.95 to 3.4. Independent experiments involving 2D blue-native polyacrylamide gel electrophoresis and chemical crosslinking establish a homotetrameric structure for Cyt572. Also, circular dichroism spectroscopy indicates that the protein is largely beta-stranded, consistent with an outer membrane location. Although no significant sequence homology to the full-length cytochrome is detected in protein databases, environmental DNA sequences from both Leptospirillum groups II and III reveal at least 17 strain variants of Cyt572. Due to its abundance, cellular location and Fe2+ oxidation activity, we propose Cyt572 is the iron oxidase of the Leptospirillum bacteria, providing a critical function for fitness within the ecological niche of this acidophilic microbial community.

  8. Draft Genome Sequence of a Novel Acidophilic Iron-Oxidizing Firmicutes Species, “Acidibacillus ferrooxidans” (SLC66T)

    PubMed Central

    Ñancucheo, Ivan; Oliveira, Renato; Dall’Agnol, Hivana; Johnson, D. Barrie; Grail, Barry; Holanda, Roseanne; Nunes, Gisele Lopes; Cuadros-Orellana, Sara

    2016-01-01

    Here, we present the draft genome sequence of the type strain of “Acidibacillus ferrooxidans,” a mesophilic, heterotrophic, and acidophilic bacterium that was isolated from mine spoilage subjected to accelerated weathering in humidity cell tests carried out by the former U.S. Bureau of Mines in Salt Lake City, UT. PMID:27198020

  9. Growth of the acidophilic iron-sulfur bacterium Acidithiobacillus ferrooxidans under Mars-like geochemical conditions

    NASA Astrophysics Data System (ADS)

    Bauermeister, Anja; Rettberg, Petra; Flemming, Hans-Curt

    2014-08-01

    The question of life on Mars has been in focus of astrobiological research for several decades, and recent missions in orbit or on the surface of the planet are constantly expanding our knowledge on Martian geochemistry. For example, massive stratified deposits have been identified on Mars containing sulfate minerals and iron oxides, which suggest the existence of acidic aqueous conditions in the past, similar to acidic iron- and sulfur-rich environments on Earth. Acidophilic organisms thriving in such habitats could have been an integral part of a possibly widely extinct Martian ecosystem, but remains might possibly even exist today in protected subsurface niches. The chemolithoautotrophic strain Acidithiobacillus ferrooxidans was selected as a model organism to study the metabolic capacities of acidophilic iron-sulfur bacteria, especially regarding their ability to grow with in situ resources that could be expected on Mars. The experiments were not designed to accurately simulate Martian physical conditions (except when certain single parameters such as oxygen partial pressure were considered), but rather the geochemical environment that can be found on Mars. A. ferrooxidans could grow solely on the minerals contained in synthetic Mars regolith mixtures with no added nutrients, using either O2 as an external electron acceptor for iron oxidation, or H2 as an external electron donor for iron reduction, and thus might play important roles in the redox cycling of iron on Mars. Though the oxygen partial pressure of the Martian atmosphere at the surface was not sufficient for detectable iron oxidation and growth of A. ferrooxidans during short-term incubation (7 days), alternative chemical O2-generating processes in the subsurface might yield microhabitats enriched in oxygen, which principally are possible under such conditions. The bacteria might also contribute to the reductive dissolution of Fe3+-containing minerals like goethite and hematite, which are

  10. Cytochrome 572 is a conspicuous membrane protein with iron oxidation activity purified directly from a natural acidophilic microbial community.

    PubMed

    Jeans, Chris; Singer, Steven W; Chan, Clara S; Verberkmoes, Nathan C; Shah, Manesh; Hettich, Robert L; Banfield, Jillian F; Thelen, Michael P

    2008-05-01

    Recently, there has been intense interest in the role of electron transfer by microbial communities in biogeochemical systems. We examined the process of iron oxidation by microbial biofilms in one of the most extreme environments on earth, where the inhabited water is pH 0.5-1.2 and laden with toxic metals. To approach the mechanism of Fe(II) oxidation as a means of cellular energy acquisition, we isolated proteins from natural samples and found a conspicuous and novel cytochrome, Cyt(572), which is unlike any known cytochrome. Both the character of its covalently bound prosthetic heme group and protein sequence are unusual. Extraction of proteins directly from environmental biofilm samples followed by membrane fractionation, detergent solubilization and gel filtration chromatography resulted in the purification of an abundant yellow-red protein. The purified protein has a cytochrome c-type heme binding motif, CxxCH, but a unique spectral signature at 572 nm, and thus is called Cyt(572). It readily oxidizes Fe(2+) in the physiologically relevant acidic regime, from pH 0.95-3.4. Other physical characteristics are indicative of a membrane-bound multimeric protein. Circular dichroism spectroscopy indicates that the protein is largely beta-stranded, and 2D Blue-Native polyacrylamide gel electrophoresis and chemical crosslinking independently point to a multi-subunit structure for Cyt(572). By analyzing environmental genomic information from biofilms in several distinctly different mine locations, we found multiple genetic variants of Cyt(572). MS proteomics of extracts from these biofilms substantiated the prevalence of these variants in the ecosystem. Due to its abundance, cellular location and Fe(2+) oxidation activity at very low pH, we propose that Cyt(572) provides a critical function for fitness within the ecological niche of these acidophilic microbial communities.

  11. Reconstruction of the Metabolic Potential of Acidophilic Sideroxydans Strains from the Metagenome of an Microaerophilic Enrichment Culture of Acidophilic Iron-Oxidizing Bacteria from a Pilot Plant for the Treatment of Acid Mine Drainage Reveals Metabolic Versatility and Adaptation to Life at Low pH

    PubMed Central

    Mühling, Martin; Poehlein, Anja; Stuhr, Anna; Voitel, Matthias; Daniel, Rolf; Schlömann, Michael

    2016-01-01

    Bacterial community analyses of samples from a pilot plant for the treatment of acid mine drainage (AMD) from the lignite-mining district in Lusatia (East Germany) had previously demonstrated the dominance of two groups of acidophilic iron oxidizers: the novel candidate genus “Ferrovum” and a group comprising Gallionella-like strains. Since pure culture had proven difficult, previous studies have used genome analyses of co-cultures consisting of “Ferrovum” and a strain of the heterotrophic acidophile Acidiphilium in order to obtain insight into the life style of these novel bacteria. Here we report on attempts to undertake a similar study on Gallionella-like acidophiles from AMD. Isolates belonging to the family Gallionellaceae are still restricted to the microaerophilic and neutrophilic iron oxidizers Sideroxydans and Gallionella. Availability of genomic or metagenomic sequence data of acidophilic strains of these genera should, therefore, be relevant for defining adaptive strategies in pH homeostasis. This is particularly the case since complete genome sequences of the neutrophilic strains G. capsiferriformans ES-2 and S. lithotrophicus ES-1 permit the direct comparison of the metabolic capacity of neutrophilic and acidophilic members of the same genus and, thus, the detection of biochemical features that are specific to acidophilic strains to support life under acidic conditions. Isolation attempts undertaken in this study resulted in the microaerophilic enrichment culture ADE-12-1 which, based on 16S rRNA gene sequence analysis, consisted of at least three to four distinct Gallionellaceae strains that appear to be closely related to the neutrophilic iron oxidizer S. lithotrophicus ES-1. Key hypotheses inferred from the metabolic reconstruction of the metagenomic sequence data of these acidophilic Sideroxydans strains include the putative role of urea hydrolysis, formate oxidation and cyanophycin decarboxylation in pH homeostasis. PMID:28066396

  12. Model-based evaluation of ferrous iron oxidation by acidophilic bacteria in chemostat and biofilm airlift reactors.

    PubMed

    Ebrahimi, Sirous; Faraghi, Neda; Hosseini, Maryam

    2015-10-01

    This article presents a model-based evaluation of ferrous iron oxidation in chemostat and biofilm airlift reactors inoculated with a mixed culture of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans bacteria. The competition between the two types of bacteria in the chemostat and in the biofilm airlift reactors together with the distribution of both bacteria along the biofilm thickness at different time sections has been studied. The bacterial distribution profiles along the biofilm in the airlift reactor at different time scales show that in the beginning A. ferrooxidans bacteria are dominant, but when the reactor operates for a long time the desirable L. ferrooxidans species outcompete A. ferrooxidans as a result of the low Fe(2+) and high Fe(3+) concentrations. The results obtained from the simulation were compared with the experimental data of continuously operated internal loop airlift biofilm reactor. The model results are in good agreement with the experimental results.

  13. Predicting Structure and Function for Novel Proteins of an Extremophilic Iron Oxidizing Bacterium

    NASA Astrophysics Data System (ADS)

    Wheeler, K.; Zemla, A.; Banfield, J.; Thelen, M.

    2007-12-01

    Proteins isolated from uncultivated microbial populations represent the functional components of microbial processes and contribute directly to community fitness under natural conditions. Investigations into proteins in the environment are hindered by the lack of genome data, or where available, the high proportion of proteins of unknown function. We have identified thousands of proteins from biofilms in the extremely acidic drainage outflow of an iron mine ecosystem (1). With an extensive genomic and proteomic foundation, we have focused directly on the problem of several hundred proteins of unknown function within this well-defined model system. Here we describe the geobiological insights gained by using a high throughput computational approach for predicting structure and function of 421 novel proteins from the biofilm community. We used a homology based modeling system to compare these proteins to those of known structure (AS2TS) (2). This approach has resulted in the assignment of structures to 360 proteins (85%) and provided functional information for up to 75% of the modeled proteins. Detailed examination of the modeling results enables confident, high-throughput prediction of the roles of many of the novel proteins within the microbial community. For instance, one prediction places a protein in the phosphoenolpyruvate/pyruvate domain superfamily as a carboxylase that fills in a gap in an otherwise complete carbon cycle. Particularly important for a community in such a metal rich environment is the evolution of over 25% of the novel proteins that contain a metal cofactor; of these, one third are likely Fe containing proteins. Two of the most abundant proteins in biofilm samples are unusual c-type cytochromes. Both of these proteins catalyze iron- oxidation, a key metabolic reaction supporting the energy requirements of this community. Structural models of these cytochromes verify our experimental results on heme binding and electron transfer reactivity, and

  14. Alicyclobacillus vulcanalis sp. nov., a thermophilic, acidophilic bacterium isolated from Coso Hot Springs, California, USA.

    PubMed

    Simbahan, Jessica; Drijber, Rhae; Blum, Paul

    2004-09-01

    A thermo-acidophilic Gram-positive bacterium, strain CsHg2T, which grows aerobically at 35-65 degrees C (optimum 55 degrees C) and at pH 2.0-6.0 (optimum 4.0), was isolated from a geothermal pool located in Coso Hot Springs in the Mojave Desert, California, USA. Phylogenetic analysis of 16S rRNA gene sequences showed that this bacterium was most closely related to the type strains of Alicyclobacillus acidocaldarius (97.8 % identity) and Alicyclobacillus sendaiensis (96.9 %), three Japanese strains denoted as UZ-1, KHA-31 and MIH 332 (96.1-96.5 %) and Alicyclobacillus genomic species FR-6 (96.3 %). Phenotypic characteristics including temperature and pH optima, G+C composition, acid production from a variety of carbon sources and sensitivity to different metal salts distinguished CsHg2T from A. acidocaldarius, A. sendaiensis and FR-6. The cell lipid membrane was composed mainly of omega-cyclohexyl fatty acid, consistent with membranes from other Alicyclobacillus species. Very low DNA-DNA hybridization values between CsHg2T and the type strains of Alicyclobacillus indicate that CsHg2T represents a distinct species. On the basis of these results, the name Alicyclobacillus vulcanalis sp. nov. is proposed for this organism. The type strain is CsHg2T (ATCC BAA-915T = DSM 16176T).

  15. Effect of external pH perturbations on in vivo protein synthesis by the acidophilic bacterium Thiobacillus ferrooxidans.

    PubMed Central

    Amaro, A M; Chamorro, D; Seeger, M; Arredondo, R; Peirano, I; Jerez, C A

    1991-01-01

    The response of the obligate acidophilic bacterium Thiobacillus ferrooxidans to external pH changes is reported. When T. ferrooxidans cells grown at pH 1.5 were shifted to pH 3.5, there were several changes in the general protein synthesis pattern, including a large stimulation of the synthesis of a 36-kDa protein (p36). The apparent low isoelectric point of p36, its location in the membrane fraction, and its cross-reaction with anti-OmpC from Salmonella typhi suggested that it may be a porin whose expression is regulated by extracellular pH. Images PMID:1987171

  16. Gene function analysis in environmental isolates: The nif regulon of the strict iron oxidizing bacterium Leptospirillum ferrooxidans

    PubMed Central

    Parro, Víctor; Moreno-Paz, Mercedes

    2003-01-01

    A random genomic library from an environmental isolate of the Gram-negative bacterium Leptospirillum ferrooxidans has been printed on a microarray. Gene expression analysis was carried out with total RNA extracted from L. ferrooxidans cultures in the presence or absence of ammonium as nitrogen source under aerobic conditions. Although practically nothing is known about the genome sequence of this bacterium, this approach allowed us the selection and sequencing of only those clones bearing genes that showed an altered expression pattern. By sequence comparison, we have identified most of the genes of nitrogen fixation regulon in L. ferrooxidans, like the nifHDKENX operon, encoding the structural components of Mo-Fe nitrogenase; nifSU-hesB-hscBA-fdx operon, for Fe-S cluster assembly; the amtB gene (ammonium transporter); modA (molybdenum ABC type transporter); some regulatory genes like ntrC, nifA (the specific activator of nif genes); or two glnB-like genes (encoding the PII regulatory protein). Our results show that shotgun DNA microarrays are very powerful tools to accomplish gene expression studies with environmental bacteria whose genome sequence is still unknown, avoiding the time and effort necessary for whole genome sequencing projects. PMID:12808145

  17. Novel thermo-acidophilic bacteria isolated from geothermal sites in Yellowstone National Park: physiological and phylogenetic characteristics.

    PubMed

    Johnson, D Barrie; Okibe, Naoko; Roberto, Francisco F

    2003-07-01

    Moderately thermophilic acidophilic bacteria were isolated from geothermal (30-83 degrees C) acidic (pH 2.7-3.7) sites in Yellowstone National Park. The temperature maxima and pH minima of the isolates ranged from 50 to 65 degrees C, and pH 1.0-1.9. Eight of the bacteria were able to catalyze the dissimilatory oxidation of ferrous iron, and eleven could reduce ferric iron to ferrous iron in anaerobic cultures. Several of the isolates could also oxidize tetrathionate. Six of the iron-oxidizing isolates, and one obligate heterotroph, were low G+C gram-positive bacteria ( Firmicutes). The former included three Sulfobacillus-like isolates (two closely related to a previously isolated Yellowstone strain, and the third to a mesophilic bacterium isolated from Montserrat), while the other three appeared to belong to a different genus. The other two iron-oxidizers were an Actinobacterium (related to Acidimicrobium ferrooxidans) and a Methylobacterium-like isolate (a genus within the alpha -Proteobacteria that has not previously been found to contain either iron-oxidizers or acidophiles). The other three (heterotrophic) isolates were also alpha-Proteobacteria and appeared be a novel thermophilic Acidisphaera sp. An ARDREA protocol was developed to discriminate between the iron-oxidizing isolates. Digestion of amplified rRNA genes with two restriction enzymes ( SnaBI and BsaAI) separated these bacteria into five distinct groups; this result was confirmed by analysis of sequenced rRNA genes.

  18. Genome sequence of Desulfosporosinus sp. OT, an acidophilic sulfate-reducing bacterium from copper mining waste in Norilsk, Northern Siberia.

    PubMed

    Abicht, Helge K; Mancini, Stefano; Karnachuk, Olga V; Solioz, Marc

    2011-11-01

    We have sequenced the genome of Desulfosporosinus sp. OT, a Gram-positive, acidophilic sulfate-reducing Firmicute isolated from copper tailing sediment in the Norilsk mining-smelting area in Northern Siberia, Russia. This represents the first sequenced genome of a Desulfosporosinus species. The genome has a size of 5.7 Mb and encodes 6,222 putative proteins.

  19. Genome-enabled studies of anaerobic, nitrate-dependent iron oxidation in the chemolithoautotrophic bacterium Thiobacillus denitrificans

    PubMed Central

    Beller, Harry R.; Zhou, Peng; Legler, Tina C.; Chakicherla, Anu; Kane, Staci; Letain, Tracy E.; A. O’Day, Peggy

    2013-01-01

    Thiobacillus denitrificans is a chemolithoautotrophic bacterium capable of anaerobic, nitrate-dependent U(IV) and Fe(II) oxidation, both of which can strongly influence the long-term efficacy of in situ reductive immobilization of uranium in contaminated aquifers. We previously identified two c-type cytochromes involved in nitrate-dependent U(IV) oxidation in T. denitrificans and hypothesized that c-type cytochromes would also catalyze Fe(II) oxidation, as they have been found to play this role in anaerobic phototrophic Fe(II)-oxidizing bacteria. Here we report on efforts to identify genes associated with nitrate-dependent Fe(II) oxidation, namely (a) whole-genome transcriptional studies [using FeCO3, Fe2+, and U(IV) oxides as electron donors under denitrifying conditions], (b) Fe(II) oxidation assays performed with knockout mutants targeting primarily highly expressed or upregulated c-type cytochromes, and (c) random transposon-mutagenesis studies with screening for Fe(II) oxidation. Assays of mutants for 26 target genes, most of which were c-type cytochromes, indicated that none of the mutants tested were significantly defective in nitrate-dependent Fe(II) oxidation. The non-defective mutants included the c1-cytochrome subunit of the cytochrome bc1 complex (complex III), which has relevance to a previously proposed role for this complex in nitrate-dependent Fe(II) oxidation and to current concepts of reverse electron transfer. A transposon mutant with a disrupted gene associated with NADH:ubiquinone oxidoreductase (complex I) was ~35% defective relative to the wild-type strain; this strain was similarly defective in nitrate reduction with thiosulfate as the electron donor. Overall, our results indicate that nitrate-dependent Fe(II) oxidation in T. denitrificans is not catalyzed by the same c-type cytochromes involved in U(IV) oxidation, nor have other c-type cytochromes yet been implicated in the process. PMID:24065960

  20. Genome-Enabled Studies of Anaerobic, Nitrate-Dependent Iron Oxidation in the Chemolithoautotrophic Bacterium Thiobacillus denitrificans

    NASA Astrophysics Data System (ADS)

    Beller, H. R.; Zhou, P.; Legler, T. C.; Chakicherla, A.; O'Day, P. A.

    2013-12-01

    Thiobacillus denitrificans is a chemolithoautotrophic bacterium capable of anaerobic, nitrate-dependent U(IV) and Fe(II) oxidation, both of which can strongly influence the long-term efficacy of in situ reductive immobilization of uranium in contaminated aquifers. We previously identified two c-type cytochromes involved in nitrate-dependent U(IV) oxidation in T. denitrificans and hypothesized that c-type cytochromes would also catalyze Fe(II) oxidation, as they have been found to play this role in anaerobic phototrophic Fe(II)-oxidizing bacteria. Here we report on efforts to identify genes associated with nitrate-dependent Fe(II) oxidation, namely (a) whole-genome transcriptional studies [using FeCO3, Fe2+, and U(IV) oxides as electron donors under denitrifying conditions], (b) Fe(II) oxidation assays performed with knockout mutants targeting primarily highly expressed or upregulated c-type cytochromes, and (c) random transposon-mutagenesis studies with screening for Fe(II) oxidation. Assays of mutants for 26 target genes, most of which were c-type cytochromes, indicated that none of the mutants tested were significantly defective in nitrate-dependent Fe(II) oxidation. The non-defective mutants included the c1-cytochrome subunit of the cytochrome bc1 complex (complex III), which has relevance to a previously proposed role for this complex in nitrate-dependent Fe(II) oxidation and to current concepts of reverse electron transfer. Of the transposon mutants defective in Fe(II) oxidation, one mutant with a disrupted gene associated with NADH:ubiquinone oxidoreductase (complex I) was ~35% defective relative to the wild-type strain; this strain was similarly defective in nitrate reduction with thiosulfate as the electron donor. Overall, our results indicate that nitrate-dependent Fe(II) oxidation in T. denitrificans is not catalyzed by the same c-type cytochromes involved in U(IV) oxidation, nor have other c-type cytochromes yet been implicated in the process.

  1. Draft genome of iron-oxidizing bacterium Leptospirillum sp. YQP-1 isolated from a volcanic lake in the Wudalianchi volcano, China.

    PubMed

    Yan, Lei; Zhang, Shuang; Yu, Gaobo; Ni, Yongqing; Wang, Weidong; Hu, Huixin; Chen, Peng

    2015-12-01

    Leptospirillum sp. YQP-1, a member of iron-oxidizing bacteria was isolated from volcanic lake in northeast China. Here, we report the draft genome sequence of the strain YQP-1 with a total genome size of 3,103,789 bp from 85 scaffolds (104 contigs) with 58.64% G + C content. The genome sequence can be accessed at DDBJ/EMBL/GenBank under the accession no. LIEB00000000.

  2. Iron and carbon metabolism by a mineral-oxidizing Alicyclobacillus-like bacterium.

    PubMed

    Yahya, Adibah; Hallberg, Kevin B; Johnson, D Barrie

    2008-04-01

    A novel iron-oxidizing, moderately thermophilic, acidophilic bacterium (strain "GSM") was isolated from mineral spoil taken from a gold mine in Montana. Biomolecular analysis showed that it was most closely related to Alicyclobacillus tolerans, although the two bacteria differed in some key respects, including the absence (in strain GSM) of varpi-alicyclic fatty acids and in their chromosomal base compositions. Isolate GSM was able to grow in oxygen-free media using ferric iron as terminal electron acceptor confirming that it was a facultative anaerobe, a trait not previously described in Alicyclobacillus spp.. The acidophile used both organic and inorganic sources of energy and carbon, although growth and iron oxidation by isolate GSM was uncoupled in media that contained both fructose and ferrous iron. Fructose utilization suppressed iron oxidation, and oxidation of ferrous iron occurred only when fructose was depleted. In contrast, fructose catabolism was suppressed when bacteria were harvested while actively oxidizing iron, suggesting that both ferrous iron- and fructose-oxidation are inducible in this acidophile. Isolate GSM accelerated the oxidative dissolution of pyrite in liquid media either free of, or amended with, organic carbon, although redox potentials were significantly different in these media. The potential of this isolate for commercial mineral processing is discussed.

  3. Novel Thermo-Acidophilic Bacteria Isolated from Geothermal Sites in Yellowstone National Park: Physiological and Phylogenetic Characteristics

    SciTech Connect

    D. B. Johnson; N. Okibe; F. F. Roberto

    2003-07-01

    Moderately thermophilic acidophilic bacteria were isolated from geothermal (30–83 °C) acidic (pH 2.7– 3.7) sites in Yellowstone National Park. The temperature maxima and pH minima of the isolates ranged from 50 to 65 °C, and pH 1.0–1.9. Eight of the bacteria were able to catalyze the dissimilatory oxidation of ferrous iron, and eleven could reduce ferric iron to ferrous iron in anaerobic cultures. Several of the isolates could also oxidize tetrathionate. Six of the iron-oxidizing isolates, and one obligate heterotroph, were low G+C gram-positive bacteria (Firmicutes). The former included three Sulfobacillus-like isolates (two closely related to a previously isolated Yellowstone strain, and the third to a mesophilic bacterium isolated from Montserrat), while the other three appeared to belong to a different genus. The other two iron-oxidizers were an Actinobacterium (related to Acidimicrobium ferrooxidans) and a Methylobacterium-like isolate (a genus within the a-Proteobacteria that has not previously been found to contain either iron-oxidizers or acidophiles). The other three (heterotrophic) isolates were also a-Proteobacteria and appeared be a novel thermophilic Acidisphaera sp. An ARDREA protocol was developed to discriminate between the iron-oxidizing isolates. Digestion of amplified rRNA genes with two restriction enzymes (SnaBI and BsaAI) separated these bacteria into five distinct groups; this result was confirmed by analysis of sequenced rRNA genes.

  4. Magnesium insertion by magnesium chelatase in the biosynthesis of zinc bacteriochlorophyll a in an aerobic acidophilic bacterium Acidiphilium rubrum.

    PubMed

    Masuda, T; Inoue, K; Masuda, M; Nagayama, M; Tamaki, A; Ohta, H; Shimada, H; Takamiya, K

    1999-11-19

    To elucidate the mechanism for formation of zinc-containing bacteriochlorophyll a in the photosynthetic bacterium Acidiphilium rubrum, we isolated homologs of magnesium chelatase subunits (bchI, -D, and -H). A. rubrum bchI and -H were encoded by single genes located on the clusters bchP-orf168-bchI-bchD-orf320-crtI and bchF-N-B-H-L as in Rhodobacter capsulatus, respectively. The deduced sequences of A. rubrum bchI, -D, and -H had overall identities of 59. 8, 40.5, and 50.7% to those from Rba. capsulatus, respectively. When these genes were introduced into bchI, bchD, and bchH mutants of Rba. capsulatus for functional complementation, all mutants were complemented with concomitant synthesis of bacteriochlorophyll a. Analyses of bacteriochlorophyll intermediates showed that A. rubrum cells accumulate magnesium protoporphyrin IX monomethyl ester without detectable accumulation of zinc protoporphyrin IX or its monomethyl ester. These results indicate that a single set of magnesium chelatase homologs in A. rubrum catalyzes the insertion of only Mg(2+) into protoporphyrin IX to yield magnesium protoporphyrin IX monomethyl ester. Consequently, it is most likely that zinc-containing bacteriochlorophyll a is formed by a substitution of Zn(2+) for Mg(2+) at a step in the bacteriochlorophyll biosynthesis after formation of magnesium protoporphyrin IX monomethyl ester.

  5. Acidiferrobacter thiooxydans, gen. nov. sp. nov.; an acidophilic, thermo-tolerant, facultatively anaerobic iron- and sulfur-oxidizer of the family Ectothiorhodospiraceae.

    PubMed

    Hallberg, Kevin B; Hedrich, Sabrina; Johnson, D Barrie

    2011-03-01

    A comprehensive physiological and phylogenetic characterisation was carried out of "Thiobacillus ferrooxidans" m-1, an acidophilic iron-oxidizing bacterium first described over 25 years ago. Phylogenetically, strain m-1 is a gammaproteobacterium, most closely related to alkaliphilic Ectothiorhodospira spp. and only distantly to iron-oxidizing acidithiobacilli. Physiological examination confirmed that strain m-1 can grow autotrophically not only by ferrous iron oxidation but also, in contrast to previous reports, by oxidation of elemental sulfur, sulfide and tetrathionate, using either oxygen or ferric iron as terminal electron acceptor. The bacterium was also found to be thermo-tolerant, growing optimally at 38°C and up to a maximum of 47°C. Growth in liquid media required an external osmotic potential of >2 bar, and was optimal at ~5 bar, though no growth occurred where the medium osmotic potential was close to that of sea water (~26 bar). From this, it was concluded that strain m-1 is a moderate osmophile. Strain m-1 was also shown to be diazotrophic and tolerant of elevated concentrations of many metals typically found in mine-impacted environments. On the basis of these data, m-1 is proposed as the type strain of a new genus and species of bacteria, Acidiferrobacter thiooxydans (DSM 2392, JCM 17358).

  6. Iron oxide surfaces

    NASA Astrophysics Data System (ADS)

    Parkinson, Gareth S.

    2016-03-01

    The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

  7. Astrobiological Significance of Chemolithoautotrophic Acidophiles

    NASA Technical Reports Server (NTRS)

    Pikuta, Elena V.; Hoover, Richard B.

    2003-01-01

    For more than a century (since Winogradsky discovered lithoautotrophic bacteria) a dilemma in microbiology has concerned life that first inhabited the Earth. Which types of life forms first appeared in the primordial oceans during the earliest geological period on Earth as the primary ancestors of modem biological diversity? How did a metabolism of ancestors evolve: from lithoautotrophic to lithohetherotrophic and organoheterotrophic or from organoheterotrophic to organoautotrophic and lithomixotrophic types? At the present time, it is known that chemolithoheterotrophic and chemolithoautotrophic metabolizing bacteria are wide spread in different ecosystems. On Earth the acidic ecosystems are associated with geysers, volcanic fumaroles, hot springs, deep sea hydrothermal vents, caves, acid mine drainage and other technogenic ecosystems. Bioleaching played a significant role on a global geological scale during the Earth's formation. This important feature of bacteria has been successfully applied in industry. The lithoautotrophs include Bacteria and Archaea belonging to diverse genera containing thermophilic and mesophilic species. In this paper we discuss the lithotrophic microbial acidophiles and present some data with a description of new acidophilic iron- and sulfur- oxidizing bacterium isolated from the Chena Hot Springs in Alaska. We also consider the possible relevance of microbial acidophiles to Venus, Io, and acidic inclusions in glaciers and icy moons.

  8. Insight into the evolution of the iron oxidation pathways.

    PubMed

    Ilbert, Marianne; Bonnefoy, Violaine

    2013-02-01

    Iron is a ubiquitous element in the universe. Ferrous iron (Fe(II)) was abundant in the primordial ocean until the oxygenation of the Earth's atmosphere led to its widespread oxidation and precipitation. This change of iron bioavailability likely put selective pressure on the evolution of life. This element is essential to most extant life forms and is an important cofactor in many redox-active proteins involved in a number of vital pathways. In addition, iron plays a central role in many environments as an energy source for some microorganisms. This review is focused on Fe(II) oxidation. The fact that the ability to oxidize Fe(II) is widely distributed in Bacteria and Archaea and in a number of quite different biotopes suggests that the dissimilatory Fe(II) oxidation is an ancient energy metabolism. Based on what is known today about Fe(II) oxidation pathways, we propose that they arose independently more than once in evolution and evolved convergently. The iron paleochemistry, the phylogeny, the physiology of the iron oxidizers, and the nature of the cofactors of the redox proteins involved in these pathways suggest a possible scenario for the timescale in which each type of Fe(II) oxidation pathways evolved. The nitrate dependent anoxic iron oxidizers are likely the most ancient iron oxidizers. We suggest that the phototrophic anoxic iron oxidizers arose in surface waters after the Archaea/Bacteria-split but before the Great Oxidation Event. The neutrophilic oxic iron oxidizers possibly appeared in microaerobic marine environments prior to the Great Oxidation Event while the acidophilic ones emerged likely after the advent of atmospheric O(2). This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems.

  9. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Iron oxides. 73.2250 Section 73.2250 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including...

  10. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Iron oxides. 73.3125 Section 73.3125 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No. 1332-37-2), Color Index No. 77491, shall conform...

  11. Iron Meteorites Can Support the Growth of Acidophilic Chemolithoautotrophic Microorganisms

    NASA Astrophysics Data System (ADS)

    González-Toril, Elena; Martínez-Frías, Jesús; Gómez, José María; Rull, Fernando; Amils, Ricardo

    2005-06-01

    Chemolithoautotrophy based on reduced inorganic minerals is considered a primitive energy transduction system. Evidence that a high number of meteorites crashed into the planet during the early period of Earth history led us to test the ability of iron-oxidizing bacteria to grow using iron meteorites as their source of energy. Here we report the growth of two acidophilic iron-oxidizing bacteria, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans, on a piece of the Toluca meteorite as the only source of energy. The alteration of the surface of the exposed piece of meteorite, the solubilization of its oxidized metal constituents, mainly ferric iron, and the formation of goethite precipitates all clearly indicate that iron-meteoritebased chemolithotrophic metabolism is viable.

  12. Iron meteorites can support the growth of acidophilic chemolithoautotrophic microorganisms.

    PubMed

    González-Toril, Elena; Martínez-Frías, Jesús; Gómez Gómez, José María; Rull, Fernando; Amils, Ricardo

    2005-06-01

    Chemolithoautotrophy based on reduced inorganic minerals is considered a primitive energy transduction system. Evidence that a high number of meteorites crashed into the planet during the early period of Earth history led us to test the ability of iron-oxidizing bacteria to grow using iron meteorites as their source of energy. Here we report the growth of two acidophilic iron-oxidizing bacteria, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans, on a piece of the Toluca meteorite as the only source of energy. The alteration of the surface of the exposed piece of meteorite, the solubilization of its oxidized metal constituents, mainly ferric iron, and the formation of goethite precipitates all clearly indicate that iron-meteorite-based chemolithotrophic metabolism is viable.

  13. 21 CFR 186.1374 - Iron oxides.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Iron oxides. 186.1374 Section 186.1374 Food and... Substances Affirmed as GRAS § 186.1374 Iron oxides. (a) Iron oxides (oxides of iron, CAS Reg. No. 1332-37-2) are undefined mixtures of iron (II) oxide (CAS Reg. No. 1345-25-1, black cubic crystals) and iron...

  14. Tannin biosynthesis of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Herrera-Becerra, R.; Rius, J. L.; Zorrilla, C.

    2010-08-01

    In this work, iron oxide nanoparticles synthesized with gallic acid and tannic acid are characterized using High-Resolution Transmission Electron Microscopy (HRTEM). Its size, form, and structure are compared with nanoparticles obtained previously using alfalfa biomass in order to find a simpler, consistent, and environmentally friendly method in the production of iron oxide nanoparticles.

  15. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron... per million. (c) Uses and restrictions. Iron oxides are safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing...

  16. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron... per million. (c) Uses and restrictions. Iron oxides are safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing...

  17. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron... per million. (c) Uses and restrictions. Iron oxides are safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing...

  18. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron... per million. (c) Uses and restrictions. Iron oxides are safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing...

  19. Indium Sorption to Iron Oxides

    NASA Astrophysics Data System (ADS)

    White, S. J.; Sacco, S. A.; Hemond, H.; Hussain, F. A.; Runkel, R. L.; Walton-Day, K. E.; Kimball, B. A.; Shine, J. P.

    2014-12-01

    Indium is an increasingly important metal in semiconductors and electronics, and its use is growing rapidly as a semiconductive coating (as indium tin oxide) for liquid crystal displays (LCDs) and flat panel displays. It also has uses in important energy technologies such as light emitting diodes (LEDs) and photovoltaic cells. Despite its rapid increase in use, very little is known about the environmental behavior of indium, and concerns are being raised over the potential health effects of this emerging metal contaminant. One source of indium to the environment is acid mine drainage from the mining of lead, zinc, and copper sulfides. In our previous studies of a stream in Colorado influenced by acid mine drainage from lead and zinc mining activities, indium concentrations were found to be 10,000 times those found in uncontaminated rivers. However, the speciation and mobility of indium could not be reliably modeled because sorption constants to environmental sorbents have not been determined. In this study, we generate sorption constants for indium to ferrihydrite in the laboratory over a range of pHs, sorbent to sorbate ratios, and ionic strengths. Ferrihydrite is one of the most important sorbents in natural systems, and sorption to amorphous iron oxides such as ferrihydrite is thought to be one of the main removal mechanisms of metals from the dissolved phase in aqueous environments. Because of its relatively low solubility, we also find that indium hydroxide precipitation can dominate indium's partitioning at micromolar concentrations of indium. This precipitation may be important in describing indium's behavior in our study stream in Colorado, where modeling sorption to iron-oxides does not explain the complete removal of indium from the dissolved phase when the pH of the system is artificially raised to above 8. This study contributes much-needed data about indium's aqueous behavior, in order to better understand its fate, transport, and impacts in the

  20. When Density Functional Approximations Meet Iron Oxides.

    PubMed

    Meng, Yu; Liu, Xing-Wu; Huo, Chun-Fang; Guo, Wen-Ping; Cao, Dong-Bo; Peng, Qing; Dearden, Albert; Gonze, Xavier; Yang, Yong; Wang, Jianguo; Jiao, Haijun; Li, Yongwang; Wen, Xiao-Dong

    2016-10-11

    Three density functional approximations (DFAs), PBE, PBE+U, and Heyd-Scuseria-Ernzerhof screened hybrid functional (HSE), were employed to investigate the geometric, electronic, magnetic, and thermodynamic properties of four iron oxides, namely, α-FeOOH, α-Fe2O3, Fe3O4, and FeO. Comparing our calculated results with available experimental data, we found that HSE (a = 0.15) (containing 15% "screened" Hartree-Fock exchange) can provide reliable values of lattice constants, Fe magnetic moments, band gaps, and formation energies of all four iron oxides, while standard HSE (a = 0.25) seriously overestimates the band gaps and formation energies. For PBE+U, a suitable U value can give quite good results for the electronic properties of each iron oxide, but it is challenging to accurately get other properties of the four iron oxides using the same U value. Subsequently, we calculated the Gibbs free energies of transformation reactions among iron oxides using the HSE (a = 0.15) functional and plotted the equilibrium phase diagrams of the iron oxide system under various conditions, which provide reliable theoretical insight into the phase transformations of iron oxides.

  1. Water soluble dendronized iron oxide nanoparticles.

    PubMed

    Daou, T J; Pourroy, G; Greneche, J M; Bertin, A; Felder-Flesch, D; Begin-Colin, S

    2009-06-21

    The grafting of pegylated dendrons on 9(2) nm and 39(5) nm iron oxide nanoparticles in water, through a phosphonate group as coupling agent has been successfully achieved and its mechanism investigated, with a view to produce biocompatible magnetic nano-objects for biomedical applications. Grafting has been demonstrated to occur by interaction of negatively charged phosphonate groups with positively charged groups and hydroxyl at the iron oxide surface. The isoelectric point of the suspension of dendronized iron oxide nanoparticles is shifted towards lower pH as the amount of dendron increases. It reaches 4.7 for the higher grafting rate and for both particle size. Thus, the grafting of molecules using a phosphonate group allows stabilizing electrostatically the suspensions at physiological pH, a prerequisite for biomedical applications. Moreover the grafting step has been shown to preserve the magnetic properties of iron oxide nanoparticles due to super-super exchange interactions through the phosphonate group.

  2. Platinum Attachments on Iron Oxide Nanoparticle Surfaces

    SciTech Connect

    Palchoudhury, Soubantika; Xu, Yaolin; An, Wei; Turner, C. H.; Bao, Yuping

    2010-04-30

    Platinum nanoparticles supported on metal oxide surfaces have shown great potential as heterogeneous catalysts to accelerate electrochemical processes, such as the oxygen reduction reaction in fuel cells. Recently, the use of magnetic supports has become a promising research topic for easy separation and recovery of catalysts using magnets, such as Pt nanoparticles supported on iron oxide nanoparticles. The attachment of Pt on iron oxide nanoparticles is limited by the wetting ability of the Pt (metal) on ceramic surfaces. A study of Pt nanoparticle attachment on iron oxide nanoparticle surfaces in an organic solvent is reported, which addresses the factors that promote or inhibit such attachment. It was discovered that the Pt attachment strongly depends on the capping molecules of the iron oxide seeds and the reaction temperature. For example, the attachment of Pt nanoparticles on oleic acid coated iron oxide nanoparticles was very challenging, because of the strong binding between the carboxylic groups and iron oxide surfaces. In contrast, when nanoparticles are coated with oleic acid/tri-n-octylphosphine oxide or oleic acid/oleylamine, a significant increase in Pt attachment was observed. Electronic structure calculations were then applied to estimate the binding energies between the capping molecules and iron ions, and the modeling results strongly support the experimental observations.

  3. Use of an Intelligent Control System To Evaluate Multiparametric Effects on Iron Oxidation by Thermophilic Bacteria

    PubMed Central

    Stoner, Daphne L.; Miller, Karen S.; Fife, Dee Jay; Larsen, Eric D.; Tolle, Charles R.; Johnson, John A.

    1998-01-01

    A learning-based intelligent control system, the BioExpert, was developed and applied to the evaluation of multiparametric effects on iron oxidation by enrichment cultures of moderately thermophilic, acidophilic mining bacteria. The control system acquired and analyzed the data and then selected and maintained the sets of conditions that were evaluated. Through multiple iterations, the BioExpert selected sets of conditions that resulted in improved iron oxidation rates. The results obtained with the BioExpert suggested that temperature and pH were coupled, or interactive, parameters. Elevated temperatures (51.5°C) in combination with a moderately high pH (pH 1.84) impaired the growth of and iron oxidation by the enrichment culture. Moderate-to-high oxidation rates were achieved with a relatively high pH in combination with a relatively low temperature or, conversely, with a relatively low pH in combination with a relatively high temperature. The interactive effect of pH and temperature was not apparent from the results obtained in an experiment in which temperature was the only parameter that was varied. When the BioExpert was applied to a mixed culture containing mesophilic and thermophilic bacteria, the computer “learned” that pH 1.8, 45°C, and an inlet iron concentration from 30 to 35 mM were most favorable for iron oxidation. In conclusion, this study demonstrated that the learning-based intelligent control system BioExpert was an effective experimental tool that can be used to examine multiparametric effects on the growth and metabolic activity of mining bacteria. PMID:9797322

  4. Geochemical and Temporal Influences on the Enrichment of Acidophilic Iron-Oxidizing Bacterial Communities

    PubMed Central

    Sheng, Yizhi; Bibby, Kyle; Grettenberger, Christen; Kaley, Bradley; Macalady, Jennifer L.; Wang, Guangcai

    2016-01-01

    ABSTRACT Two acid mine drainage (AMD) sites in the Appalachian bituminous coal basin were selected to enrich for Fe(II)-oxidizing microbes and measure rates of low-pH Fe(II) oxidation in chemostatic bioreactors. Microbial communities were enriched for 74 to 128 days in fed-batch mode, then switched to flowthrough mode (additional 52 to 138 d) to measure rates of Fe(II) oxidation as a function of pH (2.1 to 4.2) and influent Fe(II) concentration (80 to 2,400 mg/liter). Biofilm samples were collected throughout these operations, and the microbial community structure was analyzed to evaluate impacts of geochemistry and incubation time. Alpha diversity decreased as the pH decreased and as the Fe(II) concentration increased, coincident with conditions that attained the highest rates of Fe(II) oxidation. The distribution of the seven most abundant bacterial genera could be explained by a combination of pH and Fe(II) concentration. Acidithiobacillus, Ferrovum, Gallionella, Leptospirillum, Ferrimicrobium, Acidiphilium, and Acidocella were all found to be restricted within specific bounds of pH and Fe(II) concentration. Temporal distance, defined as the cumulative number of pore volumes from the start of flowthrough mode, appeared to be as important as geochemical conditions in controlling microbial community structure. Both alpha and beta diversities of microbial communities were significantly correlated to temporal distance in the flowthrough experiments. Even after long-term operation under nearly identical geochemical conditions, microbial communities enriched from the different sites remained distinct. While these microbial communities were enriched from sites that displayed markedly different field rates of Fe(II) oxidation, rates of Fe(II) oxidation measured in laboratory bioreactors were essentially the same. These results suggest that the performance of suspended-growth bioreactors for AMD treatment may not be strongly dependent on the inoculum used for reactor startup. IMPORTANCE This study showed that different microbial communities enriched from two sites maintained distinct microbial community traits inherited from their respective seed materials. Long-term operation (up to 128 days of fed-batch enrichment followed by up to 138 days of flowthrough experiments) of these two systems did not lead to the same, or even more similar, microbial communities. However, these bioreactors did oxidize Fe(II) and remove total iron [Fe(T)] at very similar rates. These results suggest that the performance of suspended-growth bioreactors for AMD treatment may not be strongly dependent on the inoculum used for reactor startup. This would be advantageous, because system performance should be well constrained and predictable for many different sites. PMID:27084004

  5. Genetic transfer in acidophilic bacteria

    SciTech Connect

    Roberto, F.F.; Glenn, A.W.; Bulmer, D.; Ward, T.E.

    1990-01-01

    There is increasing interest in the use of microorganisms to recover metals from ores, as well as to remove sulfur from coal. These so-called bioleaching processes are mediated by a number of bacteria. The best-studied of these organisms are acidophiles including Thiobacillus and Acidiphilium species. Our laboratory has focused on developing genetic strategies to allow the manipulation of acidophilic bacteria to improve and augment their utility in large scale operations. We have recently been successful in employing conjugation for interbacterial transfer of genetic information, as well as in directly transforming Acidiphilium by use of electroporation. We are now testing the properties of IncPl, IncW and IncQ plasmid vectors in Acidiphilium to determine their relative usefulness in routine manipulation of acidophiles and transfer between organisms. This study also allows us to determine the natural ability of these bacteria to transfer genetic material amongst themselves in their particular environment. 21 refs., 3 figs., 2 tabs.

  6. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Iron oxides. 73.3125 Section 73.3125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... effect. (2) Authorization and compliance with this use shall not be construed as waiving any of...

  7. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Iron oxides. 73.3125 Section 73.3125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... effect. (2) Authorization and compliance with this use shall not be construed as waiving any of...

  8. Exploring Microbial Iron Oxidation in Wetland Soils

    NASA Astrophysics Data System (ADS)

    Wang, J.; Muyzer, G.; Bodelier, P. L. E.; den Oudsten, F.; Laanbroek, H. J.

    2009-04-01

    Iron is one of the most abundant elements on earth and is essential for life. Because of its importance, iron cycling and its interaction with other chemical and microbial processes has been the focus of many studies. Iron-oxidizing bacteria (FeOB) have been detected in a wide variety of environments. Among those is the rhizosphere of wetland plants roots which release oxygen into the soil creating suboxic conditions required by these organisms. It has been reported that in these rhizosphere microbial iron oxidation proceeds up to four orders of magnitude faster than strictly abiotic oxidation. On the roots of these wetland plants iron plaques are formed by microbial iron oxidation which are involved in the sequestering of heavy metals as well organic pollutants, which of great environmental significance.Despite their important role being catalysts of iron-cycling in wetland environments, little is known about the diversity and distribution of iron-oxidizing bacteria in various environments. This study aimed at developing a PCR-DGGE assay enabling the detection of iron oxidizers in wetland habitats. Gradient tubes were used to enrich iron-oxidizing bacteria. From these enrichments, a clone library was established based on the almost complete 16s rRNA gene using the universal bacterial primers 27f and 1492r. This clone library consisted of mainly α- and β-Proteobacteria, among which two major clusters were closely related to Gallionella spp. Specific probes and primers were developed on the basis of this 16S rRNA gene clone library. The newly designed Gallionella-specific 16S rRNA gene primer set 122f/998r was applied to community DNA obtained from three contrasting wetland environments, and the PCR products were used in denaturing gradient gel electrophoresis (DGGE) analysis. A second 16S rRNA gene clone library was constructed using the PCR products from one of our sampling sites amplified with the newly developed primer set 122f/998r. The cloned 16S rRNA gene

  9. Chemical design of biocompatible iron oxide nanoparticles for medical applications.

    PubMed

    Ling, Daishun; Hyeon, Taeghwan

    2013-05-27

    Iron oxide nanoparticles are one of the most versatile and safe nanomaterials used in medicine. Recent progress in nanochemistry enables fine control of the size, crystallinity, uniformity, and surface properties of iron oxide nanoparticles. In this review, the synthesis of chemically designed biocompatible iron oxide nanoparticles with improved quality and reduced toxicity is discussed for use in diverse biomedical applications.

  10. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  11. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  12. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Synthetic iron oxide. 73.200 Section 73.200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  13. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  14. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  15. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  16. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Synthetic iron oxide. 73.200 Section 73.200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  17. Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

    NASA Astrophysics Data System (ADS)

    Evans, K.; Ferris, F.

    2009-05-01

    At concentrations above 1 mg/L, fluoride in drinking water can lead to dental and skeletal fluorosis, a disease that causes mottling of the teeth, calcification of ligaments, crippling bone deformities and many other physiological disorders that can, ultimately, lead to death. Conservative estimates are that fluorosis afflicts tens of millions of people worldwide. As there is no treatment for fluorosis, prevention is the only means of controlling the disease. While numerous defluoridation techniques have been explored, no single method has been found to be both effective and inexpensive enough to implement widely. Our research began in India, with a large-scale geochemical study of the groundwater in a fluoride-contaminated region of Orissa. Having developed a better understanding of the geochemical relationships that exist between fluoride and other parameters present in an affected area, as well as the complex relationships that arise among those parameters that can impact the presence of fluoride, we began investigating certain remediation scenarios involving iron oxides. A common approach to remediation involves the partitioning of fluoride from groundwater by sorption onto a variety of materials, one of the most effective of which is iron oxide whose surface area acts as a scavenger for fluoride. In the presence of iron oxidizing bacteria, the oxidation rate of iron has been shown to be ˜6 times greater than in their absence; fluoride should, therefore, be removed from an aqueous environment by bacteriogenic iron oxides (BIOS) much more quickly than by abiotic iron oxides. Most recently, sorption studies have been conducted using both BIOS and synthetic hydrous ferric oxides in order to compare the behavior between biotic and abiotic sorbents. These studies have provided sorption isotherms that allow comparison of fluoride removed by sorption to BIOS versus synthetic iron oxides. Sorption affinity constants have also been determined, which allow for the

  18. Metal ion binding to iron oxides

    NASA Astrophysics Data System (ADS)

    Ponthieu, M.; Juillot, F.; Hiemstra, T.; van Riemsdijk, W. H.; Benedetti, M. F.

    2006-06-01

    The biogeochemistry of trace elements (TE) is largely dependent upon their interaction with heterogeneous ligands including metal oxides and hydrous oxides of iron. The modeling of TE interactions with iron oxides has been pursued using a variety of chemical models. The objective of this work is to show that it is possible to model the adsorption of protons and TE on a crystallized oxide (i.e., goethite) and on an amorphous oxide (HFO) in an identical way. Here, we use the CD-MUSIC approach in combination with valuable and reliable surface spectroscopy information about the nature of surface complexes of the TE. The other objective of this work is to obtain generic parameters to describe the binding of the following elements (Cd, Co, Cu, Ni, Pb, and Zn) onto both iron oxides for the CD-MUSIC approach. The results show that a consistent description of proton and metal ion binding is possible for goethite and HFO with the same set of model parameters. In general a good prediction of almost all the collected experimental data sets corresponding to metal ion binding to HFO is obtained. Moreover, dominant surface species are in agreement with the recently published surface complexes derived from X-ray absorption spectroscopy (XAS) data. Until more detailed information on the structure of the two iron oxides is available, the present option seems a reasonable approximation and can be used to describe complex geochemical systems. To improve our understanding and modeling of multi-component systems we need more data obtained at much lower metal ion to iron oxide ratios in order to be able to account eventually for sites that are not always characterized in spectroscopic studies.

  19. Interactions of the metal tolerant heterotrophic microorganisms and iron oxidizing autotrophic bacteria from sulphidic mine environment during bioleaching experiments.

    PubMed

    Jeremic, Sanja; Beškoski, Vladimir P; Djokic, Lidija; Vasiljevic, Branka; Vrvić, Miroslav M; Avdalović, Jelena; Gojgić Cvijović, Gordana; Beškoski, Latinka Slavković; Nikodinovic-Runic, Jasmina

    2016-05-01

    Iron and sulfur oxidizing chemolithoautotrophic acidophilic bacteria, such as Acidithiobacillus species, hold the dominant role in mine environments characterized by low pH values and high concentrations of reduced sulfur and iron compounds, such as ores, rocks and acid drainage waters from mines. On the other hand, heterotrophic microorganisms, especially their biofilms, from these specific niches are receiving increased attention, but their potential eco-physiological roles have not been fully understood. Biofilms are considered a threat to human health, but biofilms also have beneficial properties as they are deployed in waste recycling and bioremediation systems. We have analyzed interactions of the metal tolerant heterotrophic microorganisms in biofilms with iron oxidizing autotrophic bacteria both from the sulphidic mine environment (copper mine Bor, Serbia). High tolerance to Cu(2+), Cd(2+) and Cr(6+) and the presence of genetic determinants for the respective metal tolerance and biofilm-forming ability was shown for indigenous heterotrophic bacteria that included strains of Staphylococcus and Rhodococcus. Two well characterized bacteria- Pseudomonas aeruginosa PAO1 (known biofilm former) and Cupriavidus metallidurans CH34 (known metal resistant representative) were also included in the study. The interaction and survivability of autotrophic iron oxidizing Acidithiobacillus bacteria and biofilms of heterotrophic bacteria during co-cultivation was revealed. Finally, the effect of heterotrophic biofilms on bioleaching process with indigenous iron oxidizing Acidithiobacillus species was shown not to be inhibitory under in vitro conditions.

  20. Phase Formation Behavior in Ultrathin Iron Oxide.

    PubMed

    Jõgi, Indrek; Jacobsson, T Jesper; Fondell, Mattis; Wätjen, Timo; Carlsson, Jan-Otto; Boman, Mats; Edvinsson, Tomas

    2015-11-17

    Nanostructured iron oxides, and especially hematite, are interesting for a wide range of applications ranging from gas sensors to renewable solar hydrogen production. A promising method for deposition of low-dimensional films is atomic layer deposition (ALD). Although a potent technique, ALD of ultrathin films is critically sensitive to the substrate and temperature conditions where initial formation of islands and crystallites influences the properties of the films. In this work, deposition at the border of the ALD window forming a hybrid ALD/pulsed CVD (pCVD) deposition is utilized to obtain a deposition less sensitive to the substrate. A thorough analysis of iron oxide phases formation on two different substrates, Si(100) and SiO2, was performed. Films between 3 and 50 nm were deposited and analyzed with diffraction techniques, high-resolution Raman spectroscopy, and optical spectroscopy. Below 10 nm nominal film thickness, island formation and phase dependent particle crystallization impose constraints for deposition of phase pure iron oxides on non-lattice-matching substrates. Films between 10 and 20 nm thickness on SiO2 could effectively be recrystallized into hematite whereas for the corresponding films on Si(100), no recrystallization occurred. For films thicker than 20 nm, phase pure hematite can be formed directly with ALD/pCVD with very low influence of the substrate on either Si or SiO2. For more lattice matched substrates such as SnO2:F, Raman spectroscopy indicated formation of the hematite phase already for films with 3 nm nominal thickness and clearly for 6 nm films. Analysis of the optical properties corroborated the analysis and showed a quantum confined blue-shift of the absorption edge for the thinnest films.

  1. Suspension Hydrogen Reduction of Iron Oxide Concentrates

    SciTech Connect

    H.Y. Sohn

    2008-03-31

    The objective of the project is to develop a new ironmaking technology based on hydrogen and fine iron oxide concentrates in a suspension reduction process. The ultimate objective of the new technology is to replace the blast furnace and to drastically reduce CO2 emissions in the steel industry. The goals of this phase of development are; the performance of detailed material and energy balances, thermochemical and equilibrium calculations for sulfur and phosphorus impurities, the determination of the complete kinetics of hydrogen reduction and bench-scale testing of the suspension reduction process using a large laboratory flash reactor.

  2. Modified iron oxide nanomaterials: Functionalization and application

    NASA Astrophysics Data System (ADS)

    Bagheri, Samira; Julkapli, Nurhidayatullaili Muhd

    2016-10-01

    Iron oxide magnetic nanoparticles have aroused the interest of researchers of materials' chemistry due to its exceptional properties such as decent magnetic, electric, catalytic, biocompatibility, and low toxicity. However, these magnetic nanoparticles are predisposed towards aggregation and forming larger particles, due to its strong anisotropic dipolar interactions, particularly in the aqueous phase, consequently depriving them of dispersibility and particular properties, ultimately degrading their performance. Hence, this review focuses on modified magnetic nanoparticles that are stable, easily synthesized, possess a high surface area and could be facile-separated via magnetic forces, and are of low toxicity and costs for applications such as catalyst/catalyst support, food security, biomedical, and pollutant remediation.

  3. Mineral resource of the month: iron oxide pigments

    USGS Publications Warehouse

    ,

    2008-01-01

    The article discusses iron oxide pigments, which have been used as colorants since human began painting as they resist color change due to sunlight exposure, have good chemical resistance and are stable under normal ambient conditions. Cyprus, Italy and Spain are among the countries that are known for the production of iron oxide pigments. Granular forms of iron oxides and nano-sized materials are cited as developments in the synthetic iron oxide pigment industry which are being used in computer disk drives and nuclear magnetic resonance imaging.

  4. Method for preparing hydrous iron oxide gels and spherules

    DOEpatents

    Collins, Jack L.; Lauf, Robert J.; Anderson, Kimberly K.

    2003-07-29

    The present invention is directed to methods for preparing hydrous iron oxide spherules, hydrous iron oxide gels such as gel slabs, films, capillary and electrophoresis gels, iron monohydrogen phosphate spherules, hydrous iron oxide spherules having suspendable particles homogeneously embedded within to form composite sorbents and catalysts, iron monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent, iron oxide spherules having suspendable particles homogeneously embedded within to form a composite of hydrous iron oxide fiber materials, iron oxide fiber materials, hydrous iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, dielectric spherules of barium, strontium, and lead ferrites and mixtures thereof, and composite catalytic spherules of barium or strontium ferrite embedded with oxides of Mg, Zn, Pb, Ce and mixtures thereof. These variations of hydrous iron oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters, dielectrics, and ceramics.

  5. Catalytic iron oxide for lime regeneration in carbonaceous fuel combustion

    DOEpatents

    Shen, Ming-Shing; Yang, Ralph T.

    1980-01-01

    Lime utilization for sulfurous oxides absorption in fluidized combustion of carbonaceous fuels is improved by impregnation of porous lime particulates with iron oxide. The impregnation is achieved by spraying an aqueous solution of mixed iron sulfate and sulfite on the limestone before transfer to the fluidized bed combustor, whereby the iron compounds react with the limestone substrate to form iron oxide at the limestone surface. It is found that iron oxide present in the spent limestone acts as a catalyst to regenerate the spent limestone in a reducing environment. With only small quantities of iron oxide the calcium can be recycled at a significantly increased rate.

  6. Cultivation and quantitative proteomic analyses of acidophilic microbial communities

    SciTech Connect

    Belnap, Christopher P.; Pan, Chongle; Verberkmoes, Nathan C; Power, Mary E.; Samatova, Nagiza F; Carver, Rudolf L.; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2010-01-01

    Acid mine drainage (AMD), an extreme environment characterized by low pH and high metal concentrations, can support dense acidophilic microbial biofilm communities that rely on chemoautotrophic production based on iron oxidation. Field determined production rates indicate that, despite the extreme conditions, these communities are sufficiently well adapted to their habitats to achieve primary production rates comparable to those of microbial communities occurring in some non-extreme environments. To enable laboratory studies of growth, production and ecology of AMD microbial communities, a culturing system was designed to reproduce natural biofilms, including organisms recalcitrant to cultivation. A comprehensive metabolic labeling-based quantitative proteomic analysis was used to verify that natural and laboratory communities were comparable at the functional level. Results confirmed that the composition and core metabolic activities of laboratory-grown communities were similar to a natural community, including the presence of active, low abundance bacteria and archaea that have not yet been isolated. However, laboratory growth rates were slow compared with natural communities, and this correlated with increased abundance of stress response proteins for the dominant bacteria in laboratory communities. Modification of cultivation conditions reduced the abundance of stress response proteins and increased laboratory community growth rates. The research presented here represents the first description of the application of a metabolic labeling-based quantitative proteomic analysis at the community level and resulted in a model microbial community system ideal for testing physiological and ecological hypotheses.

  7. Modified Nanoemulsions with Iron Oxide for Magnetic Resonance Imaging

    PubMed Central

    Fan, Yongyi; Guo, Rui; Shi, Xiangyang; Allen, Steven; Cao, Zhengyi; Baker, James R.; Wang, Su He

    2016-01-01

    A nanoemulsion (NE) is a surfactant-based, oil-in-water, nanoscale, high-energy emulsion with a mean droplet diameter of 400–600 nm. When mixed with antigen and applied nasally, a NE acts as a mucosal adjuvant and induces mucosal immune responses. One possible mechanism for the adjuvant effect of this material is that it augments antigen uptake and distribution to lymphoid tissues, where the immune response is generated. Biocompatible iron oxide nanoparticles have been used as a unique imaging approach to study the dynamics of cells or molecular migration. To study the uptake of NEs and track them in vivo, iron oxide nanoparticles were synthesized and dispersed in soybean oil to make iron oxide-modified NEs. Our results show that iron oxide nanoparticles can be stabilized in the oil phase of the nanoemulsion at a concentration of 30 µg/μL and the iron oxide-modified NEs have a mean diameter of 521 nm. In vitro experiments demonstrated that iron oxide-modified NEs can affect uptake by TC-1 cells (a murine epithelial cell line) and reduce the intensity of magnetic resonance (MR) images by shortening the T2 time. Most importantly, in vivo studies demonstrated that iron oxide-modified NE could be detected in mouse nasal septum by both transmission electron microscopy and MR imaging. Altogether these experiments demonstrate that iron oxide-modified NE is a unique tool that can be used to study uptake and distribution of NEs after nasal application. PMID:28335351

  8. Uptake And Intracellular Distribution Of Functionalized Iron Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Panariti, A.; Lettiero, B.; Morjan, I.; Alexandreascu, R.; Wang, D.; Bucci, C.; Miserocchi, G.; Rivolta, I.

    2010-10-01

    Iron oxide Nanoparticles represents promising nanocarrier for magnetic resonance imaging (MRI), targeted drug and gene delivery. In our study we investigated the interaction between lung alveolar epithelial cells and iron oxide NPs coated with L-Dihydroxyphenylalanina (L-Dopa)-TRITC. Our data suggest that particles crossed the plasma membrane with an energy-dependent process.

  9. Multifunctional iron oxide nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Bloemen, M.; Denis, C.; Van Stappen, T.; De Meester, L.; Geukens, N.; Gils, A.; Verbiest, T.

    2015-03-01

    Multifunctional nanoparticles have attracted a lot of attention since they can combine interesting properties like magnetism, fluorescence or plasmonic effects. As a core material, iron oxide nanoparticles have been the subject of intensive research. These cost-effective and non-toxic particles are used nowadays in many applications. We developed a heterobifunctional PEG ligand that can be used to introduce functional groups (carboxylic acids) onto the surface of the NP. Via click chemistry, a siloxane functionality was added to this ligand, for a subsequent covalent ligand exchange reaction. The functionalized nanoparticles have an excellent colloidal stability in complex environments like buffers and serum or plasma. Antibodies were coupled to the introduced carboxylic acids and these NP-antibody bioconjugates were brought into contact with Legionella bacteria for magnetic separation experiments.

  10. Biocompatible multishell architecture for iron oxide nanoparticles.

    PubMed

    Wotschadlo, Jana; Liebert, Tim; Clement, Joachim H; Anspach, Nils; Höppener, Stephanie; Rudolph, Tobias; Müller, Robert; Schacher, Felix H; Schubert, Ulrich S; Heinze, Thomas

    2013-01-01

    The coating of super-paramagnetic iron oxide nanoparticles (SPIONs) with multiple shells is demonstrated by building a layer assembled from carboxymethyldextran and poly(diallydimethylammonium chloride). Three shells are produced stepwise around aggregates of SPIONs by the formation of a polyelectrolyte complex. A growing particle size from 96 to 327 nm and a zeta potential in the range of +39 to -51 mV are measured. Microscopic techniques such as TEM, SEM, and AFM exemplify the core-shell structures. Magnetic force microscopy and vibrating sample magnetometer measurements confirm the architecture of the multishell particles. Cell culture experiments show that even nanoparticles with three shells are still taken up by cells.

  11. Multiple hearth furnace for reducing iron oxide

    DOEpatents

    Brandon, Mark M [Charlotte, NC; True, Bradford G [Charlotte, NC

    2012-03-13

    A multiple moving hearth furnace (10) having a furnace housing (11) with at least two moving hearths (20) positioned laterally within the furnace housing, the hearths moving in opposite directions and each moving hearth (20) capable of being charged with at least one layer of iron oxide and carbon bearing material at one end, and being capable of discharging reduced material at the other end. A heat insulating partition (92) is positioned between adjacent moving hearths of at least portions of the conversion zones (13), and is capable of communicating gases between the atmospheres of the conversion zones of adjacent moving hearths. A drying/preheat zone (12), a conversion zone (13), and optionally a cooling zone (15) are sequentially positioned along each moving hearth (30) in the furnace housing (11).

  12. Ferrous iron oxidation by anoxygenic phototrophic bacteria

    NASA Astrophysics Data System (ADS)

    Widdel, Friedrich; Schnell, Sylvia; Heising, Silke; Ehrenreich, Armin; Assmus, Bernhard; Schink, Bernhard

    1993-04-01

    NATURAL oxidation of ferrous to ferric iron by bacteria such as Thiobacillus ferrooxidans or Gallionella ferruginea1, or by chemical oxidation2,3 has previously been thought always to involve molecular oxygen as the electron acceptor. Anoxic photochemical reactions4-6 or a photobiological process involving two photosystems7-9 have also been discussed as mechanisms of ferrous iron oxidation. The knowledge of such processes has implications that bear on our understanding of the origin of Precambrian banded iron formations10-14. The reducing power of ferrous iron increases dramatically at pH values higher than 2-3 owing to the formation of ferric hydroxy and oxyhydroxy compounds1,2,15 (Fig. 1). The standard redox potential of Fe3+/Fe2+ (E0 = +0.77 V) is relevant only under acidic conditions. At pH 7.0, the couples Fe(OH)3/Fe2+ (E'0 = -0.236V) or Fe(OH)3 + HCO-3FeCO3 (E'0 = +0.200 V) prevail, matching redox potentials measured in natural sediments9,16,17. It should thus be possible for Fe(n) around pH 7.0 to function as an electron donor for anoxygenic photosynthesis. The midpoint potential of the reaction centre in purple bacteria is around +0.45 V (ref. 18). Here we describe purple, non-sulphur bacteria that can indeed oxidize colourless Fe(u) to brown Fe(in) and reduce CO2 to cell material, implying that oxygen-independent biological iron oxidation was possible before the evolution of oxygenic photosynthesis.

  13. Investigation of energy gene expressions and community structures of free and attached acidophilic bacteria in chalcopyrite bioleaching.

    PubMed

    Zhu, Jianyu; Jiao, Weifeng; Li, Qian; Liu, Xueduan; Qin, Wenqing; Qiu, Guanzhou; Hu, Yuehua; Chai, Liyuan

    2012-12-01

    In order to better understand the bioleaching mechanism, expression of genes involved in energy conservation and community structure of free and attached acidophilic bacteria in chalcopyrite bioleaching were investigated. Using quantitative real-time PCR, we studied the expression of genes involved in energy conservation in free and attached Acidithiobacillus ferrooxidans during bioleaching of chalcopyrite. Sulfur oxidation genes of attached A. ferrooxidans were up-regulated while ferrous iron oxidation genes were down-regulated compared with free A. ferrooxidans in the solution. The up-regulation may be induced by elemental sulfur on the mineral surface. This conclusion was supported by the results of HPLC analysis. Sulfur-oxidizing Acidithiobacillus thiooxidans and ferrous-oxidizing Leptospirillum ferrooxidans were the members of the mixed culture in chalcopyrite bioleaching. Study of the community structure of free and attached bacteria showed that A. thiooxidans dominated the attached bacteria while L. ferrooxidans dominated the free bacteria. With respect to available energy sources during bioleaching of chalcopyrite, sulfur-oxidizers tend to be on the mineral surfaces whereas ferrous iron-oxidizers tend to be suspended in the aqueous phase. Taken together, these results indicate that the main role of attached acidophilic bacteria was to oxidize elemental sulfur and dissolution of chalcopyrite involved chiefly an indirect bioleaching mechanism.

  14. Stem cell tracking using iron oxide nanoparticles.

    PubMed

    Bull, Elizabeth; Madani, Seyed Yazdan; Sheth, Roosey; Seifalian, Amelia; Green, Mark; Seifalian, Alexander M

    2014-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) are an exciting advancement in the field of nanotechnology. They expand the possibilities of noninvasive analysis and have many useful properties, making them potential candidates for numerous novel applications. Notably, they have been shown that they can be tracked by magnetic resonance imaging (MRI) and are capable of conjugation with various cell types, including stem cells. In-depth research has been undertaken to establish these benefits, so that a deeper level of understanding of stem cell migratory pathways and differentiation, tumor migration, and improved drug delivery can be achieved. Stem cells have the ability to treat and cure many debilitating diseases with limited side effects, but a main problem that arises is in the noninvasive tracking and analysis of these stem cells. Recently, researchers have acknowledged the use of SPIONs for this purpose and have set out to establish suitable protocols for coating and attachment, so as to bring MRI tracking of SPION-labeled stem cells into common practice. This review paper explains the manner in which SPIONs are produced, conjugated, and tracked using MRI, as well as a discussion on their limitations. A concise summary of recently researched magnetic particle coatings is provided, and the effects of SPIONs on stem cells are evaluated, while animal and human studies investigating the role of SPIONs in stem cell tracking will be explored.

  15. Iron oxide nanoparticle enhancement of radiation cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mazur, Courtney M.; Tate, Jennifer A.; Strawbridge, Rendall R.; Gladstone, David J.; Hoopes, P. Jack

    2013-02-01

    Iron oxide nanoparticles (IONPs) have been investigated as a promising means for inducing tumor cell-specific hyperthermia. Although the ability to generate and use nanoparticles that are biocompatible, tumor specific, and have the ability to produce adequate cytotoxic heat is very promising, significant preclinical and clinical development will be required for clinical efficacy. At this time it appears using IONP-induced hyperthermia as an adjunct to conventional cancer therapeutics, rather than as an independent treatment, will provide the initial IONP clinical treatment. Due to their high-Z characteristics, another option is to use intracellular IONPs to enhance radiation therapy without excitation with AMF (production of heat). To test this concept IONPs were added to cell culture media at a concentration of 0.2 mg Fe/mL and incubated with murine breast adenocarcinoma (MTG-B) cells for either 48 or 72 hours. Extracellular iron was then removed and all cells were irradiated at 4 Gy. Although samples incubated with IONPs for 48 hrs did not demonstrate enhanced post-irradiation cytotoxicity as compared to the non-IONP-containing cells, cells incubated with IONPs for 72 hours, which contained 40% more Fe than 48 hr incubated cells, showed a 25% decrease in clonogenic survival compared to their non-IONP-containing counterparts. These results suggest that a critical concentration of intracellular IONPs is necessary for enhancing radiation cytotoxicity.

  16. Iron Oxide Nanocrystals for Magnetic Hyperthermia Applications

    PubMed Central

    Armijo, Leisha M.; Brandt, Yekaterina I.; Mathew, Dimple; Yadav, Surabhi; Maestas, Salomon; Rivera, Antonio C.; Cook, Nathaniel C.; Withers, Nathan J.; Smolyakov, Gennady A.; Adolphi, Natalie; Monson, Todd C.; Huber, Dale L.; Smyth, Hugh D. C.; Osiński, Marek

    2012-01-01

    Magnetic nanocrystals have been investigated extensively in the past several years for several potential applications, such as information technology, MRI contrast agents, and for drug conjugation and delivery. A specific property of interest in biomedicine is magnetic hyperthermia—an increase in temperature resulting from the thermal energy released by magnetic nanocrystals in an external alternating magnetic field. Iron oxide nanocrystals of various sizes and morphologies were synthesized and tested for specific losses (heating power) using frequencies of 111.1 kHz and 629.2 kHz, and corresponding magnetic field strengths of 9 and 25 mT. Polymorphous nanocrystals as well as spherical nanocrystals and nanowires in paramagnetic to ferromagnetic size range exhibited good heating power. A remarkable 30 °C temperature increase was observed in a nanowire sample at 111 kHz and magnetic field of 25 mT (19.6 kA/m), which is very close to the typical values of 100 kHz and 20 mT used in medical treatments.

  17. Microbially Induced Iron Oxidation: What, Where, How

    SciTech Connect

    SCHIERMEYER,ELISA M.; PROVENCIO,PAULA P.; NORTHUP,DIANA E.

    2000-08-15

    From the results of the different bacterial cells seen, it is fairly certain that Gallionella is present because of the bean-shaped cells and twisted stalks found with the TEM. The authors cannot confirm, though, what other iron-oxidizing genera exist in the tubes, since the media was only preferential and not one that isolated a specific genus of bacteria. Based on the environment in which they live and the source of the water, they believe their cultures contain Gallionella, Leptothrix, and possibly Crenothrix and Sphaerotilus. They believe the genus Leptothrix rather than Sphaerotilus exist in the tubes because the water source was fresh, unlike the polluted water in which Sphaerotilus are usually found. The TEM preparations worked well. The cryogenic method rapidly froze the cells in place and allowed them to view their morphology. The FAA method, as stated previously, was the best of the three methods because it gave the best contrast. The gluteraldehyde samples did not come out as well. It is possible that the gluteraldehyde the authors prepared was still too concentrated and did not mix well. Although these bacteria were collected from springs and then cultured in an environment containing a presumably pure iron-bearing metal, it seems the tube already containing Manganese Gradient Medium could be used with a piece of metal containing these bacteria. A small piece of corroding metal could then be inserted into the test tube and cultured to study the bacteria.

  18. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    PubMed Central

    2008-01-01

    Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed. PMID:21749733

  19. 46 CFR 148.275 - Iron oxide, spent; iron sponge, spent.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Iron oxide, spent; iron sponge, spent. 148.275 Section... § 148.275 Iron oxide, spent; iron sponge, spent. (a) Before spent iron oxide or spent iron sponge is... been cooled and weathered for at least eight weeks. (b) Both spent iron oxide and spent iron sponge...

  20. 46 CFR 148.275 - Iron oxide, spent; iron sponge, spent.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Iron oxide, spent; iron sponge, spent. 148.275 Section... § 148.275 Iron oxide, spent; iron sponge, spent. (a) Before spent iron oxide or spent iron sponge is... been cooled and weathered for at least eight weeks. (b) Both spent iron oxide and spent iron sponge...

  1. 46 CFR 148.275 - Iron oxide, spent; iron sponge, spent.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Iron oxide, spent; iron sponge, spent. 148.275 Section... § 148.275 Iron oxide, spent; iron sponge, spent. (a) Before spent iron oxide or spent iron sponge is... been cooled and weathered for at least eight weeks. (b) Both spent iron oxide and spent iron sponge...

  2. 46 CFR 148.275 - Iron oxide, spent; iron sponge, spent.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Iron oxide, spent; iron sponge, spent. 148.275 Section... § 148.275 Iron oxide, spent; iron sponge, spent. (a) Before spent iron oxide or spent iron sponge is... been cooled and weathered for at least eight weeks. (b) Both spent iron oxide and spent iron sponge...

  3. Magnetic Characterization of Iron Oxide Cross Linked Hydro gels

    NASA Astrophysics Data System (ADS)

    Senaratne, U.; Powell, N.; Kroll, E.; Tsoi, G.; Naik, R.; Naik, V.; Vaishnava, P. P.; Wenger, L. E.

    2004-03-01

    Magnetic hydro gels have potential applications in drug delivery, cells sorting, sensors, and actuating technologies. Iron oxide alginate nanocomposites were synthesized following the method of Kroll et al^1 by cross linking sodium alginate with Fe^2+ and Fe^3+ in methanol: water. The ion-cross linked alginate hydro gels are oxidized in an alkaline solution. The resulting hydro gel consists of iron oxide cross linked alginate. The alginate hydro gels are inert to the reaction conditions and therefore the reaction sequence can be repeated. The multiple loadings result in an increase in the amount of iron oxide and the size of the iron oxide nanoparticles in the cross linked hydro gels. The third and sixth loaded iron oxide alginate hydro gels were dried and characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), and Superconducting Quantum Interference Device (SQUID) magnetometry. The XRD patterns have characteristic features of γ- Fe_2O3 or Fe_3O4 phases. The average particle size, calculated from the XRD peaks, for third loaded iron oxide alginate was 2 nm. The zero-field-cooled and field-cooled SQUID measurements show the iron oxide nanoparticles are superparamagnetic with blocking temperature (T_B) of approximately 35 K. Above the blocking temperature, the inverse susceptibility versus temperature relationship does not follow the Curie-Weiss law, indicating strong inter-particle interactions. The M vs. H data above the blocking temperature was fitted with a modified Langevin function to obtain additional information about the iron oxide particle size. Details of the relationship between coercive field and temperature as well as the particle size distribution obtained from XRD and TEM measurements will be presented. *Research supported by NSF grant # DGE ˜980720 **Supported by NSF REU grant # EEC-0097736 ^1E. Kroll, F.M. Winnik, and R.F. Ziolo, Chem. Mater, 8, 1594 (1996).

  4. Inhibiting mild steel corrosion from sulfate-reducing and iron-oxidizing bacteria using gramicidin-S-producing biofilms.

    PubMed

    Zuo, Rongjun; Wood, Thomas K

    2004-11-01

    A gramicidin-S-producing Bacillus brevis 18-3 biofilm was shown to reduce corrosion rates of mild steel by inhibiting both the sulfate-reducing bacterium Desulfosporosinus orientis and the iron-oxidizing bacterium Leptothrix discophora SP-6. When L. discophora SP-6 was introduced along with D. orientis to a non-antimicrobial-producing biofilm control, Paenibacillus polymyxa ATCC 10401, a corrosive synergy was created and mild steel coupons underwent more severe corrosion than when only D. orientis was present, showing a 2.3-fold increase via electrochemical impedance spectroscopy (EIS) and a 1.8-fold difference via mass-loss measurements. However, when a gramicidin-S-producing, protective B. brevis 18-3 biofilm was established on mild steel, the metal coupons were protected against the simultaneous attack of D. orientis and L. discophora SP-6. EIS data showed that the protective B. brevis 18-3 biofilm decreased the corrosion rate about 20-fold compared with the non-gramicidin-producing P. polymyxa ATCC 10401 biofilm control. The mass loss for the protected mild steel coupons was also significantly lower than that for the unprotected ones (4-fold decrease). Scanning electron microscope images corroborated the corrosion inhibition by the gramicidin-S-producing B. brevis biofilm on mild steel by showing that the metal surface remained untarnished, i.e., the polishing grooves were still visible after exposure to the simultaneous attack of the sulfate-reducing bacterium and the iron-oxidizing bacterium.

  5. Iron oxide-based nanomagnets in nanomedicine: fabrication and applications

    PubMed Central

    Meng Lin, Meng; Kim, Hyung-Hwan; Kim, Hyuck; Muhammed, Mamoun; Kyung Kim, Do

    2010-01-01

    Iron oxide-based nanomagnets have attracted a great deal of attention in nanomedicine over the past decade. Down to the nanoscale, superparamagnetic iron oxide nanoparticles can only be magnetized in the presence of an external magnetic field, which makes them capable of forming stable colloids in a physio-biological medium. Their superparamagnetic property, together with other intrinsic properties, such as low cytotoxicity, colloidal stability, and bioactive molecule conjugation capability, makes such nanomagnets ideal in both in-vitro and in-vivo biomedical applications. In this review, a chemical, physical, and biological synthetic approach to prepare iron oxide-based nanomagnets with different physicochemical properties was illustrated and compared. The growing interest in iron oxide-based nanomagnets with multifunctionalities was explored in cancer diagnostics and treatment, focusing on their combined roles in a magnetic resonance contrast agent, hyperthermia, and magnetic force assisted drug delivery. Iron oxides as magnetic carriers in gene therapy were reviewed with a focus on the sophisticated design and construction of magnetic vectors. Finally, the iron oxide-based nanomagnet also represents a very promising tool in particle/cell interfacing in controlling cellular functionalities, such as adhesion, proliferation, differentiation, and cell patterning, in stem cell therapy and tissue engineering applications. PMID:22110854

  6. Photocatalysis over titania on iron oxide

    NASA Astrophysics Data System (ADS)

    Kim, Kwi Cheol; Han, Chong Soo

    2006-03-01

    Photocatalytic activity of TiO{2} deposited on spherical sub micron-sized Fe{2}O{3} particle was investigated under ultraviolet or visible light. The Fe{2}O{3} particles were prepared using a spray pyrolysis of aqueous Fe(NO{3})3 solution in air flow. TiO{2} was deposited on Fe{2}O{3} particle by irradiation of ultraviolet or visible light to the suspension of Fe{2}O{3} particle and a TiO{2} precursor. When TiO{2} was formed under visible light (TiO{2}/Fe{2}O{3}-VIS), there were reasonable trends in the phase shift of PAS signal and EDX signal of Ti. However, there was no trend for the case of ultra violet irradiation (TiO{2}/Fe{2}O{3}-UV). TiO{2}/Fe{2}O{3}-VIS showed higher rates of decomposition of organic compound, of decrease in contact angle of water drop, and of decrease in the number of E. coli under visible light than TiO{2}/Fe{2}O{3}-UV or TiO{2} film. From the results, it was suggested that TiO{2}/Fe{2}O{3}-VIS had a regular thin layer of TiO{2} compared to TiO{2}/Fe{2}O{3}-UV and the photo-generated carrier(s) in iron oxide migrated to the surface of TiO{2} in the case of TiO{2}/Fe{2}O{3}-VIS.

  7. Ecological succession among iron-oxidizing bacteria.

    PubMed

    Fleming, Emily J; Cetinić, Ivona; Chan, Clara S; Whitney King, D; Emerson, David

    2014-04-01

    Despite over 125 years of study, the factors that dictate species dominance in neutrophilic iron-oxidizing bacterial (FeOB) communities remain unknown. In a freshwater wetland, we documented a clear ecological succession coupled with niche separation between the helical stalk-forming Gallionellales (for example, Gallionella ferruginea) and tubular sheath-forming Leptothrix ochracea. Changes in the iron-seep community were documented using microscopy and cultivation-independent methods. Quantification of Fe-oxyhydroxide morphotypes by light microscopy was coupled with species-specific fluorescent in situ hybridization (FISH) probes using a protocol that minimized background fluorescence caused by the Fe-oxyhydroxides. Together with scanning electron microscopy, these techniques all indicated that Gallionellales dominated during early spring, with L. ochracea becoming more abundant for the remainder of the year. Analysis of tagged pyrosequencing reads of the small subunit ribosomal RNA gene (SSU rRNA) collected during seasonal progression supported a clear Gallionellales to L. ochracea transition, and community structure grouped according to observed dominant FeOB forms. Axis of redundancy analysis of physicochemical parameters collected from iron mats during the season, plotted with FeOB abundance, corroborated several field and microscopy-based observations and uncovered several unanticipated relationships. On the basis of these relationships, we conclude that the ecological niche of the stalk-forming Gallionellales is in waters with low organic carbon and steep redoxclines, and the sheath-forming L. ochracea is abundant in waters that contain high concentrations of complex organic carbon, high Fe and Mn content and gentle redoxclines. Finally, these findings identify a largely unexplored relationship between FeOB and organic carbon.

  8. Ecological succession among iron-oxidizing bacteria

    PubMed Central

    Fleming, Emily J; Cetinić, Ivona; Chan, Clara S; Whitney King, D; Emerson, David

    2014-01-01

    Despite over 125 years of study, the factors that dictate species dominance in neutrophilic iron-oxidizing bacterial (FeOB) communities remain unknown. In a freshwater wetland, we documented a clear ecological succession coupled with niche separation between the helical stalk-forming Gallionellales (for example, Gallionella ferruginea) and tubular sheath-forming Leptothrix ochracea. Changes in the iron-seep community were documented using microscopy and cultivation-independent methods. Quantification of Fe-oxyhydroxide morphotypes by light microscopy was coupled with species-specific fluorescent in situ hybridization (FISH) probes using a protocol that minimized background fluorescence caused by the Fe-oxyhydroxides. Together with scanning electron microscopy, these techniques all indicated that Gallionellales dominated during early spring, with L. ochracea becoming more abundant for the remainder of the year. Analysis of tagged pyrosequencing reads of the small subunit ribosomal RNA gene (SSU rRNA) collected during seasonal progression supported a clear Gallionellales to L. ochracea transition, and community structure grouped according to observed dominant FeOB forms. Axis of redundancy analysis of physicochemical parameters collected from iron mats during the season, plotted with FeOB abundance, corroborated several field and microscopy-based observations and uncovered several unanticipated relationships. On the basis of these relationships, we conclude that the ecological niche of the stalk-forming Gallionellales is in waters with low organic carbon and steep redoxclines, and the sheath-forming L. ochracea is abundant in waters that contain high concentrations of complex organic carbon, high Fe and Mn content and gentle redoxclines. Finally, these findings identify a largely unexplored relationship between FeOB and organic carbon. PMID:24225888

  9. Stabilization and functionalization of iron oxide nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Amstad, Esther; Textor, Marcus; Reimhult, Erik

    2011-07-01

    Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding number of research and practical applications in the biomedical field, including magnetic cell labeling separation and tracking, for therapeutic purposes in hyperthermia and drug delivery, and for diagnostic purposes, e.g., as contrast agents for magnetic resonance imaging. These applications require good NP stability at physiological conditions, close control over NP size and controlled surface presentation of functionalities. This review is focused on different aspects of the stability of superparamagnetic iron oxide NPs, from its practical definition to its implementation by molecular design of the dispersant shell around the iron oxide core and further on to its influence on the magnetic properties of the superparamagnetic iron oxide NPs. Special attention is given to the selection of molecular anchors for the dispersant shell, because of their importance to ensure colloidal and functional stability of sterically stabilized superparamagnetic iron oxide NPs. We further detail how dispersants have been optimized to gain close control over iron oxide NP stability, size and functionalities by independently considering the influences of anchors and the attached sterically repulsive polymer brushes. A critical evaluation of different strategies to stabilize and functionalize core-shell superparamagnetic iron oxide NPs as well as a brief introduction to characterization methods to compare those strategies is given.Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding number of research and practical applications in the biomedical field, including magnetic cell labeling separation and tracking, for therapeutic purposes in hyperthermia and drug delivery, and for diagnostic purposes, e.g., as contrast agents for magnetic resonance imaging. These applications require good NP stability at physiological conditions, close control over NP size and controlled surface

  10. Isolation of iron-oxidizing bacteria from corroded concretes of sewage treatment plants.

    PubMed

    Maeda, T; Negishi, A; Komoto, H; Oshima, Y; Kamimura, K; Sugio, T

    1999-01-01

    Thirty-six strains of iron-oxidizing bacteria were isolated from corroded concrete samples obtained at eight sewage treatment plants in Japan. All of the strains isolated grew autotrophically in ferrous sulfate (3.0%), elemental sulfur (1.0%) and FeS (1.0%) media (pH 1.5). Washed intact cells of the 36 isolates had activities to oxidize both ferrous iron and elemental sulfur. Strain SNA-5, a representative of the isolated strains, was a gram-negative, rod-shaped bacterium (0.5-0.6x0.9-1.5 microm). The mean G+C content of its DNA was 55.9 mol%. The pH and temperature optima for growth were 1.5 and 30 degrees C, and the bacterium had activity to assimilate 14CO2 into the cells when ferrous iron or elemental sulfur was used as a sole source of energy. These results suggest that SNA-5 is Thiobacillus ferrooxidans strain. The pHs and numbers of iron-oxidizing bacteria in corroded concrete samples obtained by boring to depths of 0-1, 1-3, and 3-5 cm below the concrete surface were respectively 1.4, 1.7, and 2.0, and 1.2 x 10(8), 5 x 10(7), and 5 x 10(6) cells/g concrete. The degree of corrosion in the sample obtained nearest to the surface was more severe than in the deeper samples. The findings indicated that the levels of acidification and corrosion of the concrete structure corresponded with the number of iron-oxidizing bacteria in a concrete sample. Sulfuric acid produced by the chemolithoautotrophic sulfur-oxidizing bacterium Thiobacillus thiooxidansis known to induce concrete corrosion. Since not only T. thiooxidans but also T. ferrooxidans can oxidize reduced sulfur compounds and produce sulfuric acid, the results strongly suggest that T. ferrooxidans as well as T. thiooxidans is involved in concrete corrosion.

  11. Iron oxide and gold nanoparticles in cancer therapy

    NASA Astrophysics Data System (ADS)

    Gotman, Irena; Psakhie, Sergey G.; Lozhkomoev, Aleksandr S.; Gutmanas, Elazar Y.

    2016-08-01

    Continuous research activities in the field of nanomedicine in the past decade have, to a great extent, been focused on nanoparticle technologies for cancer therapy. Gold and iron oxide nanoparticles (NP) are two of the most studied inorganic nanomaterials due to their unique optical and magnetic properties. Both types of NPs are emerging as promising systems for anti-tumor drug delivery and for nanoparticle-mediated thermal therapy of cancer. In thermal therapy, localized heating inside tumors or in proximity of tumor cells can be induced, for example, with Au NPs by radiofrequency ablation heating or conversion of photon energy (photothermal therapy) and in iron oxide magnetic NPs by heat generation through relaxation in an alternating magnetic field (magnetic hyperthermia). Furthermore, the superparamagnetic properties of iron oxide nanoparticles have led to their use as potent MRI (magnetic resonance imaging) contrast agents. Surface modification/coating can produce NPs with tailored and desired properties, such as enhanced blood circulation time, stability, biocompatibility and water solubility. To target nanoparticles to specific tumor cells, NPs should be conjugated with targeting moieties on the surface which bind to receptors or other molecular structures on the cell surface. The article presents several approaches to enhancing the specificity of Au and iron oxide nanoparticles for tumor tissue by appropriate surface modification/functionalization, as well as the effect of these treatments on the saturation magnetization value of iron oxide NPs. The use of other nanoparticles and nanostructures in cancer treatment is also briefly reviewed.

  12. Development and use of iron oxide nanoparticles (Part 1): Synthesis of iron oxide nanoparticles for MRI

    PubMed Central

    Lodhia, J; Mandarano, G; Ferris, NJ; Eu, P; Cowell, SF

    2010-01-01

    Contrast agents, such as iron oxide, enhance MR images by altering the relaxation times of tissues in which the agent is present. They can also be used to label targeted molecular imaging probes. Unfortunately, no molecular imaging probe is currently available on the clinical MRI market. A promising platform for MRI contrast agent development is nanotechnology, where superparamagnetic iron oxide nanoparticles (SPIONS) are tailored for MR contrast enhancement, and/or for molecular imaging. SPIONs can be produced using a range of methods and the choice of method will be influenced by the characteristics most important for a particular application. In addition, the ability to attach molecular markers to SPIONS heralds their application in molecular imaging. There are many reviews on SPION synthesis for MRI; however, these tend to be targeted to a chemistry audience. The development of MRI contrast agents attracts experienced researchers from many fields including some researchers with little knowledge of medical imaging or MRI. This situation presents medical radiation practitioners with opportunities for involvement, collaboration or leadership in research depending on their level of commitment and their ability to learn. Medical radiation practitioners already possess a large portion of the understanding, knowledge and skills necessary for involvement in MRI development and molecular imaging. Their expertise in imaging technology, patient care and radiation safety provides them with skills that are directly applicable to research on the development and application of SPIONs and MRI. In this paper we argue that MRI SPIONs, currently limited to major research centres, will have widespread clinical use in the future. We believe that knowledge about this growing area of research provides an opportunity for medical radiation practitioners to enhance their specialised expertise to ensure best practice in a truly multi-disciplinary environment. This review outlines how and

  13. Virus-Templated Near-Amorphous Iron Oxide Nanotubes.

    PubMed

    Shah, Sachin N; Khan, Abid A; Espinosa, Ana; Garcia, Miguel A; Nuansing, Wiwat; Ungureanu, Mariana; Heddle, Jonathan G; Chuvilin, Andrey L; Wege, Christina; Bittner, Alexander M

    2016-06-14

    We present a simple synthesis of iron oxide nanotubes, grown under very mild conditions from a solution containing Fe(II) and Fe(III), on rod-shaped tobacco mosaic virus templates. Their well-defined shape and surface chemistry suggest that these robust bionanoparticles are a versatile platform for synthesis of small, thin mineral tubes, which was achieved efficiently. Various characterization tools were used to explore the iron oxide in detail: Electron microscopy (SEM, TEM), magnetometry (SQUID-VSM), diffraction (XRD, TEM-SAED), electron spectroscopies (EELS, EDX, XPS), and X-ray absorption (XANES with EXAFS analysis). They allowed determination of the structure, crystallinity, magnetic properties, and composition of the tubes. The protein surface of the viral templates was crucial to nucleate iron oxide, exhibiting analogies to biomineralization in natural compartments such as ferritin cages.

  14. Electrolytic photodissociation of chemical compounds by iron oxide electrodes

    SciTech Connect

    Somorjai, G.A.; Leygraf, C.H.

    1984-07-17

    Chemical compounds can be dissociated by contacting the same with a p/n type semi-conductor diode having visible light as its sole source of energy. The diode consists of low cost, readily available materials, specifically polycrystalline iron oxide doped with silicon in the case of the n-type semi-conductor electrode, and polycrystalline iron oxide doped with magnesium in the case of the p-type electrode. So long as the light source has an energy greater than 2.2 electron volts, no added energy source is needed to achieve dissociation.

  15. Iron Oxide as an MRI Contrast Agent for Cell Tracking

    PubMed Central

    Korchinski, Daniel J.; Taha, May; Yang, Runze; Nathoo, Nabeela; Dunn, Jeff F.

    2015-01-01

    Iron oxide contrast agents have been combined with magnetic resonance imaging for cell tracking. In this review, we discuss coating properties and provide an overview of ex vivo and in vivo labeling of different cell types, including stem cells, red blood cells, and monocytes/macrophages. Furthermore, we provide examples of applications of cell tracking with iron contrast agents in stroke, multiple sclerosis, cancer, arteriovenous malformations, and aortic and cerebral aneurysms. Attempts at quantifying iron oxide concentrations and other vascular properties are examined. We advise on designing studies using iron contrast agents including methods for validation. PMID:26483609

  16. Multifunctional Iron Oxide Nanoparticles for Diagnostics, Therapy and Macromolecule Delivery

    PubMed Central

    Yen, Swee Kuan; Padmanabhan, Parasuraman; Selvan, Subramanian Tamil

    2013-01-01

    In recent years, multifunctional nanoparticles (NPs) consisting of either metal (e.g. Au), or magnetic NP (e.g. iron oxide) with other fluorescent components such as quantum dots (QDs) or organic dyes have been emerging as versatile candidate systems for cancer diagnosis, therapy, and macromolecule delivery such as micro ribonucleic acid (microRNA). This review intends to highlight the recent advances in the synthesis and application of multifunctional NPs (mainly iron oxide) in theranostics, an area used to combine therapeutics and diagnostics. The recent applications of NPs in miRNA delivery are also reviewed. PMID:24396508

  17. Electrolytic photodissociation of chemical compounds by iron oxide photochemical diodes

    DOEpatents

    Somorjai, Gabor A.; Leygraf, Christofer H.

    1985-01-01

    Chemical compounds can be dissociated by contacting the same with a p/n type semi-conductor photochemical diode having visible light as its sole source of energy. The photochemical diode consists of low cost, readily available materials, specifically polycrystalline iron oxide doped with silicon in the case of the n-type semi-conductor electrode, and polycrystalline iron oxide doped with magnesium in the case of the p-type electrode. So long as the light source has an energy greater than 2.2 electron volts, no added energy source is needed to achieve dissociation.

  18. Recovery of iron oxide from coal fly ash

    DOEpatents

    Dobbins, Michael S.; Murtha, Marlyn J.

    1983-05-31

    A high quality iron oxide concentrate, suitable as a feed for blast and electric reduction furnaces is recovered from pulverized coal fly ash. The magnetic portion of the fly ash is separated and treated with a hot strong alkali solution which dissolves most of the silica and alumina in the fly ash, leaving a solid residue and forming a precipitate which is an acid soluble salt of aluminosilicate hydrate. The residue and precipitate are then treated with a strong mineral acid to dissolve the precipitate leaving a solid residue containing at least 90 weight percent iron oxide.

  19. Electrolytic photodissociation of chemical compounds by iron oxide electrodes

    DOEpatents

    Somorjai, Gabor A.; Leygraf, Christofer H.

    1984-01-01

    Chemical compounds can be dissociated by contacting the same with a p/n type semi-conductor diode having visible light as its sole source of energy. The diode consists of low cost, readily available materials, specifically polycrystalline iron oxide doped with silicon in the case of the n-type semi-conductor electrode, and polycrystalline iron oxide doped with magnesium in the case of the p-type electrode. So long as the light source has an energy greater than 2.2 electron volts, no added energy source is needed to achieve dissociation.

  20. Multifunctional superparamagnetic iron oxide nanoparticles: promising tools in cancer theranostics.

    PubMed

    Santhosh, Poornima Budime; Ulrih, Nataša Poklar

    2013-08-09

    Iron-oxide nanoparticles of small dimensions that have superparamagnetic properties show immense potential to revolutionize the future of cancer theranostics, the combinatorial diagnosis and therapeutic approach towards cancer. Superparamagnetic iron-oxide nanoparticles (SPIONs) have unique magnetic properties, due to which they show excellent tumor-targeting efficiency, and this paves the way for effective personalized cancer treatment. The aim of this review is to focus on the ability of SPIONs to perform multiple roles in the field of cancer biology, such as in diagnosis, monitoring, targeting and therapy. Also, other topics are discussed, including the synthesis of SPIONs, the challenges and recent advances.

  1. Magnetic fluid hyperthermia: focus on superparamagnetic iron oxide nanoparticles.

    PubMed

    Laurent, Sophie; Dutz, Silvio; Häfeli, Urs O; Mahmoudi, Morteza

    2011-08-10

    Due to their unique magnetic properties, excellent biocompatibility as well as multi-purpose biomedical potential (e.g., applications in cancer therapy and general drug delivery), superparamagnetic iron oxide nanoparticles (SPIONs) are attracting increasing attention in both pharmaceutical and industrial communities. The precise control of the physiochemical properties of these magnetic systems is crucial for hyperthermia applications, as the induced heat is highly dependent on these properties. In this review, the limitations and recent advances in the development of superparamagnetic iron oxide nanoparticles for hyperthermia are presented.

  2. Size-dependent magnetic properties of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Patsula, Vitalii; Moskvin, Maksym; Dutz, Silvio; Horák, Daniel

    2016-01-01

    Uniform iron oxide nanoparticles in the size range from 10 to 24 nm and polydisperse 14 nm iron oxide particles were prepared by thermal decomposition of Fe(III) carboxylates in the presence of oleic acid and co-precipitation of Fe(II) and Fe(III) chlorides by ammonium hydroxide followed by oxidation, respectively. While the first method produced hydrophobic oleic acid coated particles, the second one formed hydrophilic, but uncoated, nanoparticles. To make the iron oxide particles water dispersible and colloidally stable, their surface was modified with poly(ethylene glycol) and sucrose, respectively. Size and size distribution of the nanoparticles was determined by transmission electron microscopy, dynamic light scattering and X-ray diffraction. Surface of the PEG-functionalized and sucrose-modified iron oxide particles was characterized by Fourier transform infrared (FT-IR) and Raman spectroscopy and thermogravimetric analysis (TGA). Magnetic properties were measured by means of vibration sample magnetometry and specific absorption rate in alternating magnetic fields was determined calorimetrically. It was found, that larger ferrimagnetic particles showed higher heating performance than smaller superparamagnetic ones. In the transition range between superparamagnetism and ferrimagnetism, samples with a broader size distribution provided higher heating power than narrow size distributed particles of comparable mean size. Here presented particles showed promising properties for a possible application in magnetic hyperthermia.

  3. Synthesis of phase pure praseodymium barium copper iron oxide.

    PubMed

    Konne, Joshua L; Davis, Sean A; Glatzel, Stefan; Hall, Simon R

    2013-06-18

    The control of crystallization of praseodymium barium copper iron oxide, an intermediate temperature solid oxide fuel cell cathode material, has been demonstrated for the first time using a biotemplated sol-gel synthesis technique. The results obtained showed significant improvement in purity, synthesis time, surface area and simplicity over that previously reported.

  4. Arsenate adsorption onto iron oxide amended rice husk char.

    PubMed

    Cope, Christopher O; Webster, Damon S; Sabatini, David A

    2014-08-01

    In this study, rice husks were charred at 550 °C in a partially sealed ceramic vessel for 30minutes to create a high specific surface area (SSA) rice husk char (RHC). The RHC was then amended with iron oxides using dissolved ferric nitrate, Fe(NO3)3⋅9H2O, to provide a surface chemistry conducive to arsenic adsorption. The 550 °C iron oxide amended rice husk char's (550 IOA-RHC's) SSA was nearly 2.5 orders of magnitude higher and the arsenate adsorptive level was nearly 2 orders of magnitude higher than those reported for iron oxide amended sand, thus indicating a positive relationship between post-amendment SSA and arsenate adsorptive levels. Rice husks were then charred at temperatures ranging from 450 °C to 1050 °C to create an even higher SSA material, which might further increase arsenate adsorptive levels. The 950 °C RHC was chosen for amendment due to its high SSA and feasibility of being produced in the field. Once amended, the 950 °C iron oxide amended rice husk char (950 IOA-RHC) improved the arsenate adsorption capacity by thus confirming a positive relationship, though not a linear relationship, between post-amendment SSA and arsenic adsorptive capacity. Further study demonstrated that post-amendment mesoporous volume and mesoporous surface area appear to be better indicators of arsenic adsorptive capacity than SSA or iron content.

  5. Iron oxides, dissolved silica, and regulation of marine phosphate concentration

    NASA Astrophysics Data System (ADS)

    Planavsky, N.; Reinhard, C.; Lyons, T.

    2008-12-01

    Phosphorous concentrations in iron oxide-rich sediments reflect orthophosphate levels in the water column from which iron oxides precipitated. Sediment P/Fe ratios are also strongly influenced by the concentrations of dissolved species that inhibit orthophosphate-to-ferrihydrite sorption, most notably silica. It may, therefore, be possible to use P/Fe ratios in iron oxide-rich sediments to estimate past dissolved P concentrations, if one considers the evolution of the silica cycle. A compilation of Fe and P data in iron oxide-rich sediments through time reveals an increase in P/Fe ratios after the Jurassic. We propose that this trend indicates evolution of the iron-oxide phosphate removal mechanism caused by decreasing levels of sorption inhibition by dissolved silica. The large difference in P/Fe ratios in Cenozoic versus older iron-oxide rich sediments can be linked with Si drawdown caused by the proliferation of siliceous plankton in the Cretaceous. There is also a late Mesozoic or Cenozoic increase in V/Fe ratios, which provides additional evidence for lower ferrihydrite anion sorption efficiency prior to diatom radiation. P/Fe ratios in iron oxide-rich sediments from the early and middle Phanerozoic are comparable to the ratios in iron formations previously presented as evidence for an early Precambrian phosphate crisis (Bjerrum and Canfield, 2002, Nature, 417:159-162). Given the compelling evidence for higher Si concentrations in the Precambrian compared to the Phanerozoic and dissolved P concentrations comparable to modern levels throughout the Phanerozoic, the presented trend of P/Fe ratios suggests dissolved P concentrations were higher in Precambrian than Phanerozoic oceans. High dissolved P levels in the Precambrian may have been linked to inhibited carbonate fluorapatite (CFA) formation as a result of persistently high levels of carbonate supersaturation. Carbonate ion substitution into CFA scales with the ambient carbonate ion activity and increases

  6. Intratumoral iron oxide nanoparticle hyperthermia and radiation cancer treatment

    NASA Astrophysics Data System (ADS)

    Hoopes, P. J.; Strawbridge, R. R.; Gibson, U. J.; Zeng, Q.; Pierce, Z. E.; Savellano, M.; Tate, J. A.; Ogden, J. A.; Baker, I.; Ivkov, R.; Foreman, A. R.

    2007-02-01

    The potential synergism and benefit of combined hyperthermia and radiation for cancer treatment is well established, but has yet to be optimized clinically. Specifically, the delivery of heat via external arrays /applicators or interstitial antennas has not demonstrated the spatial precision or specificity necessary to achieve appropriate a highly positive therapeutic ratio. Recently, antibody directed and possibly even non-antibody directed iron oxide nanoparticle hyperthermia has shown significant promise as a tumor treatment modality. Our studies are designed to determine the effects (safety and efficacy) of iron oxide nanoparticle hyperthermia and external beam radiation in a murine breast cancer model. Methods: MTG-B murine breast cancer cells (1 x 106) were implanted subcutaneous in 7 week-old female C3H/HeJ mice and grown to a treatment size of 150 mm3 +/- 50 mm3. Tumors were then injected locally with iron oxide nanoparticles and heated via an alternating magnetic field (AMF) generator operated at approximately 160 kHz and 400 - 550 Oe. Tumor growth was monitored daily using standard 3-D caliper measurement technique and formula. specific Mouse tumors were heated using a cooled, 36 mm diameter square copper tube induction coil which provided optimal heating in a 1 cm wide region in the center of the coil. Double dextran coated 80 nm iron oxide nanoparticles (Triton Biosystems) were used in all studies. Intra-tumor, peri-tumor and rectal (core body) temperatures were continually measured throughout the treatment period. Results: Preliminary in vivo nanoparticle-AMF hyperthermia (167 KHz and 400 or 550 Oe) studies demonstrated dose responsive cytotoxicity which enhanced the effects of external beam radiation. AMF associated eddy currents resulted in nonspecific temperature increases in exposed tissues which did not contain nanoparticles, however these effects were minor and not injurious to the mice. These studies also suggest that iron oxide nanoparticle

  7. Gene Loss and Horizontal Gene Transfer Contributed to the Genome Evolution of the Extreme Acidophile "Ferrovum".

    PubMed

    Ullrich, Sophie R; González, Carolina; Poehlein, Anja; Tischler, Judith S; Daniel, Rolf; Schlömann, Michael; Holmes, David S; Mühling, Martin

    2016-01-01

    Acid mine drainage (AMD), associated with active and abandoned mining sites, is a habitat for acidophilic microorganisms that gain energy from the oxidation of reduced sulfur compounds and ferrous iron and that thrive at pH below 4. Members of the recently proposed genus "Ferrovum" are the first acidophilic iron oxidizers to be described within the Betaproteobacteria. Although they have been detected as typical community members in AMD habitats worldwide, knowledge of their phylogenetic and metabolic diversity is scarce. Genomics approaches appear to be most promising in addressing this lacuna since isolation and cultivation of "Ferrovum" has proven to be extremely difficult and has so far only been successful for the designated type strain "Ferrovum myxofaciens" P3G. In this study, the genomes of two novel strains of "Ferrovum" (PN-J185 and Z-31) derived from water samples of a mine water treatment plant were sequenced. These genomes were compared with those of "Ferrovum" sp. JA12 that also originated from the mine water treatment plant, and of the type strain (P3G). Phylogenomic scrutiny suggests that the four strains represent three "Ferrovum" species that cluster in two groups (1 and 2). Comprehensive analysis of their predicted metabolic pathways revealed that these groups harbor characteristic metabolic profiles, notably with respect to motility, chemotaxis, nitrogen metabolism, biofilm formation and their potential strategies to cope with the acidic environment. For example, while the "F. myxofaciens" strains (group 1) appear to be motile and diazotrophic, the non-motile group 2 strains have the predicted potential to use a greater variety of fixed nitrogen sources. Furthermore, analysis of their genome synteny provides first insights into their genome evolution, suggesting that horizontal gene transfer and genome reduction in the group 2 strains by loss of genes encoding complete metabolic pathways or physiological features contributed to the observed

  8. Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems

    PubMed Central

    Phan, Manh-Huong; Alonso, Javier; Khurshid, Hafsa; Lampen-Kelley, Paula; Chandra, Sayan; Stojak Repa, Kristen; Nemati, Zohreh; Das, Raja; Iglesias, Óscar; Srikanth, Hariharan

    2016-01-01

    The exploration of exchange bias (EB) on the nanoscale provides a novel approach to improving the anisotropic properties of magnetic nanoparticles for prospective applications in nanospintronics and nanomedicine. However, the physical origin of EB is not fully understood. Recent advances in chemical synthesis provide a unique opportunity to explore EB in a variety of iron oxide-based nanostructures ranging from core/shell to hollow and hybrid composite nanoparticles. Experimental and atomistic Monte Carlo studies have shed light on the roles of interface and surface spins in these nanosystems. This review paper aims to provide a thorough understanding of the EB and related phenomena in iron oxide-based nanoparticle systems, knowledge of which is essential to tune the anisotropic magnetic properties of exchange-coupled nanoparticle systems for potential applications. PMID:28335349

  9. Noble Metal-Iron Oxide Hybrid Nanomaterials: Emerging Applications.

    PubMed

    Leung, Ken Cham-Fai; Xuan, Shouhu

    2016-02-01

    This account provides an overview of current research activities that focus on the synthesis and applications of nanomaterials from noble metal (e.g., Au, Ag, Pd) and iron oxide (Fe3O4) hybrids. An introduction to the synthetic strategies that have been developed for generating M-Fe3O4 nanomaterials with different novel structures is presented. Surface functionalization and bioconjugation of these hybrid nanoparticles and nanocomposites are also reviewed. The utilization of the advantageous properties of both noble metals and iron oxide for a variety of applications, such as theranostics, gene delivery, biosensing, cell sorting, bioseparation, and catalysis, is discussed and highlighted. Finally, future trends and perspectives of these sophisticated nanocomposites are outlined. The fundamental requirements underpinning the effective preparation of M-Fex Oy hybrid nanomaterials shed light on the future development of heterogeneous catalysts, nanotheranostics, nanomedicines, and other chemical technologies.

  10. Porous Iron oxide nanorods and their photothermal applications

    NASA Astrophysics Data System (ADS)

    Larsen, George; Huang, Weijie; Zhao, Yiping; Hunyadi Murph, Simona E.

    2016-09-01

    Iron oxide is a unique semiconductor material, either as a single nanoparticle, or as a component of multifunctional nanoparticles. Its desirable properties, abundance, non-toxicity, and excellent magnetic properties make it a valuable for many applications. Porous iron oxide nanorods are able to transduce light into heat through the photothermal effect. Photothermal heating arises from the energy dissipated during light absorption leading to rapid temperature rise in close proximity to the surface of the nanoparticle. The heating effect can be efficiently harnessed to drive/promote different physical phenomena. In this report, we describe the synthesis and properties of porous Fe3O4 for photothermal applications. We then demonstrate their use as photothermally enhanced and recyclable materials for environmental remediation through sorption processes.

  11. Dendronized iron oxide colloids for imaging the sentinel lymph node

    NASA Astrophysics Data System (ADS)

    Jouhannaud, J.; Garofalo, A.; Felder-Flesch, D.; Pourroy, G.

    2015-03-01

    Various methods have been used in medicine for more than one century to explore the lymphatic system. Radioactive colloids (RuS labelled with 99mTc) or/and Vital Blue dye are injected around the primary tumour and detected by means of nuclear probe or visual colour inspection respectively. The simultaneous clinical use of both markers (dye and radionuclide) improves the sensitivity of detection close to 100%. Superparamagnetic iron oxides (SPIOs) are currently receiving much attention as strong T2 weighted magnetic resonance imaging contrast agents that can be potentially used for preoperative localization of sentinel nodes, but also for peroperative detection of sentinel node using hand-held probes. In that context, we present the elaboration of dendronized iron oxide nanoparticles elaborated at the Institute of Physics and Chemistry of Materials of Strasbourg.

  12. Reflection spectra and magnetochemistry of iron oxides and natural surfaces

    NASA Technical Reports Server (NTRS)

    Wasilewski, P.

    1978-01-01

    The magnetic properties and spectral characteristics of iron oxides are distinctive. Diagnostic features in reflectance spectra (0.5 to 2.4 micron) for alpha Fe2O3, gamma Fe2O3, and FeOOH include location of Fe3(+) absorption features, intensity ratios at various wavelengths, and the curve shape between 1.2 micron and 2.4 micron. The reflection spectrum of natural rock surfaces are seldom those of the bulk rock because of weathering effects. Coatings are found to be dominated by iron oxides and clay. A simple macroscopic model of rock spectra (based on concepts of stains and coatings) is considered adequate for interpretation of LANDSAT data. The magnetic properties of materials associated with specific spectral types and systematic changes in both spectra and magnetic properties are considered.

  13. Promising iron oxide-based magnetic nanoparticles in biomedical engineering.

    PubMed

    Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Vo, Toi Van; Lee, Beom-Jin

    2012-12-01

    For the past few decades biomedical engineering has imprinted its significant impact on the map of science through its wide applications on many other fields. An important example obviously proving this fact is the versatile application of magnetic nanoparticles in theranostics. Due to preferable properties such as biocompatibility, non-toxicity compared to other metal derivations, iron oxide-based magnetic nanoparticles was chosen to be addressed in this review. Aim of this review is to give the readers a whole working window of these magnetic nanoparticles in the current context of science. Thus, preparation of magnetic iron oxide nanoparticles with the so-far techniques, methods of characterizing the nanoparticles as well as their most recent biomedical applications will be stated.

  14. Nanovectors for anticancer agents based on superparamagnetic iron oxide nanoparticles

    PubMed Central

    Douziech-Eyrolles, Laurence; Marchais, Hervé; Hervé, Katel; Munnier, Emilie; Soucé, Martin; Linassier, Claude; Dubois, Pierre; Chourpa, Igor

    2007-01-01

    During the last decade, the application of nanotechnologies for anticancer drug delivery has been extensively explored, hoping to improve the efficacy and to reduce side effects of chemotherapy. The present review is dedicated to a certain kind of anticancer drug nanovectors developed to target tumors with the help of an external magnetic field. More particularly, this work treats anticancer drug nanoformulations based on superparamagnetic iron oxide nanoparticles coated with biocompatible polymers. The major purpose is to focus on the specific requirements and technological difficulties related to controlled delivery of antitumoral agents. We attempt to state the problem and its possible perspectives by considering the three major constituents of the magnetic therapeutic vectors: iron oxide nanoparticles, polymeric coating and anticancer drug. PMID:18203422

  15. 1H, 13C, and 15N backbone, side-chain, and heme chemical shift assignments for oxidized and reduced forms of the monoheme c-type cytochrome ApcA isolated from the acidophilic metal-reducing bacterium Acidiphilium cryptum.

    SciTech Connect

    Cort, John R.; Swenson, Michael; Magnuson, Timothy S.

    2011-03-04

    We report the 1H, 13C, and 15N chemical shift assignments of both oxidized and reduced forms of an abundant periplasmic c-type cytochrome, designated ApcA, from the acidophilic gram-negative facultatively anaerobic metal-reducing alpha-proteobacterium Acidiphilium cryptum. These resonance assignments prove that ApcA is a monoheme cytochrome c2 and the product of the Acry_2099 gene. An absence of resonance peaks in the NMR spectra for the 21 N-terminal residues suggests that a predicted N-terminal signal sequence is cleaved. We also describe the preparation and purification of the protein in labeled form from laboratory cultures of A. cryptum growing on 13C- and 15N- labeled substrates.

  16. Iron oxide magnetic nanoparticles synthesized by atmospheric microplasmas

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Kaur, Parvin; Tan, Augustine Tuck Lee; Singh, Rajveer; Lee, Paul Choon Keat; Springham, Stuart Victor; Ramanujan, Raju V.; Rawat, R. S.

    2014-08-01

    This paper presents the synthesis of iron oxide nanoparticles using the atmospheric microplasma (AMP). The properties of iron oxide nanoparticles synthesized using AMP are compared with particles (i) formed in as-prepared solution and (ii) prepared using thermal decomposition method. Iron oxide nanoparticles prepared by all the 3 treatment methods exhibit quite soft ferromagnetic properties with coercivities less than 10 G. The AMP synthesis technique was found to be more efficient and better than thermal decomposition method due to ultra-shorter experiment time (around 2.5 min) as compared to 90 min required for thermal decomposition method. Moreover, AMP synthesized nanoparticles are better isolated and of smaller size than thermal decomposition ones. The effect of plasma discharge timings on synthesized nanoparticles has also been studied in this work. Coercivity of synthesized nanoparticles decreases with the increasing plasma discharge timings from 3 to 10 min. The nanoparticles synthesized using plasma discharge timing of 10 min exhibit the smallest coercivity of around 3 G. This suggests a high possibility of achieving super-paramagnetic nanoparticles by optimizing the plasma discharge timings of AMP.

  17. Synthesis, characterization, applications, and challenges of iron oxide nanoparticles

    PubMed Central

    Ali, Attarad; Zafar, Hira; Zia, Muhammad; ul Haq, Ihsan; Phull, Abdul Rehman; Ali, Joham Sarfraz; Hussain, Altaf

    2016-01-01

    Recently, iron oxide nanoparticles (NPs) have attracted much consideration due to their unique properties, such as superparamagnetism, surface-to-volume ratio, greater surface area, and easy separation methodology. Various physical, chemical, and biological methods have been adopted to synthesize magnetic NPs with suitable surface chemistry. This review summarizes the methods for the preparation of iron oxide NPs, size and morphology control, and magnetic properties with recent bioengineering, commercial, and industrial applications. Iron oxides exhibit great potential in the fields of life sciences such as biomedicine, agriculture, and environment. Nontoxic conduct and biocompatible applications of magnetic NPs can be enriched further by special surface coating with organic or inorganic molecules, including surfactants, drugs, proteins, starches, enzymes, antibodies, nucleotides, nonionic detergents, and polyelectrolytes. Magnetic NPs can also be directed to an organ, tissue, or tumor using an external magnetic field for hyperthermic treatment of patients. Keeping in mind the current interest in iron NPs, this review is designed to report recent information from synthesis to characterization, and applications of iron NPs. PMID:27578966

  18. Modulated self-reversed magnetic hysteresis in iron oxides

    PubMed Central

    Ma, Ji; Chen, Kezheng

    2017-01-01

    The steadfast rule of a ferromagnetic hysteresis loop claims its saturation positioned within the first and third quadrants, whereas its saturation positioned in the second and fourth quadrants (named as self-reversed magnetic hysteresis) is usually taken as an experimental artifact and is always intentionally ignored. In this report, a new insight in this unique hysteresis phenomenon and its modulation were discussed in depth. Different iron oxides (magnetite, maghemite and hematite) with varying dimensions were soaked in FeCl3 aqueous solution and absorbed Fe3+ cations due to their negative enough surface zeta potentials. These iron oxides@Fe3+ core-shell products exhibit well pronounced self-reversed magnetic hysteresis which concurrently have typical diamagnetic characteristics and essential ferromagnetic features. The presence of pre-magnetized Fe3+ shell and its negatively magnetic exchange coupling with post-magnetized iron-oxide core is the root cause for the observed phenomena. More strikingly, this self-reversed magnetic hysteresis can be readily modulated by changing the core size or by simply controlling Fe3+ concentration in aqueous solution. It is anticipated that this work will shed new light on the development of spintronics, magnetic recording and other magnetically-relevant fields. PMID:28220793

  19. Characterization of iron oxide layers using Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Bizjak, Milan; Zalar, Anton; Panjan, Peter; Zorko, Benjamin; Praček, Borut

    2007-02-01

    Metals can form several kinds of oxides. Iron forms wustite (FeO), magnetite (FeO + Fe 2O 3 or Fe 3O 4) and haematite (Fe 2O 3). Iron oxides, especially magnetite, are used for insulation between the lamellas of an electromotor made of electromagnetic sheet. In this work, iron oxide layers were characterized on industrial samples of electromagnetic sheet by AES depth profile analysis, and iron oxides with known chemical composition were used as reference samples, i.e. a magnetite mineral and a standard haematite reference sample. The magnetite mineral was chosen because it can be found in nature in a very pure form. The selection of reference samples was also verified on samples with an oxide layer of known composition, which were prepared by sputter deposition. The composition of the sputtered oxide layers was analysed by the weight-gain method and Rutherford backscattering without the use of standard reference materials (SRM), and the results were then compared with those obtained by AES depth profile analysis.

  20. Modulated self-reversed magnetic hysteresis in iron oxides.

    PubMed

    Ma, Ji; Chen, Kezheng

    2017-02-21

    The steadfast rule of a ferromagnetic hysteresis loop claims its saturation positioned within the first and third quadrants, whereas its saturation positioned in the second and fourth quadrants (named as self-reversed magnetic hysteresis) is usually taken as an experimental artifact and is always intentionally ignored. In this report, a new insight in this unique hysteresis phenomenon and its modulation were discussed in depth. Different iron oxides (magnetite, maghemite and hematite) with varying dimensions were soaked in FeCl3 aqueous solution and absorbed Fe(3+) cations due to their negative enough surface zeta potentials. These iron oxides@Fe(3+) core-shell products exhibit well pronounced self-reversed magnetic hysteresis which concurrently have typical diamagnetic characteristics and essential ferromagnetic features. The presence of pre-magnetized Fe(3+) shell and its negatively magnetic exchange coupling with post-magnetized iron-oxide core is the root cause for the observed phenomena. More strikingly, this self-reversed magnetic hysteresis can be readily modulated by changing the core size or by simply controlling Fe(3+) concentration in aqueous solution. It is anticipated that this work will shed new light on the development of spintronics, magnetic recording and other magnetically-relevant fields.

  1. Modulated self-reversed magnetic hysteresis in iron oxides

    NASA Astrophysics Data System (ADS)

    Ma, Ji; Chen, Kezheng

    2017-02-01

    The steadfast rule of a ferromagnetic hysteresis loop claims its saturation positioned within the first and third quadrants, whereas its saturation positioned in the second and fourth quadrants (named as self-reversed magnetic hysteresis) is usually taken as an experimental artifact and is always intentionally ignored. In this report, a new insight in this unique hysteresis phenomenon and its modulation were discussed in depth. Different iron oxides (magnetite, maghemite and hematite) with varying dimensions were soaked in FeCl3 aqueous solution and absorbed Fe3+ cations due to their negative enough surface zeta potentials. These iron oxides@Fe3+ core-shell products exhibit well pronounced self-reversed magnetic hysteresis which concurrently have typical diamagnetic characteristics and essential ferromagnetic features. The presence of pre-magnetized Fe3+ shell and its negatively magnetic exchange coupling with post-magnetized iron-oxide core is the root cause for the observed phenomena. More strikingly, this self-reversed magnetic hysteresis can be readily modulated by changing the core size or by simply controlling Fe3+ concentration in aqueous solution. It is anticipated that this work will shed new light on the development of spintronics, magnetic recording and other magnetically-relevant fields.

  2. Reducing arsenic accumulation in rice grain through iron oxide amendment.

    PubMed

    Farrow, Eric M; Wang, Jianmin; Burken, Joel G; Shi, Honglan; Yan, Wengui; Yang, John; Hua, Bin; Deng, Baolin

    2015-08-01

    Effects of soil-arsenic (As), phosphorus and iron oxide on As accumulation in rice grain were investigated. Cultivars that have significantly different sensitivity to As, straighthead-resistant Zhe 733 and straighthead-susceptible Cocodrie, were used to represent different cultivar varieties. The grain accumulation of other elements of concern, selenium (Se), molybdenum (Mo), and cadmium (Cd) was also monitored. Results demonstrated that high soil-As not only resulted in high grain-As, but could also result in high grain-Se, and Zhe 733 had significantly less grain-As than Cocodrie did. However, soil-As did not impact grain-Mo and Cd. Among all elements monitored, iron oxide amendment significantly reduced grain-As for both cultivars, while the phosphate application only reduced grain-Se for Zhe 733. Results also indicated that cultivar type significantly impacted grain accumulation of all monitored trace elements. Therefore, applying iron oxide to As-contaminated land, in addition to choosing appropriate rice cultivar, can effectively reduce the grain accumulation of As.

  3. Safety assessment of chronic oral exposure to iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Chamorro, Susana; Gutiérrez, Lucía; Vaquero, María Pilar; Verdoy, Dolores; Salas, Gorka; Luengo, Yurena; Brenes, Agustín; José Teran, Francisco

    2015-05-01

    Iron oxide nanoparticles with engineered physical and biochemical properties are finding a rapidly increasing number of biomedical applications. However, a wide variety of safety concerns, especially those related to oral exposure, still need to be addressed for iron oxide nanoparticles in order to reach clinical practice. Here, we report on the effects of chronic oral exposure to low doses of γ-Fe2O3 nanoparticles in growing chickens. Animal observation, weight, and diet intake reveal no adverse signs, symptoms, or mortality. No nanoparticle accumulation was observed in liver, spleen, and duodenum, with feces as the main excretion route. Liver iron level and duodenal villi morphology reflect the bioavailability of the iron released from the partial transformation of γ-Fe2O3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe2O3 nanoparticles indicate the enhancement of a ferric over ferrous pathway supporting the role of mucins. Our findings reveal that oral administration of iron oxide nanoparticles is a safe route for drug delivery at low nanoparticle doses.

  4. RGD-conjugated iron oxide magnetic nanoparticles for magnetic resonance imaging contrast enhancement and hyperthermia.

    PubMed

    Zheng, S W; Huang, M; Hong, R Y; Deng, S M; Cheng, L F; Gao, B; Badami, D

    2014-03-01

    The purpose of this study was to develop a specific targeting magnetic nanoparticle probe for magnetic resonance imaging and therapy in the form of local hyperthermia. Carboxymethyl dextran-coated ultrasmall superparamagnetic iron oxide nanoparticles with carboxyl groups were coupled to cyclic arginine-glycine-aspartic peptides for integrin α(v)β₃ targeting. The particle size, magnetic properties, heating effect, and stability of the arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide were measured. The arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide demonstrates excellent stability and fast magneto-temperature response. Magnetic resonance imaging signal intensity of Bcap37 cells incubated with arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide was significantly decreased compared with that incubated with plain ultrasmall superparamagnetic iron oxide. The preferential uptake of arginine-glycine-aspartic-ultrasmall superparamagnetic iron oxide by target cells was further confirmed by Prussian blue staining and confocal laser scanning microscopy.

  5. VEGF-Iron Oxide Conjugate for Dual MR and PET Imaging of Breast Cancer Angiogenesis

    DTIC Science & Technology

    2007-09-01

    iron oxide nanoparticles conjugated with macrocyclic chelating agent DOTA for 64Cu-labeling and cyclic RGD peptide for integrin alpha (v)beta(3...Nanoparticles We have developed two types of novel superparamagentic iron oxide nanoparticles (USPIO), namely, PVP -IO and PASP-IO...Polyvinylpyrrolidone ( PVP )-coated iron oxide ( PVP -IO) nanoparticles were synthesized by a one-step thermal decomposition method (Fig. 3). The overall size of the

  6. Delivery of tobramycin coupled to iron oxide nanoparticles across the biofilm of mucoidal Pseudonomas aeruginosa and investigation of its efficacy

    NASA Astrophysics Data System (ADS)

    Armijo, Leisha M.; Kopciuch, Michael; Olszá½¹wka, Zuzia; Wawrzyniec, Stephen J.; Rivera, Antonio C.; Plumley, John B.; Cook, Nathaniel C.; Brandt, Yekaterina I.; Huber, Dale L.; Smolyakov, Gennady A.; Adolphi, Natalie L.; Smyth, Hugh D. C.; Osiński, Marek

    2014-03-01

    Pseudomonas aeruginosa bacterium is a deadly pathogen, leading to respiratory failure in cystic fibrosis and nosocomial pneumonia, and responsible for high mortality rates in these diseases. P. aeruginosa has inherent as well as acquired resistance to many drug classes. In this paper, we investigate the effectiveness of two classes; aminoglycoside (tobramycin) and fluoroquinolone (ciprofloxacin) administered alone, as well as conjugated to iron oxide (magnetite) nanoparticles. P. aeruginosa possesses the ability to quickly alter its genetics to impart resistance to the presence of new, unrecognized treatments. As a response to this impending public health threat, we have synthesized and characterized magnetite nanoparticles capped with biodegradable short-chain carboxylic acid derivatives conjugated to common antibiotic drugs. The functionalized nanoparticles may carry the drug past the mucus and biofilm layers to target the bacterial colonies via magnetic gradient-guided transport. Additionally, the magnetic ferrofluid may be used under application of an oscillating magnetic field to raise the local temperature, causing biofilm disruption, slowed growth, and mechanical disruption. These abilities of the ferrofluid would also treat multi-drug resistant strains, which appear to be increasing in many nosocomial as well as acquired opportunistic infections. In this in vitro model, we show that the iron oxide alone can also inhibit bacterial growth and biofilm formation.

  7. Nanocrystalline iron oxide aerogels as mesoporous magnetic architectures.

    PubMed

    Long, Jeffrey W; Logan, Michael S; Rhodes, Christopher P; Carpenter, Everett E; Stroud, Rhonda M; Rolison, Debra R

    2004-12-29

    We have developed crystalline nanoarchitectures of iron oxide that exhibit superparamagnetic behavior while still retaining the desirable bicontinuous pore-solid networks and monolithic nature of an aerogel. Iron oxide aerogels are initially produced in an X-ray-amorphous, high-surface-area form, by adapting recently established sol-gel methods using Fe(III) salts and epoxide-based proton scavengers. Controlled temperature/atmosphere treatments convert the as-prepared iron oxide aerogels into nanocrystalline forms with the inverse spinel structure. As a function of the bathing gas, treatment temperature, and treatment history, these nanocrystalline forms can be reversibly tuned to predominantly exhibit either Fe(3)O(4) (magnetite) or gamma-Fe(2)O(3) (maghemite) phases, as verified by electron microscopy, X-ray and electron diffraction, microprobe Raman spectroscopy, and magnetic analysis. Peak deconvolution of the Raman-active Fe-O bands yields valuable information on the local structure and vacancy content of the various aerogel forms, and facilitates the differentiation of Fe(3)O(4) and gamma-Fe(2)O(3) components, which are difficult to assign using only diffraction methods. These nanocrystalline, magnetic forms retain the inherent characteristics of aerogels, including high surface area (>140 m(2) g(-1)), through-connected porosity concentrated in the mesopore size range (2-50 nm), and nanoscale particle sizes (7-18 nm). On the basis of this synthetic and processing protocol, we produce multifunctional nanostructured materials with effective control of the pore-solid architecture, the nanocrystalline phase, and subsequent magnetic properties.

  8. Comparative genomic insights into ecophysiology of neutrophilic, microaerophilic iron oxidizing bacteria

    SciTech Connect

    Kato, Shingo; Ohkuma, Moriya; Powell, Deborah H.; Krepski, Sean T.; Oshima, Kenshiro; Hattori, Masahira; Shapiro, Nicole; Woyke, Tanja; Chan, Clara S.

    2015-11-13

    Neutrophilic microaerophilic iron-oxidizing bacteria (FeOB) are thought to play a significant role in cycling of carbon, iron and associated elements in both freshwater and marine iron-rich environments. However, the roles of the neutrophilic microaerophilic FeOB are still poorly understood due largely to the difficulty of cultivation and lack of functional gene markers. Here, we analyze the genomes of two freshwater neutrophilic microaerophilic stalk-forming FeOB, Ferriphaselus amnicola OYT1 and Ferriphaselus strain R-1. Phylogenetic analyses confirm that these are distinct species within Betaproteobacteria; we describe strain R-1 and propose the name F. globulitus. We compare the genomes to those of two freshwater Betaproteobacterial and three marine Zetaproteobacterial FeOB isolates in order to look for mechanisms common to all FeOB, or just stalk-forming FeOB. The OYT1 and R-1 genomes both contain homologs to cyc2, which encodes a protein that has been shown to oxidize Fe in the acidophilic FeOB, Acidithiobacillus ferrooxidans. This c-type cytochrome common to all seven microaerophilic FeOB isolates, strengthening the case for its common utility in the Fe oxidation pathway. In contrast, the OYT1 and R-1 genomes lack mto genes found in other freshwater FeOB. OYT1 and R-1 both have genes that suggest they can oxidize sulfur species. Both have the genes necessary to fix carbon by the Calvin–Benson– Basshom pathway, while only OYT1 has the genes necessary to fix nitrogen. The stalk-forming FeOB share xag genes that may help form the polysaccharide structure of stalks. Both OYT1 and R-1 make a novel biomineralization structure, short rod-shaped Fe oxyhydroxides much smaller than their stalks; these oxides are constantly shed, and may be a vector for C, P, and metal transport to downstream environments. Lastly, our results show that while different FeOB are adapted to particular niches, freshwater and marine FeOB likely share

  9. Comparative genomic insights into ecophysiology of neutrophilic, microaerophilic iron oxidizing bacteria

    DOE PAGES

    Kato, Shingo; Ohkuma, Moriya; Powell, Deborah H.; ...

    2015-11-13

    Neutrophilic microaerophilic iron-oxidizing bacteria (FeOB) are thought to play a significant role in cycling of carbon, iron and associated elements in both freshwater and marine iron-rich environments. However, the roles of the neutrophilic microaerophilic FeOB are still poorly understood due largely to the difficulty of cultivation and lack of functional gene markers. Here, we analyze the genomes of two freshwater neutrophilic microaerophilic stalk-forming FeOB, Ferriphaselus amnicola OYT1 and Ferriphaselus strain R-1. Phylogenetic analyses confirm that these are distinct species within Betaproteobacteria; we describe strain R-1 and propose the name F. globulitus. We compare the genomes to those of two freshwatermore » Betaproteobacterial and three marine Zetaproteobacterial FeOB isolates in order to look for mechanisms common to all FeOB, or just stalk-forming FeOB. The OYT1 and R-1 genomes both contain homologs to cyc2, which encodes a protein that has been shown to oxidize Fe in the acidophilic FeOB, Acidithiobacillus ferrooxidans. This c-type cytochrome common to all seven microaerophilic FeOB isolates, strengthening the case for its common utility in the Fe oxidation pathway. In contrast, the OYT1 and R-1 genomes lack mto genes found in other freshwater FeOB. OYT1 and R-1 both have genes that suggest they can oxidize sulfur species. Both have the genes necessary to fix carbon by the Calvin–Benson– Basshom pathway, while only OYT1 has the genes necessary to fix nitrogen. The stalk-forming FeOB share xag genes that may help form the polysaccharide structure of stalks. Both OYT1 and R-1 make a novel biomineralization structure, short rod-shaped Fe oxyhydroxides much smaller than their stalks; these oxides are constantly shed, and may be a vector for C, P, and metal transport to downstream environments. Lastly, our results show that while different FeOB are adapted to particular niches, freshwater and marine FeOB likely share common mechanisms for Fe

  10. Comparative Genomic Insights into Ecophysiology of Neutrophilic, Microaerophilic Iron Oxidizing Bacteria

    PubMed Central

    Kato, Shingo; Ohkuma, Moriya; Powell, Deborah H.; Krepski, Sean T.; Oshima, Kenshiro; Hattori, Masahira; Shapiro, Nicole; Woyke, Tanja; Chan, Clara S.

    2015-01-01

    Neutrophilic microaerophilic iron-oxidizing bacteria (FeOB) are thought to play a significant role in cycling of carbon, iron and associated elements in both freshwater and marine iron-rich environments. However, the roles of the neutrophilic microaerophilic FeOB are still poorly understood due largely to the difficulty of cultivation and lack of functional gene markers. Here, we analyze the genomes of two freshwater neutrophilic microaerophilic stalk-forming FeOB, Ferriphaselus amnicola OYT1 and Ferriphaselus strain R-1. Phylogenetic analyses confirm that these are distinct species within Betaproteobacteria; we describe strain R-1 and propose the name F. globulitus. We compare the genomes to those of two freshwater Betaproteobacterial and three marine Zetaproteobacterial FeOB isolates in order to look for mechanisms common to all FeOB, or just stalk-forming FeOB. The OYT1 and R-1 genomes both contain homologs to cyc2, which encodes a protein that has been shown to oxidize Fe in the acidophilic FeOB, Acidithiobacillus ferrooxidans. This c-type cytochrome common to all seven microaerophilic FeOB isolates, strengthening the case for its common utility in the Fe oxidation pathway. In contrast, the OYT1 and R-1 genomes lack mto genes found in other freshwater FeOB. OYT1 and R-1 both have genes that suggest they can oxidize sulfur species. Both have the genes necessary to fix carbon by the Calvin–Benson–Basshom pathway, while only OYT1 has the genes necessary to fix nitrogen. The stalk-forming FeOB share xag genes that may help form the polysaccharide structure of stalks. Both OYT1 and R-1 make a novel biomineralization structure, short rod-shaped Fe oxyhydroxides much smaller than their stalks; these oxides are constantly shed, and may be a vector for C, P, and metal transport to downstream environments. Our results show that while different FeOB are adapted to particular niches, freshwater and marine FeOB likely share common mechanisms for Fe oxidation electron

  11. Iron oxide hydroxide nanoflower assisted removal of arsenic from water

    SciTech Connect

    Raul, Prasanta Kumar; Devi, Rashmi Rekha; Umlong, Iohborlang M.; Thakur, Ashim Jyoti; Banerjee, Saumen; Veer, Vijay

    2014-01-01

    Graphical abstract: Non-magnetic polycrystalline iron oxide hydroxide nanoparticle with flower like morphology is found to play as an effective adsorbent media to remove As(III) from 300 μg L{sup −1} to less than 10 μg L{sup −1} from drinking water over wide range of pH. TEM image clearly reveals that the nanoparticle looks flower like morphology with average particle size less than 20 nm. The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic at room temperature and the data fitted to different isotherm models indicate the heterogeneity of the adsorbent surface. The material can be regenerated up to 70% using dilute hydrochloric acid and it would be utilized for de-arsenification purposes. - Highlights: • The work includes synthesis of iron oxide hydroxide nanoflower and its applicability for the removal of arsenic from water. • The nanoparticle was characterized using modern instrumental methods like FESEM, TEM, BET, XRD, etc. • The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic at room temperature. • The sorption is multilayered on the heterogeneous surface of the nano adsorbent. • The mechanism of arsenic removal of IOH nanoflower follows both adsorption and ion-exchange. - Abstract: Non-magnetic polycrystalline iron oxide hydroxide nanoparticle with flower like morphology is found to play as an effective adsorbent media to remove As(III) from 300 μg L{sup −1} to less than 10 μg L{sup −1} from drinking water over wide range of pH. The nanoparticle was characterized by X-ray powder diffraction analysis (XRD), BET surface area, FTIR, FESEM and TEM images. TEM image clearly reveals flower like morphology with average particle size less than 20 nm. The nanoflower morphology is also supported by FESEM images. The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic and the data fitted to different isotherm models indicate the

  12. Resistive switching in iron-oxide-filled carbon nanotubes.

    PubMed

    Cava, Carlos E; Persson, Clas; Zarbin, Aldo J G; Roman, Lucimara S

    2014-01-07

    Iron-oxide-filled carbon nanotubes exhibit an intriguing charge bipolarization behavior which allows the material to be applied in resistive memory devices. Raman analysis conducted with an electric field applied in situ shows the Kohn anomalies and a strong modification of the electronic properties related to the applied voltage intensity. In addition, the I(D)/I(G) ratio indicated the reversibility of this process. The electrical characterization indicated an electronic transport governed by two main kinds of charge hopping, one between the filling and the nanotube and the other between the nanotube shells.

  13. Acidophilic algae isolated from mine-impacted environments and their roles in sustaining heterotrophic acidophiles.

    PubMed

    Nancucheo, Ivan; Barrie Johnson, D

    2012-01-01

    Two acidophilic algae, identified as strains of Chlorella protothecoides var. acidicola and Euglena mutabilis, were isolated in pure culture from abandoned copper mines in Spain and Wales and grown in pH- and temperature-controlled bioreactors. The Chlorella isolate grew optimally at pH 2.5 and 30°C, with a corresponding culture doubling time of 9 h. The isolates displayed similar tolerance (10-50 mM) to four transition metals tested. Growth of the algae in liquid media was paralleled with increasing concentrations of dissolved organic carbon (DOC). Glycolic acid was identified as a significant component (12-14%) of total DOC. Protracted incubation resulted in concentrations of glycolic acid declining in both cases, and glycolic acid added to a culture of Chlorella incubated in the dark was taken up by the alga (~100% within 3 days). Two monosaccharides were identified in cell-free liquors of each algal isolate: fructose and glucose (Chlorella), and mannitol and glucose (Euglena). These were rapidly metabolized by acidophilic heterotrophic bacteria (Acidiphilium and Acidobacterium spp.) though only fructose was utilized by the more fastidious heterotroph "Acidocella aromatica." The significance of algae in promoting the growth of iron- (and sulfate-) reducing heterotrophic acidophiles that are important in remediating mine-impacted waters (MIWs) is discussed.

  14. Cerebral Blood Volume MRI with Intravascular Superparamagentic Iron Oxide Nanoparticles

    PubMed Central

    Kim, Seong-Gi; Harel, Noam; Jin, Tao; Kim, Tae; Lee, Phil; Zhao, Fuqiang

    2013-01-01

    Cerebral blood volume (CBV) is a crucial physiological indicator of tissue viability and vascular reactivity. Thus, non-invasive CBV mapping has been of great interest. For this, ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) including monocrystalline iron oxide nanoparticles (MION) can be used as long half-life, intravascular susceptibility agents of CBV MRI measurements. Also, CBV-weighted fMRI with USPIO provides enhanced sensitivity, reduced large vessel contribution, and improved spatial specificity compared to conventional blood oxygenation-level dependent (BOLD) fMRI, and measures a single physiological parameter that is easily interpretable. We review physiochemical and magnetic properties as well as pharmacokinetics of USPIO in brief. We then extensively discuss quantifications of baseline CBV, vessel size index, and functional CBV change. We also provide reviews of dose-dependent sensitivity, vascular filter function, specificity, characteristics, and impulse response function of CBV fMRI. Examples of CBV fMRI specificity at the laminar and columnar resolution are provided. Finally, we briefly review application of CBV measurements to functional and pharmacological studies in animals. Overall, the use of USPIO can determine baseline CBV and its changes induced by functional activity and pharmacological interventions. PMID:23208650

  15. Tuning the structure and habit of iron oxide mesocrystals

    SciTech Connect

    Wetterskog, Erik; Klapper, Alice; Disch, Sabrina; Josten, Elisabeth; Hermann, Raphaël P.; Rücker, Ulrich; Brückel, Thomas; Bergström, Lennart; Salazar-Alvarez, German

    2016-07-11

    A precise control over the meso- and microstructure of ordered and aligned nanoparticle assemblies, i.e., mesocrystals, is essential in the quest for exploiting the collective material properties for potential applications. In this work, we produced evaporation-induced self-assembled mesocrystals with different mesostructures and crystal habits based on iron oxide nanocubes by varying the nanocube size and shape and by applying magnetic fields. A full 3D characterization of the mesocrystals was performed using image analysis, high-resolution scanning electron microscopy and Grazing Incidence Small Angle X-ray Scattering (GISAXS). This enabled the structural determination of e.g. multi-domain mesocrystals with complex crystal habits and the quantification of interparticle distances with sub-nm precision. Mesocrystals of small nanocubes (l = 8.6 12.6 nm) are isostructural with a body centred tetragonal (bct ) lattice whereas assemblies of the largest nanocubes in this study (l = 13.6 nm) additionally form a simple cubic (sc) lattice. The mesocrystal habit can be tuned from a square, hexagonal to star-like and pillar shapes depending on the particle size and shape and the strength of the applied magnetic field. Finally, we outline a qualitative phase diagram of the evaporation-induced self-assembled superparamagnetic iron oxide nanocube mesocrystals based on nanocube edge length and magnetic field strength.

  16. Tuning the structure and habit of iron oxide mesocrystals

    DOE PAGES

    Wetterskog, Erik; Klapper, Alice; Disch, Sabrina; ...

    2016-07-11

    A precise control over the meso- and microstructure of ordered and aligned nanoparticle assemblies, i.e., mesocrystals, is essential in the quest for exploiting the collective material properties for potential applications. In this work, we produced evaporation-induced self-assembled mesocrystals with different mesostructures and crystal habits based on iron oxide nanocubes by varying the nanocube size and shape and by applying magnetic fields. A full 3D characterization of the mesocrystals was performed using image analysis, high-resolution scanning electron microscopy and Grazing Incidence Small Angle X-ray Scattering (GISAXS). This enabled the structural determination of e.g. multi-domain mesocrystals with complex crystal habits and themore » quantification of interparticle distances with sub-nm precision. Mesocrystals of small nanocubes (l = 8.6 12.6 nm) are isostructural with a body centred tetragonal (bct ) lattice whereas assemblies of the largest nanocubes in this study (l = 13.6 nm) additionally form a simple cubic (sc) lattice. The mesocrystal habit can be tuned from a square, hexagonal to star-like and pillar shapes depending on the particle size and shape and the strength of the applied magnetic field. Finally, we outline a qualitative phase diagram of the evaporation-induced self-assembled superparamagnetic iron oxide nanocube mesocrystals based on nanocube edge length and magnetic field strength.« less

  17. Mercury removal in wastewater by iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Vélez, E.; Campillo, G. E.; Morales, G.; Hincapié, C.; Osorio, J.; Arnache, O.; Uribe, J. I.; Jaramillo, F.

    2016-02-01

    Mercury is one of the persistent pollutants in wastewater; it is becoming a severe environmental and public health problem, this is why nowadays its removal is an obligation. Iron oxide nanoparticles are receiving much attention due to their properties, such as: great biocompatibility, ease of separation, high relation of surface-area to volume, surface modifiability, reusability, excellent magnetic properties and relative low cost. In this experiment, Fe3O4 and γ-Fe2O3 nanoparticles were synthesized using iron salts and NaOH as precipitation agents, and Aloe Vera as stabilizing agent; then these nanoparticles were characterized by three different measurements: first, using a Zetasizer Nano ZS for their size estimation, secondly UV-visible spectroscopy which showed the existence of resonance of plasmon at λmax∼360 nm, and lastly by Scanning Electron Microscopy (SEM) to determine nanoparticles form. The results of this characterization showed that the obtained Iron oxides nanoparticles have a narrow size distribution (∼100nm). Mercury removal of 70% approximately was confirmed by atomic absorption spectroscopy measurements.

  18. Crystal structure of iron-oxide nanoparticles synthesized from ferritin

    NASA Astrophysics Data System (ADS)

    Krispin, Michael; Ullrich, Aladin; Horn, Siegfried

    2012-02-01

    We have investigated the crystal structure of nanosized iron-oxide by X-ray diffraction (XRD), extended X-ray absorption fine structure measurements at the iron K-edge as well as by transmission electron microscopy (TEM). Iron-oxide nanoparticles were produced by thermal treatment of horse spleen ferritin molecules. The structure of these particles was compared to α-Fe2O3 and γ-Fe2O3 nanopowder references. The thermal treatment of a submonolayer film of ferritin molecules results in pure γ-Fe2O3 nanoparticles, while for films above a certain thickness α-Fe2O3 and γ-Fe2O3 coexist, exhibiting two different crystallite sizes. TEM shows a characteristic particle diameter of 7 nm for γ-Fe2O3 resulting from thermal treatment of monolayers, consistent with the crystallite size of the γ-phase as obtained from XRD measurements on multi-layered samples. XRD shows the α-Fe2O3 phase to be characterized by a crystallite size of 34 nm.

  19. Iron-oxide minerals affect extracellular electron-transfer paths of Geobacter spp.

    PubMed

    Kato, Souichiro; Hashimoto, Kazuhito; Watanabe, Kazuya

    2013-01-01

    Some bacteria utilize (semi)conductive iron-oxide minerals as conduits for extracellular electron transfer (EET) to distant, insoluble electron acceptors. A previous study demonstrated that microbe/mineral conductive networks are constructed in soil ecosystems, in which Geobacter spp. share dominant populations. In order to examine how (semi)conductive iron-oxide minerals affect EET paths of Geobacter spp., the present study grew five representative Geobacter strains on electrodes as the sole electron acceptors in the absence or presence of (semi)conductive iron oxides. It was found that iron-oxide minerals enhanced current generation by three Geobacter strains, while no effect was observed in another strain. Geobacter sulfurreducens was the only strain that generated substantial amounts of currents both in the presence and absence of the iron oxides. Microscopic, electrochemical and transcriptomic analyses of G. sulfurreducens disclosed that this strain constructed two distinct types of EET path; in the absence of iron-oxide minerals, bacterial biofilms rich in extracellular polymeric substances were constructed, while composite networks made of mineral particles and microbial cells (without polymeric substances) were developed in the presence of iron oxides. It was also found that uncharacterized c-type cytochromes were up-regulated in the presence of iron oxides that were different from those found in conductive biofilms. These results suggest the possibility that natural (semi)conductive minerals confer energetic and ecological advantages on Geobacter, facilitating their growth and survival in the natural environment.

  20. Dopamine Serves as a Stable Surface Modifier for Iron Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chi, Xiaoqin; Wang, Xiaomin; Hu, Juan; Wang, Lirong; Gao, Jinhao; Zhang, Bei; Zhang, Xixiang

    2013-03-01

    Iron oxide nanoparticles are an important class of nanomaterials in a broad range of biomedical applications because of their superparamagnetism and biocompatibility. The success of biomedical applications of iron oxide nanoparticles relies on the particles' surface functionalization, which requires robust and versatile surface anchors. Here, we report on a detailed examination of the dopamine-based surface modification of iron oxide nanoparticles. We used dopamine (2-(3,4-dihydroxyphenyl)ethylamine) and L-dopa (3,4-dihydroxy-L-phenylalanine) as two surface modifiers and chose Fe2O3 hollow nanoparticles and Fe3O4 nanoparticles as two representative substrates. Optical and TEM images showed that iron oxide nanoparticles dispersed very well in water after surface modification. The analysis of the UV-Vis spectra indicated that dopamine and L-dopa are stable after being immobilized on the surface of iron oxide nanoparticles when the pH value of the environment is about 7. The magnetic properties analysis further showed that the blocking temperature of the dopamine- or L-dopa-decorated iron oxide nanoparticles hardly changed over 20 days, confirming long-term stability of these surface modified nanoparticles. Cell assay indicated that these dopamine- or L-dopa-modified iron oxide nanoparticles were biocompatible. These results confirm that dopamine serves as a stable modifier and a robust anchor to functionalize iron oxide nanoparticles in biomedical applications.

  1. Biological iron oxidation by Gallionella spp. in drinking water production under fully aerated conditions.

    PubMed

    de Vet, W W J M; Dinkla, I J T; Rietveld, L C; van Loosdrecht, M C M

    2011-11-01

    Iron oxidation under neutral conditions (pH 6.5-8) may be a homo- or heterogeneous chemically- or a biologically-mediated process. The chemical oxidation is supposed to outpace the biological process under slightly alkaline conditions (pH 7-8). The iron oxidation kinetics and growth of Gallionella spp. - obligatory chemolithotrophic iron oxidizers - were assessed in natural, organic carbon-containing water, in continuous lab-scale reactors and full-scale groundwater trickling filters in the Netherlands. From Gallionella cell numbers determined by qPCR, balances were made for all systems. The homogeneous chemical iron oxidation occurred in accordance with the literature, but was retarded by a low water temperature (13 °C). The contribution of the heterogeneous chemical oxidation was, despite the presence of freshly formed iron oxyhydroxides, much lower than in previous studies in ultrapure water. This could be caused by the adsorption of natural organic matter (NOM) on the iron oxide surfaces. In the oxygen-saturated natural water with a pH ranging from 6.5 to 7.7, Gallionella spp. grew uninhibited and biological iron oxidation was an important, and probably the dominant, process. Gallionella growth was not even inhibited in a full-scale filter after plate aeration. From this we conclude that Gallionella spp. can grow under neutral pH and fully aerated conditions when the chemical iron oxidation is retarded by low water temperature and inhibition of the autocatalytic iron oxidation.

  2. Iron-Oxide Minerals Affect Extracellular Electron-Transfer Paths of Geobacter spp

    PubMed Central

    Kato, Souichiro; Hashimoto, Kazuhito; Watanabe, Kazuya

    2013-01-01

    Some bacteria utilize (semi)conductive iron-oxide minerals as conduits for extracellular electron transfer (EET) to distant, insoluble electron acceptors. A previous study demonstrated that microbe/mineral conductive networks are constructed in soil ecosystems, in which Geobacter spp. share dominant populations. In order to examine how (semi)conductive iron-oxide minerals affect EET paths of Geobacter spp., the present study grew five representative Geobacter strains on electrodes as the sole electron acceptors in the absence or presence of (semi)conductive iron oxides. It was found that iron-oxide minerals enhanced current generation by three Geobacter strains, while no effect was observed in another strain. Geobacter sulfurreducens was the only strain that generated substantial amounts of currents both in the presence and absence of the iron oxides. Microscopic, electrochemical and transcriptomic analyses of G. sulfurreducens disclosed that this strain constructed two distinct types of EET path; in the absence of iron-oxide minerals, bacterial biofilms rich in extracellular polymeric substances were constructed, while composite networks made of mineral particles and microbial cells (without polymeric substances) were developed in the presence of iron oxides. It was also found that uncharacterized c-type cytochromes were up-regulated in the presence of iron oxides that were different from those found in conductive biofilms. These results suggest the possibility that natural (semi)conductive minerals confer energetic and ecological advantages on Geobacter, facilitating their growth and survival in the natural environment. PMID:23363619

  3. Complete genome sequence of the bioleaching bacterium Leptospirillum sp. group II strain CF-1.

    PubMed

    Ferrer, Alonso; Bunk, Boyke; Spröer, Cathrin; Biedendieck, Rebekka; Valdés, Natalia; Jahn, Martina; Jahn, Dieter; Orellana, Omar; Levicán, Gloria

    2016-03-20

    We describe the complete genome sequence of Leptospirillum sp. group II strain CF-1, an acidophilic bioleaching bacterium isolated from an acid mine drainage (AMD). This work provides data to gain insights about adaptive response of Leptospirillum spp. to the extreme conditions of bioleaching environments.

  4. Designed synthesis and surface engineering strategies of magnetic iron oxide nanoparticles for biomedical applications.

    PubMed

    Wu, Wei; Jiang, Chang Zhong; Roy, Vellaisamy A L

    2016-12-01

    Iron oxide nanoparticles (NPs) hold great promise for future biomedical applications because of their magnetic properties as well as other intrinsic properties such as low toxicity, colloidal stability, and surface engineering capability. Numerous related studies on iron oxide NPs have been conducted. Recent progress in nanochemistry has enabled fine control over the size, crystallinity, uniformity, and surface properties of iron oxide NPs. This review examines various synthetic approaches and surface engineering strategies for preparing naked and functional iron oxide NPs with different physicochemical properties. Growing interest in designed and surface-engineered iron oxide NPs with multifunctionalities was explored in in vitro/in vivo biomedical applications, focusing on their combined roles in bioseparation, as a biosensor, targeted-drug delivery, MR contrast agents, and magnetic fluid hyperthermia. This review outlines the limitations of extant surface engineering strategies and several developing strategies that may overcome these limitations. This study also details the promising future directions of this active research field.

  5. Genotoxicity of Superparamagnetic Iron Oxide Nanoparticles in Granulosa Cells

    PubMed Central

    Pöttler, Marina; Staicu, Andreas; Zaloga, Jan; Unterweger, Harald; Weigel, Bianca; Schreiber, Eveline; Hofmann, Simone; Wiest, Irmi; Jeschke, Udo; Alexiou, Christoph; Janko, Christina

    2015-01-01

    Nanoparticles that are aimed at targeting cancer cells, but sparing healthy tissue provide an attractive platform of implementation for hyperthermia or as carriers of chemotherapeutics. According to the literature, diverse effects of nanoparticles relating to mammalian reproductive tissue are described. To address the impact of nanoparticles on cyto- and genotoxicity concerning the reproductive system, we examined the effect of superparamagnetic iron oxide nanoparticles (SPIONs) on granulosa cells, which are very important for ovarian function and female fertility. Human granulosa cells (HLG-5) were treated with SPIONs, either coated with lauric acid (SEONLA) only, or additionally with a protein corona of bovine serum albumin (BSA; SEONLA-BSA), or with dextran (SEONDEX). Both micronuclei testing and the detection of γH2A.X revealed no genotoxic effects of SEONLA-BSA, SEONDEX or SEONLA. Thus, it was demonstrated that different coatings of SPIONs improve biocompatibility, especially in terms of genotoxicity towards cells of the reproductive system. PMID:26540051

  6. Low-temperature formation of magnetic iron oxides

    NASA Technical Reports Server (NTRS)

    Koch, Chr. Bender; Madsen, M. B.

    1992-01-01

    Elemental analysis and magnetic measurements of the surface of Mars have indicated the presence of an iron oxide with a considerable magnetic moment. Identification of the oxide phase(s) is an important subject as this may be used to identify the process of weathering on the martian surface as well as the composition of the Mars regolith itself. Consequently, interest was in evidence of new formation of strongly magnetic phases (e.g., magnetite, maghemite, feroxyhyte) in terrestrially derived Mars sample analogs. Within the group of Mars sample analogs derived from low-temperature weathering of basalts in Arctic regions, evidence of magnetic oxides formed at the outermost weathering rind was never observed. However, in one instance where the weathering products accumulating in a crack of a basaltic stone were investigated, evidence of magnetite was found. The experimental details are presented.

  7. Magnetic iron oxide nanoclusters with tunable optical response

    NASA Astrophysics Data System (ADS)

    Kostopoulou, Athanasia; Tsiaoussis, Ioannis; Lappas, Alexandros

    2011-04-01

    We have developed a modified synthetic protocol for the growth of monodispersed, superparamagnetic, flower-like colloidal nanoclusters (CNCs), which are consisted of smaller iron oxide nanocrystals with adjustable size. We show that their optical properties can be tuned by applying an external magnetic field. The latter controls the subtle balance of the CNCs’ mutual interactions (magnetic versus electrostatic) and drives their assembly in aqueous media. Spectrophotometric measurements reveal that a diffuse reflectance maximum, in the visible range, is related to the CNCs organization. As the strength of the external magnetic field increases, in the range 160-600 G, the spectral weight of this feature shifts towards the blue region of the spectrum. The induced photonic crystal-like response entails a remarkable magneto-optical behavior, closely associated with the size-dependent characteristics of the CNCs ensemble. Such materials pave the way for promising technological implementations in photonics.

  8. Magneto-optical Properties of Iron Oxide Nanoclusters

    NASA Astrophysics Data System (ADS)

    Kostopoulou, Athanasia; Tsiaoussis, Ioannis; Lappas, Alexandros

    2010-11-01

    We have developed a modified synthetic protocol for the growth of monodispersed, superparamagnetic, flower-like colloidal nanoclusters (CNCs) with 40-120 nm average diameters. Importantly, these are consisted of smaller iron oxide nanocrystals, also with adjustable size (12.2-7.7 nm). We show that their optical properties can be tuned by applying an external magnetic field. Spectrophotometric measurements under these conditions reveal a diffuse reflectance maximum in the visible range, which is related to the CNCs assembly in ordered structures. The increasing field strength leads to a blue shift in the spectral weight when the size of the CNCs is above a critical diameter. The size-dependent characteristics of the CNCs determine their magneto-optical behavior and their potential in photonic crystal based technologies.

  9. In Vivo Clearance and Toxicity of Monodisperse Iron Oxide Nanocrystals

    PubMed Central

    Gu, Luo; Fang, Ronnie H.; Sailor, Michael J.; Park, Ji-Ho

    2012-01-01

    Thermal decomposition of organometallic precursors have been found to generate highly crystalline iron oxide (IO) nanocrystals that display superior MR contrast and lower polydispersity than IO nanocrystals synthesized by aqueous precipitation. In the present study, the in vivo characteristics of IO nanocrystals prepared by the thermal decomposition route and then coated with a phospholipid containing a pendant poly(ethylene glycol) chain are examined. The size and surface chemistry of the IO nanocrystal influences the biodistibution, the rate of biodegradation and bioclearance, and the biodegradation products. We conclude that the in vivo fate of PEGylated monodisperse IO nanocrystals and the iron, phospholipid, and oleic acid biodegradation products may influence the cellular environments in the organs and blood that can determine their safety in the body. PMID:22646927

  10. Hydrophilic Packaging of Iron Oxide Nanoclusters for Highly Sensitive Imaging

    PubMed Central

    Smith, Cartney E.; Ernenwein, Dawn; Shkumatov, Artem; Clay, Nicholas; Lee, JuYeon; Melhem, Molly; Misra, Sanjay; Zimmerman, Steven C.; Kong, Hyunjoon

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) are used as imaging probes to provide contrast in magnetic resonance images. Successful use of SPIONs in targeted applications greatly depends on their ability to generate contrast, even at low levels of accumulation, in the tissue of interest. In the present study, we report that SPION nanoclusters packaged to a controlled size by a hyperbranched polyglycerol (HPG) can target tissue defects and have a high relaxivity of 719 mM−1s−1, which was close to their theoretical maximal limit. The resulting nanoclusters were able to identify regions of defective vasculature in an ischemic murine hindlimb using MRI with iron doses that were 5–10 fold lower than those typically used in preclinical studies. Such high relaxivity was attributed to the molecular architecture of HPG, which mimics that of the water retentive polysaccharide, glycogen. The results of this study will be broadly useful in sensitive imaging applications. PMID:26291408

  11. Study of nanocomposites based on iron oxides and pectin

    SciTech Connect

    Chistyakova, Nataliya I. Shapkin, Alexey A. Sirazhdinov, Ruslan R. Gubaidulina, Tatiana V. Kiseleva, Tatiana Yu. Kazakov, Alexander P. Rusakov, Vyacheslav S.

    2014-10-27

    Mössbauer and X-ray diffraction study of nanocomposites based on iron oxides and pectin (PC) was carried out involving magnetization measurements. The concentrations of PC in nanocomposites varied from 0 to 10%. Mössbauer investigations of nanocomposites were carried out in the temperature range from 5 to 300 K. Many-state superparamagnetic relaxation model was used for spectra fitting. The magnetization, M(T,H), was measured in the temperature interval of 80-300 K and magnetic field up to 10 kOe. Formation of the 'iron-polymer' interface was not observed. Particle sizes were estimated using the Mössbauer and X-ray powder diffraction data.

  12. Study of nanocomposites based on iron oxides and pectin

    NASA Astrophysics Data System (ADS)

    Chistyakova, Nataliya I.; Shapkin, Alexey A.; Sirazhdinov, Ruslan R.; Gubaidulina, Tatiana V.; Kiseleva, Tatiana Yu.; Kazakov, Alexander P.; Rusakov, Vyacheslav S.

    2014-10-01

    Mössbauer and X-ray diffraction study of nanocomposites based on iron oxides and pectin (PC) was carried out involving magnetization measurements. The concentrations of PC in nanocomposites varied from 0 to 10%. Mössbauer investigations of nanocomposites were carried out in the temperature range from 5 to 300 K. Many-state superparamagnetic relaxation model was used for spectra fitting. The magnetization, M(T,H), was measured in the temperature interval of 80-300 K and magnetic field up to 10 kOe. Formation of the "iron-polymer" interface was not observed. Particle sizes were estimated using the Mössbauer and X-ray powder diffraction data.

  13. System for recycling char in iron oxide reducing kilns

    SciTech Connect

    Baker, A.C.; Keran, V.P.

    1983-03-08

    A method and means for improving the efficiency of the process for directly reducing ore containing iron oxide in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the ore feed and discharge ends of the kiln, as both fuel and reductant, is disclosed wherein the charred coal or char found in the discharge product is recycled into the process at the discharge end of the kiln rather than the feed end as in the prior art. In particular, the recovered char, both coarse and finer particles, are transported to a recycle bin from which they are returned at a preselected rate to the kiln process by being injected along with the coal blown into the discharge end of the kiln. Alternatively, the recycle char alone may be fed without any coal at the discharge end of the kiln.

  14. Uptake and metabolism of iron oxide nanoparticles in brain cells.

    PubMed

    Petters, Charlotte; Irrsack, Ellen; Koch, Michael; Dringen, Ralf

    2014-09-01

    Magnetic iron oxide nanoparticles (IONPs) are used for various applications in biomedicine, for example as contrast agents in magnetic resonance imaging, for cell tracking and for anti-tumor treatment. However, IONPs are also known for their toxic effects on cells and tissues which are at least in part caused by iron-mediated radical formation and oxidative stress. The potential toxicity of IONPs is especially important concerning the use of IONPs for neurobiological applications as alterations in brain iron homeostasis are strongly connected with human neurodegenerative diseases. Since IONPs are able to enter the brain, potential adverse consequences of an exposure of brain cells to IONPs have to be considered. This article describes the pathways that allow IONPs to enter the brain and summarizes the current knowledge on the uptake, the metabolism and the toxicity of IONPs for the different types of brain cells in vitro and in vivo.

  15. Colloidal stability of iron oxide nanoparticles with multivalent polymer surfactants.

    PubMed

    Choi, Young-Wook; Lee, Hoik; Song, Youngjun; Sohn, Daewon

    2015-04-01

    This paper introduces a new approach for preparing magnetic colloidal suspensions with electrostatic repulsion between particles and polyelectrolyte surfactants. The surface charge of the iron oxide particles was positive in acidic aqueous conditions; however the surface charge of the colloid was negative in basic aqueous conditions due to the amphoteric property of Fe2O3. The long-term colloidal stability and particle distribution of the multivalent charged polymers, Poly(4-vinylbenzenesulfonate sodium salt) (PSS), Poly(acrylic acid) (PAA), and Poly(allylamine hydrochloride) (PAH) were compared with the monovalent surfactant sodium dodecyl sulfate (SDS). Both mono- and multivalent surfactant molecules showed good colloidal stability for extended periods of time. However, the particle distribution was dependent on the hydrophobicity of the surfactants' functional groups. Polyelectrolytes with a negatively charged functional group showed good long-term stability of particles and a narrow particle distribution regardless of the acid dissociation constant (pKa) of the polymer.

  16. Transformation of iron oxides on PI electrospun membranes

    NASA Astrophysics Data System (ADS)

    Li, Penggang; Lv, Fengzhu; Liu, Leipeng; Ding, Ling; Zhang, Yihe

    2016-09-01

    Iron oxides/PI fiber membranes, especially magnetic PI membranes, are important flexible porous materials available application in the field of wave absorption, magnetic recording, membrane separation and catalysts. Therefore, α-Fe2O3 loaded PI composite fibers were prepared by electrospinning of poly(amic acid) PAA solution followed by loading Fe3+ on the PAA membrane by ion-exchange and then imidization. Then the α-Fe2O3 on PI membrane were reduced by H2 to give magnetic PI membranes. The content of α-Fe2O3 and Fe3O4 on PI can be controlled by adjustment the ion-exchange time. The saturation magnetization of the composite membranes can reach up to 4 emu/g and the final composite membranes have magnetic response ability.

  17. Superparamagnetic iron oxide nanoparticles (SPIONs) for targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Garg, Vijayendra K.; Kuzmann, Erno; Sharma, Virender K.; Kumar, Arun; Oliveira, Aderbal C.

    2016-10-01

    Studies of superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively carried out. Since the earlier work on Mössbauer studies on SPIONs in 1970s, many biomedical applications and their uses in innovative methods to produce new materials with improved performance have appeared. Applications of SPIONs in environmental remediation are also forthcoming. Several different methods of synthesis and coating of the magnetic particles have been described in the literature, and Mössbauer spectroscopy has been an important tool in the characterization of these materials. It is quite possible that the interpretation of the Mössbauer spectra might not be entirely correct because the possible presence of maghemite in the end product of SPIONs might not have been taken into consideration. Nanotechnology is an emerging field that covers a wide range of new technologies under development in nanoscale (1 to 100 nano meters) to produce new products and methodology.

  18. Mutagenic Effects of Iron Oxide Nanoparticles on Biological Cells.

    PubMed

    Dissanayake, Niluka M; Current, Kelley M; Obare, Sherine O

    2015-09-30

    In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism's ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the OPEN ACCESS Int. J. Mol. Sci. 2015, 16 23483 transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells.

  19. Mutagenic Effects of Iron Oxide Nanoparticles on Biological Cells

    PubMed Central

    Dissanayake, Niluka M.; Current, Kelley M.; Obare, Sherine O.

    2015-01-01

    In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism’s ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells. PMID:26437397

  20. Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers

    PubMed Central

    Wahajuddin; Arora, Sumit

    2012-01-01

    A targeted drug delivery system is the need of the hour. Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the principle behind the development of superparamagnetic iron oxide nanoparticles (SPIONs) as novel drug delivery vehicles. SPIONs are small synthetic γ-Fe2O3 (maghemite) or Fe3O4 (magnetite) particles with a core ranging between 10 nm and 100 nm in diameter. These magnetic particles are coated with certain biocompatible polymers, such as dextran or polyethylene glycol, which provide chemical handles for the conjugation of therapeutic agents and also improve their blood distribution profile. The current research on SPIONs is opening up wide horizons for their use as diagnostic agents in magnetic resonance imaging as well as for drug delivery vehicles. Delivery of anticancer drugs by coupling with functionalized SPIONs to their targeted site is one of the most pursued areas of research in the development of cancer treatment strategies. SPIONs have also demonstrated their efficiency as nonviral gene vectors that facilitate the introduction of plasmids into the nucleus at rates multifold those of routinely available standard technologies. SPION-induced hyperthermia has also been utilized for localized killing of cancerous cells. Despite their potential biomedical application, alteration in gene expression profiles, disturbance in iron homeostasis, oxidative stress, and altered cellular responses are some SPION-related toxicological aspects which require due consideration. This review provides a comprehensive understanding of SPIONs with regard to their method of preparation, their utility as drug delivery vehicles, and some concerns which need to be resolved before they can be moved from bench top to bedside. PMID:22848170

  1. Gene Loss and Horizontal Gene Transfer Contributed to the Genome Evolution of the Extreme Acidophile “Ferrovum”

    PubMed Central

    Ullrich, Sophie R.; González, Carolina; Poehlein, Anja; Tischler, Judith S.; Daniel, Rolf; Schlömann, Michael; Holmes, David S.; Mühling, Martin

    2016-01-01

    Acid mine drainage (AMD), associated with active and abandoned mining sites, is a habitat for acidophilic microorganisms that gain energy from the oxidation of reduced sulfur compounds and ferrous iron and that thrive at pH below 4. Members of the recently proposed genus “Ferrovum” are the first acidophilic iron oxidizers to be described within the Betaproteobacteria. Although they have been detected as typical community members in AMD habitats worldwide, knowledge of their phylogenetic and metabolic diversity is scarce. Genomics approaches appear to be most promising in addressing this lacuna since isolation and cultivation of “Ferrovum” has proven to be extremely difficult and has so far only been successful for the designated type strain “Ferrovum myxofaciens” P3G. In this study, the genomes of two novel strains of “Ferrovum” (PN-J185 and Z-31) derived from water samples of a mine water treatment plant were sequenced. These genomes were compared with those of “Ferrovum” sp. JA12 that also originated from the mine water treatment plant, and of the type strain (P3G). Phylogenomic scrutiny suggests that the four strains represent three “Ferrovum” species that cluster in two groups (1 and 2). Comprehensive analysis of their predicted metabolic pathways revealed that these groups harbor characteristic metabolic profiles, notably with respect to motility, chemotaxis, nitrogen metabolism, biofilm formation and their potential strategies to cope with the acidic environment. For example, while the “F. myxofaciens” strains (group 1) appear to be motile and diazotrophic, the non-motile group 2 strains have the predicted potential to use a greater variety of fixed nitrogen sources. Furthermore, analysis of their genome synteny provides first insights into their genome evolution, suggesting that horizontal gene transfer and genome reduction in the group 2 strains by loss of genes encoding complete metabolic pathways or physiological features

  2. Application of Iron Oxide as a pH-dependent Indicator for Improving the Nutritional Quality

    PubMed Central

    2016-01-01

    Acid food indicators can be used as pH indicators for evaluating the quality and freshness of fermented products during the full course of distribution. Iron oxide particles are hardly suspended in water, but partially or completely agglomerated. The agglomeration degree of the iron oxide particles depends on the pH. The pH-dependent particle agglomeration or dispersion can be useful for monitoring the acidity of food. The zeta potential of iron oxide showed a decreasing trend as the pH increased from 2 to 8, while the point of zero charge (PZC) was observed around at pH 6.0-7.0. These results suggested that the size of the iron oxide particles was affected by the change in pH levels. As a result, the particle sizes of iron oxide were smaller at lower pH than at neutral pH. In addition, agglomeration of the iron oxide particles increased as the pH increased from 2 to 7. In the time-dependent aggregation test, the average particle size was 730.4 nm and 1,340.3 nm at pH 2 and 7, respectively. These properties of iron oxide particles can be used to develop an ideal acid indicator for food pH and to monitor food quality, besides a colorant or nutrient for nutrition enhancement and sensory promotion in food industry. PMID:27482521

  3. Environment friendly route of iron oxide nanoparticles from Zingiber officinale (ginger) root extract

    NASA Astrophysics Data System (ADS)

    Xin Hui, Yau; Yi Peng, Teoh; Wei Wen, Liu; Zhong Xian, Ooi; Peck Loo, Kiew

    2016-11-01

    Iron oxide nanoparticles were prepared from the reaction between the Zingiber officinale (ginger) root extracts and ferric chloride solution at 50°C for 2 h in mild stirring condition. The synthesized powder forms of nanoparticles were further characterized by using UV-Vis spectroscopy and X-ray Diffraction spectrometry. UV-Vis analysis shows the absorption peak of iron oxide nanoparticles is appeared at 370 nm. The calculation of crystallite size from the XRD showed that the average particle size of iron oxide nanoparticles was 68.43 nm. Therefore, this eco-friendly technique is low cost and large scale nanoparticles synthesis to fulfill the demand of various applications.

  4. Decaking of coal or oil shale during pyrolysis in the presence of iron oxides

    DOEpatents

    Khan, M. Rashid

    1989-01-01

    A method for producing a fuel from the pyrolysis of coal or oil shale in the presence of iron oxide in an inert gas atmosphere. The method includes the steps of pulverizing feed coal or oil shale, pulverizing iron oxide, mixing the pulverized feed and iron oxide, and heating the mixture in a gas atmosphere which is substantially inert to the mixture so as to form a product fuel, which may be gaseous, liquid and/or solid. The method of the invention reduces the swelling of coals, such as bituminous coal and the like, which are otherwise known to swell during pyrolysis.

  5. Decaking of coal or oil shale during pyrolysis in the presence of iron oxides

    DOEpatents

    Rashid Khan, M.

    1988-05-05

    A method for producing a fuel from the pyrolysis of coal or oil shale in the presence of iron oxide in an inert gas atmosphere is described. The method includes the steps of pulverizing feed coal or oil shale, pulverizing iron oxide, mixing the pulverized feed and iron oxide, and heating the mixture in a gas atmosphere which is substantially inert to the mixture so as to form a product fuel, which may be gaseous, liquid and/or solid. The method of the invention reduces the swelling of coals, such as bituminous coal and the like, which are otherwise known to swell during pyrolysis. 4 figs., 8 tabs.

  6. Hawaiian submarine manganese-iron oxide crusts - A dating tool?

    USGS Publications Warehouse

    Moore, J.G.; Clague, D.A.

    2004-01-01

    Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measured on samples collected since 1965 on the Hawaiian Ridge from 140 dive or dredge localities. Fifty-nine (42%) of the sites were collected in 2001 by remotely operated vehicles (ROVs). The thinner crusts on many samples apparently result from post-depositional breakage, landsliding, and intermittent burial of outcrops by sediment. The maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site. The measurements show an irregular progressive thickening of the crusts toward the northwest-i.e., progressive thickening toward the older volcanic features with increasing distance from the Hawaiian hotspot. Comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust-growth rate of about 2.5 mm/m.y. The thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes, but also provides specific age estimates of volcanic and landslide deposits. The data indicate that some of the landslide blocks within the south Kona landslide are the oldest exposed rock on Mauna Loa, Kilauea, or Loihi volcanoes. Crusts on the floors of submarine canyons off Kohala and East Molokai volcanoes indicate that these canyons are no longer serving as channelways for downslope, sediment-laden currents. Mahukona volcano was approximately synchronous with Hilo Ridge, both being younger than Hana Ridge. The Nuuanu landslide is considerably older than the Wailau landslide. The Waianae

  7. Acidophilic Methanotrophic Communities from Sphagnum Peat Bogs

    PubMed Central

    Dedysh, Svetlana N.; Panikov, Nicolai S.; Tiedje, James M.

    1998-01-01

    Highly enriched methanotrophic communities (>25 serial transfers) were obtained from acidic ombrotrophic peat bogs from four boreal forest sites. The enrichment strategy involved using media conditions that were associated with the highest rates of methane uptake by the original peat samples, namely, the use of diluted mineral medium of low buffering capacity, moderate incubation temperature (20°C), and pH values of 3 to 6. Enriched communities contained a mixture of rod-shaped bacteria arranged in aggregates with a minor contribution of Hyphomicrobium-like cells. The growth stoichiometry of isolates was characteristic of methanotrophic bacteria (CH4/O2/CO2=1:1.1:0.59), with an average apparent yield of 0.41 ± 0.03 g of biomass C/g of CH4-C. DNA from each enrichment yielded a PCR product of the expected size with primers for both mmoX and mmoY genes of soluble methane monooxygenase. Two types of sequences were obtained for PCR-amplified fragments of mmoX. One of them exhibited high identity to the mmoX protein of the Methylocystis-Methylosinus group, whereas the other showed an equal level of divergence from both the Methylosinus-Methylocystis group and Methylococcus capsulatus (Bath) and formed a distinct branch. The pH optimum for growth and for CH4 uptake was 4.5 to 5.5, which is very similar to that for the optimum CH4 uptake observed in the original peat samples. These methanotrophs are moderate acidophiles rather than acidotolerant organisms, since their growth rate and methane uptake were much lower at neutral pH. The growth of the methanotrophic community was enhanced by using media with a very low salt content (20 to 200 mg/liter), more typical of their natural environment. All four enriched communities grew on N-free medium. PMID:9501432

  8. Mapping the Iron Oxidation State in Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Martin, A. M.; Treimann, A. H.; Righter, K.

    2017-01-01

    Several types of Martian igneous meteorites have been identified: clinopyroxenites (nakhlites), basaltic shergottites, peridotitic shergottites, dunites (chassignites) and orthopyroxenites [1,2]. In order to constrain the heterogeneity of the Martian mantle and crust, and their evolution through time, numerous studies have been performed on the iron oxidation state of these meteorites [3,4,5,6,7,8,9]. The calculated fO2 values all lie within the FMQ-5 to FMQ+0.5 range (FMQ representing the Fayalite = Magnetite + Quartz buffer); however, discrepancies appear between the various studies, which are either attributed to the choice of the minerals/melts used, or to the precision of the analytical/calculation method. The redox record in volcanic samples is primarily related to the oxidation state in the mantle source(s). However, it is also influenced by several deep processes: melting, crystallization, magma mixing [10], assimilation and degassing [11]. In addition, the oxidation state in Martian meteorites is potentially affected by several surface processes: assimilation of sediment/ crust during lava flowing at Mars' surface, low temperature micro-crystallization [10], weathering at the surface of Mars and low temperature reequilibration, impact processes (i.e. high pressure phase transitions, mechanical mixing, shock degassing and melting), space weathering, and weathering on Earth (at atmospheric conditions different from Mars). Decoding the redox record of Martian meteorites, therefore, requires large-scale quantitative analysis methods, as well as a perfect understanding of oxidation processes.

  9. Magnetic resonance imaging of microvessels using iron-oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Olamaei, N.; Cheriet, F.; Martel, S.

    2013-03-01

    The visualization of microstructures including blood vessels with an inner overall cross-sectional area below approximately 200 μm remains beyond the capabilities of current clinical imaging modalities. But with magnetic resonance (MR) imaging, magnetic entities cause susceptibility artifacts in the images by disrupting the homogeneous magnetic field in a much larger scale than their actual size. As validated in this paper through simulation and in-vitro experiments, these artifacts can serve as a source of contrast, enabling microvessels with an inner diameter below the spatial resolution of any medical imaging modalities to be visualized using a clinical MR scanner. For such experiments, micron-sized agglomerations of iron-oxide (Fe3O4) nanoparticles were injected in microchannels with internal diameters of 200 and 50 μm equivalent to a narrower artery or a larger arteriole, and down to a smaller arteriole, respectively. The results show the feasibility of the proposed method for micro-particle detection and the visualization of microvessels using a 1.5 T clinical MR scanner. It was confirmed that the method is reproducible and accurate at the sub-pixel level.

  10. Superparamagnetic Iron Oxide Nanoparticle-Based Delivery Systems for Biotherapeutics

    PubMed Central

    Mok, Hyejung; Zhang, Miqin

    2014-01-01

    Introduction Superparamagnetic iron oxide nanoparticle (SPION)-based carrier systems have many advantages over other nanoparticle-based systems. They are biocompatible, biodegradable, facilely tunable, and superparamagnetic and thus controllable by an external magnetic field. These attributes enable their broad biomedical applications. In particular, magnetically-driven carriers are drawing considerable interest as an emerging therapeutic delivery system because of their superior delivery efficiency. Area covered This article reviews the recent advances in use of SPION-based carrier systems to improve the delivery efficiency and target specificity of biotherapeutics. We examine various formulations of SPION-based delivery systems, including SPION micelles, clusters, hydrogels, liposomes, and micro/nanospheres, as well as their specific applications in delivery of biotherapeutics. Expert opinion Recently, biotherapeutics including therapeutic cells, proteins and genes have been studied as alternative treatments to various diseases. Despite the advantages of high target specificity and low adverse effects, clinical translation of biotherapeutics has been hindered by the poor stability and low delivery efficiency compared to chemical drugs. Accordingly, biotherapeutic delivery systems that can overcome these limitations are actively pursued. SPION-based materials can be ideal candidates for developing such delivery systems because of their excellent biocompatibility and superparamagnetism that enables long-term accumulation/retention at target sites by utilization of a suitable magnet. In addition, synthesis technologies for production of finely-tuned, homogeneous SPIONs have been well developed, which may promise their rapid clinical translation. PMID:23199200

  11. Iron oxide nanoparticles in modern microbiology and biotechnology.

    PubMed

    Dinali, Ranmadugala; Ebrahiminezhad, Alireza; Manley-Harris, Merilyn; Ghasemi, Younes; Berenjian, Aydin

    2017-01-10

    Iron oxide nanoparticles (IONs) are one of the most developed and used nanomaterials in biotechnology and microbiology. These particles have unique physicochemical properties, which make them unique among nanomaterials. Therefore, many experiments have been conducted to develop facile synthesis methods for these particles and to make them biocompatible. Various effects of IONs on microorganisms have been reported. Depending on the microbial strain and nanoparticle (NP) concentration, IONs can stimulate or inhibit microbial growth. Due to the superparamagnetic properties of IONs, these NPs have used as nano sources of heat for hyperthermia in infected tissues. Antibiotic-loaded IONs are used for targeted delivery of chemical therapy direct to the infected organ and IONs have been used as a dirigible carrier for more potent antimicrobial nanomaterials such as silver nanoparticles. Magnetic NPs have been used for specific separation of pathogen and non-pathogen bacterial strains. Very recently, IONs were used as a novel tool for magnetic immobilization of microbial cells and process intensification in a biotechnological process. This review provides an overview of application of IONs in different microbial processes. Recommendations are also given for areas of future research.

  12. Ultrafast optical modification of exchange interactions in iron oxides.

    PubMed

    Mikhaylovskiy, R V; Hendry, E; Secchi, A; Mentink, J H; Eckstein, M; Wu, A; Pisarev, R V; Kruglyak, V V; Katsnelson, M I; Rasing, Th; Kimel, A V

    2015-09-16

    Ultrafast non-thermal manipulation of magnetization by light relies on either indirect coupling of the electric field component of the light with spins via spin-orbit interaction or direct coupling between the magnetic field component and spins. Here we propose a scenario for coupling between the electric field of light and spins via optical modification of the exchange interaction, one of the strongest quantum effects with strength of 10(3) Tesla. We demonstrate that this isotropic opto-magnetic effect, which can be called inverse magneto-refraction, is allowed in a material of any symmetry. Its existence is corroborated by the experimental observation of terahertz emission by spin resonances optically excited in a broad class of iron oxides with a canted spin configuration. From its strength we estimate that a sub-picosecond modification of the exchange interaction by laser pulses with fluence of about 1 mJ cm(-2) acts as a pulsed effective magnetic field of 0.01 Tesla.

  13. Magnetic hyperthermia in phosphate coated iron oxide nanofluids

    NASA Astrophysics Data System (ADS)

    Lahiri, B. B.; Muthukumaran, T.; Philip, John

    2016-06-01

    We study the magnetic field induced hyperthermia in water based phosphate coated Fe3O4 nanofluids, synthesized by a co-precipitation method using ferrous and ferric salt solutions, ammonia and orthophosphoric acid. The specific absorption rate (SAR) values were measured at a fixed frequency of 126 kHz and at extremely low field amplitudes. The SAR values were determined from the initial rate of temperature rise curves under non-adiabatic conditions. It was observed that the SAR initially increases with sample concentration, attains a maximum at an optimum concentration and beyond which SAR decreases. The decrease in SAR values beyond the optimum concentration was attributed to the enhancement of dipolar interaction and agglomeration of the particles. The system independent intrinsic loss power (ILP) values, obtained by normalizing the SAR values with respect to field amplitude and frequency, were found to vary between 158-125 nHm2 kg-1, which were the highest benchmark values reported in the biologically safe experimental limit of 1.03-0.92×108 Am-1 s-1. The very high value of ILP observed in the bio-compatible phosphate coated iron oxide nanofluids may find practical applications for these nanoparticles in tumor targeted hyperthermia treatment.

  14. Ultrafast optical modification of exchange interactions in iron oxides

    PubMed Central

    Mikhaylovskiy, R.V.; Hendry, E.; Secchi, A.; Mentink, J.H.; Eckstein, M.; Wu, A.; Pisarev, R.V.; Kruglyak, V.V.; Katsnelson, M.I.; Rasing, Th.; Kimel, A.V.

    2015-01-01

    Ultrafast non-thermal manipulation of magnetization by light relies on either indirect coupling of the electric field component of the light with spins via spin-orbit interaction or direct coupling between the magnetic field component and spins. Here we propose a scenario for coupling between the electric field of light and spins via optical modification of the exchange interaction, one of the strongest quantum effects with strength of 103 Tesla. We demonstrate that this isotropic opto-magnetic effect, which can be called inverse magneto-refraction, is allowed in a material of any symmetry. Its existence is corroborated by the experimental observation of terahertz emission by spin resonances optically excited in a broad class of iron oxides with a canted spin configuration. From its strength we estimate that a sub-picosecond modification of the exchange interaction by laser pulses with fluence of about 1 mJ cm−2 acts as a pulsed effective magnetic field of 0.01 Tesla. PMID:26373688

  15. Macroscopic and microscopic biodistribution of intravenously administered iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Misra, Adwiteeya; Petryk, Alicia A.; Strawbridge, Rendall R.; Hoopes, P. Jack

    2015-03-01

    Iron oxide nanoparticles (IONP) are being developed for use as a cancer treatment. They have demonstrated efficacy when used either as a monotherapy or in conjunction with conventional chemotherapy and radiation. The success of IONP as a therapeutic tool depends on the delivery of a safe and controlled cytotoxic thermal dose to tumor tissue following activation with an alternating magnetic field (AMF). Prior to clinical approval, knowledge of IONP toxicity, biodistribution and physiological clearance is essential. This preliminary time-course study determines the acute toxicity and biodistribution of 110 nm dextran-coated IONP (iron) in mice, 7 days post systemic, at doses of 0.4, 0.6, and 1.0 mg Fe/ g mouse bodyweight. Acute toxicity, manifested as changes in the behavior of mice, was only observed temporarily at 1.0 mg Fe/ g mouse bodyweight, the highest dose administered. Regardless of dose, mass spectrometry and histological analysis demonstrated over 3 mg Fe/g tissue in organs within the reticuloendotheilial system (i.e. liver, spleen, and lymph nodes). Other organs (brain, heart, lungs, and kidney) had less than 0.5 mg Fe/g tissue with iron predominantly confined to the organ vasculature.

  16. Oxalic acid capped iron oxide nanorods as a sensing platform.

    PubMed

    Sharma, Anshu; Baral, Dinesh; Bohidar, H B; Solanki, Pratima R

    2015-08-05

    A label free impedimetric immunosensor has been fabricated using protein bovine serum albumin (BSA) and monoclonal antibodies against Vibrio cholerae (Ab) functionalized oxalic acid (OA) capped iron oxide (Fe3O4) nanorods for V. cholerae detection. The structural and morphological studies of Fe3O4 and OA-Fe3O4, were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS) techniques. The average crystalline size of Fe3O4, OA-Fe3O4 nanorods were obtained as about 29±1 and 39±1nm, respectively. The hydrodynamic radius of nanorods is found as 116nm (OA-Fe3O4) and 77nm (Fe3O4) by DLS measurement. Cytotoxicity of Fe3O4 and OA-Fe3O4 nanorods has been investigated in the presence of human epithelial kidney (HEK) cell line 293 using MTT assay. The cell viability and proliferation studies reveal that the OA-Fe3O4 nanorods facilitate cell growth. The results of electrochemical response studies of the fabricated BSA/Ab/OA-Fe2O3/ITO immunosensor exhibits good linearity in the range of 12.5-500ng mL(-1) with low detection limit of 0.5ng mL(-1), sensitivity 0.1Ωng(-1)ml(-1)cm(-2) and reproducibility more than 11 times.

  17. Are iron oxide nanoparticles safe? Current knowledge and future perspectives.

    PubMed

    Valdiglesias, Vanessa; Fernández-Bertólez, Natalia; Kiliç, Gözde; Costa, Carla; Costa, Solange; Fraga, Sonia; Bessa, Maria Joao; Pásaro, Eduardo; Teixeira, João Paulo; Laffon, Blanca

    2016-12-01

    Due to their unique physicochemical properties, including superparamagnetism, iron oxide nanoparticles (ION) have a number of interesting applications, especially in the biomedical field, that make them one of the most fascinating nanomaterials. They are used as contrast agents for magnetic resonance imaging, in targeted drug delivery, and for induced hyperthermia cancer treatments. Together with these valuable uses, concerns regarding the onset of unexpected adverse health effects following exposure have been also raised. Nevertheless, despite the numerous ION purposes being explored, currently available information on their potential toxicity is still scarce and controversial data have been reported. Although ION have traditionally been considered as biocompatible - mainly on the basis of viability tests results - influence of nanoparticle surface coating, size, or dose, and of other experimental factors such as treatment time or cell type, has been demonstrated to be important for ION in vitro toxicity manifestation. In vivo studies have shown distribution of ION to different tissues and organs, including brain after passing the blood-brain barrier; nevertheless results from acute toxicity, genotoxicity, immunotoxicity, neurotoxicity and reproductive toxicity investigations in different animal models do not provide a clear overview on ION safety yet, and epidemiological studies are almost inexistent. Much work has still to be done to fully understand how these nanomaterials interact with cellular systems and what, if any, potential adverse health consequences can derive from ION exposure.

  18. Biocompatible capped iron oxide nanoparticles for Vibrio cholerae detection

    NASA Astrophysics Data System (ADS)

    Sharma, Anshu; Baral, Dinesh; Rawat, Kamla; Solanki, Pratima R.; Bohidar, H. B.

    2015-05-01

    We report the studies relating to fabrication of an efficient immunosensor for Vibrio cholerae detection. Magnetite (iron oxide (Fe3O4)) nanoparticles (NPs) have been synthesized by the co-precipitation method and capped by citric acid (CA). These NPs were electrophoretically deposited onto indium-tin-oxide (ITO)-coated glass substrate and used for immobilization of monoclonal antibodies against Vibrio cholerae (Ab) and bovine serum albumin (BSA) for Vibrio cholerae detection using an electrochemical technique. The structural and morphological studies of Fe3O4 and CA-Fe3O4/ITO were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS) techniques. The average crystalline size of Fe3O4, CA-Fe3O4 nanoparticles obtained were about 29 ± 1 nm and 37 ± 1 nm, respectively. The hydrodynamic radius of the nanoparticles was found to be 77.35 nm (Fe3O4) and 189.51 nm (CA-Fe3O4) by DLS measurement. The results of electrochemical response studies of the fabricated BSA/Ab/CA-Fe2O3/ITO immunosensor exhibits a good detection range of 12.5-500 ng mL-1 with a low detection limit of 0.32 ng mL-1, sensitivity 0.03 Ω/ng ml-1 cm-2, and reproducibility more than 11 times.

  19. Inverse-Photoemission Spectroscopy of Iron Oxides, Silver

    NASA Astrophysics Data System (ADS)

    Kim, Bongsoo

    1990-01-01

    I measured the inverse-photoemission spectra (IPES) of iron oxides grown on an Fe substrate, and calculated the band structure of paramagnetic FeO to analyze the IPES. The band calculation showed some overlap between Fe _3_{rm d} states and O_2_{rm p} states in the region of occupied states, and s,p-like states of Fe in the unoccupied region. Isochromatic IPES showed structures at ~2.5 eV and ~7.5 eV above the Fermi energy. I estimate the full band gap of FeO as 2.5 eV from the IPES data. Angle-resolved inverse-photoemission spectra (ARIPES) have been measured on single-crystal Ag. The results are compared with the predictions of bulk band-structure theory and a free-electron model. The latter gives good agreement for the structure with a final state near the Fermi energy. Band theory is needed for the structure 17 eV above the Fermi energy. This structure is very nondispersive, indicating the existence of a very flat band throughout the IXUL plane.

  20. Cell Labeling and Targeting with Superparamagnetic Iron Oxide Nanoparticles

    PubMed Central

    Tefft, Brandon J.; Uthamaraj, Susheil; Harburn, J. Jonathan; Klabusay, Martin; Dragomir-Daescu, Dan; Sandhu, Gurpreet S.

    2015-01-01

    Targeted delivery of cells and therapeutic agents would benefit a wide range of biomedical applications by concentrating the therapeutic effect at the target site while minimizing deleterious effects to off-target sites. Magnetic cell targeting is an efficient, safe, and straightforward delivery technique. Superparamagnetic iron oxide nanoparticles (SPION) are biodegradable, biocompatible, and can be endocytosed into cells to render them responsive to magnetic fields. The synthesis process involves creating magnetite (Fe3O4) nanoparticles followed by high-speed emulsification to form a poly(lactic-co-glycolic acid) (PLGA) coating. The PLGA-magnetite SPIONs are approximately 120 nm in diameter including the approximately 10 nm diameter magnetite core. When placed in culture medium, SPIONs are naturally endocytosed by cells and stored as small clusters within cytoplasmic endosomes. These particles impart sufficient magnetic mass to the cells to allow for targeting within magnetic fields. Numerous cell sorting and targeting applications are enabled by rendering various cell types responsive to magnetic fields. SPIONs have a variety of other biomedical applications as well including use as a medical imaging contrast agent, targeted drug or gene delivery, diagnostic assays, and generation of local hyperthermia for tumor therapy or tissue soldering. PMID:26554870

  1. Solution voltammetry of 4 nm magnetite iron oxide nanoparticles.

    PubMed

    Roberts, Joseph J P; Westgard, John A; Cooper, Laura M; Murray, Royce W

    2014-07-30

    The voltammetry of solution-dispersed magnetite iron oxide Fe3O4 nanoparticles is described. Their currents are controlled by nanoparticle transport rates, as shown with potential step chronoamperometry and rotated disk voltammetry. In pH 2 citrate buffer with added NaClO4 electrolyte, solution cyclic voltammetry of these nanoparticles (average diameter 4.4 ± 0.9 nm, each containing ca. 30 Fe sites) displays an electrochemically irreversible oxidation with E(PEAK) at ca. +0.52 V and an irreversible reduction with E(PEAK) at ca. +0.2 V vs Ag/AgCl reference electrode. These processes are presumed to correspond to the formal potentials for one-electron oxidation of Fe(II) and reduction of Fe(III) at their different sites in the magnetite nanoparticle structure. The heterogeneous electrode reaction rates of the nanoparticles are very slow, in the 10(-5) cm/s range. The nanoparticles are additionally characterized by a variety of tools, e.g., TEM, UV/vis, and XPS spectroscopies.

  2. Niobian iron oxides as heterogeneous Fenton catalysts for environmental remediation

    NASA Astrophysics Data System (ADS)

    Oliveira, Diana Q. L.; Oliveira, Luiz C. A.; Murad, Enver; Fabris, José D.; Silva, Adilson C.; de Menezes, Lucas Morais

    2010-01-01

    Heterogeneous Fenton or Fenton-like reagents consist of a mixture of an iron-containing solid matrix and a liquid medium with H2O2. The Fenton system is based on the reaction between Fe2 + and H2O2 to produce highly reactive intermediate hydroxyl radicals ( • OH), which are able to oxidize organic contaminants, whereas the Fenton-like reaction is based on the reaction between Fe3 + and H2O2. These heterogeneous systems offer several advantages over their homogeneous counterparts, such as no sludge formation, operation at near-neutral pH and the possibility of recycling the iron promoter. Some doping transition cations in the iron oxide structure are believed to enhance the catalytic efficiency for the oxidation of organic substrates in water. In this work, goethites synthesized in presence of niobium served as precursors for the preparation of magnetites (niobian magnetites) via chemical reduction with hydrogen at 400°C. These materials were used as Fenton-like catalysts. Both groups of (Nb, Fe)-oxide samples were characterized by 57Fe Mössbauer spectroscopy at 298 K. The results show that increasing niobium contents raise the catalytic potential for decomposition of methylene blue, which was, in this work, used as a model molecule for organic substrates in water.

  3. Iron oxide nanoparticles for magnetically assisted patterned coatings

    NASA Astrophysics Data System (ADS)

    Dodi, Gianina; Hritcu, Doina; Draganescu, Dan; Popa, Marcel I.

    2015-08-01

    Iron oxide nanoparticles able to magnetically assemble during the curing stage of a polymeric support to create micro-scale surface protuberances in a controlled manner were prepared and characterized. The bare Fe3O4 particles were obtained by two methods: co-precipitation from an aqueous solution containing Fe3+/Fe2+ ions with a molar ratio of 2:1 and partial oxidation of ferrous ions in alkaline conditions. The products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and magnetization measurement. They were subsequently functionalized using oleic acid, sodium oleate, or non-ionic surfactant mixtures with various hydrophilic to lipophilic balance (HLB) values. Composite nanoparticle-polymer films prepared by spraying were deposited and cured by drying on glass slides under a static magnetic field in the range of 1.5-5.5 mT. Magnetic field generated surface roughness was evidenced by optical and scanning electron microscopy. The optimum hierarchical patterning was obtained with the nanoparticles produced by partial oxidation and functionalized with hydrophobic surfactants. Possible applications may include ice-phobic composite coatings.

  4. Exceedingly small iron oxide nanoparticles as positive MRI contrast agents.

    PubMed

    Wei, He; Bruns, Oliver T; Kaul, Michael G; Hansen, Eric C; Barch, Mariya; Wiśniowska, Agata; Chen, Ou; Chen, Yue; Li, Nan; Okada, Satoshi; Cordero, Jose M; Heine, Markus; Farrar, Christian T; Montana, Daniel M; Adam, Gerhard; Ittrich, Harald; Jasanoff, Alan; Nielsen, Peter; Bawendi, Moungi G

    2017-02-28

    Medical imaging is routine in the diagnosis and staging of a wide range of medical conditions. In particular, magnetic resonance imaging (MRI) is critical for visualizing soft tissue and organs, with over 60 million MRI procedures performed each year worldwide. About one-third of these procedures are contrast-enhanced MRI, and gadolinium-based contrast agents (GBCAs) are the mainstream MRI contrast agents used in the clinic. GBCAs have shown efficacy and are safe to use with most patients; however, some GBCAs have a small risk of adverse effects, including nephrogenic systemic fibrosis (NSF), the untreatable condition recently linked to gadolinium (Gd) exposure during MRI with contrast. In addition, Gd deposition in the human brain has been reported following contrast, and this is now under investigation by the US Food and Drug Administration (FDA). To address a perceived need for a Gd-free contrast agent with pharmacokinetic and imaging properties comparable to GBCAs, we have designed and developed zwitterion-coated exceedingly small superparamagnetic iron oxide nanoparticles (ZES-SPIONs) consisting of ∼3-nm inorganic cores and ∼1-nm ultrathin hydrophilic shell. These ZES-SPIONs are free of Gd and show a high T1 contrast power. We demonstrate the potential of ZES-SPIONs in preclinical MRI and magnetic resonance angiography.

  5. Observational evidence of crystalline iron oxides on Mars

    SciTech Connect

    Bell, J.F. III; McCord, T.B.; Owensby, P.D. )

    1990-08-30

    Visible to near-IR (0.4-1.0 {mu}m) spectral reflectance observations of Mars during the 1988 opposition were performed at Mauna Kea Observatory using a circular variable filter spectrometer at a spectral resolution R = {lambda}/{Delta}{lambda} {approx} 80. On August 13 and 14 1988, UT, 41 regions 500-600 km in diameter were observed on Mars. The data have been reduced both to reflectance relative to solar analog (Mars/16 Cyg B) and to relative reflectance (spot/spot). The spectra show the strong near-UV reflectance dropoff characteristic of Mars as well as absorptions at 0.62-0.72 {mu}m and 0.81-0.94 {mu}m both seen here clearly for the first time. These absorption features are interpreted as Fe{sup 3+} electronic transition bands that indicate the presence of crystalline ferric oxide or hydroxide minerals on the Martian surface. Comparison of these data with laboratory spectra obtained by other workers supports the conclusion that a single iron oxide phase, most likely hematite, could account for all of the observed spectral behavior of the Martian surface soils and airborne dust in the 0.4-1.0 {mu}m region. This possibility must be reconciled with data from other possible spectral analogs and other wavelength regions as well as geochemical and mineral stability considerations to arrive at a more complete understanding of the role of ferric minerals in Martian surface mineralogy and weathering.

  6. Chemical characterization of iron oxide precipitates from wetlands constructed to treat polluted mine drainage

    SciTech Connect

    Fish, C.L.; Partezana, J.M.; Hedin, R.S.

    1996-12-31

    The passive treatment of abandoned mine drainage using wetlands will produce a significant amount of iron rich sludge which will require costly removal and disposal. An alternative to disposal may be the use of this iron oxide material as pigments which could defray some of these costs. In this research, iron deposits from five alkaline mine drainage wetlands were collected and a series of standard tests were run. The tests included loss on ignition, moisture, pH, acid soluble metals, oil absorption, and water soluble matter. The results of these tests were compared to those achieved using commercially available natural and synthetic iron oxides. The results indicate that iron oxides from constructed wetlands have chemical properties that are intermediate to those of natural and synthetic iron oxide products.

  7. Eco-Friendly Magnetic Iron Oxide Pillared Montmorillonite for Advanced Catalytic Degradation of Dichlorophenol

    EPA Science Inventory

    Eco-friendly pillared montmorillonites, in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties that are applicable for environmental decontamination. Completely “green” and effective composite was synthesized using mild reactio...

  8. On the electrical arc interruption by using PMMA/iron oxide nanocomposites

    NASA Astrophysics Data System (ADS)

    Doddapaneni, Venkatesh; Saleemi, Mohsin; Ye, Fei; Gati, Rudolf; Toprak, Muhammet S.

    2016-10-01

    An experimental study is undertaken on the fabrication of poly (methyl methacrylate) (PMMA)/iron oxide nanocomposites to determine their potential use for electrical arc interruption in the electrical switching applications such as circuit breakers. Monodisperse iron oxide nanoparticles of average size ∼11 nm are synthesized via thermal decomposition method and then homogeneously dispersed in the PMMA matrix by in situ polymerization. PMMA/iron oxide nanocomposites with different nanoparticle loading have been fabricated to study the effect of loading content on the thermal energy absorption. Detailed physicochemical characterizations on synthesized material are performed using x-ray powder diffraction, scanning electron microscopy, TEM, thermogravimetric analysis and differential scanning calorimetry at different processing stages. A test-setup was designed to evaluate the quality of the nanocomposites for electric arc interruption capability. The results showed that PMMA/iron oxide nanocomposites have a clear impact on the electric arc interruption and therefore should be considered as promising candidates for electrical switching applications.

  9. Effects of Iron Oxides on the Rheological Properties of Cementitious Slurry

    SciTech Connect

    Chung, Chul-Woo; Chun, Jaehun; Wang, Guohui; Um, Wooyong

    2014-04-02

    Iron oxide has been considered a promising host for immobilizing and encapsulating radioactive 99Tc (t1/2=2.1x105 year), which significantly enhances the stability of 99Tc within a cementitious waste form. However, the flow behavior of cementitious slurry containing iron oxide has never been investigated to ensure its workability, which directly influences the preparation and performance of the cementitious waste form monolith. Variation in the rheological properties of the cementitious slurry were studied using rheometry and ultrasonic wave reflection to understand the effects of various iron oxides (magnetite, hematite, ferrihydrite, and goethite) during the cement setting and stiffening processes. The rheological behavior significantly varied with the addition of different chemical compounds of iron oxides. Complementary microscopic characteristics such as colloidal vibration currents, morphology, and particle size distributions further suggest that the most adverse alteration of cement setting and stiffening behavior caused by the presence of goethite may be attributed to its acicular shape.

  10. Porous Iron Oxide Ribbons Grown on Graphene for High-Performance Lithium Storage

    PubMed Central

    Yang, Shubin; Sun, Yi; Chen, Long; Hernandez, Yenny; Feng, Xinliang; Müllen, Klaus

    2012-01-01

    A well-designed nanostructure of transition metal oxides has been regarded as a key to solve their problems of large volume changes during lithium insertion-desertion processes which are associated with pulverization of the electrodes and rapid capacity decay. Here we report an effective approach for the fabrication of porous iron oxide ribbons by controlling the nucleation and growth of iron precursor onto the graphene surface and followed by an annealing treatment. The resultant iron oxide ribbons possess large aspect ratio, porous structure, thin feature and enhanced open-edges. These characteristics are favorable for the fast diffusion of lithium ions and electrons, and meanwhile can effectively accommodate the volume change of iron oxides during the cycling processes. As a consequence, the graphene-induced porous iron oxide ribbons exhibit a high reversible capacity and excellent cycle stability for lithium storage. PMID:22645643

  11. Recent progress in magnetic iron oxide-semiconductor composite nanomaterials as promising photocatalysts

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Changzhong Jiang, Affc; Roy, Vellaisamy A. L.

    2014-11-01

    Photocatalytic degradation of toxic organic pollutants is a challenging tasks in ecological and environmental protection. Recent research shows that the magnetic iron oxide-semiconductor composite photocatalytic system can effectively break through the bottleneck of single-component semiconductor oxides with low activity under visible light and the challenging recycling of the photocatalyst from the final products. With high reactivity in visible light, magnetic iron oxide-semiconductors can be exploited as an important magnetic recovery photocatalyst (MRP) with a bright future. On this regard, various composite structures, the charge-transfer mechanism and outstanding properties of magnetic iron oxide-semiconductor composite nanomaterials are sketched. The latest synthesis methods and recent progress in the photocatalytic applications of magnetic iron oxide-semiconductor composite nanomaterials are reviewed. The problems and challenges still need to be resolved and development strategies are discussed.

  12. A Holistic Model That Physicochemically Links Iron Oxide - Apatite and Iron Oxide - Copper - Gold Deposits to Magmas

    NASA Astrophysics Data System (ADS)

    Simon, A. C.; Reich, M.; Knipping, J.; Bilenker, L.; Barra, F.; Deditius, A.; Lundstrom, C.; Bindeman, I. N.

    2015-12-01

    Iron oxide-apatite (IOA) and iron oxide-copper-gold deposits (IOCG) are important sources of their namesake metals and increasingly for rare earth metals in apatite. Studies of natural systems document that IOA and IOCG deposits are often spatially and temporally related with one another and coeval magmatism. However, a genetic model that accounts for observations of natural systems remains elusive, with few observational data able to distinguish among working hypotheses that invoke meteoric fluid, magmatic-hydrothermal fluid, and immiscible melts. Here, we use Fe and O isotope data and high-resolution trace element (e.g., Ti, V, Mn, Al) data of individual magnetite grains from the world-class Los Colorados (LC) IOA deposit in the Chilean Iron Belt to elucidate the origin of IOA and IOCG deposits. Values of d56Fe range from 0.08‰ to 0.26‰, which are within the global range of ~0.06‰ to 0.5‰ for magnetite formed at magmatic conditions. Values of δ18O for magnetite and actinolite are 2.04‰ and 6.08‰, respectively, consistent with magmatic values. Ti, V, Al, and Mn are enriched in magnetite cores and decrease systematically from core to rim. Plotting [Al + Mn] vs. [Ti + V] indicates that magnetite cores are consistent with magmatic and/or magmatic-hydrothermal (i.e., porphyry) magnetites. Decreasing Al, Mn, Ti, V is consistent with a cooling trend from porphyry to Kiruna to IOCG systems. The data from LC are consistent with the following new genetic model for IOA and IOCG systems: 1) magnetite cores crystallize from silicate melt; 2) these magnetite crystals are nucleation sites for aqueous fluid that exsolves and scavenges inter alia Fe, P, S, Cu, Au from silicate melt; 3) the magnetite-fluid suspension is less dense that the surrounding magma, allowing ascent; 4) as the suspension ascends, magnetite grows in equilibrium with the fluid and takes on a magmatic-hydrothermal character (i.e., lower Al, Mn, Ti, V); 5) during ascent, magnetite, apatite and

  13. Gold and iron oxide associations under supergene conditions: An experimental approach

    NASA Astrophysics Data System (ADS)

    Greffié, Catherine; Benedetti, Marc F.; Parron, Claude; Amouric, Marc

    1996-05-01

    Abstract-The interaction of gold hydroxo-chloro complexes with iron oxides (ferrihydrites, goethites) during coprecipitation experiments is investigated. Chemical analyses of solids and solutions are coupled with a detailed characterization of the iron oxides with various methods, including X-ray diffraction, High Resolution Transmission Electron Microscopy (HRTEM), and Mössbauer spectroscopy. HCl solutions containing varying amounts of AuCl 4- and ferric nitrate were titrated to neutral or alkaline pH, resulting in the coprecipitation of gold and iron oxide phases (ferrihydrite or goethite). Reference titrations were performed in the absence of iron. Most of the gold was removed from solution in the presence of iron oxides whereas gold remained dissolved in the reference samples. In association with iron oxides two forms of gold have been identified by HRTEM and 197Au Mössbauer spectroscopy: metallic gold as well as chloro and/or hydroxo combined gold. This combined gold is in a trivalent state as the primary product which means that a reduction process is not a necessary step for the adsorption of gold species on iron oxides. Metallic gold characterized in these products by means of HRTEM consists mainly of colloids ranging from 3-60 nm in diameter embedded in the ferrihydrite matrix, as isolated particles or as particles associated with goethite laths. The smallest metallic gold particles detected would be almost invisible to classical observation techniques used for solid phases. In our experiments, oxidation-reduction reactions between Fe 2+ and Au 3+ are responsible for the presence of metallic gold observed on the iron phases. Photochemical reactions may also take part in the reduction process. Colloidal gold and gold complexes could be associated to the iron oxides by strong electrostatic interactions. Our results suggest that poorly ordered iron oxides are highly efficient in trapping gold from solutions thanks to their high surface area, and favor gold

  14. Biomedical properties and preparation of iron oxide-dextran nanostructures by MAPLE technique

    PubMed Central

    2012-01-01

    Background In this work the chemical structure of dextran-iron oxide thin films was reported. The films were obtained by MAPLE technique from composite targets containing 10 wt. % dextran with 1 and 5 wt.% iron oxide nanoparticles (IONPs). The IONPs were synthesized by co-precipitation method. A KrF* excimer laser source (λ = 248 nm, τFWHM≅25 ns, ν = 10 Hz) was used for the growth of the hybrid, iron oxide NPs-dextran thin films. Results Dextran coated iron oxide nanoparticles thin films were indexed into the spinel cubic lattice with a lattice parameter of 8.36 Å. The particle sized calculated was estimated at around 7.7 nm. The XPS shows that the binding energy of the Fe 2p3/2 of two thin films of dextran coated iron oxide is consistent with Fe3+ oxides. The atomic percentage of the C, O and Fe are 66.71, 32.76 and 0.53 for the films deposited from composite targets containing 1 wt.% maghemite and 64.36, 33.92 and 1.72 respectively for the films deposited from composite targets containing 5 wt.% maghemite. In the case of cells cultivated on dextran coated 5% maghemite γ-Fe2O3, the number of cells and the level of F-actin were lower compared to the other two types of thin films and control. Conclusions The dextran-iron oxide continuous thin films obtained by MAPLE technique from composite targets containing 10 wt.% dextran as well as 1 and 5 wt.% iron oxide nanoparticles synthesized by co-precipitation method presented granular surface morphology. Our data proved a good viability of Hep G2 cells grown on dextran coated maghemite thin films. Also, no changes in cells morphology were noticed under phase contrast microscopy. The data strongly suggest the potential use of iron oxide-dextran nanocomposites as a potential marker for biomedical applications. PMID:22410001

  15. The detection of HBV DNA with gold-coated iron oxide nanoparticle gene probes

    NASA Astrophysics Data System (ADS)

    Xi, Dong; Luo, XiaoPing; Lu, QiangHua; Yao, KaiLun; Liu, ZuLi; Ning, Qin

    2008-03-01

    Gold-coated iron oxide nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Gold-coated iron oxide nanoparticles were prepared by the citrate reduction of tetra-chloroauric acid in the presence of iron oxide nanoparticles which were added as seeds. With a fluorescence-based method, the maximal surface coverage of hexaethiol 30-mer oligonucleotides and the maximal percentage of hybridization strands on gold-coated iron oxide nanoparticles were (120 ± 8) oligonucleotides per nanoparticle, and (14 ± 2%), respectively, which were comparable with those of (132 ± 10) and (22 ± 3%) in Au nanoparticle groups. Large network aggregates were formed when gold-coated iron oxide nanoparticle HBV DNA gene probe was applied to detect HBV DNA molecules as evidenced by transmission electron microscopy and the high specificity was verified by blot hybridization. Our results further suggested that detecting DNA with iron oxide nanoparticles and magnetic separator was feasible and might be an alternative effective method.

  16. Magnetic iron oxide nanoparticles: Synthesis and surface coating techniques for biomedical applications

    NASA Astrophysics Data System (ADS)

    Sun, Sheng-Nan; Wei, Chao; Zhu, Zan-Zan; Hou, Yang-Long; Subbu, S. Venkatraman; Xu, Zhi-Chuan

    2014-03-01

    Iron oxide nanoparticles are the most popular magnetic nanoparticles used in biomedical applications due to their low cost, low toxicity, and unique magnetic property. Magnetic iron oxide nanoparticles, including magnetite (Fe3O4) and maghemite (γ-Fe2O3), usually exhibit a superparamagnetic property as their size goes smaller than 20 nm, which are often denoted as superparamagnetic iron oxide nanoparticles (SPIONs) and utilized for drug delivery, diagnosis, therapy, and etc. This review article gives a brief introduction on magnetic iron oxide nanoparticles in terms of their fundamentals of magnetism, magnetic resonance imaging (MRI), and drug delivery, as well as the synthesis approaches, surface coating, and application examples from recent key literatures. Because the quality and surface chemistry play important roles in biomedical applications, our review focuses on the synthesis approaches and surface modifications of iron oxide nanoparticles. We aim to provide a detailed introduction to readers who are new to this field, helping them to choose suitable synthesis methods and to optimize the surface chemistry of iron oxide nanoparticles for their interests.

  17. Properties and suspension stability of dendronized iron oxide nanoparticles for MRI applications.

    PubMed

    Basly, B; Felder-Flesch, D; Perriat, P; Pourroy, G; Bégin-Colin, S

    2011-01-01

    Functionalized iron oxide nanoparticles have attracted an increasing interest in the last 10 years as contrast agents for MRI. One challenge is to obtain homogeneous and stable aqueous suspensions of iron oxide nanoparticles without aggregates. Iron oxide nanoparticles with sizes around 10 nm were synthesized by two methods: the particle size distribution in water suspension of iron oxide nanoparticles synthesized by the co-precipitation method was improved by a process involving two steps of ligand exchange and phase transfer and was compared with that of iron oxide nanoparticles synthesized by thermal decomposition and functionalized by the same dendritic molecule. The saturation magnetization of dendronized nanoparticles synthesized by thermal decomposition was lower than that of nanoparticles synthesized by co-precipitation. The r(2) relaxivity values were shown to decrease with the agglomeration state in suspension and high r(2) values and r(2) /r(1) ratios were obtained with nanoparticles synthesized by co-precipitation by comparison with those of commercial products. Dendronized iron oxide nanoparticles thus have potential properties as contrast agent.

  18. Respiratory interactions of soil bacteria with (semi)conductive iron-oxide minerals.

    PubMed

    Kato, Souichiro; Nakamura, Ryuhei; Kai, Fumiyoshi; Watanabe, Kazuya; Hashimoto, Kazuhito

    2010-12-01

    Pure-culture studies have shown that dissimilatory metal-reducing bacteria are able to utilize iron-oxide nanoparticles as electron conduits for reducing distant terminal acceptors; however, the ecological relevance of such energy metabolism is poorly understood. Here, soil microbial communities were grown in electrochemical cells with acetate as the electron donor and electrodes (poised at 0.2 V versus Ag/AgCl) as the electron acceptors in the presence and absence of iron-oxide nanoparticles, and respiratory current generation and community structures were analysed. Irrespective of the iron-oxide species (hematite, magnetite or ferrihydrite), the supplementation with iron-oxide minerals resulted in large increases (over 30-fold) in current, while only a moderate increase (∼10-fold) was observed in the presence of soluble ferric/ferrous irons. During the current generation, insulative ferrihydrite was transformed into semiconductive goethite. Clone-library analyses of 16S rRNA gene fragments PCR-amplified from the soil microbial communities revealed that iron-oxide supplementation facilitated the occurrence of Geobacter species affiliated with subsurface clades 1 and 2. We suggest that subsurface-clade Geobacter species preferentially thrive in soil by utilizing (semi)conductive iron oxides for their respiration.

  19. New Insight into Microbial Iron Oxidation as Revealed by the Proteomic Profile of an Obligate Iron-Oxidizing Chemolithoautotroph.

    PubMed

    Barco, Roman A; Emerson, David; Sylvan, Jason B; Orcutt, Beth N; Jacobson Meyers, Myrna E; Ramírez, Gustavo A; Zhong, John D; Edwards, Katrina J

    2015-09-01

    Microaerophilic, neutrophilic, iron-oxidizing bacteria (FeOB) grow via the oxidation of reduced Fe(II) at or near neutral pH, in the presence of oxygen, making them relevant in numerous environments with elevated Fe(II) concentrations. However, the biochemical mechanisms for Fe(II) oxidation by these neutrophilic FeOB are unknown, and genetic markers for this process are unavailable. In the ocean, microaerophilic microorganisms in the genus Mariprofundus of the class Zetaproteobacteria are the only organisms known to chemolithoautotrophically oxidize Fe and concurrently biomineralize it in the form of twisted stalks of iron oxyhydroxides. The aim of this study was to identify highly expressed proteins associated with the electron transport chain of microaerophilic, neutrophilic FeOB. To this end, Mariprofundus ferrooxydans PV-1 was cultivated, and its proteins were extracted, assayed for redox activity, and analyzed via liquid chromatography-tandem mass spectrometry for identification of peptides. The results indicate that a cytochrome c4, cbb3-type cytochrome oxidase subunits, and an outer membrane cytochrome c were among the most highly expressed proteins and suggest an involvement in the process of aerobic, neutrophilic bacterial Fe oxidation. Proteins associated with alternative complex III, phosphate transport, carbon fixation, and biofilm formation were abundant, consistent with the lifestyle of Mariprofundus.

  20. Magnetization measurements and XMCD studies on ion irradiated iron oxide and core-shell iron/iron-oxide nanomaterials

    SciTech Connect

    Kaur, Maninder; Qiang, You; Jiang, Weilin; Pearce, Carolyn; McCloy, John S.

    2014-12-02

    Magnetite (Fe3O4) and core-shell iron/iron-oxide (Fe/Fe3O4) nanomaterials prepared by a cluster deposition system were irradiated with 5.5 MeV Si2+ ions and the structures determined by x-ray diffraction as consisting of 100% magnetite and 36/64 wt% Fe/FeO, respectively. However, x-ray magnetic circular dichroism (XMCD) indicates similar surfaces in the two samples, slightly oxidized and so having more Fe3+ than the expected magnetite structure, with XMCD intensity much lower for the irradiated core-shell samples indicating weaker magnetism. X-ray absorption spectroscopy (XAS) data lack the signature for FeO, but the irradiated core-shell system consists of Fe-cores with ~13 nm of separating oxide crystallite, so it is likely that FeO exists deeper than the probe depth of the XAS (~5 nm). Exchange bias (Hex) for both samples becomes increasingly negative as temperature is lowered, but the irradiated Fe3O4 sample shows greater sensitivity of cooling field on Hex. Loop asymmetries and Hex sensitivities of the irradiated Fe3O4 sample are due to interfaces and interactions between grains which were not present in samples before irradiation as well as surface oxidation. Asymmetries in the hysteresis curves of the irradiated core/shell sample are related to the reversal mechanism of the antiferromagnetic FeO and possibly some near surface oxidation.

  1. New Insight into Microbial Iron Oxidation as Revealed by the Proteomic Profile of an Obligate Iron-Oxidizing Chemolithoautotroph

    PubMed Central

    Emerson, David; Sylvan, Jason B.; Orcutt, Beth N.; Jacobson Meyers, Myrna E.; Ramírez, Gustavo A.; Zhong, John D.; Edwards, Katrina J.

    2015-01-01

    Microaerophilic, neutrophilic, iron-oxidizing bacteria (FeOB) grow via the oxidation of reduced Fe(II) at or near neutral pH, in the presence of oxygen, making them relevant in numerous environments with elevated Fe(II) concentrations. However, the biochemical mechanisms for Fe(II) oxidation by these neutrophilic FeOB are unknown, and genetic markers for this process are unavailable. In the ocean, microaerophilic microorganisms in the genus Mariprofundus of the class Zetaproteobacteria are the only organisms known to chemolithoautotrophically oxidize Fe and concurrently biomineralize it in the form of twisted stalks of iron oxyhydroxides. The aim of this study was to identify highly expressed proteins associated with the electron transport chain of microaerophilic, neutrophilic FeOB. To this end, Mariprofundus ferrooxydans PV-1 was cultivated, and its proteins were extracted, assayed for redox activity, and analyzed via liquid chromatography-tandem mass spectrometry for identification of peptides. The results indicate that a cytochrome c4, cbb3-type cytochrome oxidase subunits, and an outer membrane cytochrome c were among the most highly expressed proteins and suggest an involvement in the process of aerobic, neutrophilic bacterial Fe oxidation. Proteins associated with alternative complex III, phosphate transport, carbon fixation, and biofilm formation were abundant, consistent with the lifestyle of Mariprofundus. PMID:26092463

  2. Quantitative proteomic analyses of the response of acidophilic microbial communities to different pH conditions.

    PubMed

    Belnap, Christopher P; Pan, Chongle; Denef, Vincent J; Samatova, Nagiza F; Hettich, Robert L; Banfield, Jillian F

    2011-07-01

    Extensive genomic characterization of multi-species acid mine drainage microbial consortia combined with laboratory cultivation has enabled the application of quantitative proteomic analyses at the community level. In this study, quantitative proteomic comparisons were used to functionally characterize laboratory-cultivated acidophilic communities sustained in pH 1.45 or 0.85 conditions. The distributions of all proteins identified for individual organisms indicated biases for either high or low pH, and suggests pH-specific niche partitioning for low abundance bacteria and archaea. Although the proteome of the dominant bacterium, Leptospirillum group II, was largely unaffected by pH treatments, analysis of functional categories indicated proteins involved in amino acid and nucleotide metabolism, as well as cell membrane/envelope biogenesis were overrepresented at high pH. Comparison of specific protein abundances indicates higher pH conditions favor Leptospirillum group III, whereas low pH conditions promote the growth of certain archaea. Thus, quantitative proteomic comparisons revealed distinct differences in community composition and metabolic function of individual organisms during different pH treatments. Proteomic analysis revealed other aspects of community function. Different numbers of phage proteins were identified across biological replicates, indicating stochastic spatial heterogeneity of phage outbreaks. Additionally, proteomic data were used to identify a previously unknown genotypic variant of Leptospirillum group II, an indication of selection for a specific Leptospirillum group II population in laboratory communities. Our results confirm the importance of pH and related geochemical factors in fine-tuning acidophilic microbial community structure and function at the species and strain level, and demonstrate the broad utility of proteomics in laboratory community studies.

  3. Quantitative proteomic analyses of the response of acidophilic microbial communities to different pH conditions

    SciTech Connect

    Belnap, Christopher P.; Pan, Chongle; Denef, Vincent; Samatova, Nagiza F; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2011-01-01

    Extensive genomic characterization of multi-species acid mine drainage microbial consortia combined with laboratory cultivation has enabled the application of quantitative proteomic analyses at the community level. In this study, quantitative proteomic comparisons were used to functionally characterize laboratory-cultivated acidophilic communities sustained in pH 1.45 or 0.85 conditions. The distributions of all proteins identified for individual organisms indicated biases for either high or low pH, and suggests pH-specific niche partitioning for low abundance bacteria and archaea. Although the proteome of the dominant bacterium, Leptospirillum group II, was largely unaffected by pH treatments, analysis of functional categories indicated proteins involved in amino acid and nucleotide metabolism, as well as cell membrane/envelope biogenesis were overrepresented at high pH. Comparison of specific protein abundances indicates higher pH conditions favor Leptospirillum group III, whereas low pH conditions promote the growth of certain archaea. Thus, quantitative proteomic comparisons revealed distinct differences in community composition and metabolic function of individual organisms during different pH treatments. Proteomic analysis revealed other aspects of community function. Different numbers of phage proteins were identified across biological replicates, indicating stochastic spatial heterogeneity of phage outbreaks. Additionally, proteomic data were used to identify a previously unknown genotypic variant of Leptospirillum group II, an indication of selection for a specific Leptospirillum group II population in laboratory communities. Our results confirm the importance of pH and related geochemical factors in fine-tuning acidophilic microbial community structure and function at the species and strain level, and demonstrate the broad utility of proteomics in laboratory community studies.

  4. Mechanisms of iron oxide transformation in hydrothermal systems.

    SciTech Connect

    Otake, Tsubasa; Wesolowski, David J; Anovitz, Lawrence {Larry} M

    2010-11-01

    Coexistence of magnetite and hematite in hydrothermal systems has often been used to constrain the redox potential of fluids, assuming that the redox equilibrium is attained among all minerals and aqueous species. However, as temperature decreases, disequilibrium mineral assemblages may occur due to the slow kinetics of reaction involving the minerals and fluids. In this study, we conducted a series of experiments in which hematite or magnetite was reacted with an acidic solution under H{sub 2}-rich hydrothermal conditions (T = 100-250 C, P{sub H{sub 2}} = 0.05-5 MPa) to investigate the kinetics of redox and non-redox transformations between hematite and magnetite, and the mechanisms of iron oxide transformation under hydrothermal conditions. The formation of euhedral crystals of hematite in 150 and 200 C experiments, in which magnetite was used as the starting material, indicates that non-redox transformation of magnetite to hematite occurred within 24 h. The chemical composition of the experimental solutions was controlled by the non-redox transformation between magnetite and hematite throughout the experiments. While solution compositions were controlled by the non-redox transformation in the first 3 days in a 250 C experiment, reductive dissolution of magnetite became important after 5 days and affected the solution chemistry. At 100 C, the presence of maghemite was indicated in the first 7 days. Based on these results, equilibrium constants of non-redox transformation between magnetite and hematite and those of non-redox transformation between magnetite and maghemite were calculated. Our results suggest that the redox transformation of hematite to magnetite occurs in the following steps: (1) reductive dissolution of hematite to Fe{sub (aq)}{sup 2+} and (2) non-redox transformation of hematite and Fe{sub (aq)}{sup 2+} to magnetite.

  5. Mechanisms of iron oxide transformations in hydrothermal systems.

    SciTech Connect

    Otake, Tsubasa; Wesolowski, David J; Anovitz, Lawrence {Larry} M; Allard Jr, Lawrence Frederick; Ohmoto, Hiroshi

    2010-01-01

    Coexistence of magnetite and hematite in hydrothermal systems has often been used to constrain the redox potential of fluids, assuming that the redox equilibrium is attained among all minerals and aqueous species. However, as temperature decreases, disequilibrium mineral assemblages may occur due to the slow kinetics of reaction involving the minerals and fluids. In this study, we conducted a series of experiments in which hematite or magnetite was reacted with an acidic solution under H2-rich hydrothermal conditions (T = 100 250 C,) to investigate the kinetics of redox and non-redox transformations between hematite and magnetite, and the mechanisms of iron oxide transformation under hydrothermal conditions. The formation of euhedral crystals of hematite in 150 and 200 C experiments, in which magnetite was used as the starting material, indicates that non-redox transformation of magnetite to hematite occurred within 24 h. The chemical composition of the experimental solutions was controlled by the non-redox transformation between magnetite and hematite throughout the experiments. While solution compositions were controlled by the non-redox transformation in the first 3 days in a 250 C experiment, reductive dissolution of magnetite became important after 5 days and affected the solution chemistry. At 100 C, the presence of maghemite was indicated in the first 7 days. Based on these results, equilibrium constants of non-redox transformation between magnetite and hematite and those of non-redox transformation between magnetite and maghemite were calculated. Our results suggest that the redox transformation of hematite to magnetite occurs in the following steps: (1) reductive dissolution of hematite to and (2) non-redox transformation of hematite and to magnetite.

  6. Magnetic field calculations for iron oxide nanoparticles for MRI

    NASA Astrophysics Data System (ADS)

    Hernandez, Ricardo; Mendez Rojas, Miguel; Dies Suarez, Pilar; Hidalgo Tobón, Silvia

    2014-11-01

    The susceptibility effects of superparamagnetic iron oxide nanoparticles (SPIONs) functionalized with triethylenglycol (TREG) and Polyethylen Glycol (PEG) has been studied, those nanoparticles have the necessary properties to be used in the clinic as contrast media in imaging by MRI[1-3]. We are considering the behavior of the magnetic field as plane wave to explain the electrical and magnetic field produced by SPIONs. Images were acquired on a 1.5T imager Philips, using mFFE Sequence. Three glass capillary tubes with a) TREG (10nm) concentration of 300 μg/ml, and PEGCOOH 6000(10nm) with 300 μg/ml, and 2% agarosa. Magnetic field simulations were calculated in Matlab. The plane wave that comes in contact with a sphere of radius a, an propagation constant k1, and it is in an homogeneous space k2. We consider that the electric field is linearly polarized on x-direction, with a propagation on z-positive-axis. The secondary induced field can be explained from the interior of the sphere and valid exterior points. The referred waves are transmitted and reflected, this is valid only when the wavelength is smaller than the radius of the sphere. The obtained vibrational mode is an answer of the electrical oscillation and this is projection of the disturbed magnetic field. TREG-SPIONs produce more serious susceptibility artefacts compared to PEG-SPIONs. This study is promissory due to the concordance of the results of the simulations and the inhomogeneities showed in the MR images.

  7. Ultrasonic computed tomography imaging of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Perlman, Or; Azhari, Haim

    2017-02-01

    Iron oxide nanoparticles (IONPs) are becoming increasingly used and intensively investigated in the field of medical imaging. They are currently FDA approved for magnetic resonance imaging (MRI), and it would be highly desirable to visualize them by ultrasound as well. Previous reports using the conventional ultrasound B-scan (pulse-echo) imaging technique have shown very limited detectability of these particles. The aim of this study is to explore the feasibility of imaging IONPs using the through-transmission ultrasound methodology and demonstrate their detectability using ultrasonic computed tomography (UCT). Commercially available IONPs were acoustically analysed to quantify their effect on the speed of sound (SOS) and acoustic attenuation as a function of concentration. Next, through-transmission projection and UCT imaging were performed on a breast mimicking phantom and on an ex vivo tissue model, to which IONPs were injected. Finally, an MRI scan was performed to verify that the same particles examined in the ultrasound experiment can be imaged by magnetic resonance, using the same clinically relevant concentrations. The results have shown a consistent concentration dependent speed of sound increase (1.86 \\text{m}{{\\text{s}}^{-1}} rise per 100 µg · ml-1 IONPs). Imaging based on this property has shown a substantial contrast-to-noise ratio improvement (up to 5 fold, p  <  0.01). The SOS-related effect generated a well discernible image contrast and allowed the detection of the particles existence and location, in both raster-scan projection and UCT imaging. Conversely, no significant change in the acoustic attenuation coefficient was noted. Based on these findings, it is concluded that IONPs can be used as an effective SOS-based contrast agent, potentially useful for ultrasonic breast imaging. Furthermore, the particle offers the capacity of significantly enhancing diagnosis accuracy using multimodal MRI-ultrasound imaging capabilities.

  8. Physicochemical Characterization of Nebulized Superparamagnetic Iron Oxide Nanoparticles (SPIONs)

    PubMed Central

    Graczyk, Halshka; Bryan, Louise C.; Lewinski, Nastassja; Suarez, Guillaume; Coullerez, Geraldine; Bowen, Paul

    2015-01-01

    Abstract Background: Aerosol-mediated delivery of nano-based therapeutics to the lung has emerged as a promising alternative for treatment and prevention of lung diseases. Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted significant attention for such applications due to their biocompatibility and magnetic properties. However, information is lacking about the characteristics of nebulized SPIONs for use as a therapeutic aerosol. To address this need, we conducted a physicochemical characterization of nebulized Rienso, a SPION-based formulation for intravenous treatment of anemia. Methods: Four different concentrations of SPION suspensions were nebulized with a one-jet nebulizer. Particle size was measured in suspension by transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), and nanoparticle tracking analysis (NTA), and in the aerosol by a scanning mobility particle sizer (SMPS). Results: The average particle size in suspension as measured by TEM, PCS, and NTA was 9±2 nm, 27±7 nm, and 56±10 nm, respectively. The particle size in suspension remained the same before and after the nebulization process. However, after aerosol collection in an impinger, the suspended particle size increased to 159±46 nm as measured by NTA. The aerosol particle concentration increased linearly with increasing suspension concentration, and the aerodynamic diameter remained relatively stable at around 75 nm as measured by SMPS. Conclusions: We demonstrated that the total number and particle size in the aerosol were modulated as a function of the initial concentration in the nebulizer. The data obtained mark the first known independent characterization of nebulized Rienso and, as such, provide critical information on the behavior of Rienso nanoparticles in an aerosol. The data obtained in this study add new knowledge to the existing body of literature on potential applications of SPION suspensions as inhaled aerosol therapeutics. PMID

  9. The responses of immune cells to iron oxide nanoparticles.

    PubMed

    Xu, Yaolin; Sherwood, Jennifer A; Lackey, Kimberly H; Qin, Ying; Bao, Yuping

    2016-04-01

    Immune cells play an important role in recognizing and removing foreign objects, such as nanoparticles. Among various parameters, surface coatings of nanoparticles are the first contact with biological system, which critically affect nanoparticle interactions. Here, surface coating effects on nanoparticle cellular uptake, toxicity and ability to trigger immune response were evaluated on a human monocyte cell line using iron oxide nanoparticles. The cells were treated with nanoparticles of three types of coatings (negatively charged polyacrylic acid, positively charged polyethylenimine and neutral polyethylene glycol). The cells were treated at various nanoparticle concentrations (5, 10, 20, 30, 50 μg ml(-1) or 2, 4, 8, 12, 20 μg cm(-2)) with 6 h incubation or treated at a nanoparticle concentration of 50 μg ml(-1) (20 μg cm(-2)) at different incubation times (6, 12, 24, 48 or 72 h). Cell viability over 80% was observed for all nanoparticle treatment experiments, regardless of surface coatings, nanoparticle concentrations and incubation times. The much lower cell viability for cells treated with free ligands (e.g. ~10% for polyethylenimine) suggested that the surface coatings were tightly attached to the nanoparticle surfaces. The immune responses of cells to nanoparticles were evaluated by quantifying the expression of toll-like receptor 2 and tumor necrosis factor-α. The expression of tumor necrosis factor-α and toll-like receptor 2 were not significant in any case of the surface coatings, nanoparticle concentrations and incubation times. These results provide useful information to select nanoparticle surface coatings for biological and biomedical applications.

  10. Detection, isolation, and characterization of acidophilic methanotrophs from Sphagnum mosses.

    PubMed

    Kip, Nardy; Ouyang, Wenjing; van Winden, Julia; Raghoebarsing, Ashna; van Niftrik, Laura; Pol, Arjan; Pan, Yao; Bodrossy, Levente; van Donselaar, Elly G; Reichart, Gert-Jan; Jetten, Mike S M; Damsté, Jaap S Sinninghe; Op den Camp, Huub J M

    2011-08-15

    Sphagnum peatlands are important ecosystems in the methane cycle. Methane-oxidizing bacteria in these ecosystems serve as a methane filter and limit methane emissions. Yet little is known about the diversity and identity of the methanotrophs present in and on Sphagnum mosses of peatlands, and only a few isolates are known. The methanotrophic community in Sphagnum mosses, originating from a Dutch peat bog, was investigated using a pmoA microarray. A high biodiversity of both gamma- and alphaproteobacterial methanotrophs was found. With Sphagnum mosses as the inoculum, alpha- and gammaproteobacterial acidophilic methanotrophs were isolated using established and newly designed media. The 16S rRNA, pmoA, pxmA, and mmoX gene sequences showed that the alphaproteobacterial isolates belonged to the Methylocystis and Methylosinus genera. The Methylosinus species isolated are the first acid-tolerant members of this genus. Of the acidophilic gammaproteobacterial strains isolated, strain M5 was affiliated with the Methylomonas genus, and the other strain, M200, may represent a novel genus, most closely related to the genera Methylosoma and Methylovulum. So far, no acidophilic or acid-tolerant methanotrophs in the Gammaproteobacteria class are known. All strains showed the typical features of either type I or II methanotrophs and are, to the best of our knowledge, the first isolated (acidophilic or acid-tolerant) methanotrophs from Sphagnum mosses.

  11. Synthesis and characterization of platinum decorated iron oxide nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Palchoudhury, Soubantika

    This dissertation focuses on the development of a bifunctional nanoparticle system that can potentially offer simultaneous imaging and therapy in the future. Recently, small platinum (Pt) nanoparticles (< 5 nm) have shown great potential in therapeutic applications, such as DNA dissociation, radiation therapy, and oxidative stress treatment. Therefore, the small Pt nanoparticles of size comparable to DNA grooves are chosen as potential therapeutic components in this research. However, such small sized Pt nanoparticles tends to aggregate, and are difficult to target. Therefore, this research reports the synthesis, characterization, and DNA interaction of small Pt decorated iron oxide nanoparticles. The iron oxide carriers provide stability to the small Pt nanoparticles, and can potentially serve as MRI contrast agents. The hypothesis of this research is that the Pt nanoparticles supported on iron oxide nanoparticle surfaces can effectively interact with DNA molecules similar to the free Pt nanoparticles. A reproducible synthetic technique was first developed to prepare iron oxide nanoparticles with excellent size control and narrow size distribution. Subsequently, two different approaches were utilized to produce multiple small Pt nanoparticle attached iron oxide nanoparticles. The first route involved attachment of Pt nanoparticles onto iron oxide seeds of various shapes in an organic solvent, followed by an aqueous phase transfer. Here, the shape of the nanoparticles was controlled to facilitate heterogeneous nucleation of Pt nanoparticles. The protective biocompatible polymer coating (polyacrylic acid) in this method could prevent interaction of the Pt nanoparticles with undesirable biomolecules. Several non-spherical iron oxide nanoparticles were explored, including whiskers, worms, plates, and flowers. In the second method, an aqueous phase ligand exchange process was performed first, prior to the deposition of multiple Pt nanoparticles. This facile method

  12. Recovery of iron oxides from acid mine drainage and their application as adsorbent or catalyst.

    PubMed

    Flores, Rubia Gomes; Andersen, Silvia Layara Floriani; Maia, Leonardo Kenji Komay; José, Humberto Jorge; Moreira, Regina de Fatima Peralta Muniz

    2012-11-30

    Iron oxide particles recovered from acid mine drainage represent a potential low-cost feedstock to replace reagent-grade chemicals in the production of goethite, ferrihydrite or magnetite with relatively high purity. Also, the properties of iron oxides recovered from acid mine drainage mean that they can be exploited as catalysts and/or adsorbents to remove azo dyes from aqueous solutions. The main aim of this study was to recover iron oxides with relatively high purity from acid mine drainage to act as a catalyst in the oxidation of dye through a Fenton-like mechanism or as an adsorbent to remove dyes from an aqueous solution. Iron oxides (goethite) were recovered from acid mine drainage through a sequential precipitation method. Thermal treatment at temperatures higher than 300 °C produces hematite through a decrease in the BET area and an increase in the point of zero charge. In the absence of hydrogen peroxide, the solids adsorbed the textile dye Procion Red H-E7B according to the Langmuir model, and the maximum amount adsorbed decreased as the temperature of the thermal treatment increased. The decomposition kinetics of hydrogen peroxide is dependent on the H(2)O(2) concentration and iron oxides dosage, but the second-order rate constant normalized to the BET surface area is similar to that for different iron oxides tested in this and others studies. These results indicate that acid mine drainage could be used as a source material for the production of iron oxide catalysts/adsorbents, with comparable quality to those produced using analytical-grade reagents.

  13. Iron-oxide-supported nanocarbon in lithium-ion batteries, medical, catalytic, and environmental applications.

    PubMed

    Tuček, Jiří; Kemp, Kingsley Christian; Kim, Kwang Soo; Zbořil, Radek

    2014-08-26

    Owing to the three different orbital hybridizations carbon can adopt, the existence of various carbon nanoallotropes differing also in dimensionality has been already affirmed with other structures predicted and expected to emerge in the future. Despite numerous unique features and applications of 2D graphene, 1D carbon nanotubes, or 0D fullerenes, nanodiamonds, and carbon quantum dots, which have been already heavily explored, any of the existing carbon allotropes do not offer competitive magnetic properties. For challenging applications, carbon nanoallotropes are functionalized with magnetic species, especially of iron oxide nature, due to their interesting magnetic properties (superparamagnetism and strong magnetic response under external magnetic fields), easy availability, biocompatibility, and low cost. In addition, combination of iron oxides (magnetite, maghemite, hematite) and carbon nanostructures brings enhanced electrochemical performance and (photo)catalytic capability due to synergetic and cooperative effects. This work aims at reviewing these advanced applications of iron-oxide-supported nanocarbon composites where iron oxides play a diverse role. Various architectures of carbon/iron oxide nanocomposites, their synthetic procedures, physicochemical properties, and applications are discussed in details. A special attention is devoted to hybrids of carbon nanotubes and rare forms (mesoporous carbon, nanofoam) with magnetic iron oxide carriers for advanced environmental technologies. The review also covers the huge application potential of graphene/iron oxide nanocomposites in the field of energy storage, biomedicine, and remediation of environment. Among various discussed medical applications, magnetic composites of zero-dimensional fullerenes and carbon dots are emphasized as promising candidates for complex theranostics and dual magneto-fluorescence imaging.

  14. Synthesis of hybrid gold/iron oxide nanoparticles in block copolymer micelles for imaging, drug delivery and magnetic hyperthermia.

    SciTech Connect

    Kim, D.-H.; Rozhkova, E. A.; Rajh, T.; Bader, S. D.; Novosad, V.

    2009-10-01

    In our study, hybrid gold/iron oxide loaded thermoresponsive micelles were synthesized for combined hyperthermia and chemotherapy, and optical imaging. Polymeric micelles made of amphiphilic block copolymer of poly(N-isopropylacrylamide-co-acrylamide)-block-poly({var_epsilon}-caprolactone) were conjugated with gold/iron oxide particles which are self-assembled at the hydrophobic polymer core. Thermal sensitivity and magnetic and optical properties of the hybrid gold/iron oxide micelles were investigated for the combined therapy and optical imaging.

  15. Effect of iron oxide loading on the phase transformation and physicochemical properties of nanosized mesoporous ZrO{sub 2}

    SciTech Connect

    Basahel, S.N.; Ali, Tarek T.; Narasimharao, K.; Bagabas, A.A.; Mokhtar, M.

    2012-11-15

    Highlights: ► Modified preparation method for nanosized iron oxide supported ZrO{sub 2} catalysts. ► Systematic study of effect of high iron oxide loading over ZrO{sub 2}. ► Influence of iron oxide on the stabilization of tetragonal ZrO{sub 2} phase. ► A mesoporous nature of zirconia changed upon changing iron oxide loading. ► Surface to bulk migration of iron oxide evidenced by XPS technique. -- Abstract: Mesoporous ZrO{sub 2}-supported iron oxide materials were prepared with nominal loadings of iron oxide of 5, 10, 15 and 20 wt.% using a modified co-precipitation method. The physicochemical properties of the catalysts were characterized by thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy, N{sub 2} adsorption, X-ray photoelectron spectroscopy and infrared spectroscopy methods. A delay in the ZrO{sub 2} phase transformation as a result of the incorporation of iron was determined using TG/DSC measurements. XRD, Raman spectroscopy and HRTEM results revealed that an increase of iron oxide loading from 5 to 15 wt.% enhanced the transformation of the monoclinic to tetragonal phase. Unexpectedly, 20 wt.% iron oxide loading was required for complete tetragonal structure stabilization due to the mesoporosity of the ZrO{sub 2} support. Iron oxide loadings from 5 to 15 wt.% showed an increase in the BET-surface area due to the presence of amorphous iron oxide on the surface. XPS and FTIR results indicated that increasing the iron oxide content to 20 wt.% resulted in stabilization of the tetragonal zirconia phase as a result of surface-to-bulk migration and incorporation of Fe{sup 3+} ions in the ZrO{sub 2} lattice.

  16. Chemical synthesis and assembly of uniformly sized iron oxide nanoparticles for medical applications.

    PubMed

    Ling, Daishun; Lee, Nohyun; Hyeon, Taeghwan

    2015-05-19

    Magnetic iron oxide nanoparticles have been extensively investigated for their various biomedical applications including diagnostic imaging, biological sensing, drug, cell, and gene delivery, and cell tracking. Recent advances in the designed synthesis and assembly of uniformly sized iron oxide nanoparticles have brought innovation in the field of nanomedicine. This Account provides a review on the recent progresses in the controlled synthesis and assembly of uniformly sized iron oxide nanoparticles for medical applications. In particular, it focuses on three topics: stringent control of particle size during synthesis via the "heat-up" process, surface modification for the high stability and biocompatibility of the nanoparticles for diagnostic purposes, and assembly of the nanoparticles within polymers or mesoporous silica matrices for theranostic applications. Using extremely small 3 nm sized iron oxide nanoparticles (ESION), a new nontoxic T1 MRI contrast agent was realized for high-resolution MRI of blood vessels down to 0.2 mm. Ferrimagnetic iron oxide nanoparticles (FION) that are larger than 20 nm exhibit extremely large magnetization and coercivity values. The cells labeled with FIONs showed very high T2 contrast effect so that even a single cell can be readily imaged. Designed assembly of iron oxide nanoparticles with mesoporous silica and polymers was conducted to fabricate multifunctional nanoparticles for theranostic applications. Mesoporous silica nanoparticles are excellent scaffolds for iron oxide nanoparticles, providing magnetic resonance and fluorescence imaging modalities as well as the functionality of the drug delivery vehicle. Polymeric ligands could be designed to respond to various biological stimuli such as pH, temperature, and enzymatic activity. For example, we fabricated tumor pH-sensitive magnetic nanogrenades (termed PMNs) composed of self-assembled iron oxide nanoparticles and pH-responsive ligands. They were utilized to visualize

  17. Dominance of Ferritrophicum populations at an AMD site with rapid iron oxidation

    NASA Astrophysics Data System (ADS)

    Grettenberger, C.; Pearce, A.; Bibby, K. J.; Burgos, W.; Jones, D. S.; Macalady, J.

    2015-12-01

    Acid mine drainage is a major environmental problem affecting watersheds across the globe. Bioremediation of AMD relies on microbial communities to oxidize and thus remove iron from the system. Iron-oxidation rates in AMD environments are highly variable across sites. At Scalp Level Run in Summerset County PA, iron-oxidation rates are five to eight times faster than other coal-associated AMD sites. We examined the microbial community at Scalp Level Run to determine whether a unique microbial community may be responsible for the observed rapid iron-oxidation rates. Using MiSeq sequence tags, 16S rRNA gene clone libraries, and fluorescence in situ hybridization, we found that Scalp Level Run sediments host microbial populations closely related to the betaproteobacterium Ferritrophicum radicicola, an iron-oxidizing species isolated from an acid mine drainage wetland in Virginia. Ferritrophicum spp. was not found at the four other coal-associated AMD sites in the study and is uncommon in the published literature. The influence of Ferritrophicum spp. populations in biogeochemical cycling, specifically their role in determining the iron-oxidation rate at Scalp Level Run is unknown. Therefore, we employed metagenomic sequencing to examine the metabolic potential of the microbial community at Scalp Level Run.

  18. Biomedical microdevices synthesis of iron oxide nanoparticles using a microfluidic system.

    PubMed

    Lee, Wen-Bin; Weng, Chen-Hsun; Cheng, Fong-Yu; Yeh, Chen-Sheng; Lei, Huan-Yao; Lee, Gwo-Bin

    2009-02-01

    The preparation of nanoparticles is essential in the application of many nanotechnologies and various preparation methods have been explored in the previous decades. Among them, iron oxide nanoparticles have been widely investigated in applications ranging from bio-imaging to bio-sensing due to their unique magnetic properties. Recently, microfluidic systems have been utilized for synthesis of nanoparticles, which have the advantages of automation, well-controlled reactions, and a high particle uniformity. In this study, a new microfluidic system capable of mixing, transporting and reacting was developed for the synthesis of iron oxide nanoparticles. It allowed for a rapid and efficient approach to accelerate and automate the synthesis of the iron oxide nanoparticles as compared with traditional methods. The microfluidic system uses micro-electro-mechanical-system technologies to integrate a new double-loop micromixer, two micropumps, and a microvalve on a single chip. When compared with large-scale synthesis systems with commonly-observed particle aggregation issues, successful synthesis of dispersed and uniform iron oxide nanoparticles has been observed within a shorter period of time (15 min). It was found that the size distribution of these iron oxide nanoparticles is superior to that of the large-scale systems without requiring any extra additives or heating. The size distribution had a variation of 16%. This is much lower than a comparable large-scale system (34%). The development of this microfluidic system is promising for the synthesis of nanoparticles for many future biomedical applications.

  19. Removal of arsenic(V) from aqueous solutions using iron-oxide-coated modified activated carbon.

    PubMed

    Zhang, Q L; Gao, Nai-Yun; Lin, Y C; Xu, Bin; Le, Lin-sheng

    2007-08-01

    Removal of arsenic(V) from aqueous solutions was evaluated with the following three different sorption materials: coal-based activated carbon 12 x 40 (activated carbon), iron(II) oxide (FeO)/activated carbon-H, and iron oxide. The apparent characteristics and physical chemistry performances of these adsorbents were investigated by X-ray diffraction, nitrogen adsorption, and scanning electronic microscope. Also, batch experiments for arsenic removal were performed, and the effects of pH value on arsenic(V) removal were studied. The results suggest that the main phases of the iron oxide surface are magnetite, maghemite, hematite, and goethite; fine and uniform iron oxide particles can cover activated carbon surfaces and affect the surface area or pore structures of activated carbon; adsorption kinetics obey a pseudo-first-order rate equation; and adsorption capacities of adsorbents are affected by the values of pH. The optimum value of pH for iron oxide lies in a narrow range between 4.0 and 5.5, and arsenic(V) removal by FeO/activated carbon-H is ideal and stable in the pH range 3 to 7, while activated carbon has the lowest adsorption capacity in the entire pH range. Also, the adsorption characteristics of FeO/activated carbon-H composites and virgin activated carbon match well the Langmuir adsorption model, while those of iron oxide fit well the Freundlich adsorption model.

  20. Preparation and characterization of thermosensitive PNIPAA-coated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Shengmao; Zhang, Linna; He, Benfang; Wu, Zhishen

    2008-08-01

    A new and facile approach was established to fabricate thermoresponsive poly(N-isopropylacrylamide) (PNIPAA) coated iron oxide nanoparticles in a non-aqueous medium. The morphology and structure of the nanoparticle-doped composite were analyzed by means of transmission electron microscopy (TEM), x-ray powder diffraction (XRD), and Fourier transformation infrared spectrometry (FTIR). The thermosensitivity of the composite was also investigated. Results indicated that the oil-soluble iron oxide nanoparticles encapsulated with PNIPAA, composed of an inorganic iron oxide core and biocompatible PNIPAA shell, were dispersed well in water and had a sphere-like shape. The PNIPAA-coated iron oxide nanoparticles with such a kind of core-shell structure showed excellent thermosensitivity. Namely, the aqueous suspension of PNIPAA-coated iron oxide nanoparticles dramatically changed from transparent to opaque as the temperature increased from room temperature to 38 °C, showing potential as optical transmittance switch materials and their significance in the fields of protein adsorption and purification controlled release, and drug delivery.

  1. Gene Expression Profiling Reveals Early Cellular Responses to Intracellular Magnetic Labeling with Superparamagnetic Iron Oxide Nanoparticles

    PubMed Central

    Kedziorek, Dorota A.; Muja, Naser; Walczak, Piotr; Ruiz-Cabello, Jesus; Gilad, Assaf A.; Jie, Chunfa C.; Bulte, Jeff W. M.

    2010-01-01

    With MRI (stem) cell tracking having entered the clinic, studies on the cellular genomic response toward labeling are warranted. Gene expression profiling was applied to C17.2 neural stem cells following superparamagnetic iron oxide/PLL (poly-L-lysine) labeling over the course of 1 week. Relative to unlabeled cells, less than 1% of genes (49 total) exhibited greater than 2-fold difference in expression in response to superparamagnetic iron oxide/PLL labeling. In particular, transferrin receptor 1 (Tfrc) and heme oxygenase 1 (Hmox1) expression was downregulated early, whereas genes involved in lysosomal function (Sulf1) and detoxification (Clu, Cp, Gstm2, Mgst1) were upregulated at later time points. Relative to cells treated with PLL only, cells labeled with superparamagnetic iron oxide/PLL complexes exhibited differential expression of 1399 genes. Though these differentially expressed genes exhibited altered expression over time, the overall extent was limited. Gene ontology analysis of differentially expressed genes showed that genes encoding zinc-binding proteins are enriched after superparamagnetic iron oxide/PLL labeling relative to PLL only treatment, whereas members of the apoptosis/ programmed cell death pathway did not display increased expression. Overexpression of the differentially expressed genes Rnf138 and Abcc4 were confirmed by quantitative real-time polymerase chain reaction. These results demonstrate that, although early reactions responsible for iron homeostasis are induced, overall neural stem cell gene expression remains largely unaltered following superparamagnetic iron oxide/PLL labeling. PMID:20373404

  2. Enhanced Yields of Iron-Oxidizing Bacteria by In Situ Electrochemical Reduction of Soluble Iron in the Growth Medium

    PubMed Central

    Blake, Robert C.; Howard, Gary T.; McGinness, Stephen

    1994-01-01

    An electrochemical apparatus for culturing chemolithotrophic bacteria that respire aerobically on ferrous ions is described. Enhanced yields of the bacteria were achieved by the in situ electrochemical reduction of soluble iron in the growth medium. When subjected to a direct current of 30 A for 60 days, a 45-liter culture of Thiobacillus ferrooxidans grew from 6 × 107 to 9.5 × 109 cells per ml. Growth of the bacterium within the electrolytic bioreactor was linear with time. A final cell density corresponding to 4.7 g of wet cell paste per liter was achieved, and a total of 320 g of wet cell paste was harvested from one culture. The apparatus was designed to deliver protons concomitantly with electrons; therefore, the pH of the culture remained stable at 1.6 ± 0.1 for the duration of growth. This laboratory-scale apparatus may be readily adapted to pilot or production scale. It is thus anticipated that abundant numbers of iron-oxidizing bacteria may be obtained for both fundamental and applied studies. PMID:16349344

  3. In situ affinity purification of his-tagged protein A from Bacillus megaterium cultivation using recyclable superparamagnetic iron oxide nanoparticles.

    PubMed

    Gädke, Johannes; Kleinfeldt, Lennart; Schubert, Chris; Rohde, Manfred; Biedendieck, Rebekka; Garnweitner, Georg; Krull, Rainer

    2017-01-20

    This paper discusses the use of recyclable functionalized nanoparticles for an improved downstream processing of recombinant products. The Gram-positive bacterium Bacillus megaterium was used to secrete recombinant protein A fused to a histidine tag into the culture supernatant in shaker flasks. Superparamagnetic iron oxide nanoparticles functionalized with 3-glycidoxypropyl-trimethoxysilane-coupled-nitrilotriacetic-acid groups (GNTA-SPION) were synthesized and added directly to the growing culture. After 10min incubation time, >85% of the product was adsorbed onto the particles. The particles were magnetically separated using handheld neodymium magnets and the product was eluted. The GNTA-SPION were successfully regenerated and reused in five consecutive cycles. In the one-step purification, the purity of the product reached >99.9% regarding protein A. A very low particle concentration of 0.5g/L was sufficient for effective product separation. Bacterial growth was not influenced negatively by this concentration. Particle analysis showed similar properties between freshly synthesized and regenerated GNTA-SPION. The overall process efficiency was however influenced by partial disintegration of particle agglomerates and thus loss of particles. The demonstration of very fast in situ product removal from growing bacterial culture combined with a very high product purity within one step shows possibilities for automated large scale purification combined with recycling of biomass.

  4. Ligand-Enhanced Abiotic Iron Oxidation and the Effects of Chemical versus Biological Iron Cycling in Anoxic Environments

    PubMed Central

    2013-01-01

    This study introduces a newly isolated, genetically tractable bacterium (Pseudogulbenkiania sp. strain MAI-1) and explores the extent to which its nitrate-dependent iron-oxidation activity is directly biologically catalyzed. Specifically, we focused on the role of iron chelating ligands in promoting chemical oxidation of Fe(II) by nitrite under anoxic conditions. Strong organic ligands such as nitrilotriacetate and citrate can substantially enhance chemical oxidation of Fe(II) by nitrite at circumneutral pH. We show that strain MAI-1 exhibits unambiguous biological Fe(II) oxidation despite a significant contribution (∼30–35%) from ligand-enhanced chemical oxidation. Our work with the model denitrifying strain Paracoccus denitrificans further shows that ligand-enhanced chemical oxidation of Fe(II) by microbially produced nitrite can be an important general side effect of biological denitrification. Our assessment of reaction rates derived from literature reports of anaerobic Fe(II) oxidation, both chemical and biological, highlights the potential competition and likely co-occurrence of chemical Fe(II) oxidation (mediated by microbial production of nitrite) and truly biological Fe(II) oxidation. PMID:23402562

  5. Biogenic Fabrication of Iron/Iron Oxide Nanoparticles and Their Application

    NASA Astrophysics Data System (ADS)

    Siddiqi, Khwaja Salahuddin; ur Rahman, Aziz; Tajuddin; Husen, Azamal

    2016-11-01

    Enshrined in this review are the biogenic fabrication and applications of coated and uncoated iron and iron oxide nanoparticles. Depending on their magnetic properties, they have been used in the treatment of cancer, drug delivery system, MRI, and catalysis and removal of pesticides from potable water. The polymer-coated iron and iron oxide nanoparticles are made biocompatible, and their slow release makes them more effective and lasting. Their cytotoxicity against microbes under aerobic/anaerobic conditions has also been discussed. The magnetic moment of superparamagnetic iron oxide nanoparticles changes with their interaction with biomolecules as a consequence of which their size decreases. Their biological efficacy has been found to be dependent on the shape, size, and concentration of these nanoparticles.

  6. Preparation and characterization of an iron oxide-hydroxyapatite nanocomposite for potential bone cancer therapy.

    PubMed

    Sneha, Murugesan; Sundaram, Nachiappan Meenakshi

    2015-01-01

    Recently, multifunctional magnetic nanostructures have been found to have potential applications in biomedical and tissue engineering. Iron oxide nanoparticles are biocompatible and have distinctive magnetic properties that allow their use in vivo for drug delivery and hyperthermia, and as T2 contrast agents for magnetic resonance imaging. Hydroxyapatite is used frequently due to its well-known biocompatibility, bioactivity, and lack of toxicity, so a combination of iron oxide and hydroxyapatite materials could be useful because hydroxyapatite has better bone-bonding ability. In this study, we prepared nanocomposites of iron oxide and hydroxyapatite and analyzed their physicochemical properties. The results suggest that these composites have superparamagnetic as well as biocompatible properties. This type of material architecture would be well suited for bone cancer therapy and other biomedical applications.

  7. Reversible immobilization of invertase on Cu-chelated polyvinylimidazole-grafted iron oxide nanoparticles.

    PubMed

    Uzun, Kerem; Çevik, Emre; Şenel, Mehmet; Baykal, Abdülhadi

    2013-12-01

    Polyvinylimidazole (PVI)-grafted iron oxide nanoparticles (PVIgMNP) were prepared by grafting of telomere of PVI on the iron oxide nanoparticles. Different metal ions (Cu(2+), Zn(2+), Cr(2+), Ni(2+)) ions were chelated on polyvinylimidazole-grafted iron oxide nanoparticles, and then the metal-chelated magnetic particles were used in the adsorption of invertase. The maximum invertase immobilization capacity of the PVIgMNP-Cu(2+) beads was observed to be 142.856 mg/g (invertase/PVIgMNP) at pH 5.0. The values of the maximum reaction rate (V max) and Michaelis-Menten constant (Km) were determined for the free and immobilized enzymes. The enzyme adsorption-desorption studies, pH effect on the adsorption efficiency, affinity of different metal ions, the kinetic parameters and storage stability of free and immobilized enzymes were evaluated.

  8. Decolorization of black liquor from bioethanol G2 production using iron oxide coating sands

    NASA Astrophysics Data System (ADS)

    Barlianti, Vera; Triwahyuni, Eka; Waluyo, Joko; Sari, Ajeng Arum

    2017-01-01

    Bioethanol G2 production using oil palm empty fruit bunch as raw material consists of four steps, namely pretreatment, hydrolysis, fermentation, and purification process. Pretreatment process generates black liquor that causes serious environmental pollution if it is released to the environment. The objective of this research is studying the ability of iron oxide coating sands to adsorb the color of black liquor. The iron oxide coating sands were synthesized from FeCl3.6H2O with quartz sands as support material. This research was conducted on batch mode using black liquor in various pH values. Result obtained that kind of iron oxide on quartz sands's surface was goethite. The result also indicated decreasing of color intensity of black liquor after adsorption process. This research supports local material utilization in environmental technology development to solve some environmental problems.

  9. Defective iron-oxide nanoparticles synthesised by high temperature plasma processing: a magnetic characterisation versus temperature

    NASA Astrophysics Data System (ADS)

    Balasubramanian, C.; Joseph, B.; Orpe, PB; Saini, NL; Mukherjee, S.; Dziedzic-Kocurek, K.; Stanek, J.; Di Gioacchino, D.; Marcelli, A.

    2016-11-01

    Magnetic properties and phase compositions of iron-oxide nanoparticles synthesised by a high temperature arc plasma route have been investigated by Mössbauer spectroscopy and high harmonic magnetic AC susceptibility measurements, and correlated with morphological and structural properties for different synthesis conditions. The Mössbauer spectra precisely determined the presence of different iron-oxide fractions in the investigated nanoparticles, while the high harmonic magnetic susceptibility measurements revealed the occurrence of metastable magnetic phases evolving in temperature and time. This study illustrates magnetic properties and dynamics of the magnetic configurations of iron-oxide nanoparticles grown by high temperature plasma, a process less explored so far but extremely useful for synthesising large numbers of nanoparticles for industrial applications.

  10. Influence of Fe(2+)-catalysed iron oxide recrystallization on metal cycling.

    PubMed

    Latta, Drew E; Gorski, Christopher A; Scherer, Michelle M

    2012-12-01

    Recent work has indicated that iron (oxyhydr-)oxides are capable of structurally incorporating and releasing metals and nutrients as a result of Fe2+-induced iron oxide recrystallization. In the present paper, we briefly review the current literature examining the mechanisms by which iron oxides recrystallize and summarize how recrystallization affects metal incorporation and release. We also provide new experimental evidence for the Fe2+-induced release of structural manganese from manganese-doped goethite. Currently, the exact mechanism(s) for Fe2+-induced recrystallization remain elusive, although they are likely to be both oxide-and metal-dependent. We conclude by discussing some future research directions for Fe2+-catalysed iron oxide recrystallization.

  11. Iron Oxides from Volcanic Soils as Potential Catalysts in the Water Gas Shift Reaction

    SciTech Connect

    Pizarro, C.; Escudey, M.; Moya, S.A.; Fabris, J.D.

    2005-04-26

    This study was focused on changes of the iron oxide mineralogy with temperature of two Chilean soils (Andisol and Ultisol) derived from volcanic materials and their use as iron-based catalysts in the water gas shift reaction (WGSR). Ultisol materials produced about twice as much hydrogen than did those from Andisol upon WGSR, but in both cases hydrogen yielding increased as the heating temperature of the soil materials increased from 124 deg. C to 500 deg. C. The room temperature Moessbauer spectra showed an increase of the relative proportion of the magnetically ordered components as temperature increased. Higher heating temperature produced a negative effect on the catalytic activity, whereas the organic matter destruction led to a positive effect, due to an increasing exposition of the iron oxide surfaces; heating the soil sample at 600 deg. C induced changes on the iron oxide mineralogy with a significant decrease of the catalytic activity.

  12. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    SciTech Connect

    Ngoi, Kuan Hoon; Chia, Chin-Hua Zakaria, Sarani; Chiu, Wee Siong

    2015-09-25

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.

  13. Size- and composition-dependent radio frequency magnetic permeability of iron oxide nanocrystals.

    PubMed

    Yun, Hongseok; Liu, Xiyu; Paik, Taejong; Palanisamy, Duraivelan; Kim, Jungkwun; Vogel, William D; Viescas, Arthur J; Chen, Jun; Papaefthymiou, Georgia C; Kikkawa, James M; Allen, Mark G; Murray, Christopher B

    2014-12-23

    We investigate the size- and composition-dependent ac magnetic permeability of superparamagnetic iron oxide nanocrystals for radio frequency (RF) applications. The nanocrystals are obtained through high-temperature decomposition synthesis, and their stoichiometry is determined by Mössbauer spectroscopy. Two sets of oxides are studied: (a) as-synthesized magnetite-rich and (b) aged maghemite nanocrystals. All nanocrystalline samples are confirmed to be in the superparamagnetic state at room temperature by SQUID magnetometry. Through the one-turn inductor method, the ac magnetic properties of the nanocrystalline oxides are characterized. In magnetite-rich iron oxide nanocrystals, size-dependent magnetic permeability is not observed, while maghemite iron oxide nanocrystals show clear size dependence. The inductance, resistance, and quality factor of hand-wound inductors with a superparamagnetic composite core are measured. The superparamagnetic nanocrystals are successfully embedded into hand-wound inductors to function as inductor cores.

  14. Gold nanotriangles decorated with superparamagnetic iron oxide nanoparticles: a compositional and microstructural study

    DOE PAGES

    Hachtel, J. A.; Yu, S.; Lupini, A. R.; ...

    2016-03-11

    The combination of iron oxide and gold in a single nanoparticle results in both magnetic and plasmonic properties that can stimulate novel applications in bio-sensing, medical imaging, or therapeutics. Microwave assisted heating allows the fabrication of multi-component, multi-functional nanostructures by promoting selective heating at desired sites. Recently, we reported a microwave-assisted polyol route yielding gold nanotriangles decorated with iron oxide nanoparticles. Here, we present an in-depth microstructural and compositional characterization of the system by using scanning transmission electron microscopy (STEM) and electron energy loss (EELS) spectroscopy. A method to remove the iron oxide nanoparticles from the gold nanocrystals and somemore » insights on crystal nucleation and growth mechanisms are also provided.« less

  15. Gold nanotriangles decorated with superparamagnetic iron oxide nanoparticles: a compositional and microstructural study

    SciTech Connect

    Hachtel, J. A.; Yu, S.; Lupini, A. R.; Pantelides, S. T.; Gich, M.; Laromaine, A.; Roig, A.

    2016-03-11

    The combination of iron oxide and gold in a single nanoparticle results in both magnetic and plasmonic properties that can stimulate novel applications in bio-sensing, medical imaging, or therapeutics. Microwave assisted heating allows the fabrication of multi-component, multi-functional nanostructures by promoting selective heating at desired sites. Recently, we reported a microwave-assisted polyol route yielding gold nanotriangles decorated with iron oxide nanoparticles. Here, we present an in-depth microstructural and compositional characterization of the system by using scanning transmission electron microscopy (STEM) and electron energy loss (EELS) spectroscopy. A method to remove the iron oxide nanoparticles from the gold nanocrystals and some insights on crystal nucleation and growth mechanisms are also provided.

  16. Size- and Composition-Dependent Radio Frequency Magnetic Permeability of Iron Oxide Nanocrystals

    SciTech Connect

    Yun, H; Liu, XY; Paik, T; Palanisamy, D; Kim, J; Vogel, WD; Viescas, AJ; Chen, J; Papaefthymiou, GC; Kikkawa, JM; Allen, MG; Murray, CB

    2014-12-01

    We investigate the size- and composition-dependent ac magnetic permeability of superparamagnetic iron oxide nanocrystals for radio frequency (RF) applications. The nanocrystals are obtained through high-temperature decomposition synthesis, and their stoichiometry is determined by Mossbauer spectroscopy. Two sets of oxides are studied: (a) as-synthesized magnetite-rich and (b) aged maghemite nanocrystals. All nanocrystalline samples are confirmed to be in the superparamagnetic state at room temperature by SQUID magnetometry. Through the one-turn inductor method, the ac magnetic properties of the nanocrystalline oxides are characterized. In magnetite-rich iron oxide nanocrystals, size-dependent magnetic permeability is not observed, while maghemite iron oxide nanocrystals show clear size dependence. The inductance, resistance, and quality factor of hand-wound inductors with a superparamagnetic composite core are measured. The superparamagnetic nanocrystals are successfully embedded into hand-wound inductors to function as inductor cores.

  17. Magnetic iron oxide nanoparticles as drug delivery system in breast cancer

    NASA Astrophysics Data System (ADS)

    Marcu, A.; Pop, S.; Dumitrache, F.; Mocanu, M.; Niculite, C. M.; Gherghiceanu, M.; Lungu, C. P.; Fleaca, C.; Ianchis, R.; Barbut, A.; Grigoriu, C.; Morjan, I.

    2013-09-01

    Present work was focused on producing improved iron oxide nanoparticles for targeted drug delivery in breast cancer. Nanometric-sized iron oxide particles were synthesized by laser pyrolysis and were morphologically/structurally characterized. These new nanoparticles were compared with some commercial, chemically prepared iron oxide ones. Cytotoxicity and the anti-proliferation effects of nanoparticles were tested in vitro on the breast adenocarcinoma cell line MCF-7. Nanoparticles were further coated with the antracyclinic antibiotic Violamycine B1 and tested for the anti-tumor effect on MCF-7 cells. The nanoparticles produced by us seem more effective in vitro than the commercial ones, with respect to cellular uptake and VB1 delivery. Violamycine B1 bound on nanoparticles is as efficient as the free form, but is better delivered into tumor cells.

  18. Functional Iron Oxide-Silver Hetero-Nanocomposites: Controlled Synthesis and Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Trang, Vu Thi; Tam, Le Thi; Van Quy, Nguyen; Huy, Tran Quang; Thuy, Nguyen Thanh; Tri, Doan Quang; Cuong, Nguyen Duy; Tuan, Pham Anh; Van Tuan, Hoang; Le, Anh-Tuan; Phan, Vu Ngoc

    2017-02-01

    Iron oxide-silver nanocomposites are of great interest for their antibacterial and antifungal activities. We report a two-step synthesis of functional magnetic hetero-nanocomposites of iron oxide nanoparticles and silver nanoparticles (Fe3O4-Ag). Iron oxide nanoparticles were prepared first by a co-precipitation method followed by the deposition of silver nanoparticles via a hydrothermal route. The prepared Fe3O4-Ag hetero-nanocomposites were characterized by x-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy and vibrating sample magnetometry. Their antibacterial activities were investigated by using paper-disc diffusion and direct-drop diffusion methods. The results indicate that the Fe3O4-Ag hetero-nanocomposites exhibit excellent antibacterial activities against two Gram-negative bacterial strains (Salmonella enteritidis and Klebsiella pneumoniae).

  19. The concept of delayed nucleation in nanocrystal growthdemonstrated for the case of iron oxide nanodisks

    SciTech Connect

    Casula, Maria F.; Jun, Young-wook; Zaziski, David J.; Chan, EmoryM.; Corrias, Anna; Alivisatos, Paul A.

    2005-09-09

    A comprehensive study of iron oxide nanocrystal growth through non-hydrolitic, surfactant-mediated thermal reaction of iron pentacarbonyl and an oxidizer has been conducted, which includes size control, anisotropic shape evolution, and crystallographic phase transition of monodisperse iron oxide colloidal nanocrystals. The reaction was monitored by in situ UV-Vis spectroscopy taking advantage of the color change accompanying the iron oxide colloid formation allowing measurement of the induction time for nucleation. Features of the synthesis such as the size control and reproducibility are related to the occurrence of the observed delayed nucleation process. As a separate source of iron and oxygen is adopted, phase control could also be achieved by sequential injections of oxidizer.

  20. Effect of iron oxide nanoparticles on the permeability properties of Sf21 cells.

    PubMed

    Wang, Jianye; Zhao, Gang; Shu, Zhiquan; Zhou, Ping; Cao, Yunxia; Gao, Dayong

    2016-02-01

    It was recently reported that nanoparticles could significantly modulate the thermal properties of solutions at subzero temperatures, and as a result, nanoparticles have been widely used in both cryopreservation and cryosurgery. In cryopreservation, the water permeability coefficient of cell membrane is an essential parameter for quantitative investigation of cell dehydration and intracellular ice formation. However, few studies were focused on the effects of nanoparticles on the permeability properties of cell membrane. In order to optimize the processes of cryopreservation with nanoparticles, we measured the permeability properties of Sf21 cells in the presence of iron oxide nanoparticles in this study. The responses of Sf21 cells with iron oxide nanoparticles were obtained by the microperfusion system at -2, 5, 15 and 25 °C, respectively. The osmotically inactive cell volume (Vb), the cell membrane hydraulic conductivity (Lp) and it's activation energy (ELp), and the reference value of Lp at the reference temperature (Lpg) with 0.02%, 0.1% and 0.5% (w/w) iron oxide nanoparticles were determined by 2-parameter (2-p) model at -2, 5, 15 and 25 °C. We analyzed the effects of iron oxide nanoparticles on the permeability properties of the Sf21 cells. The results indicated that iron oxide nanoparticles have a significant influence on membrane permeability properties (Lpg and ELp) of Sf21 cells. The introduction of iron oxide nanoparticles tends to increase the values of Vb and Lpg, while decrease the value of ELp. These findings may provide a new route to optimize the biomaterial cryopreservation.

  1. Iron oxide nanoparticles stabilized with dendritic polyglycerols as selective MRI contrast agents.

    PubMed

    Nordmeyer, Daniel; Stumpf, Patrick; Gröger, Dominic; Hofmann, Andreas; Enders, Sven; Riese, Sebastian B; Dernedde, Jens; Taupitz, Matthias; Rauch, Ursula; Haag, Rainer; Rühl, Eckart; Graf, Christina

    2014-08-21

    Monodisperse small iron oxide nanoparticles functionalized with dendritic polyglycerol (dPG) or dendritic polyglycerol sulfate (dPGS) are prepared. They are highly stable in aqueous solutions as well as physiological media. In particular, oleic acid capped iron oxide particles (core diameter = 11 ± 1 nm) were modified by a ligand exchange process in a one pot synthesis with dPG and dPGS bearing phosphonate as anchor groups. Dynamic light scattering measurements performed in water and different biological media demonstrate that the hydrodynamic diameter of the particles is only slightly increased by the ligand exchange process resulting in a final diameter of less than 30 nm and that the particles are stable in these media. It is also revealed by magnetic resonance studies that their magnetic relaxivity is reduced by the surface modification but it is still sufficient for high contrast magnetic resonance imaging (MRI). Additionally, incubation of dPGS functionalized iron oxide nanoparticles with human umbilical vein endothelial cells showed a 50% survival at 85 nM (concentration of nanoparticles). Surface plasmon resonance (SPR) studies demonstrate that the dPGS functionalized iron oxide nanoparticles inhibit L-selectin ligand binding whereas the particles containing only dPG do not show this effect. Experiments in a flow chamber with human myelogenous leukemia cells confirmed L-selectin inhibition of the dPGS functionalized iron oxide nanoparticles and with that the L-selectin mediated leukocyte adhesion. These results indicate that dPGS functionalized iron oxide nanoparticles are a promising contrast agent for inflamed tissue probed by MRI.

  2. Pilot scale application of nanosized iron oxides as electron acceptors for bioremediation

    NASA Astrophysics Data System (ADS)

    Bosch, Julian; Fritzsche, Andreas; Frank-Fahle, Beatrice; Lüders, Tilmann; Höss, Sebastian; Eisenmann, Heinrich; Held, Thomas; Totsche, Kai U.; Meckenstock, Rainer U.

    2014-05-01

    Microbial reduction of ferric iron is a major biogeochemical process in groundwater aquifer ecosystems and often associated with the degradation of organic contaminants, as bacteria couple iron reduction to the oxidation reduced carbon like e.g. BTEX. Yet in general the low bioavailability of natural iron oxides limits microbial reduction rates. However, nanosized iron oxides have an unequally enhanced bioavailability and reactivity compared to their respective bulk, macro-sized, and more crystalline materials. At the same time, nanosized iron oxides can be produced in stable colloidal suspensions, permitting efficient injections into contaminated aquifers. We examined the reactivity of nanosized synthetic colloidal iron oxides in microbial iron reduction. Application of colloidal nanoparticles led to a strong and sustainable enhancement of microbial reaction rates in batch experiments and sediment columns. Toluene oxidation was increased five-fold as compared to bulk, non-colloidal ferrihydrite as electron acceptor. Furthermore, we developed a unique approach for custom-tailoring the subsurface mobility of these particles after being injected into a contaminant plume. In a field pilot application, we injected 18 m3 of an iron oxide nanoparticle solution into a BTEX contaminated aquifer with a maximum excess pressure as low as 0.2 bar. The applied suspension showed a superior subsurface mobility, creating a reactive zone of 4 m height (corresponding to the height of the confined aquifer) and 6 m in diameter. Subsequent monitoring of BTEX, microbial BTEX degradation metabolites, ferrous iron generation, stable isotopes fractionation, microbial populations, and methanogenesis demonstrated the strong impact of our approach. Mathematic processed X-ray diffractograms and FTIR spectra provided a semi-quantitatively estimate of the long-term fate of the iron oxide colloids in the aquifer. Potential environmental risks of the injection itself were monitored with

  3. Bacillus acidicola sp. nov., a novel mesophilic, acidophilic species isolated from acidic Sphagnum peat bogs in Wisconsin.

    PubMed

    Albert, Richard A; Archambault, Julieta; Rosselló-Mora, Ramón; Tindall, Brian J; Matheny, Mike

    2005-09-01

    A mesophilic, acidophilic, spore-forming bacterium, strain 105-2(T), was isolated from an acidic Sphagnum peat bog in Wisconsin, USA. Strain 105-2(T) has 16S rRNA gene sequence similarity to Bacillus sporothermodurans DSM 10599(T) and Bacillus oleronius DSM 9356(T) of 97.4 and 97.8%, respectively. The primary lipoquinone is MK-7 and the major fatty acids are 15:0 iso, 15:0 anteiso and 17:0 anteiso. The predominant polar lipids were found to be diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and a glycolipid. The DNA G+C content was found to be 43.2 mol%. The phenotypic, chemotaxonomic and molecular analyses identified strain 105-2(T) as a novel Bacillus species, for which the name Bacillus acidicola is proposed. The type strain is 105-2(T) (=DSM 14745(T)=ATCC BAA-366(T)=NRRL B-23453(T)).

  4. Surprising abundance of Gallionella-related iron oxidizers in creek sediments at pH 4.4 or at high heavy metal concentrations

    PubMed Central

    Fabisch, Maria; Beulig, Felix; Akob, Denise M.; Küsel, Kirsten

    2013-01-01

    We identified and quantified abundant iron-oxidizing bacteria (FeOB) at three iron-rich, metal-contaminated creek sites with increasing sediment pH from extremely acidic (R1, pH 2.7), to moderately acidic (R2, pH 4.4), to slightly acidic (R3, pH 6.3) in a former uranium-mining district. The geochemical parameters showed little variations over the 1.5 year study period. The highest metal concentrations found in creek sediments always coincided with the lowest metal concentrations in creek water at the slightly acidic site R3. Sequential extractions of R3 sediment revealed large portions of heavy metals (Ni, Cu, Zn, Pb, U) bound to the iron oxide fraction. Light microscopy of glass slides exposed in creeks detected twisted stalks characteristic of microaerobic FeOB of the family Gallionellaceae at R3 but also at the acidic site R2. Sequences related to FeOB such as Gallionella ferruginea, Sideroxydans sp. CL21, Ferritrophicum radicicola, and Acidovorax sp. BrG1 were identified in the sediments. The highest fraction of clone sequences similar to the acidophilic “Ferrovum myxofaciens” was detected in R1. Quantitative PCR using primer sets specific for Gallionella spp., Sideroxydans spp., and “Ferrovum myxofaciens” revealed that ~72% (R2 sediment) and 37% (R3 sediment) of total bacterial 16S rRNA gene copies could be assigned to groups of FeOB with dominance of microaerobic Gallionella spp. at both sites. Gallionella spp. had similar and very high absolute and relative gene copy numbers in both sediment communities. Thus, Gallionella-like organisms appear to exhibit a greater acid and metal tolerance than shown before. Microaerobic FeOB from R3 creek sediment enriched in newly developed metal gradient tubes tolerated metal concentrations of 35 mM Co, 24 mM Ni, and 1.3 mM Cd, higher than those in sediments. Our results will extend the limited knowledge of FeOB at contaminated, moderately to slightly acidic environments. PMID:24385973

  5. Surprising abundance of Gallionella-related iron oxidizers in creek sediments at pH 4.4 or at high heavy metal concentrations

    USGS Publications Warehouse

    Fabisch, Maria; Beulig, Felix; Akob, Denise M.; Küsel, Kirsten

    2013-01-01

    We identified and quantified abundant iron-oxidizing bacteria (FeOB) at three iron-rich, metal-contaminated creek sites with increasing sediment pH from extremely acidic (R1, pH 2.7), to moderately acidic (R2, pH 4.4), to slightly acidic (R3, pH 6.3) in a former uranium-mining district. The geochemical parameters showed little variations over the 1.5 year study period. The highest metal concentrations found in creek sediments always coincided with the lowest metal concentrations in creek water at the slightly acidic site R3. Sequential extractions of R3 sediment revealed large portions of heavy metals (Ni, Cu, Zn, Pb, U) bound to the iron oxide fraction. Light microscopy of glass slides exposed in creeks detected twisted stalks characteristic of microaerobic FeOB of the family Gallionellaceae at R3 but also at the acidic site R2. Sequences related to FeOB such as Gallionella ferruginea, Sideroxydans sp. CL21, Ferritrophicum radicicola, and Acidovorax sp. BrG1 were identified in the sediments. The highest fraction of clone sequences similar to the acidophilic “Ferrovum myxofaciens” was detected in R1. Quantitative PCR using primer sets specific for Gallionella spp., Sideroxydans spp., and “Ferrovum myxofaciens” revealed that ~72% (R2 sediment) and 37% (R3 sediment) of total bacterial 16S rRNA gene copies could be assigned to groups of FeOB with dominance of microaerobic Gallionella spp. at both sites. Gallionella spp. had similar and very high absolute and relative gene copy numbers in both sediment communities. Thus, Gallionella-like organisms appear to exhibit a greater acid and metal tolerance than shown before. Microaerobic FeOB from R3 creek sediment enriched in newly developed metal gradient tubes tolerated metal concentrations of 35 mM Co, 24 mM Ni, and 1.3 mM Cd, higher than those in sediments. Our results will extend the limited knowledge of FeOB at contaminated, moderately to slightly acidic environments.

  6. Colloidal Stability and Monodispersible Magnetic Iron Oxide Nanoparticles in Biotechnology Application

    NASA Astrophysics Data System (ADS)

    Shamili, K.; Rajesh, E. M.; Rajendran, R.; Madhan Shankar, S. R.; Elango, M.; Abitha Devi, N.

    2013-02-01

    Magnetic iron oxide nanoparticles are promising material for various biological applications. In the recent decades, magnetic iron oxide nanoparticles (MNPs) have great attention in biomedical applications such as drug delivery, magnetic resonance imaging (MRI) and magnetic fluid hyperthermia (MFH). This review focuses on the colloidal stability and monodispersity properties of MNPs, which pay more attention toward biomedical applications. The simplest and the most promising method for the synthesis of MNPs is co-precipitation. The biocompatible MNPs are more interested in MRI application. This review also apportions synthesis, characterization and applications of MNP in biological and biomedical as theranostics and imaging.

  7. Doped, porous iron oxide films and their optical functions and anodic photocurrents for solar water splitting

    SciTech Connect

    Kronawitter, Coleman X.; Mao, Samuel S.; Antoun, Bonnie R.

    2011-02-28

    The fabrication and morphological, optical, and photoelectrochemical characterization of doped iron oxide films is presented. The complex index of refraction and absorption coefficient of polycrystalline films are determined through measurement and modeling of spectral transmission and reflection data using appropriate dispersion relations. Photoelectrochemical characterization for water photo-oxidation reveals that the conversion efficiencies of electrodes are strongly influenced by substrate temperature during their oblique-angle physical vapor deposition. These results are discussed in terms of the films' morphological features and the known optoelectronic limitations of iron oxide films for application in solar water splitting devices.

  8. Microbial Communities Associated with Biogenic Iron Oxide Mineralization in Circumneutral pH Environments

    NASA Astrophysics Data System (ADS)

    Chan, C. S.; Banfield, J. F.

    2002-12-01

    Lithotrophic growth on iron is a metabolism that has been found in a variety of neutral pH environments and is likely important in sustaining life in microaerophilic solutions, especially those low in organics. The composition of the microbial communities, especially the organisms that are responsible for iron oxidation, and carbon and nitrogen fixation, are not known, yet the ability to recognize these contributions is vital to our understanding of iron cycling in natural environments. Our approach has been to study the microbial community structure, mineralogy, and geochemistry of ~20 cm thick, 100's meters long, fluffy iron oxide-encrusted biological mats growing in the Piquette Mine tunnel, and to compare the results to those from geochemically similar environments. In situ measurements (Hydrolab) and geochemical characterization of bulk water samples and peepers (dialysis sampling vials) indicate that the environment is microaerobic, with micromolar levels of iron, high carbonate and sulfate, and typical groundwater nitrate and nitrite concentrations. 16S rDNA clone libraries show that the microbial mat and water contain communities with considerable diversity within the Bacterial domain, a large proportion of Nitrospira and Betaproteobacteria, and no Archaea. Because clone library data are not necessarily indicative of actual abundance, fluorescence in-situ hybridization (FISH) was performed on water, mat, and sediment samples from the Piquette mine and two circumneutral iron- and carbonate-rich springs in the Oregon Cascade Range. Domain- and phylum-level probes were chosen based on the clone library results (Nitrospira, Beta- and Gammaproteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, and Planctomyces). FISH data reveal spatial associations between specific microbial groups and mineralized structures. The organisms responsible for making the mineralized sheaths that compose the bulk of the iron oxide mat are Betaproteobacteria (probably Leptothrix

  9. Two-component magnetic structure of iron oxide nanoparticles mineralized in Listeria innocua protein cages

    NASA Astrophysics Data System (ADS)

    Usselman, Robert J.; Klem, Michael T.; Russek, Stephen E.; Young, Mark; Douglas, Trevor; Goldfarb, Ron B.

    2010-06-01

    Magnetometry was used to determine the magnetic properties of maghemite (γ-Fe2O3) nanoparticles formed within Listeria innocua protein cage. The electron magnetic resonance spectrum shows the presence of at least two magnetization components. The magnetization curves are explained by a sum of two Langevin functions in which each filled protein cage contains both a large magnetic iron oxide core plus an amorphous surface consisting of small noncoupled iron oxide spin clusters. This model qualitatively explains the observed decrease in the temperature dependent saturation moment and removes an unrealistic temperature dependent increase in the particle moment often observed in nanoparticle magnetization measurements.

  10. Catechol versus bisphosphonate ligand exchange at the surface of iron oxide nanoparticles: towards multi-functionalization

    NASA Astrophysics Data System (ADS)

    Guénin, Erwann; Lalatonne, Yoann; Bolley, Julie; Milosevic, Irena; Platas-Iglesias, Carlos; Motte, Laurence

    2014-11-01

    We report an investigation of the ligand exchange at the surface of iron oxide nanoparticles in water. For this purpose we compared two strong chelating agents on the iron oxide surface containing catechol and bisphosphonate moieties. Interactions between the coating agents (catechol/bisphosphonate) and the nanoparticle's surface were studied by FTIR and DFT calculations. Ligand exchange experiments were performed using sonication and the exchange yield was characterized by FTIR and EDX. This methodology allowed introducing bisphosphonates with various functionalities (alkyne or biotin) permitting multi-functionalization.

  11. Genomics and Metagenomics of Extreme Acidophiles in Biomining Environments

    NASA Astrophysics Data System (ADS)

    Holmes, D. S.

    2015-12-01

    Over 160 draft or complete genomes of extreme acidophiles (pH < 3) have been published, many of which are from bioleaching and other biomining environments, or are closely related to such microorganisms. In addition, there are over 20 metagenomic studies of such environments. This provides a rich source of latent data that can be exploited for understanding the biology of biomining environments and for advancing biotechnological applications. Genomic and metagenomic data are already yielding valuable insights into cellular processes, including carbon and nitrogen management, heavy metal and acid resistance, iron and sulfur oxido-reduction, linking biogeochemical processes to organismal physiology. The data also allow the construction of useful models of the ecophysiology of biomining environments and provide insight into the gene and genome evolution of extreme acidophiles. Additionally, since most of these acidophiles are also chemoautolithotrophs that use minerals as energy sources or electron sinks, their genomes can be plundered for clues about the evolution of cellular metabolism and bioenergetic pathways during the Archaean abiotic/biotic transition on early Earth. Acknowledgements: Fondecyt 1130683.

  12. Carbon monoxide hydrogenation over rhenium-iron oxide catalysts and their characterization by soft X-ray spectroscopy

    SciTech Connect

    Komlyama, M.; Tsunoda, T.; Ogino, Y.

    1986-03-01

    Rhenium-iron oxide catalysts, prepared by the conventional impregnation technique and activated by reduction under various conditions, gave higher selectivities to oxygenates (mainly alcohols) in carbon monoxide hydrogenation than the control iron oxide (magnetite) catalysts. Bulk-sensitive soft X-ray spectroscopy (SXS) along with X-ray diffraction and Mossbauer spectroscopy found that in rhenium-iron oxide catalysts iron oxide is in the form of an intermediate phase represented as (1 - x)Fe/sub 3/O/sub 4/.xFe/sub 8/3/O/sub 4/; between Fe/sub 3/O/sub 4/ and ..gamma..-Fe/sub 2//O/sub 3/. The extent of the formation of this intermediate phase was correlated with the oxygenate selectivities of the rhenium-iron oxide catalysts. The usefulness of SXS in characterizing bulk of solid catalysts was demonstrated.

  13. Magnetic and gravity gradiometry framework for Mesoproterozoic iron oxide-apatite and iron oxide-copper-gold deposits, southeast Missouri, USA

    USGS Publications Warehouse

    McCafferty, Anne E.; Phillips, Jeffrey; Driscoll, Rhonda L.

    2016-01-01

    High-resolution airborne magnetic and gravity gradiometry data provide the geophysical framework for evaluating the exploration potential of hidden iron oxide deposits in Mesoproterozoic basement rocks of southeast Missouri. The data are used to calculate mineral prospectivity for iron oxide-apatite (IOA) ± rare earth element (REE) and iron oxide-copper-gold (IOCG) deposits. Results delineate the geophysical footprints of all known iron oxide deposits and reveal several previously unrecognized prospective areas. The airborne data are also inverted to three-dimensional density and magnetic susceptibility models over four concealed deposits at Pea Ridge (IOA ± REE), Boss (IOCG), Kratz Spring (IOA), and Bourbon (IOCG). The Pea Ridge susceptibility model shows a magnetic source that is vertically extensive and traceable to a depth of greater than 2 km. A smaller density source, located within the shallow Precambrian basement, is partly coincident with the magnetic source at Pea Ridge. In contrast, the Boss models show a large (625-m-wide), vertically extensive, and coincident dense and magnetic stock with shallower adjacent lobes that extend more than 2,600 m across the shallow Precambrian paleosurface. The Kratz Spring deposit appears to be a smaller volume of iron oxides and is characterized by lower density and less magnetic rock compared to the other iron deposits. A prospective area identified south of the Kratz Spring deposit shows the largest volume of coincident dense and nonmagnetic rock in the subsurface, and is interpreted as prospective for a hematite-dominant lithology that extends from the top of the Precambrian to depths exceeding 2 km. The Bourbon deposit displays a large bowl-shaped volume of coincident high density and high-magnetic susceptibility rock, and a geometry that suggests the iron mineralization is vertically restricted to the upper parts of the Precambrian basement. In order to underpin the evaluation of the prospectivity and three

  14. Community Genomic and Proteomic Analyses of Chemoautotrophic Iron-Oxidizing "Leptospirillum rubarum" (Group II) and "Leptospirillum ferrodiazotrophum" (Group III) Bacteria in Acid Mine Drainage Biofilms

    SciTech Connect

    Goltsman, Daniela; Denef, Vincent; Singer, Steven; Verberkmoes, Nathan C; Lefsrud, Mark G; Mueller, Ryan; Dick, Gregory J.; Sun, Christine; Wheeler, Korin; Zelma, Adam; Baker, Brett J.; Hauser, Loren John; Land, Miriam L; Shah, Manesh B; Thelen, Michael P.; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2009-01-01

    We analyzed near-complete population (composite) genomic sequences for coexisting acidophilic iron-oxidizing Leptospirillum group II and III bacteria (phylum Nitrospirae) and an extrachromosomal plasmid from a Richmond Mine, Iron Mountain, CA, acid mine drainage biofilm. Community proteomic analysis of the genomically characterized sample and two other biofilms identified 64.6% and 44.9% of the predicted proteins of Leptospirillum groups II and III, respectively, and 20% of the predicted plasmid proteins. The bacteria share 92% 16S rRNA gene sequence identity and >60% of their genes, including integrated plasmid-like regions. The extrachromosomal plasmid carries conjugation genes with detectable sequence similarity to genes in the integrated conjugative plasmid, but only those on the extrachromosomal element were identified by proteomics. Both bacterial groups have genes for community-essential functions, including carbon fixation and biosynthesis of vitamins, fatty acids, and biopolymers (including cellulose); proteomic analyses reveal these activities. Both Leptospirillum types have multiple pathways for osmotic protection. Although both are motile, signal transduction and methyl-accepting chemotaxis proteins are more abundant in Leptospirillum group III, consistent with its distribution in gradients within biofilms. Interestingly, Leptospirillum group II uses a methyl-dependent and Leptospirillum group III a methyl-independent response pathway. Although only Leptospirillum group III can fix nitrogen, these proteins were not identified by proteomics. The abundances of core proteins are similar in all communities, but the abundance levels of unique and shared proteins of unknown function vary. Some proteins unique to one organism were highly expressed and may be key to the functional and ecological differentiation of Leptospirillum groups II and III.

  15. Community genomic and proteomic analysis of chemoautotrophic, iron-oxidizing "Leptospirillum rubarum" (Group II) and Leptospirillum ferrodiazotrophum (Group III) in acid mine drainage biofilms

    SciTech Connect

    Goltsman, Daniela; Denef, Vincent; Singer, Steven; Verberkmoes, Nathan C; Lefsrud, Mark G; Mueller, Ryan; Dick, Gregory J.; Sun, Christine; Wheeler, Korin; Zelma, Adam; Baker, Brett J.; Hauser, Loren John; Land, Miriam L; Shah, Manesh B; Thelen, Michael P.; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2009-01-01

    We analyzed near-complete population (composite) genomic sequences for coexisting acidophilic iron-oxidizing Leptospirillum Groups II and III bacteria (phylum Nitrospirae) and an extrachromosomal plasmid from a Richmond Mine, CA acid mine drainage (AMD) biofilm. Community proteomic analysis of the genomically characterized sample and two other biofilms identified 64.6% and 44.9% of the predicted proteins of Leptospirillum Groups II and III, respectively and 20% of the predicted plasmid proteins. The bacteria share 92% 16S rRNA gene sequence identity and > 60% of their genes, including integrated plasmid-like regions. The extrachromosomal plasmid encodes conjugation genes with detectable sequence similarity to genes in the integrated conjugative plasmid, but only those on the extrachromosomal element were identified by proteomics. Both bacteria have genes for community-essential functions, including carbon fixation, biosynthesis of vitamins, fatty acids and biopolymers (including cellulose); proteomic analyses reveal these activities. Both Leptospirillum types have multiple pathways for osmotic protection. Although both are motile, signal transduction and methyl-accepting chemotaxis proteins are more abundant in Leptospirillum Group III, consistent with its distribution in gradients within biofilms. Interestingly, Leptospirillum Group II uses a methyl-dependent and Leptospirillum Group III a methyl-independent response pathway. Although only Leptospirillum Group III can fix nitrogen, these proteins were not identified by proteomics. Abundances of core proteins are similar in all communities, but abundance levels of unique and shared proteins of unknown function vary. Some proteins unique to one organism were highly expressed and may be key to the functional and ecological differentiation of Leptospirillum Groups II and III.

  16. Plasmon bleaching dynamics in colloidal gold-iron oxide nanocrystal heterodimers.

    PubMed

    Comin, Alberto; Korobchevskaya, Kseniya; George, Chandramohan; Diaspro, Alberto; Manna, Liberato

    2012-02-08

    Colloidal nanocrystal heterodimers composed of a plasmonic and a magnetic domain have been widely studied as potential materials for various applications in nanomedicine, biology, and photocatalysis. One of the most popular nanocrystal heterodimers is represented by a structure made of a Au domain and a iron oxide domain joined together. Understanding the nature of the interface between the two domains in such type of dimer and how this influences the energy relaxation processes is a key issue. Here, we present the first broad-band transient absorption study on gold/iron oxide nanocrystal heterodimers that explains how the energy relaxation is affected by the presence of such interface. We found faster electron-electron and electron-phonon relaxation times for the gold "nested" in the iron oxide domain in the heterodimers with respect to gold "only" nanocrystals, that is, free-standing gold nanocrystals in solution. We relate this effect to the decreased electron screening caused by spill-out of the gold electron distribution at gold/iron oxide interface.

  17. Spectral characteristics of the iron oxides with application to the Martian bright region mineralogy

    NASA Technical Reports Server (NTRS)

    Sherman, D. M.; Burns, R. G.; Mee Burns, V.

    1982-01-01

    Reflectance spectra of eight polymorphs of FeOOH and Fe2O3 are determined in order to clarify the nature and significance of the iron oxide mineralogy on Mars. The effect of other components that might interfere with iron oxide absorption features is qualitatively constrained through the use of the Kebulka-Munk theory. It is found that the effect of temperature complicates the identification of a given Fe(3+) phase based on the position of the 6A1-4T1 absorption feature. While the Fe(3+) crystal field transitions are spin forbidden, most of the iron oxide polymorphs exhibit anomalously intense crystal field absorption features due to magnetic coupling between adjacent FeO6 octahedra. It is suggested that the resulting deviations from observed remotely sensed reflectance spectra of Mars may provide a basis for the exclusion of many iron oxide phases as significant components of the Martian Fe(3+) mineralogy. A comparison of these results with the visible region spectra of Martian bright regions indicates that the predominant Fe(3+)-bearing phase may be a magnetically disordered material, such as amorphous gels, some ferric sulphates, and other minerals in which Fe(3+) ions in the crystal structure are not magnetically coupled.

  18. Thermal and magnetic properties of iron oxide colloids: influence of surfactants

    NASA Astrophysics Data System (ADS)

    Soares, Paula I. P.; Lochte, Frederik; Echeverria, Coro; Pereira, Laura C. J.; Coutinho, Joana T.; Ferreira, Isabel M. M.; Novo, Carlos M. M.; Borges, João P. M. R.

    2015-10-01

    Iron oxide nanoparticles (NPs) have been extensively studied in the last few decades for several biomedical applications such as magnetic resonance imaging, magnetic drug delivery and hyperthermia. Hyperthermia is a technique used for cancer treatment which consists in inducing a temperature of about 41-45 °C in cancerous cells through magnetic NPs and an external magnetic field. Chemical precipitation was used to produce iron oxide NPs 9 nm in size coated with oleic acid and trisodium citrate. The influence of both stabilizers on the heating ability and in vitro cytotoxicity of the produced iron oxide NPs was assessed. Physicochemical characterization of the samples confirmed that the used surfactants do not change the particles’ average size and that the presence of the surfactants has a strong effect on both the magnetic properties and the heating ability. The heating ability of Fe3O4 NPs shows a proportional increase with the increase of iron concentration, although when coated with trisodium citrate or oleic acid the heating ability decreases. Cytotoxicity assays demonstrated that both pristine and trisodium citrate Fe3O4 samples do not reduce cell viability. However, oleic acid Fe3O4 strongly reduces cell viability, more drastically in the SaOs-2 cell line. The produced iron oxide NPs are suitable for cancer hyperthermia treatment and the use of a surfactant brings great advantages concerning the dispersion of NPs, also allowing better control of the hyperthermia temperature.

  19. Identification of a membrane cytochrome c from neutrophilic, iron-oxidizing Mariprofundus ferrooxydans, strain PV-1

    NASA Astrophysics Data System (ADS)

    Barco, R. A.; Zhong, J.; Ramirez, G. A.; Reese, B. K.; Edwards, K. J.

    2012-12-01

    Neutrophilic-iron oxidizing bacteria (FeOB) are a group of bacteria that can oxidize iron at -or near neutral pH, making them relevant in habitats with naturally high levels of reduced iron (i.e. Fe2+) such as hydrothermal vents. In the ocean, microorganisms in the Mariprofundus genus (zeta- Proteobacteria) are the only known organisms to chemolithoautotrophically oxidize iron. In order to identify the active bacterial oxidation of iron in the environment (i.e. in the deep biosphere), biomarkers for this functionality are needed. The aim of this study is to confirm the expression of potential functional biomarkers that are diagnostic of neutrophilic bacterial iron-oxidation. To this end, Mariprofundus ferrooxydans, strain PV-1 was cultivated in large batches and its proteins extracted via a methodology to circumvent protein binding to filamentous material. Proteins were assayed for redox-activity and for iron-oxidation activity. The bands of the gel that showed activity were analyzed via LC-MS/MS for identification of peptides and subsequently protein-matched to the M. ferrooxydans proteome database. The results indicate that a membrane cytochrome c with homology to the iron-oxidizing Cyt572 from Leptospirillum Group II is expressed in M. ferrooxydans when it is active. Other proteins associated with the electron transport chain of M. ferroxydans such as cbb3-type cytochrome oxidase subunits were identified and validated separately through reverse transcription followed by PCR amplification.

  20. Application of novel iron core/iron oxide shell nanoparticles to sentinel lymph node identification

    NASA Astrophysics Data System (ADS)

    Cousins, Aidan; Howard, Douglas; Henning, Anna M.; Nelson, Melanie R. M.; Tilley, Richard D.; Thierry, Benjamin

    2015-12-01

    Current `gold standard' staging of breast cancer and melanoma relies on accurate in vivo identification of the sentinel lymph node. By replacing conventional tracers (dyes and radiocolloids) with magnetic nanoparticles and using a handheld magnetometer probe for in vivo identification, it is believed the accuracy of sentinel node identification in nonsuperficial cancers can be improved due to increased spatial resolution of magnetometer probes and additional anatomical information afforded by MRI road-mapping. By using novel iron core/iron oxide shell nanoparticles, the sensitivity of sentinel node mapping via MRI can be increased due to an increased magnetic saturation compared to traditional iron oxide nanoparticles. A series of in vitro magnetic phantoms (iron core vs. iron oxide nanoparticles) were prepared to simulate magnetic particle accumulation in the sentinel lymph node. A novel handheld magnetometer probe was used to measure the relative signals of each phantom, and determine if clinical application of iron core particles can improve in vivo detection of the sentinel node compared to traditional iron oxide nanoparticles. The findings indicate that novel iron core nanoparticles above a certain size possess high magnetic saturation, but can also be produced with low coercivity and high susceptibility. While some modification to the design of handheld magnetometer probes may be required for particles with large coercivity, use of iron core particles could improve MRI and magnetometer probe detection sensitivity by up to 330 %.

  1. Expeditious organic–free assembly: morphologically controlled synthesis of iron oxides using microwaves

    EPA Science Inventory

    A microwave hydrothermal method is developed for the synthesis of iron oxides, α-Fe2O3, β-FeOOH, and the junction of α-Fe2O3–β-FeOOH. This method is absolutely organic-free, and various structures could be obtained simply by changing th...

  2. Biocompatible Colloidal Suspensions Based on Magnetic Iron Oxide Nanoparticles: Synthesis, Characterization and Toxicological Profile

    PubMed Central

    Coricovac, Dorina-Elena; Moacă, Elena-Alina; Pinzaru, Iulia; Cîtu, Cosmin; Soica, Codruta; Mihali, Ciprian-Valentin; Păcurariu, Cornelia; Tutelyan, Victor A.; Tsatsakis, Aristidis; Dehelean, Cristina-Adriana

    2017-01-01

    The use of magnetic iron oxide nanoparticles in biomedicine has evolved intensely in the recent years due to the multiple applications of these nanomaterials, mainly in domains like cancer. The aim of the present study was: (i) to develop biocompatible colloidal suspensions based on magnetic iron oxide nanoparticles as future theranostic tools for skin pathology and (ii) to test their effects in vitro on human keratinocytes (HaCat cells) and in vivo by employing an animal model of acute dermal toxicity. Biocompatible colloidal suspensions were obtained by coating the magnetic iron oxide nanoparticles resulted during the solution combustion synthesis with a double layer of oleic acid, as innovative procedure in increasing bioavailability. The colloidal suspensions were characterized in terms of dynamic light scattering (DLS) and transmission electron microscopy (TEM). The in vitro effects of these suspensions were tested by means of Alamar blue assay and the noxious effects at skin level were measured using non-invasive methods. The in vitro results indicated a lack of toxicity on normal human cells induced by the iron oxide nanoparticles colloidal suspensions after an exposure of 24 h to different concentrations (5, 10, and 25 μg·mL−1). The dermal acute toxicity test showed that the topical applications of the colloidal suspensions on female and male SKH-1 hairless mice were not associated with significant changes in the quality of barrier skin function.

  3. Stable Strontium Isotopic Fractionation During Sorption onto Magnetic Nano-Humid Acid Coated Iron Oxide Particles

    NASA Astrophysics Data System (ADS)

    Liu, H.-C.; You, C.-F.; Tu, Y.-J.

    2012-04-01

    The mobility of strontium (Sr) through hydrological systems is critically governed by sorption reactions of solid phases such as iron oxides and clay minerals. Inorganic precipitated and bacteriogenic iron oxides are widespread in marine and fresh systems fed by iron-rich supplies, which may impact the global Sr cycle. A series of laboratory batch experiments of Sr sorption onto humid acid coated magnetic nano iron oxides using high purity in-house standard were performed in this study and aimed for gaining a better understanding of mechanisms controlling Sr mobility. The results indicate that Sr sorption is a function of pH, 100 % Sr remains unbounded at pH <4 and more than 85 % absorbed at pH >8. Temperature controlled experiments in the range of 5 - 35 degrees C indicate a positive relationship between sorption capacity and temperature. Measurements of stable Sr isotopes (δ88Sr and δ87Sr) in batch experiments show that lighter isotopes reacted preferentially with iron oxides, and a negligible pH effect on isotopic fractionation. To calculate the degree of the kinetic isotope effect, Rayleigh fractionation model is applied to evaluate the isotope fractionation factor, α is 0.99985 at pH 8.17 (equals to Δ88Sr ~ 0.15 ‰). Temperature exerts only minor isotopic fractionation effect and reveals more importance at lower temperatures. This new finding provides crucial information for a detail evaluation of sorption processes in natural environments.

  4. Discovery of Fe7O9: a new iron oxide with a complex monoclinic structure

    NASA Astrophysics Data System (ADS)

    Sinmyo, Ryosuke; Bykova, Elena; Ovsyannikov, Sergey V.; McCammon, Catherine; Kupenko, Ilya; Ismailova, Leyla; Dubrovinsky, Leonid

    2016-09-01

    Iron oxides are fundamentally important compounds for basic and applied sciences as well as in numerous industrial applications. In this work we report the synthesis and investigation of a new binary iron oxide with the hitherto unknown stoichiometry of Fe7O9. This new oxide was synthesized at high-pressure high-temperature (HP-HT) conditions, and its black single crystals were successfully recovered at ambient conditions. By means of single crystal X-ray diffraction we determined that Fe7O9 adopts a monoclinic C2/m lattice with the most distorted crystal structure among the binary iron oxides known to date. The synthesis of Fe7O9 opens a new portal to exotic iron-rich (M,Fe)7O9 oxides with unusual stoichiometry and distorted crystal structures. Moreover, the crystal structure and phase relations of such new iron oxide groups may provide new insight into the cycling of volatiles in the Earth’s interior.

  5. Synthesis of phase-pure and monodisperse iron oxide nanoparticles by thermal decomposition

    SciTech Connect

    Hufschmid, Ryan D.; Arami, Hamed; Ferguson, R. Matthew; Gonzales, Marcela; Teeman, Eric M.; Brush, Lucien N.; Browning, Nigel D.; Krishnan, Kannan M.

    2015-06-03

    We present a comprehensive template for the design and synthesis of iron oxide nanoparticles with control over size, size distribution, phase, and resulting properties. Monodisperse superparamagnetic iron oxide nanoparticles were synthesized by thermal decomposition of three different iron containing precursors (iron oleate, iron pentacarbonyl, and iron oxyhydroxide) in organic solvents under a variety of synthetic conditions. We compare the suitability of these three kinetically controlled synthesis protocols, which have in common the use of iron oleate as a starting precursor or reaction intermediate, for producing nanoparticles with specific size and magnetic properties. Monodisperse particles were produced over a tunable range of sizes from approximately 2-30 nm. Reaction parameters such as precursor concentration, addition of surfactant, temperature, ramp rate, and time were adjusted to kinetically control size and size-distribution. In particular, large quantities of excess surfactant (up to 25:1 molar ratio) alter reaction kinetics and result in larger particles with uniform size; however, there is often a trade-off between large particles and a narrow size distribution. Iron oxide phase is also critical for establishing magnetic properties. As an example, we show the importance of obtaining the required iron oxide phase for application to Magnetic Particle Imaging (MPI), and describe how phase purity can be controlled.

  6. Catalytic decomposition of hydrogen peroxide and 2-chlorophenol with iron oxides.

    PubMed

    Huang, H H; Lu, M C; Chen, J N

    2001-06-01

    The aim of this study was to examine the catalyzed decomposition of hydrogen peroxide and 2-chlorophenol (2-CP) in the presence of iron oxides. Granular ferrihydrite, goethite, and hematite were selected as catalysts in this study. 2-CP was used as the model compound because it is a typical toxic compound and has not been investigated in the catalytic decomposition by iron oxides. The catalytic activity for hydrogen peroxide decomposition followed the sequence: granular ferrihydrite > goethite > hematite. However, hematite exhibited the highest activity in catalyzing 2-CP oxidation. The oxidation efficiency of 2-CP corresponded with the inverse sequence of specific area and pHpzc of the iron oxides. The catalytic activity of granular ferrihydrite was affected significantly by the mixing speed and particle size for its large value of Thiele modulus (phi) and Damkohler number (Da). The strong diffusion resistance for granular ferrihydrite was attributed either to its microporous structure or to the formation of oxygen in the pores of the iron oxide leading to the unexpected catalytic activity of granular ferrihydrite to hydrogen peroxide and 2-CP.

  7. Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water

    NASA Astrophysics Data System (ADS)

    Gui, Minghui; Smuleac, Vasile; Ormsbee, Lindell E.; Sedlak, David L.; Bhattacharyya, Dibakar

    2012-05-01

    The potential for using hydroxyl radical (OH•) reactions catalyzed by iron oxide nanoparticles (NPs) to remediate toxic organic compounds was investigated. Iron oxide NPs were synthesized by controlled oxidation of iron NPs prior to their use for contaminant oxidation (by H2O2 addition) at near-neutral pH values. Cross-linked polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) microfiltration membranes were prepared by in situ polymerization of acrylic acid inside the membrane pores. Iron and iron oxide NPs (80-100 nm) were directly synthesized in the polymer matrix of PAA/PVDF membranes, which prevented the agglomeration of particles and controlled the particle size. The conversion of iron to iron oxide in aqueous solution with air oxidation was studied based on X-ray diffraction, Mössbauer spectroscopy and BET surface area test methods. Trichloroethylene (TCE) was selected as the model contaminant because of its environmental importance. Degradations of TCE and H2O2 by NP surface generated OH• were investigated. Depending on the ratio of iron and H2O2, TCE conversions as high as 100 % (with about 91 % dechlorination) were obtained. TCE dechlorination was also achieved in real groundwater samples with the reactive membranes.

  8. Discovery of Fe7O9: a new iron oxide with a complex monoclinic structure

    PubMed Central

    Sinmyo, Ryosuke; Bykova, Elena; Ovsyannikov, Sergey V.; McCammon, Catherine; Kupenko, Ilya; Ismailova, Leyla; Dubrovinsky, Leonid

    2016-01-01

    Iron oxides are fundamentally important compounds for basic and applied sciences as well as in numerous industrial applications. In this work we report the synthesis and investigation of a new binary iron oxide with the hitherto unknown stoichiometry of Fe7O9. This new oxide was synthesized at high-pressure high-temperature (HP-HT) conditions, and its black single crystals were successfully recovered at ambient conditions. By means of single crystal X-ray diffraction we determined that Fe7O9 adopts a monoclinic C2/m lattice with the most distorted crystal structure among the binary iron oxides known to date. The synthesis of Fe7O9 opens a new portal to exotic iron-rich (M,Fe)7O9 oxides with unusual stoichiometry and distorted crystal structures. Moreover, the crystal structure and phase relations of such new iron oxide groups may provide new insight into the cycling of volatiles in the Earth’s interior. PMID:27605075

  9. Removal of heavy metal ions by iron oxide coated sewage sludge.

    PubMed

    Phuengprasop, Thapanapong; Sittiwong, Jarinya; Unob, Fuangfa

    2011-02-15

    The municipal sewage sludge was modified with iron oxide employed in metal ions removal. The surface modification method was proposed and the effect of parameters in the preparation was studied. The iron oxide coated sludge had higher surface area, pore volume and iron content, compared to uncoated sludge. The suitable conditions for removal of Cu(II), Cd(II), Ni(II) and Pb(II) ions from solutions were investigated using batch method. The suitable pH value in the extraction was 7 for adsorption of Cd(II) and Ni(II), 6 for Cu(II) and 5 for Pb(II) ions. The presence of NaNO(3), Ca(NO(3))(2) and Na(2)SO(4) in metal solution in the concentration of 0.01 M and 0.50 M could reduce the removal efficiency. The adsorption isotherms for the adsorption of the metal ions were defined by Langmuir relation. The maximum adsorption capacity of the iron oxide coated sludge for Cu(II), Cd(II), Ni(II) and Pb(II) was 17.3, 14.7, 7.8 and 42.4 mg g(-1), respectively. The adsorption kinetics for every metal ions followed pseudo-second order model. The metal removal from wastewater by iron oxide coated sludge was also demonstrated.

  10. Descriptive and Grade-Tonnage Models and Database for Iron Oxide Cu-Au Deposits

    USGS Publications Warehouse

    Cox, Dennis P.; Singer, Donald A.

    2007-01-01

    Iron oxide Cu-Au deposits are veins and breccia-hosted bodies of hematite and/or magnetite with disseminated Cu + Au ? Ag ? Pd ? Pt ? Ni ? U ? LREE minerals formed in sedimentary or volcano-sedimentary basins intruded by igneous rocks. Deposits are associated with broad redox boundaries and feature sodic alteration of source rocks and potassic alteration of host rocks.

  11. Unprecedented Selective Oxidation of Styrene Derivatives using a Supported Iron Oxide Nanocatalyst in Aqueous Medium

    EPA Science Inventory

    Iron oxide nanoparticles supported on mesoporous silica-type materials have been successfully utilized in the aqueous selective oxidation of alkenes under mild conditions using hydrogen peroxide as a green oxidant. Catalysts could be easily recovered after completion of the reac...

  12. Biosynthesis of stable iron oxide nanoparticles in aqueous extracts of Hordeum vulgare and Rumex acetosa plants.

    PubMed

    Makarov, Valentin V; Makarova, Svetlana S; Love, Andrew J; Sinitsyna, Olga V; Dudnik, Anna O; Yaminsky, Igor V; Taliansky, Michael E; Kalinina, Natalia O

    2014-05-27

    We report the synthesis and characterization of amorphous iron oxide nanoparticles from iron salts in aqueous extracts of monocotyledonous (Hordeum vulgare) and dicotyledonous (Rumex acetosa) plants. The nanoparticles were characterized by TEM, absorbance spectroscopy, SAED, EELS, XPS, and DLS methods and were shown to contain mainly iron oxide and iron oxohydroxide. H. vulgare extracts produced amorphous iron oxide nanoparticles with diameters of up to 30 nm. These iron nanoparticles are intrinsically unstable and prone to aggregation; however, we rendered them stable in the long term by addition of 40 mM citrate buffer pH 3.0. In contrast, amorphous iron oxide nanoparticles (diameters of 10-40 nm) produced using R. acetosa extracts are highly stable. The total protein content and antioxidant capacity are similar for both extracts, but pH values differ (H. vulgare pH 5.8 vs R. acetosa pH 3.7). We suggest that the presence of organic acids (such oxalic or citric acids) plays an important role in the stabilization of iron nanoparticles, and that plants containing such constituents may be more efficacious for the green synthesis of iron nanoparticles.

  13. Suppressing iron oxide nanoparticle toxicity by vascular targeted antioxidant polymer nanoparticles.

    PubMed

    Cochran, David B; Wattamwar, Paritosh P; Wydra, Robert; Hilt, J Zach; Anderson, Kimberly W; Eitel, Richard E; Dziubla, Thomas D

    2013-12-01

    The biomedical use of superparamagnetic iron oxide nanoparticles has been of continued interest in the literature and clinic. Their ability to be used as contrast agents for imaging and/or responsive agents for remote actuation makes them exciting materials for a wide range of clinical applications. Recently, however, concern has arisen regarding the potential health effects of these particles. Iron oxide toxicity has been demonstrated in in vivo and in vitro models, with oxidative stress being implicated as playing a key role in this pathology. One of the key cell types implicated in this injury is the vascular endothelial cells. Here, we report on the development of a targeted polymeric antioxidant, poly(trolox ester), nanoparticle that can suppress oxidative damage. As the polymer undergoes enzymatic hydrolysis, active trolox is locally released, providing a long term protection against pro-oxidant agents. In this work, poly(trolox) nanoparticles are targeted to platelet endothelial cell adhesion molecules (PECAM-1), which are able to bind to and internalize in endothelial cells and provide localized protection against the cytotoxicity caused by iron oxide nanoparticles. These results indicate the potential of using poly(trolox ester) as a means of mitigating iron oxide toxicity, potentially expanding the clinical use and relevance of these exciting systems.

  14. Synthesis and Evaluation of Nanostructured Gold-Iron Oxide Catalysts for the Oxidative Dehydrogenation of Cyclohexane

    NASA Astrophysics Data System (ADS)

    Wu, Peng

    Shape-controlled iron oxide and gold-iron oxide catalysts with a cubic inverse spinel structure were studied in this thesis for the oxidative dehydrogenation of cyclohexane. The structure of iron oxide and gold-iron oxide catalysts has no major impact on their oxidative dehydrogenation activity. However, the product selectivity is influenced. Both cyclohexene and benzene are formed on bare iron oxide nanoshapes, while benzene is the only dehydrogenation product in the presence of gold. The selectivity of benzene over CO2 depends strongly on the stability of the iron oxide support and the gold-support interaction. The highest benzene yield has been observed on gold-iron oxide octahedra. {111}-bound nanooctahedra are highly stable in reaction conditions at 300 °C, while {100}-bound nanocubes start to sinter above 250 °C. The highest benzene yield has been observed on gold-iron oxide nanooctahedra, which are likely to have gold atoms, and few-atom gold clusters strongly-bound on their surface. Cationic gold appears to be the active site for benzene formation. An all-organic method to prepare Au-FeOx nano-catalysts is needed due to the inconvenience of the half-organic, half-inorganic synthesis process discussed above. Several methods from the literature to prepare gold-iron oxide nanocomposites completely in organic solvents were reviewed and followed. FeOx Au synthesis procedures in literatures are initially designed for a Au content of over 70%. This approach was tried here to prepare composites with a much lower Au content (2-5 atom. %). Heat treatment is required to bond Au and FeOx NPs in the organic-phase syntheses. Au-FeOx-4 was obtained as a selective catalyst for the ODH of cyclohexane. A Audelta+ peak is observed in the UV-Vis spectrum of sample Au-FeOx-4. This different Au delta+ form may be cationic Au nano-clusters interacting with the FeOx support. It has been demonstrated that cationic gold is responsible for dehydrogenation behavior. Furthermore, the

  15. MR Imaging of Tumor Associated Macrophages with Clinically-Applicable Iron Oxide Nanoparticles

    PubMed Central

    Daldrup-Link, Heike E.; Golovko, Daniel; Ruffell, Brian; DeNardo, David G.; Castaneda, Rosalinda; Ansari, Celina; Rao, Jianghong; Tikhomirov, Grigory A.; Wendland, Mike; Corot, Claire; Coussens, Lisa M.

    2011-01-01

    Purpose The presence of tumor-associated macrophages (TAMs) in breast cancer correlates strongly with poor outcome. The purpose of this study was to develop a clinically applicable, non-invasive diagnostic assay for selective targeting and visualization of TAMs in breast cancer, based on magnetic resonance (MR) imaging and clinically applicable iron oxide nanoparticles. Experimental Design F4/80-negative mammary carcinoma cells and F4/80-positive TAMs were incubated with iron oxide nanoparticles and were compared regarding MR signal changes and iron uptake. MMTV-PyMT transgenic mice harboring mammary carcinomas underwent nanoparticle-enhanced MR up to 1 hour (h) and at 24 h post injection (p.i.). The tumor enhancement on MR images was correlated with the presence and location of TAMs and nanoparticles on confocal microscopy. Results In vitro studies revealed that iron oxide nanoparticles are preferentially phagocytosed by TAMs, but not by malignant tumor cells. In vivo, all tumors demonstrated an initial contrast agent perfusion on immediate postcontrast MR images with gradual transendothelial leakage into the tumor interstitium. At 24 h p.i., all tumors demonstrated a persistent signal decline on MR scans. TAM-depletion via αCSF1 mAb lead to significant inhibition of tumor nanoparticle enhancement. Detection of iron using DAB-enhanced Prussian Blue staining, and immunodetection of CD68 localized iron oxide nanoparticles to TAMs, indicating that the MR signal effects on delayed MR images were largely due to TAM-mediated uptake of contrast agent. Conclusion These data indicate that tumor-enhancement with clinically applicable iron oxide nanoparticles may serve as a new biomarker for long-term prognosis, related treatment decisions and the evaluation of new immune-targeted therapies. PMID:21791632

  16. Solid-stabilized emulsion formation using stearoyl lactylate coated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Vengsarkar, Pranav S.; Roberts, Christopher B.

    2014-10-01

    Iron oxide nanoparticles can exhibit highly tunable physicochemical properties that are extremely important in applications such as catalysis, biomedicine and environmental remediation. The small size of iron oxide nanoparticles can be used to stabilize oil-in-water Pickering emulsions due to their high energy of adsorption at the interface of oil droplets in water. The objective of this work is to investigate the effect of the primary particle characteristics and stabilizing agent chemistry on the stability of oil-in-water Pickering emulsions. Iron oxide nanoparticles were synthesized by the co-precipitation method using stoichiometric amounts of Fe2+ and Fe3+ salts. Sodium stearoyl lactylate (SSL), a Food and Drug Administration approved food additive, was used to functionalize the iron oxide nanoparticles. SSL is useful in the generation of fat-in-water emulsions due to its high hydrophilic-lipophilic balance and its bilayer-forming capacity. Generation of a monolayer or a bilayer coating on the nanoparticles was controlled through systematic changes in reagent concentrations. The coated particles were then characterized using various analytical techniques to determine their size, their crystal structure and surface functionalization. The capacity of these bilayer coated nanoparticles to stabilize oil-in-water emulsions under various salt concentrations and pH values was also systematically determined using various characterization techniques. This study successfully demonstrated the ability to synthesize iron oxide nanoparticles (20-40 nm) coated with SSL in order to generate stable Pickering emulsions that were pH-responsive and resistant to significant destabilization in a saline environment, thereby lending themselves to applications in advanced oil spill recovery and remediation.

  17. Dominance of sulfur-fueled iron oxide reduction in low-sulfate freshwater sediments

    PubMed Central

    Hansel, Colleen M; Lentini, Chris J; Tang, Yuanzhi; Johnston, David T; Wankel, Scott D; Jardine, Philip M

    2015-01-01

    A central tenant in microbial biogeochemistry is that microbial metabolisms follow a predictable sequence of terminal electron acceptors based on the energetic yield for the reaction. It is thereby oftentimes assumed that microbial respiration of ferric iron outcompetes sulfate in all but high-sulfate systems, and thus sulfide has little influence on freshwater or terrestrial iron cycling. Observations of sulfate reduction in low-sulfate environments have been attributed to the presumed presence of highly crystalline iron oxides allowing sulfate reduction to be more energetically favored. Here we identified the iron-reducing processes under low-sulfate conditions within columns containing freshwater sediments amended with structurally diverse iron oxides and fermentation products that fuel anaerobic respiration. We show that despite low sulfate concentrations and regardless of iron oxide substrate (ferrihydrite, Al-ferrihydrite, goethite, hematite), sulfidization was a dominant pathway in iron reduction. This process was mediated by (re)cycling of sulfur upon reaction of sulfide and iron oxides to support continued sulfur-based respiration—a cryptic sulfur cycle involving generation and consumption of sulfur intermediates. Although canonical iron respiration was not observed in the sediments amended with the more crystalline iron oxides, iron respiration did become dominant in the presence of ferrihydrite once sulfate was consumed. Thus, despite more favorable energetics, ferrihydrite reduction did not precede sulfate reduction and instead an inverse redox zonation was observed. These findings indicate that sulfur (re)cycling is a dominant force in iron cycling even in low-sulfate systems and in a manner difficult to predict using the classical thermodynamic ladder. PMID:25871933

  18. Genome Analysis of the Biotechnologically Relevant Acidophilic Iron Oxidising Strain JA12 Indicates Phylogenetic and Metabolic Diversity within the Novel Genus “Ferrovum”

    PubMed Central

    Ullrich, Sophie R.; Poehlein, Anja; Tischler, Judith S.; González, Carolina; Ossandon, Francisco J.; Daniel, Rolf; Holmes, David S.; Schlömann, Michael; Mühling, Martin

    2016-01-01

    Background Members of the genus “Ferrovum” are ubiquitously distributed in acid mine drainage (AMD) waters which are characterised by their high metal and sulfate loads. So far isolation and microbiological characterisation have only been successful for the designated type strain “Ferrovum myxofaciens” P3G. Thus, knowledge about physiological characteristics and the phylogeny of the genus “Ferrovum” is extremely scarce. Objective In order to access the wider genetic pool of the genus “Ferrovum” we sequenced the genome of a “Ferrovum”-containing mixed culture and successfully assembled the almost complete genome sequence of the novel “Ferrovum” strain JA12. Phylogeny and Lifestyle The genome-based phylogenetic analysis indicates that strain JA12 and the type strain represent two distinct “Ferrovum” species. “Ferrovum” strain JA12 is characterised by an unusually small genome in comparison to the type strain and other iron oxidising bacteria. The prediction of nutrient assimilation pathways suggests that “Ferrovum” strain JA12 maintains a chemolithoautotrophic lifestyle utilising carbon dioxide and bicarbonate, ammonium and urea, sulfate, phosphate and ferrous iron as carbon, nitrogen, sulfur, phosphorous and energy sources, respectively. Unique Metabolic Features The potential utilisation of urea by “Ferrovum” strain JA12 is moreover remarkable since it may furthermore represent a strategy among extreme acidophiles to cope with the acidic environment. Unlike other acidophilic chemolithoautotrophs “Ferrovum” strain JA12 exhibits a complete tricarboxylic acid cycle, a metabolic feature shared with the closer related neutrophilic iron oxidisers among the Betaproteobacteria including Sideroxydans lithotrophicus and Thiobacillus denitrificans. Furthermore, the absence of characteristic redox proteins involved in iron oxidation in the well-studied acidophiles Acidithiobacillus ferrooxidans (rusticyanin) and Acidithiobacillus

  19. Mineralized iron oxidizing bacteria from hydrothermal vents: targeting biosignatures on Mars

    NASA Astrophysics Data System (ADS)

    Leveille, R. J.

    2010-12-01

    Putative hydrothermal systems have been identified on Mars based on orbital imagery and rover-based analyses. Based on Earth analogs, hydrothermal systems on Mars would be highly attractive for their potential for preserving organic and inorganic biosignatures. For example, iron oxidizing bacteria are ubiquitous in marine and terrestrial hydrothermal systems, where they often display distinctive cell morphologies and are commonly encrusted by minerals, especially bacteriogenic iron oxides and silica. Microfossils of iron oxidizing bacteria have been found in ancient Si-Fe deposits and iron oxidation may be an ancient and widespread metabolic pathway. In order to investigate mineralized iron oxidizing bacteria as a biosignature, we have examined samples collected from extinct hydrothermal vents along Explorer Ridge, NE Pacific Ocean. In addition, microaerophilic iron oxidizing bacteria, isolated from active Pacific hydrothermal vents, were grown in a Fe-enriched seawater medium at constant pH (6.5) and O2 concentration (5%) in a controlled bioreactor system. Samples and experimental products were examined with a combination of variable-pressure and field-emission scanning electron microscopy (SEM), in some cases by preparing samples with a focused ion beam (FIB) milling system. Light-toned seafloor samples display abundant filamentous forms resembling, in both size and shape (1-5 microns in diameter and up to several microns in length), the twisted stalks of Gallionella and the elongated filaments of Leptothrix. Some samples consist entirely of low-density masses of silica (>90% Si) encrusted filamentous forms. The presence of unmineralized filamentous matter rich in C and Fe suggests that these are the remains of iron oxidizing bacteria. Mineralized filaments sectioned by FIB show variable internal material within semi-hollow, tubular-like features. Silica encrustations also show pseudo-concentric growth bands. In the bioreactor runs, abundant microbial growth and

  20. Fossilization of Iron-Oxidizing Bacteria at Hydrothermal Vents: a Useful Biosignature on Mars?

    NASA Astrophysics Data System (ADS)

    Leveille, R. J.; Lui, S.

    2009-05-01

    Iron oxidizing bacteria are ubiquitous in marine and terrestrial environments on Earth, where they often display distinctive cell morphologies and are commonly encrusted by minerals, especially bacteriogenic iron oxides and silica. Putative microfossils of iron oxidizing bacteria have been found in jaspers as old as 490Ma and microbial iron oxidation may be an ancient metabolic pathway. In order to investigate the usefulness of mineralized iron oxidizing bacteria as a biosignature, we have examined mineral samples collected from relict hydrothermal systems along Explorer Ridge, NE Pacific Ocean. In addition, microaerophilic, neutrophilic iron oxidizing bacteria, isolated from Pacific hydrothermal vents, were grown in a Fe-enriched seawater medium at constant pH (6.5) and oxygen concentration (5 percent) in a controlled bioreactor system. Both natural samples and experimental products were examined with a combination of variable pressure scanning electron microscopy (SEM), field emission gun SEM, and in some cases by preparing samples with a focused ion beam (FIB) milling system. Natural seafloor samples display abundant filamentous forms often resembling, in both size and shape, the twisted stalks of Gallionella and the elongated filaments of Leptothrix. Generally, these filamentous features are 1-5 microns in diameter and up to several microns in length. Some samples consist entirely of low- density, porous masses of silica encrusted filamentous forms. Presumably, these masses were formed by a rapid precipitation by the influx of silica-rich fluids into a microbial mat dominated by bacteria with filamentous morphologies. The presence of rare, amorphous (unmineralized) filamentous matter rich in C and Fe suggests that these bacteria were iron oxidizers. There is no evidence that sulfur oxidizers were present. Filamentous features sectioned by FIB milling show internal material within semi-hollow tubular-like features. Silica encrustations also show pseudo

  1. Precise control over shape and size of iron oxide nanocrystals suitable for assembly into ordered particle arrays

    PubMed Central

    Wetterskog, Erik; Agthe, Michael; Mayence, Arnaud; Grins, Jekabs; Wang, Dong; Rana, Subhasis; Ahniyaz, Anwar; Salazar-Alvarez, German; Bergström, Lennart

    2014-01-01

    Here we demonstrate how monodisperse iron oxide nanocubes and nanospheres with average sizes between 5 and 27 nm can be synthesized by thermal decomposition. The relative importance of the purity of the reactants, the ratio of oleic acid and sodium oleate, the maximum temperature, and the rate of temperature increase, on robust and reproducible size and shape-selective iron oxide nanoparticle synthesis are identified and discussed. The synthesis conditions that generate highly monodisperse iron oxide nanocubes suitable for producing large ordered arrays, or mesocrystals are described in detail. PMID:27877722

  2. Size-dependent cytotoxicity and inflammatory responses of PEGylated silica-iron oxide nanocomposite size series

    NASA Astrophysics Data System (ADS)

    Injumpa, Wishulada; Ritprajak, Patcharee; Insin, Numpon

    2017-04-01

    Iron oxides nanoparticles have been utilized in biological systems and biomedical applications for many years because they are relatively safe and stable comparing to other magnetic nanomaterials. In some applications, iron oxide nanoparticles were modified with silica in order to be more stable in biological systems and able to be functionalized with various functional groups. Moreover, poly(ethylene glycol) (PEG) was one on the most used polymer to graft onto the nanoparticles in order to increase their biocompatibility, dispersibility and stability in aqueous solutions. Therefore, the nanocomposites comprising iron oxide nanoparticles, silica, and PEG could become multifunctional carriers combining superparamagnetic character, multi-functionality and high stability in biological environments. Herein, we reported the preparation of the nanocomposites and effects of their sizes on cytotoxicity and inflammatory responses. The PEGylated silica-iron oxide nanocomposites were prepared by coating of poly(poly(ethylene glycol) monomethyl ether methacrylate) (PPEGMA) on magnetic nanoparticle-silica nanocomposites via Atom Transfer Radical Polymerization (ATRP). The iron oxide nanoparticles were synthesized using a thermal decomposition method. The silica shells were then coated on iron oxides nanoparticles using reverse microemulsion and sol-gel methods. The size series of the nanocomposites with the diameter of 24.86±4.38, 45.24±5.00, 98.10±8.88 and 202.22±6.70 nm as measured using TEM were obtained. Thermogravimetric analysis (TGA) was used for the determination of % weight of PPEGMA on the nanocomposites showing the weight loss of ranging from 65% for smallest particles to 30% for largest particles. The various sizes (20, 40, 100, 200 nm) and concentrations (10, 100, 1000 μg/mL) of the nanocomposites were tested for their cytotoxicity in fibroblast and macrophage cell lines using MTT assay. The different sizes did not affect cell viability of fibroblast, albeit

  3. In Situ Probing Nucleation, Growth, and Aggregation of Iron Oxides in Geochemical Aquatic Systems

    NASA Astrophysics Data System (ADS)

    Jun, Y.; Hu, Y.; Ray, J. R.

    2012-12-01

    Nucleation, growth, and aggregation of iron oxide nanoparticles can significantly alter the fate of organic and inorganic contaminants in geochemical aquatic systems. This talk will address how we can improve our understanding of nucleation, growth, and aggregation of iron oxide nanoparticles by providing more accurate quantitative and qualitative empirical information. In this study, a novel environmental setup—which allows time-resolved simultaneous measurements of small angle x-ray scattering (SAXS) and grazing incidence small-angle scattering (GISAXS) in the presence of bulk solution—was utilized for real-time monitoring of nanoparticle formation at water-mineral interfaces. This setup enabled us to probe the size, shape, and location of iron oxide nanoparticles on the substrate and in solution without dehydration of samples. Experiments were conducted with 10-4 M ferric ions in the presence of environmentally important and abundant anions (nitrate, chlorite, sulfate) and cations (aluminum) at pH = 3.7 ± 0.1. The substrates used were geologically ubiquitous media such as quartz, mica, and organic polymer-coated surfaces. Once ferric solutions were introduced, the homogeneous and heterogeneous nucleation of iron oxides occurred and the size and volume evolution of nanoparticles were monitored. To complement these observations, atomic force microscopy, high-resolution transmission electron microscopy, high-resolution x-ray diffraction, contact angle analysis, dynamic light scattering, and electrophoretic mobility analysis were utilized. Based on in situ measurements of initial nuclei evolution at aqueous interfaces, this approach provided new, important information for upscaling such as size, volume, surface area, and location (i.e., in solution vs. on mineral surfaces) of iron oxides precipitates formed in the presence of organic matter and different substrate morphological and chemical properties. Using this quantitative information, we identified the

  4. Simultaneous reductive dissolution of iron oxide and oxidation of iodide in ice.

    NASA Astrophysics Data System (ADS)

    Kim, Kitae; Choi, Wonyong

    2015-04-01

    Iron is an important trace element controlling the metabolism and growth of all kinds of living species. Especially, the bio-availability of iron has been regarded as the limiting factor for primary productivity in HNLC (High Nutrients Low Chlorophyll) regions including Southern ocean. The dissolution of iron oxide provides enhanced the bio-availability of iron for phytoplankton growth. The halogen chemistry in polar regions is related to various important environmental processes such as Antarctic Ozone Depletion Event(ODE), mercury depletion, oxidative processes in atmosphere, and the formation of CCN (Cloud Condensation Nuclei). In this study, we investigated the reductive dissolution of iron oxide particles to produce Fe(II)aq and simultaneous oxidation of I- (iodide) to I3- (tri-iodide) in ice phase under UV irradiation or dark condition. The reductive generation of Fe(II)aq from iron oxides and oxidation of iodide to I3- were negligible in water but significantly accelerated in frozen solution both in the presence and absence of light. The enhanced reductive generation of Fe(II)aq and oxidative formation of I3- in ice were observed regardless of the various types of iron oxides [hematite (α-Fe2O3) maghemite (γ- Fe2O3), goethite (α-FeOOH), lepidocrocite (γ-FeOOH) and, magnetite (Fe3O4)]. We explained that the enhanced redox production of Fe(II)aq and I3- in ice is contributed to the freeze concentration of iodides, protons, and dissolved oxygen in the unfrozen solution. When the concentration of both iodides and protons were raised by 10-fold each, the formation of Fe(II)aq in water under UV irradiation was approached to those in ice. The outdoor experiments were carried out under ambient solar radiation in winter season of mid-latitude (Pohang, Korea: 36°N latitude) and also confirmed that the production of Fe(II)aq via reductive dissolution of iron oxide and I3- generation via I- oxidation were enhanced in frozen solution. These results suggest that iron

  5. Specific Bonds between an Iron Oxide Surface and Outer Membrane Cytochromes MtrC and OmcA from Shewanella oneidensis MR-1

    SciTech Connect

    Lower, Brian H.; Shi, Liang; Yongsunthon, Ruchirej; Droubay, Timothy C.; Mccready, David E.; Lower, Steven

    2007-07-31

    Shewanella oneidensis MR-1 is purported to express outer membrane cytochromes (e.g., MtrC and OmcA) that transfer electrons directly to Fe(III) in a mineral during anaerobic respiration.  A prerequisite for this type of reaction would be the formation of a stable bond between a cytochrome and an iron oxide surface.  Atomic force microscopy (AFM) was used to detect whether a specific bond forms between a hematite (Fe2O3) thin film, created with oxygen plasma assisted molecular beam epitaxy (MBE), and recombinant MtrC or OmcA molecules coupled to gold substrates.  Force spectra displayed a unique force signature indicative of a specific bond between each cytochrome and the hematite surface.  The strength of the OmcA-hematite bond was approximately twice as strong as the MtrC-hematite bond, but direct binding to hematite was twice as favorable for MtrC.  Reversible folding/unfolding reactions were observed for mechanically denatured MtrC molecules bound to hematite.  The force measurements for the hematite-cytochrome pairs were compared to spectra collected between an iron oxide and S. oneidensis under anaerobic conditions.  There is a strong correlation between the whole cell and pure protein force spectra suggesting that the unique binding attributes of each cytochrome complement one another and allow both MtrC and OmcA to play a prominent role in the transfer of electrons to Fe(III) in minerals.  Finally, by comparing the magnitude of binding force for the whole cell vs. pure protein data, we were able to estimate that a single bacterium of S. oneidensis (2 x 0.5 μm) expresses ~104 cytochromes on its outer surface. 

  6. Shape and size controlled synthesis of uniform iron oxide nanocrystals through new non-hydrolytic routes

    NASA Astrophysics Data System (ADS)

    Li, Wenlu; Lee, Seung Soo; Wu, Jiewei; Hinton, Carl H.; Fortner, John D.

    2016-08-01

    New, non-hydrolytic routes to synthesize highly crystalline iron oxide nanocrystals (8-40 nm, magnetite) are described in this report whereby particle size and morphology were precisely controlled through reactant (precursor, e.g. (FeO(OH)) ratios, co-surfactant and organic additive, and/or reaction time. Particle size, with high monodispersivity (<10%), is demonstrated to be a function of precursor concentrations and through the addition of different cosurfactants and/or additives, cubic, octahedral, potato-like, and flower-like iron oxide nanocrystals can be reproducibly synthesized through simple one-pot thermal decomposition methods. High resolution transmission electron microscope, x-ray diffraction, and superconducting quantum interference device were used to characterize the size, structure and magnetic properties of the resulting nanocrystals. For aqueous applications, materials synthesized/purified in organic solvents are broadly water dispersible through a variety of phase (aqueous) transfer method(s).

  7. Study of Organic and Inorganic Binders on Strength of Iron Oxide Pellets

    NASA Astrophysics Data System (ADS)

    Srivastava, Urvashi; Kawatra, S. Komar; Eisele, Timothy C.

    2013-08-01

    Bentonite is a predominant binder used in iron ore pelletization. However, the presence of a high content of silica and alumina in bentonite is considered undesirable for ironmaking operations. The objective of this study was to identify the alternatives of bentonite for iron ore pelletization. To achieve this goal, different types of organic and inorganic binders were utilized to produce iron oxide pellets. The quality of these iron oxide pellets was compared with pellets made using bentonite. All pellets were tested for physical strength at different stages of pelletization to determine their ability to survive during shipping and handling. The results show that organic binders such as lactose monohydrate, hemicellulose, and sodium lignosulfonate can provide sufficient strength to indurated pellets.

  8. Acetone Sensing Properties of a Gas Sensor Composed of Carbon Nanotubes Doped With Iron Oxide Nanopowder

    PubMed Central

    Tan, Qiulin; Fang, Jiahua; Liu, Wenyi; Xiong, Jijun; Zhang, Wendong

    2015-01-01

    Iron oxide (Fe2O3) nanopowder was prepared by a precipitation method and then mixed with different proportions of carbon nanotubes. The composite materials were characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. A fabricated heater-type gas sensor was compared with a pure Fe2O3 gas sensor under the influence of acetone. The effects of the amount of doping, the sintering temperature, and the operating temperature on the response of the sensor and the response recovery time were analyzed. Experiments show that doping of carbon nanotubes with iron oxide effectively improves the response of the resulting gas sensors to acetone gas. It also reduces the operating temperature and shortens the response recovery time of the sensor. The response of the sensor in an acetone gas concentration of 80 ppm was enhanced, with good repeatability. PMID:26569253

  9. Lipidoid-coated iron oxide nanoparticles for efficient DNA and siRNA delivery.

    PubMed

    Jiang, Shan; Eltoukhy, Ahmed A; Love, Kevin T; Langer, Robert; Anderson, Daniel G

    2013-03-13

    The safe, targeted and effective delivery of gene therapeutics remains a significant barrier to their broad clinical application. Here we develop a magnetic nucleic acid delivery system composed of iron oxide nanoparticles and cationic lipid-like materials termed lipidoids. Coated nanoparticles are capable of delivering DNA and siRNA to cells in culture. The mean hydrodynamic size of these nanoparticles was systematically varied and optimized for delivery. While nanoparticles of different sizes showed similar siRNA delivery efficiency, nanoparticles of 50-100 nm displayed optimal DNA delivery activity. The application of an external magnetic field significantly enhanced the efficiency of nucleic acid delivery, with performance exceeding that of the commercially available lipid-based reagent, Lipofectamine 2000. The iron oxide nanoparticle delivery platform developed here offers the potential for magnetically guided targeting, as well as an opportunity to combine gene therapy with MRI imaging and magnetic hyperthermia.

  10. Synthesis and Magneto-Thermal Actuation of Iron Oxide Core–PNIPAM Shell Nanoparticles

    PubMed Central

    2015-01-01

    Superparamagnetic nanoparticles have been proposed for many applications in biotechnology and medicine. In this paper, it is demonstrated how the excellent colloidal stability and magnetic properties of monodisperse and individually densely grafted iron oxide nanoparticles can be used to manipulate reversibly the solubility of nanoparticles with a poly(N-isopropylacrylamide)nitrodopamine shell. “Grafting-to” and “grafting-from” methods for synthesis of an irreversibly anchored brush shell to monodisperse, oleic acid coated iron oxide cores are compared. Thereafter, it is shown that local heating by magnetic fields as well as global thermal heating can be used to efficiently and reversibly aggregate, magnetically extract nanoparticles from solution and spontaneously redisperse them. The coupling of magnetic and thermally responsive properties points to novel uses as smart materials, for example, in integrated devices for molecular separation and extraction. PMID:26270412

  11. Low Temperature CO oxidation over Iron Oxide Nanoparticles Decorating Internal Structures of a Mesoporous Alumina

    PubMed Central

    Kim, Il Hee; Seo, Hyun Ook; Park, Eun Ji; Han, Sang Wook; Kim, Young Dok

    2017-01-01

    Using a chemical vapor deposition method with regulated sample temperatures under ambient pressure conditions, we were able to fully decorate the internal structure of a mesoporous Al2O3 bead (~1 mm in particle diameter) with iron oxide nanoparticles (with a mean lateral size of less than 1 nm). The iron oxide-decorated Al2O3 showed a high CO oxidation reactivity, even at room temperature. Very little deactivation of the CO oxidation activity was observed with increasing reaction time at ~100 °C. Additionally, this catalyst showed high CO oxidation activity, even after annealing at ~900 °C under atmospheric conditions (i.e., the structure of the catalysts could be maintained under very harsh treatment conditions). We show that our catalysts have potential for application as oxidation catalysts in industrial processes due to the simplicity of their fabrication process as well as the high and stable catalytic performance. PMID:28091561

  12. A novel nanostructured iron oxide-gold bioelectrode for hydrogen peroxide sensing

    NASA Astrophysics Data System (ADS)

    Thandavan, Kavitha; Gandhi, Sakthivel; Sethuraman, Swaminathan; Bosco Balaguru Rayappan, John; Maheswari Krishnan, Uma

    2011-07-01

    Fe3O4 nanoparticles covalently linked to a gold electrode have been used for immobilizing catalase (CAT) enzyme to sense the presence of various concentrations of H2O2. These nanoparticles ranging from 20 to 30 nm were synthesized by thermal co-precipitation of ferric and ferrous chlorides. SEM and XRD have been used for morphological and structural characterization of Fe3O4 nanoparticles. CAT enzyme was linked covalently to the surface of iron oxide using carbodiimide in phosphate buffer (pH 7.4) at 4 °C. The enzyme-iron oxide link was confirmed by FT-IR spectroscopy. Sensing studies carried out using cyclic voltammetry showed a linear response of the CAT/nano Fe3O4/Au bioelectrode towards H2O2 between 1.5 and 13.5 µM with a very sharp response time of 2 s.

  13. Synthesis of a red iron oxide/montmorillonite pigment in a CO2-rich brine solution.

    PubMed

    Montes-Hernandez, G; Pironon, J; Villieras, F

    2006-11-15

    The homoionic calcium-montmorillonite was used to synthesize a red iron oxide/clay pigment in a CO2-rich brine solution (0.5 M of NaCl) by using an agitated batch-reactor (engineer autoclave). The operating conditions were 15 days of reaction, 200 bars of pressure and 150 degrees C of temperature. SEM/EDS, STEM/EDS, XRD and Infrared Spectrometry were performed to characterize before and after reaction the solid phase. The results showed the precipitation of spherical nanoparticles (50-500 nm) of iron oxide (Fe2O3) dispersed and/or coagulated in the clay-matrix. Evidently, this oxide produced red coloration in the final product. For this case, the Fe3+ cation was provided to the aqueous solution by the dissolution of Ca-montmorillonite, particularly, the dissolution of most fine particles contained in the starting clay material. The cation exchange process and precipitation of polymorph silica were also observed.

  14. Magnetic steering of iron oxide microparticles using propulsion gradient coils in MRI.

    PubMed

    Mathieu, Jean-Baptiste; Martel, Sylvain

    2006-01-01

    Steering micro-carriers being tracked by an MRI system may be very attractive in oncology. Here, iron oxide microparticles have been steered in a Y-shaped microchannel placed between a Maxwell pair (dB/dz=443 mT/m) located in the center of an MRI bore. A suspension of 10.82 microm iron oxide particles was injected into the channel and a magnetic gradient generated by the Maxwell pair was used to deflect their trajectory. The experimental results based on the percentage of particles retrieved at the targeted outlet during the experiments show that magnetic gradient steering in the human cardiovascular system within an MRI bore can be envisioned.

  15. T1-MRI Fluorescent Iron Oxide Nanoparticles by Microwave Assisted Synthesis

    PubMed Central

    Bhavesh, Riju; Lechuga-Vieco, Ana V.; Ruiz-Cabello, Jesús; Herranz, Fernando

    2015-01-01

    Iron oxide nanoparticles have long been studied as a T2 contrast agent in MRI due to their superparamagnetic behavior. T1-based positive contrast, being much more favorable for clinical application due to brighter and more accurate signaling is, however, still limited to gadolinium- or manganese-based imaging tools. Though being the only available commercial positive-contrast agents, they lack an efficient argument when it comes to biological toxicity and their circulatory half-life in blood. The need arises to design a biocompatible contrast agent with a scope for easy surface functionalization for long circulation in blood and/or targeted imaging. We hereby propose an extremely fast microwave synthesis for fluorescein-labeled extremely-small iron oxide nanoparticles (fdIONP), in a single step, as a viable tool for cell labeling and T1-MRI. We demonstrate the capabilities of such an approach through high-quality magnetic resonance angiographic images of mice. PMID:28347101

  16. Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

    NASA Astrophysics Data System (ADS)

    Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira; Qin, Ying; Bao, Yuping

    2017-04-01

    We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

  17. Iron oxide nanoparticles embedded in activated carbons prepared from hydrothermally treated waste biomass.

    PubMed

    Hao, Wenming; Björkman, Eva; Yun, Yifeng; Lilliestråle, Malte; Hedin, Niklas

    2014-03-01

    Particles of iron oxide (Fe3O4 ; 20–40 nm) were embedded within activated carbons during the activation of hydrothermally carbonized (HTC) biomasses in a flow of CO2. Four different HTC biomass samples (horse manure, grass cuttings, beer production waste, and biosludge) were used as precursors for the activated carbons. Nanoparticles of iron oxide formed from iron catalyst included in the HTC biomasses. After systematic optimization, the activated carbons had specific surface areas of about 800 m2g1. The pore size distributions of the activated carbons depended strongly on the degree of carbonization of the precursors. Activated carbons prepared from highly carbonized precursors had mainly micropores, whereas those prepared from less carbonized precursors contained mainly mesopores. Given the strong magnetism of the activated carbon–nano-Fe3O4 composites, they could be particularly useful for water purification.

  18. Effect of Iron Oxide and Phase Separation on the Color of Blue Jun Ware Glaze.

    PubMed

    Wang, Fen; Yang, Changan; Zhu, Jianfeng; Lin, Ying

    2015-09-01

    Based on the traditional Jun ware glaze, the imitated Jun ware glazes were prepared by adding iron oxide and introducing phase separation agent apatite through four-angle-method. The effect of iron oxide contents, phase separation and the firing temperature on the color of Jun ware glazes were investigated by a neutral atmosphere experiment, optical microscope and scanning electronic microscope. The results showed that the colorant, mainly Fe2O3, contributed to the Jun ware glaze blue and cyan colors of Jun ware glaze. The light scatter caused by the small droplets in phase separation structure only influenced the shade of the glaze color, intensify or weaken the color, and thus made the glaze perfect and elegant opal visual effects, but was not the origin of general blue or cyan colors of Jun ware glaze. In addition, the firing temperature and the basic glaze composition affected the glaze colors to some extent.

  19. Magnetic iron oxide nanoparticles: Recent trends in design and synthesis of magnetoresponsive nanosystems.

    PubMed

    Tombácz, Etelka; Turcu, Rodica; Socoliuc, Vlad; Vékás, Ladislau

    2015-12-18

    Recent developments in nanotechnology and application of magnetic nanoparticles, in particular in magnetic iron oxide nanosystems, offer exciting possibilities for nanomedicine. Facile and precise synthesis procedures, high magnetic response, tunable morphologies and multiple bio-functionalities of single- and multi-core magnetic particles designed for nanomedicine applications are thoroughly appraised. This review focuses on the structural and magnetic characterization of the cores, the synthesis of single- and multicore iron oxide NPs, especially the design of the latter, as well as their protection, stabilization and functionalization by desired coating in order to protect against the corrosion of core, to prevent non-specific protein adsorption and particle aggregation in biological media, and to provide binding sites for targeting and therapeutic agents.

  20. Integrated Chemical Systems: The Simultaneous Formation of Hybrid Nanocomposites of Iron Oxide and Organo Silsesquioxanes

    SciTech Connect

    Zhao, L; Clapsaddle, B; Jr., J S; Schaefer, D; Shea, K

    2004-10-15

    A sol-gel approach for the synthesis of hybrid nanocomposites of iron oxide and bridged polysilsesquioxanes has been established. The procedures allow for the simultaneous formation of iron oxide and polysilsesquioxane networks in monolithic xerogels and aerogels. These hybrid nanocomposites are synthesized from FeCl{sub 3} {center_dot} 6H{sub 2}O and functionalized silsesquioxane monomers in a one-pot reaction using epoxides as a gelation agent. The porosity and microstructure of the materials has been determined by nitrogen porosimetry, electron microscopy and ultra small angle X-ray scattering (USAXS). The hybrid nanocomposites exhibit a uniform dispersion of both components with no evidence for phase separation at length scales > 5 nm. At this limit of resolution it is not possible to distinguish between two independent interpenetrating networks integrated at molecular length scales or a random copolymer or mixtures of both.

  1. Template assisted self-assembly of iron oxide nanoparticles: An x-ray structural analysis

    SciTech Connect

    Mishra, D.; Zabel, H.; Ulyanov, S. V.; Romanov, V. P.; Uzdin, V. M.

    2014-02-07

    We have fabricated by e-beam lithography periodic arrays of rectangular shaped trenches of different widths into Si substrates. The trenches were filled with iron oxide nanoparticles, 20 nm in diameter, by spin-coating them onto the Si substrate. The trenches have the purpose to assist the self-assembly of the iron oxide nanoparticles. Using x-ray scattering techniques, we have analyzed the structure factor of the trenches before and after filling in order to determine the filling factor. We present a theoretical analysis of the x-ray scattering function within the distorted-wave Born approximation and we present a quantitative comparison between theory and experiment.

  2. Nucleation of Iron Oxide Nanoparticles Mediated by Mms6 Protein in Situ

    SciTech Connect

    Kashyap, Sanjay; Woehl, Taylor J; Liu, Xunpei; Mallapragada, Surya K; Prozorov, Tanya

    2014-09-23

    Biomineralization proteins are widely used as templating agents in biomimetic synthesis of a variety of organic–inorganic nanostructures. However, the role of the protein in controlling the nucleation and growth of biomimetic particles is not well understood, because the mechanism of the bioinspired reaction is often deduced from ex situ analysis of the resultant nanoscale mineral phase. Here we report the direct visualization of biomimetic iron oxide nanoparticle nucleation mediated by an acidic bacterial recombinant protein, Mms6, during an in situ reaction induced by the controlled addition of sodium hydroxide to solution-phase Mms6 protein micelles incubated with ferric chloride. Using in situ liquid cell scanning transmission electron microscopy we observe the liquid iron prenucleation phase and nascent amorphous nanoparticles forming preferentially on the surface of protein micelles. Our results provide insight into the early steps of protein-mediated biomimetic nucleation of iron oxide and point to the importance of an extended protein surface during nanoparticle formation.

  3. Preparation of iron oxide nanoparticles from FeCl3 solid powder using microemulsions

    NASA Astrophysics Data System (ADS)

    Nassar, Nashaat; Husein, Maen

    2006-05-01

    Nanoparticles of iron oxide were prepared by subjecting iron chloride powder to (w/o) microemulsions consisting of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), isooctane and water. FeCl3 was first dissolved in the water pools of the microemulsion, and then reacted with NaOH added as an aqueous solution to form iron oxide. The amount of NaOH solution was limited so that single microemulsion phase is obtained. This technique serves as an in-situ nanoparticle preparation technique aimed at minimizing particle aggregation associated with particle transportation to required sites. In this study, the effects of AOT concentration and water to AOT mole ratio on the nanoparticle size were investigated. UV/Vis spectrophotometry and transmission electron microscopy (TEM) were used to measure the particle size distribution.

  4. Shape and size controlled synthesis of uniform iron oxide nanocrystals through new non-hydrolytic routes.

    PubMed

    Li, Wenlu; Lee, Seung Soo; Wu, Jiewei; Hinton, Carl H; Fortner, John D

    2016-08-12

    New, non-hydrolytic routes to synthesize highly crystalline iron oxide nanocrystals (8-40 nm, magnetite) are described in this report whereby particle size and morphology were precisely controlled through reactant (precursor, e.g. (FeO(OH)) ratios, co-surfactant and organic additive, and/or reaction time. Particle size, with high monodispersivity (<10%), is demonstrated to be a function of precursor concentrations and through the addition of different cosurfactants and/or additives, cubic, octahedral, potato-like, and flower-like iron oxide nanocrystals can be reproducibly synthesized through simple one-pot thermal decomposition methods. High resolution transmission electron microscope, x-ray diffraction, and superconducting quantum interference device were used to characterize the size, structure and magnetic properties of the resulting nanocrystals. For aqueous applications, materials synthesized/purified in organic solvents are broadly water dispersible through a variety of phase (aqueous) transfer method(s).

  5. Low Temperature CO oxidation over Iron Oxide Nanoparticles Decorating Internal Structures of a Mesoporous Alumina

    NASA Astrophysics Data System (ADS)

    Kim, Il Hee; Seo, Hyun Ook; Park, Eun Ji; Han, Sang Wook; Kim, Young Dok

    2017-01-01

    Using a chemical vapor deposition method with regulated sample temperatures under ambient pressure conditions, we were able to fully decorate the internal structure of a mesoporous Al2O3 bead (~1 mm in particle diameter) with iron oxide nanoparticles (with a mean lateral size of less than 1 nm). The iron oxide-decorated Al2O3 showed a high CO oxidation reactivity, even at room temperature. Very little deactivation of the CO oxidation activity was observed with increasing reaction time at ~100 °C. Additionally, this catalyst showed high CO oxidation activity, even after annealing at ~900 °C under atmospheric conditions (i.e., the structure of the catalysts could be maintained under very harsh treatment conditions). We show that our catalysts have potential for application as oxidation catalysts in industrial processes due to the simplicity of their fabrication process as well as the high and stable catalytic performance.

  6. Clinical applications of iron oxide nanoparticles for magnetic resonance imaging of brain tumors.

    PubMed

    Iv, Michael; Telischak, Nicholas; Feng, Dan; Holdsworth, Samantha J; Yeom, Kristen W; Daldrup-Link, Heike E

    2015-01-01

    Current neuroimaging provides detailed anatomic and functional evaluation of brain tumors, allowing for improved diagnostic and prognostic capabilities. Some challenges persist even with today's advanced imaging techniques, including accurate delineation of tumor margins and distinguishing treatment effects from residual or recurrent tumor. Ultrasmall superparamagnetic iron oxide nanoparticles are an emerging tool that can add clinically useful information due to their distinct physiochemical features and biodistribution, while having a good safety profile. Nanoparticles can be used as a platform for theranostic drugs, which have shown great promise for the treatment of CNS malignancies. This review will provide an overview of clinical ultrasmall superparamagnetic iron oxides and how they can be applied to the diagnostic and therapeutic neuro-oncologic setting.

  7. Determination of anisotropy constants of protein encapsulated iron oxide nanoparticles by electron magnetic resonance

    NASA Astrophysics Data System (ADS)

    Li, Hongyan; Klem, Michael T.; Sebby, Karl B.; Singel, David J.; Young, Mark; Douglas, Trevor; Idzerda, Yves U.

    2009-02-01

    Angle-dependent electron magnetic resonance was performed on 4.9, 8.0, and 19 nm iron oxide nanoparticles encapsulated within protein capsids and suspended in water. Measurements were taken at liquid nitrogen temperature after cooling in a 1 T field to partially align the particles. The angle dependence of the shifts in the resonance field for the iron oxide nanoparticles (synthesized within Listeria-Dps, horse spleen ferritin, and cowpea chlorotic mottle virus) all show evidence of a uniaxial anisotropy. Using a Boltzmann distribution for the particles' easy-axis direction, we are able to use the resonance field shifts to extract a value for the anisotropy energy, showing that the anisotropy energy density increases with decreasing particle size. This suggests that surface anisotropy plays a significant role in magnetic nanoparticles of this size.

  8. Characterization of the oleic acid/iron oxide nanoparticle interface by magnetic resonance

    NASA Astrophysics Data System (ADS)

    Masur, S.; Zingsem, B.; Marzi, T.; Meckenstock, R.; Farle, M.

    2016-10-01

    The synthesis of colloidal nanoparticles involves surfactant molecules, which bind to the particle surface and stabilize nanoparticles against aggregation. In many cases these protecting shells also can be used for further functionalization. In this study, we investigated monodisperse single crystalline iron oxide core/shell nanoparticles (FexOy-NPs) in situ covered with an oleic acid layer which showed two electron spin resonance (ESR) signals. The nanoparticles with the ligands attached were characterized by transmission electron microscopy (TEM) and ferro- and paramagnetic resonance (FMR, EPR). Infrared spectroscopy confirmed the presence of the functional groups and revealed that the oleic acid (OA) is chemisorbed as a carboxylate on the iron oxide and is coordinated symmetrically to the oxide atoms. We show that the EPR signal of the OA ligand molecule can be used as a local probe to determine the temperature changes at the surface of the nanoparticle.

  9. Iron oxide nanoparticles stabilized with a bilayer of oleic acid for magnetic hyperthermia and MRI applications

    NASA Astrophysics Data System (ADS)

    Soares, Paula I. P.; Laia, César A. T.; Carvalho, Alexandra; Pereira, Laura C. J.; Coutinho, Joana T.; Ferreira, Isabel M. M.; Novo, Carlos M. M.; Borges, João Paulo

    2016-10-01

    Iron oxide nanoparticles (Fe3O4, IONPs) are promising candidates for several biomedical applications such as magnetic hyperthermia and as contrast agents for magnetic resonance imaging (MRI). However, their colloidal stability in physiological conditions hinders their application requiring the use of biocompatible surfactant agents. The present investigation focuses on obtaining highly stable IONPs, stabilized by the presence of an oleic acid bilayer. Critical aspects such as oleic acid concentration and pH were optimized to ensure maximum stability. NPs composed of an iron oxide core with an average diameter of 9 nm measured using transmission electron microscopy (TEM) form agglomerates with an hydrodynamic diameter of around 170 nm when dispersed in water in the presence of an oleic acid bilayer, remaining stable (zeta potential of -120 mV). Magnetic hyperthermia and the relaxivities measurements show high efficiency at neutral pH which enables their use for both magnetic hyperthermia and MRI.

  10. High-performance iron oxide nanoparticles for magnetic particle imaging - guided hyperthermia (hMPI)

    NASA Astrophysics Data System (ADS)

    Bauer, Lisa M.; Situ, Shu F.; Griswold, Mark A.; Samia, Anna Cristina S.

    2016-06-01

    Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI).Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal

  11. Surface modification of iron oxide nanoparticles and their conjuntion with water soluble polymers for biomedical application

    NASA Astrophysics Data System (ADS)

    Thanh Huong, Nguyen; Thi Kieu Giang, Lam; Thanh Binh, Nguyen; Minh, Le Quoc

    2009-09-01

    Superparamagnetic iron oxide nanoparticles (SPION) coated with suitable bio-compatible substances have been used in biomedicine, particularly in magnetic resonance imaging (MRI), tissue engineering, and hyperthermia and drug delivery. In this study, we describe the synthesis of SPION and its surface modification for in-vitro experiments. The particle diameter and structure were estimated by FESEM, TEM, XRD analyses. The saturation magnetization was characterized. SPION with a mean size of 12 nm have been prepared under N2 atmosphere, with support of natural polymeric starch, by controlling chemical coprecipitation of magnetite phase from aqueous solutions containing suitable salts ratios of Fe2+ and Fe3+. The surface of SPION-nanoparticles was treated with a coordinatable agent for higher dispersion ability in water and remaining the superparamagnetic behavior. The prepared iron oxide nanoparticles were coated with starch, dextran, PEG or MPEG to extend the application potential in the quite different engineering field of nano biomedicine.

  12. Growth of textured thin Au coatings on iron oxide nanoparticles with near infrared absorbance

    PubMed Central

    Ma, L L; Borwankar, A U; Willsey, B W; Yoon, K Y; Tam, J O; Sokolov, K V; Feldman, M D; Milner, T E; Johnston, K P

    2013-01-01

    A homologous series of Au-coated iron oxide nanoparticles, with hydrodynamic diameters smaller than 60 nm was synthesized with very low Auto-iron mass ratios as low as 0.15. The hydrodynamic diameter was determined by dynamic light scattering and the composition by atomic absorption spectroscopy and energy dispersive x-ray spectroscopy (EDS). Unusually low Au precursor supersaturation levels were utilized to nucleate and grow Au coatings on iron oxide relative to formation of pure Au nanoparticles. This approach produced unusually thin coatings, by lowering autocatalytic growth of Au on Au, as shown by transmission electron microscopy (TEM). Nearly all of the nanoparticles were attracted by a magnet indicating a minimal amount of pure Au particles The coatings were sufficiently thin to shift the surface plasmon resonance (SPR) to the near infrared (NIR), with large extinction coefficients., despite the small particle hydrodynamic diameters, observed from dynamic light scattering to be less than 60 nm. PMID:23238021

  13. Ultrasmall iron oxide nanoparticles for biomedical applications: improving the colloidal and magnetic properties.

    PubMed

    Costo, Rocio; Bello, Valentina; Robic, Caroline; Port, Marc; Marco, Jose F; Puerto Morales, M; Veintemillas-Verdaguer, Sabino

    2012-01-10

    A considerable increase in the saturation magnetization, M(s) (40%), and initial susceptibility of ultrasmall (<5 nm) iron oxide nanoparticles prepared by laser pyrolysis was obtained through an optimized acid treatment. Moreover, a significant enhancement in the colloidal properties, such as smaller aggregate sizes in aqueous media and increased surface charge densities, was found after this chemical protocol. The results are consistent with a reduction in nanoparticle surface disorder induced by a dissolution-recrystallization mechanism.

  14. Tissue Plasminogen Activator Binding to Superparamagnetic Iron Oxide Nanoparticle—Covalent Versus Adsorptive Approach

    NASA Astrophysics Data System (ADS)

    Friedrich, Ralf P.; Zaloga, Jan; Schreiber, Eveline; Tóth, Ildikó Y.; Tombácz, Etelka; Lyer, Stefan; Alexiou, Christoph

    2016-06-01

    Functionalized superparamagnetic iron oxide nanoparticles are frequently used to develop vehicles for drug delivery, hyperthermia, and photodynamic therapy and as tools used for magnetic separation and purification of proteins or for biomolecular imaging. Depending on the application, there are various possible covalent and non-covalent approaches for the functionalization of particles, each of them shows different advantages and disadvantages for drug release and activity at the desired location.

  15. Iron oxide particles as a catalyst in chemical oxidation of organic contaminants

    SciTech Connect

    Gurol, M.D.; Lin, S.S.; Bhat, N.

    1995-12-31

    This research addresses the use of ozone and hydrogen peroxide in the presence of iron oxide particles which provide a catalytic surface for conversion to hydroxyl free radical. N-butylchloride (BuCl) and monochlorobenzene (MCB) were oxidized using goethite as the catalyst. The effect of varying the dosage of hydrogen peroxide or ozone, the mass and the size of the geothite particles, the mixing speed, and the gas flow rate for ozonation was investigated. The effect of water quality in terms of pH, carbonate alkalinity and initial organic concentration on reaction rates was addressed as well. Experimental observations showed that varying the stirring speed in the reactor or the size of the iron oxide particles did not have any significant effect on the oxidation rates, indicating that the rate was controlled by the intrinsic reaction rates on iron oxide surfaces. The presence of hydrogen peroxide significantly increased the removal of BuCl, and higher dosages caused considerably higher removal. Results also demonstrated a strong dependence of BuCl removal on the iron oxide dosage. MCB adsorbed strongly on goethite, but was oxidized effectively by ozone. Hydrogen peroxide decomposed rapidly in the presence of goethite at a rate directly proportional to the rate of BuCl oxidation. These results indicate that the interaction of hydrogen peroxide with goethite particles leads to the formation of hydroxyl free radical, which is responsible for oxidation of BuCl. Similarly, ozone decomposed in the presence of goethite. The oxidation efficiency for hydrogen peroxide/goethite remained unaffected when the pH and the alkalinity were varied. Furthermore, the ozone/goethite system provided mineralization as measured by the removal of the total organic carbon. Hence, both of these oxidation processes promise to be effective in oxidation of organic compounds, and may not suffer from the limitations of other radical processes.

  16. Detection of viruses in drinking water by concentration on magnetic iron oxide.

    PubMed

    Rao, V C; Waghmare, S V; Lakhe, S B

    1981-09-01

    Discharge of raw domestic wastes containing human enteric viruses into water courses, consumption of untreated water from canals, streams, and shallow wells in villages, and cross-contamination of water in the distribution system because of intermittent water supply in urban areas continue to cause widespread outbreaks of infectious hepatitis in India. To detect a low number of viruses in 50- to 100-liter samples of water, a method was developed with magnetic iron oxide as the virus adsorbent. Poliovirus-seeded dechlorinated tap water, adjusted to pH 3.0 and 0.0005 M AlCl3, was filtered through a 10-g bed of iron oxide sandwiched between two AP20 prefilter pads held in a 142-mm-diameter, stainless-steel holder. Virus was eluted from iron oxide by recirculating three times a 100-ml volume of 3% beef extract, pH 9.0. The eluate was reconcentrated to 5 ml by adjusting to pH 3, adding 1 g of iron oxide, stirring for 30 min, and eluting the readsorbed virus with 5 ml of beef extract, pH 9.0. Virus recovery varied from 60 to 80%. Using the above method, we took a survey of drinking water at three locations in Nagpur during 1976 and found the presence of virus in 7 of 50 samples. The quantity of virus recovered ranged from 1 to 7 plaque-forming units per 30 to 60 liters. Virus was detected in some samples even with residual chlorine. No coliforms were detected in the virus-positive samples.

  17. Cluster molecular orbital description of the electronic structures of mixed-valence iron oxides and silicates

    USGS Publications Warehouse

    Sherman, David M.

    1986-01-01

    A molecular orbital description, based on spin-unrestricted X??-scattered wave calculations, is given for the electronic structures of mixed valence iron oxides and silicates. The cluster calculations show that electron hopping and optical intervalence charge-transger result from weak FeFe bonding across shared edges of FeO6 coordination polyhedra. In agreement with Zener's double exchange model, FeFe bonding is found to stabilize ferromagnetic coupling between Fe2+ and Fe3+ cations. ?? 1986.

  18. Microbial iron oxidation in the Arctic tundra and its implications for biogeochemical cycling.

    PubMed

    Emerson, David; Scott, Jarrod J; Benes, Joshua; Bowden, William B

    2015-12-01

    The role that neutrophilic iron-oxidizing bacteria play in the Arctic tundra is unknown. This study surveyed chemosynthetic iron-oxidizing communities at the North Slope of Alaska near Toolik Field Station (TFS) at Toolik Lake (lat 68.63, long -149.60). Microbial iron mats were common in submerged habitats with stationary or slowly flowing water, and their greatest areal extent is in coating plant stems and sediments in wet sedge meadows. Some Fe-oxidizing bacteria (FeOB) produce easily recognized sheath or stalk morphotypes that were present and dominant in all the mats we observed. The cool water temperatures (9 to 11°C) and reduced pH (5.0 to 6.6) at all sites kinetically favor microbial iron oxidation. A microbial survey of five sites based on 16S rRNA genes found a predominance of Proteobacteria, with Betaproteobacteria and members of the family Comamonadaceae being the most prevalent operational taxonomic units (OTUs). In relative abundance, clades of lithotrophic FeOB composed 5 to 10% of the communities. OTUs related to cyanobacteria and chloroplasts accounted for 3 to 25% of the communities. Oxygen profiles showed evidence for oxygenic photosynthesis at the surface of some mats, indicating the coexistence of photosynthetic and FeOB populations. The relative abundance of OTUs belonging to putative Fe-reducing bacteria (FeRB) averaged around 11% in the sampled iron mats. Mats incubated anaerobically with 10 mM acetate rapidly initiated Fe reduction, indicating that active iron cycling is likely. The prevalence of iron mats on the tundra might impact the carbon cycle through lithoautotrophic chemosynthesis, anaerobic respiration of organic carbon coupled to iron reduction, and the suppression of methanogenesis, and it potentially influences phosphorus dynamics through the adsorption of phosphorus to iron oxides.

  19. Manipulating the dimensional assembly pattern and crystalline structures of iron oxide nanostructures with a functional polyolefin.

    PubMed

    He, Qingliang; Yuan, Tingting; Wang, Yiran; Guleria, Abhishant; Wei, Suying; Zhang, Guoqi; Sun, Luyi; Liu, Jingjing; Yu, Jingfang; Young, David P; Lin, Hongfei; Khasanov, Airat; Guo, Zhanhu

    2016-01-28

    Controlled crystalline structures (α- and γ-phase) and assembly patterns (1-D, 2-D and 3-D) were achieved in the synthesized iron oxide (Fe2O3) nanoparticles (NPs) using polymeric surfactant-polypropylene grafted maleic anhydride (PP-g-MA) with different concentrations. In addition, the change of the crystalline structure from the α- and γ-phase also led to the significantly increased saturation magnetization and coercivity.

  20. Whole tissue AC susceptibility after superparamagnetic iron oxide contrast agent administration in a rat model

    NASA Astrophysics Data System (ADS)

    Lázaro, Francisco José; Gutiérrez, Lucía; Rosa Abadía, Ana; Soledad Romero, María; López, Antonio; Jesús Muñoz, María

    2007-04-01

    A magnetic AC susceptibility characterisation of rat tissues after intravenous administration of superparamagnetic iron oxide (Endorem ®), at the same dose as established for Magnetic Resonance Imaging (MRI) contrast enhancement in humans, has been carried out. The measurements reveal the presence of the contrast agent as well as that of physiological ferritin in liver and spleen while no traces have been magnetically detected in heart and kidney. This preliminary work opens suggestive possibilities for future biodistribution studies of any type of magnetic carriers.

  1. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    NASA Astrophysics Data System (ADS)

    Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

    2016-11-01

    Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to <20 nM coincident with a maximum in particulate iron concentration. Within the iron gradient, we found an increased expression of the key functional marker gene for nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

  2. Trace element cycling through iron oxide minerals during redox-driven dynamic recrystallization

    SciTech Connect

    Frierdich, Andrew J.; Luo, Yun; Catalano, Jeffrey G.

    2011-11-17

    Microbially driven iron redox cycling in soil and sedimentary systems, including during diagenesis and fluid migration, may activate secondary abiotic reactions between aqueous Fe(II) and solid Fe(III) oxides. These reactions catalyze dynamic recrystallization of iron oxide minerals through localized and simultaneous oxidative adsorption of Fe(II) and reductive dissolution of Fe(III). Redox-active trace elements undergo speciation changes during this process, but the impact redox-driven recrystallization has on redox-inactive trace elements associated with iron oxides is uncertain. Here we demonstrate that Ni is cycled through the minerals goethite and hematite during redox-driven recrystallization. X-ray absorption spectroscopy demonstrates that during this process adsorbed Ni becomes progressively incorporated into the minerals. Kinetic studies using batch reactors containing aqueous Fe(II) and Ni preincorporated into iron oxides display substantial release of Ni to solution. We conclude that iron oxide recrystallization activated by aqueous Fe(II) induces cycling of Ni through the mineral structure, with adsorbed Ni overgrown in regions of Fe(II) oxidative adsorption and incorporated Ni released in regions of reductive dissolution of structural Fe(III). The redistribution of Ni among the mineral bulk, mineral surface, and aqueous solution appears to be thermodynamically controlled and catalyzed by Fe(II). Our work suggests that important proxies for ocean composition on the early Earth may be invalid, identifies new processes controlling micronutrient availability in soil, sedimentary, and aquatic ecosystems, and points toward a mechanism for trace element mobilization during diagenesis and enrichment in geologic fluids.

  3. Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs

    SciTech Connect

    Beam, Jake; Bernstein, Hans C.; Jay, Z.; Kozubal, Mark; Jennings, Ryan; Tringe, Susannah G.; Inskeep, William P.

    2016-02-15

    Iron oxide microbial mats are ubiquitous geobiological features on Earth and occur in extant acidic hot springs of Yellowstone National Park (YNP), WY, USA, and form as a result of microbial processes. The relative contribution of different organisms to the development of these mat ecosystems is of specific interest. We hypothesized that chemolithoautotrophic organisms contribute to the early development and production of Fe(III)-oxide mats, which could support later-colonizing heterotrophic microorganisms. Sterile glass slides were incubated in the outflow channels of two acidic geothermal springs in YNP, and spatiotemporal changes in Fe(III)-oxide accretion and abundance of relevant community members were measured. Lithoautotrophic Hydrogenobaculum spp. were first colonizers and the most abundant taxa identified during early successional stages (7 – 40 days). Populations of M. yellowstonensis colonized after ~ 7 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized after 30 days, and emerge as the dominant functional guild in mature iron oxide mats (1 – 2 cm thick) that form after 70 – 120 days. First-order rate constants of iron oxide accretion ranged from 0.05 – 0.046 day-1, and reflected the absolute amount of iron accreted. Micro- and macroscale microterracettes were identified during iron oxide mat development, and suggest that the mass transfer of oxygen limits microbial growth. This was also demonstrated using microelectrode measurements of oxygen as a function of mat depth, which showed steep gradients in oxygen from the aqueous mat interface to ~ 1 mm. The formation and succession of amorphous Fe(III)-oxide mat communities follows a predictable pattern of distinct stages and growth. The successional stages and microbial signatures observed in these extant Fe(III)-oxide mat communities may be relevant to other past or present Fe(III)-oxide mineralizing systems.

  4. Microbial Iron Oxidation in the Arctic Tundra and Its Implications for Biogeochemical Cycling

    PubMed Central

    Scott, Jarrod J.; Benes, Joshua; Bowden, William B.

    2015-01-01

    The role that neutrophilic iron-oxidizing bacteria play in the Arctic tundra is unknown. This study surveyed chemosynthetic iron-oxidizing communities at the North Slope of Alaska near Toolik Field Station (TFS) at Toolik Lake (lat 68.63, long −149.60). Microbial iron mats were common in submerged habitats with stationary or slowly flowing water, and their greatest areal extent is in coating plant stems and sediments in wet sedge meadows. Some Fe-oxidizing bacteria (FeOB) produce easily recognized sheath or stalk morphotypes that were present and dominant in all the mats we observed. The cool water temperatures (9 to 11°C) and reduced pH (5.0 to 6.6) at all sites kinetically favor microbial iron oxidation. A microbial survey of five sites based on 16S rRNA genes found a predominance of Proteobacteria, with Betaproteobacteria and members of the family Comamonadaceae being the most prevalent operational taxonomic units (OTUs). In relative abundance, clades of lithotrophic FeOB composed 5 to 10% of the communities. OTUs related to cyanobacteria and chloroplasts accounted for 3 to 25% of the communities. Oxygen profiles showed evidence for oxygenic photosynthesis at the surface of some mats, indicating the coexistence of photosynthetic and FeOB populations. The relative abundance of OTUs belonging to putative Fe-reducing bacteria (FeRB) averaged around 11% in the sampled iron mats. Mats incubated anaerobically with 10 mM acetate rapidly initiated Fe reduction, indicating that active iron cycling is likely. The prevalence of iron mats on the tundra might impact the carbon cycle through lithoautotrophic chemosynthesis, anaerobic respiration of organic carbon coupled to iron reduction, and the suppression of methanogenesis, and it potentially influences phosphorus dynamics through the adsorption of phosphorus to iron oxides. PMID:26386054

  5. Structural characterization, antibacterial and catalytic effect of iron oxide nanoparticles synthesised using the leaf extract of Cynometra ramiflora

    NASA Astrophysics Data System (ADS)

    Groiss, Silvia; Selvaraj, Raja; Varadavenkatesan, Thivaharan; Vinayagam, Ramesh

    2017-01-01

    In the present investigation, the leaf extract of Cynometra ramiflora was used to synthesize iron oxide nanoparticles. Within minutes of adding iron sulphate to the leaf extract, iron oxide nanoparticles were formed and thus, the method is very simple and fast. UV-VIS spectra showed the strong absorption band in the visible region. SEM images showed discrete spherical shaped particles and EDS spectra confirmed the iron and oxygen presence. The XRD results depicted the crystalline structure of iron oxide nanoparticles. FT-IR spectra portrayed the existence of functional groups of phytochemicals which are probably involved in the formation and stabilization of nanoparticles. The iron oxide nanoparticles exhibited effective inhibition against E. coli and S. epidermidis which may find its applications in the antibacterial drug development. Furthermore, the catalytic activity of the nanoparticles as Fenton-like catalyst was successfully investigated for the degradation of Rhodamine-B dye. This outcome could play a prominent role in the wastewater treatment.

  6. Distribution Behavior of Phosphorus and Metallization of Iron Oxide in Carbothermic Reduction of High-Phosphorus Iron Ore

    NASA Astrophysics Data System (ADS)

    Cha, Ji-Whoe; Kim, Dong-Yuk; Jung, Sung-Mo

    2015-10-01

    Distribution behavior of phosphorus and metallization of iron ore in the carbothermic reduction of high-phosphorus iron ore were investigated. Reduction degree of the iron oxide was evaluated by quadruple mass spectrometry connected to thermogravimetric analysis. The distribution of some elements including phosphorus was examined by electron probe micro-analyzer mapping analyses. The reduction behavior of high-phosphorus iron ore was evaluated as a function of reduction temperature, C/O molar ratio, and CaO addition. High reduction temperature accelerated the reduction of both iron oxide and hydroxylapatite, and high C/O molar ratio also promotes both of them. Those were contradictory to the targets of higher reduction degree of iron oxide and of lower one of hydroxylapatite. It was confirmed that appropriate amount of CaO addition could enhance the reduction of iron oxide, and regulate the reduction of hydroxylapatite.

  7. [Study on fast discrimination of varieties of acidophilous milk using near infrared spectra].

    PubMed

    He, Yong; Feng, Shui-juan; Li, Xiao-li; Qiu, Zheng-jun

    2006-11-01

    A new method for the discrimination of varieties of near acidophilous milk by means of near infrared spectroscopy (NIRS) was developed. Firstly, through the principal component analysis (PCA) of spectroscopic curves of 5 typical kinds of acidophilous milk, the clustering of acidophilous milk varieties was processed. The analysis results showed that the cumulate reliabilities of PC1 and PC2 (the first two principal components) reached 98.96%, and the cumulate reliabilities of PC1 to PC7 (the first seven principal components) were 99.97%. Secondly, a discrimination model of artificial neural network (ANN-BP) was set up. The first seven principal components of the samples were applied as ANN-BP inputs, and the values of type of acidophilous milk were applied as outputs, then the three layer ANN-BP model was build. In this model, every variety of acidophilous milk includes 27 samples, the total number of samples is 135, and the rest 25 samples were used as prediction set. Calculation results showed that the distinguishing rate of the five acidophilous milk varieties was 100%. This model is reliable and practicable. So a new approach to the rapid and lossless discrimination of varieties of acidophilous milk was put forward.

  8. Fluorophore Conjugated Iron Oxide Nanoparticle Labeling and Analysis of Engrafting Human Hematopoietic Stem Cells

    PubMed Central

    Maxwell, Dustin J.; Bonde, Jesper; Hess, David A.; Hohm, Sarah A.; Lahey, Ryan; Creer, Michael H.; Piwnica-Worms, David; Nolta, Jan A.

    2010-01-01

    The use of nanometer-sized iron oxide particles combined with molecular imaging techniques enable dynamic studies of homing and trafficking of human hematopoietic stem cells (HSC). Identifying clinically applicable strategies for loading nanoparticles into primitive HSC requires strictly defined culture conditions to maintain viability without inducing terminal differentiation. In the current study, fluorescent molecules were covalently linked to dextran-coated iron oxide nanoparticles (Feridex) to characterize human HSC labeling to monitor the engraftment process. Conjugating fluorophores to the dextran coat for FACS purification eliminated spurious signals from non-sequestered nanoparticle contaminants. A short-term defined incubation strategy was developed which allowed efficient labeling of both quiescent and cycling HSC, with no discernable toxicity in vitro or in vivo. Transplantation of purified primary human cord blood lineage-depleted and CD34+ cells into immunodeficient mice allowed detection of labeled human HSC in the recipient bones. Flow cytometry was used to precisely quantitate the cell populations that had sequestered the nanoparticles, and to follow their fate post-transplantation. Flow cytometry endpoint analysis confirmed the presence of nanoparticle-labeled human stem cells in the marrow. The use of fluorophore-labeled iron oxide nanoparticles for fluorescence imaging in combination with flow cytometry allows evaluation of labeling efficiencies and homing capabilities of defined human HSC subsets. PMID:18055451

  9. NIR-activated iron oxides as a new multi-functional contrast agent of photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Ting, Pei-Hsien; Huang, Chih-Chia; Li, Meng-Lin

    2014-03-01

    Iron oxide nanoparticles are commonly used contrast agents for theranostic nanomedicines because of their advantages of good biocompatibility, high stability in physiological conditions, low cytotoxicity and excellent safety record in clinical settings for human use. In this study, we developed a NIR-activated iron oxide (NIR-Fe3O4) nanoparticle as a new multi-functional contrast agent of photoacoustic (PA) imaging. Unlike traditional iron oxides, the developed NIR-Fe3O4 owns biocompatibility and optical tunability capable of providing strong optical absorption in the NIR range for PA signal generation. Its intrinsic magnetic property enables the active magnetic tumor targeting. Phantom experiments were performed to confirm the tunability of NIR-Fe3O4's optical absorption in NIR and demonstrate its magnetic targeting capability. The PA signal response of NIR-Fe3O4 as a function of concentration was also investigated. The results showed that the PA signal of NIR-Fe3O4 with OD=1.25 was comparable to that of blood at 715 nm - the wavelength of peak absorption of the used NIR-Fe3O4. Moreover, the PA signal from NIR-Fe3O4 could be further improved by magnetic targeting. Overall, we proved that the potential of the developed NIR-Fe3O4 as a good tumor targeting contrast agent of PA imaging.

  10. Chondroitin sulfate-capped super-paramagnetic iron oxide nanoparticles as potential carriers of doxorubicin hydrochloride.

    PubMed

    Mallick, Neha; Anwar, Mohammed; Asfer, Mohammed; Mehdi, Syed Hassan; Rizvi, Mohammed Moshahid Alam; Panda, Amulya Kumar; Talegaonkar, Sushama; Ahmad, Farhan Jalees

    2016-10-20

    Chondroitin-4-sulfate (CS), a glycosaminoglycan, was used to prepare CS-capped super-paramagnetic iron oxide nanoparticles, which were further employed for loading a water-soluble chemotherapeutic agent (doxorubicin hydrochloride, DOX). CS-capped SPIONs have potential biomedical application in cancer targeting. The optimized formulation had a hydrodynamic size of 91.2±0.8nm (PDI; 0.228±0.004) and zeta potential of -49.1±1.66mV. DOX was loaded onto the formulation up to 2% (w/w) by physical interaction with CS. TEM showed nano-sized particles having a core-shell structure. XRD confirmed crystal phase of iron oxide. FT-IR conceived the interaction of iron oxide with CS as bidentate chelation and also confirmed DOX loading. Vibration sample magnetometry confirmed super-paramagnetic nature of nanoparticles, with saturation magnetization of 0.238emug(-1). In vitro release profile at pH 7.4 showed that 96.67% of DOX was released within 24h (first order kinetics). MTT assay in MCF7 cells showed significantly higher (p<0.0001) cytotoxicity for DOX in SPIONs than DOX solution (IC50 values 6.294±0.4169 and 11.316±0.1102μgmL(-1), respectively).

  11. Hydrous iron oxide modified diatomite as an active filtration medium for phosphate capture.

    PubMed

    Wang, Zhe; Lin, Yan; Wu, Deyi; Kong, Hainan

    2016-02-01

    A simple method to functionalize diatomite with hydrous iron oxide was attempted and its performance as a new active filtration material to remove and recover phosphate from water was investigated under varying solution conditions. The Langmuir phosphate adsorption capacity increased from 0.6 mgP/g for raw diatomite to 4.89, 14.71, 25.02 mgP/g for hydrous iron oxide modified diatomite (HIOMD), depending on the amount of iron loaded. Loading of hydrous iron oxide caused the increase in true and bulk density and a decline in filtration rate, but to a lesser extent. It was shown that the HIOMD product with suitable iron content could retain a good filtration performance with a greatly increased adsorption capacity for phosphate. The phosphate adsorption increased by decreasing pH and by increasing ionic strength at high pH levels. The adsorption process was interpreted by ligand exchange. Coexisting oxyanions of sulfate, nitrate, citrate, carbonate, silicate and humic acid showed different effects on phosphate fixation but it was presumed that their influence at their concentrations and pH levels commonly encountered in effluent or natural waters was limited, i.e., HIOMD had a reasonably good selectivity. Results in repeated adsorption, desorption and regeneration experiment showed that the adsorbed phosphate could be recovered and the material could be reused after regeneration. The column test showed that HIOMD could be potentially utilized as an adsorption filtration medium for phosphate removal and recovery from water.

  12. Synthesis of iron oxide nanotubes and their applications in neuroscience and drug delivery

    NASA Astrophysics Data System (ADS)

    Chen, Linfeng; Xie, Jining; Aatre, Kiran R.; Yancey, Justin; Srivatsan, Malathi; Varadan, Vijay K.

    2012-10-01

    This paper reports the synthesis of three types of iron oxide nanotubes, including hematite (α-Fe2O3), maghemite (γ-Fe2O3) and magnetite (Fe3O4), and their applications in neuroscience and drug delivery. Two methods, template-assisted thermal decomposition method and hydrothermal method, were used for synthesizing hematite nanotubes, and maghemite nanotubes were obtained from hematite nanotubes by thermal treatment. Template-assisted filtering method was used for synthesizing magnetite nanotubes from ferrofluid. The crystalline, morphology and magnetic properties of the synthesized iron oxide nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM), respectively. The biocompatibility of the synthesized hematite nanotubes was confirmed by the survival and differentiation of PC12 cells in the presence of the hematite nanotubes coupled to nerve growth factor (NGF). The capacity of hematite nanotubes for coupling and leasing NGF was confirmed by cultivating PC12 cells in the presence of NGF-loaded hematite nanotubes. The drug loading and release capabilities of hematite nanotubes were tested by using ibuprofen sodium salt (ISS) as a drug model. Based on the experimental results presented in this paper, it can be concluded that iron oxide nanotubes have good biocompatibility with neurons, could be used in guding neurite growth, and are promising candidates for drug delivery.

  13. In situ synthesis of hydroxyapatite nanocomposites using iron oxide nanofluids at ambient conditions.

    PubMed

    Sheikh, Lubna; Mahto, Neha; Nayar, Suprabha

    2015-01-01

    This paper describes a simple method for the room temperature synthesis of magnetite/hydroxyapatite composite nanocomposites using ferrofluids. The in situ synthesis of magnetic-hydroxyapatite results in a homogenous distribution of the two phases as seen both in transmission electron micrographs and assembled to a micron range in the confocal micrographs. The selected area diffraction pattern analysis shows the presence of both phases of iron oxide and hydroxyapatite. To the dialyzed ferrofluid, the constituents of hydroxyapatite synthesis was added, the presence of the superparamagnetic iron oxide particles imparts directionality to the hydroxyapatite crystal growth. Electron probe microanalysis confirms the co-existence of both iron and calcium atoms. Vibrating Sample magnetometer data shows magnetization three times more than the parent ferrofluid, the local concentration of iron oxide nanoparticles affects the strength of dipolar interparticle interactions changing the energy barrier for determining the collective magnetic behavior of the sample. The limitations inherent to the use of external magnetic fields which can be circumvented by the introduction of internal magnets located in the proximity of the target by a minimal surgery or by using a superparamagnetic scaffold under the influence of externally applied magnetic field inspires us to increase the magnetization of our samples. The composite in addition shows anti-bacterial properties against the two gram (-ve) bacteria tested. This work is significant as magnetite-hydroxyapatite composites are attracting a lot of attention as adsorbents, catalysts, hyperthermia agents and even as regenerative medicine.

  14. Authigenic iron oxide formation in the estuarine mixing zone of the Yangtze River

    NASA Astrophysics Data System (ADS)

    Fan, D. J.; Neuser, R. D.; Sun, X. G.; Yang, Z. S.; Guo, Z. G.; Zhai, S. K.

    2008-02-01

    Estuaries are elementary geochemical fronts where river water and seawater mix. Within this mixing zone, iron and other non-conservative elements can undergo complex reactions to form new solid phases. In order to understand authigenic iron oxide formation in the Yangtze River Estuary, two onsite water-mixing sets of experiments were conducted, one by mixing variable amounts of unfiltered Yangtze River water with filtered East China Sea water of different salinity (set 1), the other by mixing variable amounts of filtered Yangtze River water with filtered East China Sea water of different salinity (set 2). In set 2, the minerals newly formed in the course of mixing were investigated by means of a scanning electron microscope fitted with an energy-dispersive X-ray analytical system. It was found that ferrihydrite and lepidocrocite were formed in these mixing experiments, coexisting in nearly equal amounts. These iron oxides appear as aggregated particles with a large grain-size range of several microns to more than 100 μm. The electrolytic properties of seawater played an important role in the formation of these authigenic iron oxides. Kaolinite and organic aggregates were also found in the experimentally mixed pre-filtered waters. Amounts of newly formed suspended matter (set 2) were one to three orders of magnitude lower than those of total suspended matter (TSM) (set 1). This implies that newly formed minerals represent only a very small proportion of TSM in the estuarine mixing zone of the Yangtze River.

  15. Chromium removal by combining the magnetic properties of iron oxide with adsorption properties of carbon nanotubes.

    PubMed

    Gupta, V K; Agarwal, Shilpi; Saleh, Tawfik A

    2011-03-01

    The adsorption features of multiwall carbon nanotubes (MWCNTs) with the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. Composites of MWCNT/nano-iron oxide were prepared, and were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR). XRD suggests that the magnetic phase formed is maghemite and/or magnetite. FESEM image shows nano-iron oxides attached to a network of MWCNTs. The adsorption capability of the composites was tested in batch and fixed bed modes. The composites have demonstrated a superior adsorption capability to that of activated carbon. The results also show that the adsorptions of Cr(III) on the composites is strongly dependent on contact time, agitation speed and pH, in the batch mode; and on flow rate and the bed thickness in the fixed bed mode. Along with the high surface area of the MWCNTs, the advantage of the magnetic composite is that it can be used as adsorbent for contaminants in water and can be subsequently controlled and removed from the medium by a simple magnetic process.

  16. Gold and gold-iron oxide magnetic glyconanoparticles: synthesis, characterization and magnetic properties.

    PubMed

    de la Fuente, Jesús M; Alcántara, David; Eaton, Peter; Crespo, Patricia; Rojas, Teresa C; Fernandez, Asunción; Hernando, Antonio; Penadés, Soledad

    2006-07-06

    The preparation, characterization and the magnetic properties of gold and gold-iron oxide glyconanoparticles (GNPs) are described. Glyconanoparticles were prepared in a single step procedure in the presence of aqueous solution of thiol functionalized neoglycoconjugates and either gold salts or both gold and iron salts. Neoglycoconjugates of lactose and maltose disaccharides with different linkers were used. Iron-free gold or gold-iron oxide GNPs with controlled gold-iron ratios were obtained. The average core-size diameters are in the range of 1.5-2.5 nm. The GNPs are fully characterized by (1)H NMR spectrometry, transmission electron microscopy (TEM), and UV-vis and X-ray absorption (XAS) spectroscopies. Inductive plasma-atomic emission spectrometry (ICP) and elemental analysis gave the average number of neoglycoconjugates per cluster. The magnetic properties were measured in a SQUID magnetometer. The most remarkable results was the observation of a permanent magnetism up to room temperature in the iron-free gold GNPs, that was not present in the corresponding gold-iron oxide GNPs.

  17. DNA-Based Synthesis and Assembly of Organized Iron Oxide Nanostructures

    NASA Astrophysics Data System (ADS)

    Khomutov, Gennady B.

    Organized bio-inorganic and hybrid bio-organic-inorganic nanostructures consisting of iron oxide nanoparticles and DNA complexes have been formed using methods based on biomineralization, interfacial and bulk phase assembly, ligand exchange and substitution, Langmuir-Blodgett technique, DNA templating and scaffolding. Interfacially formed planar DNA complexes with water-insoluble amphiphilic polycation or intercalator Langmuir monolayers were prepared and deposited on solid substrates to form immobilized DNA complexes. Those complexes were then used for the synthesis of organized DNA-based iron oxide nanostructures. Planar net-like and circular nanostructures of magnetic Fe3O4 nanoparticles were obtained via interaction of cationic colloid magnetite nanoparticles with preformed immobilized DNA/amphiphilic polycation complexes of net-like and toroidal morphologies. The processes of the generation of iron oxide nanoparticles in immobilized DNA complexes via redox synthesis with various iron sources of biological (ferritin) and artificial (FeCl3) nature have been studied. Bulk-phase complexes of magnetite nanoparticles with biomolecular ligands (DNA, spermine) were formed and studied. Novel nano-scale organized bio-inorganic nanostructures - free-floating sheet-like spermine/magnetite nanoparticle complexes and DNA/spermine/magnetite nanoparticle complexes were synthesized in bulk aqueous phase and the effect of DNA molecules on the structure of complexes was discovered.

  18. Biodiversity and emerging biogeography of the neutrophilic iron-oxidizing Zetaproteobacteria.

    PubMed

    McAllister, Sean M; Davis, Richard E; McBeth, Joyce M; Tebo, Bradley M; Emerson, David; Moyer, Craig L

    2011-08-01

    Members of the neutrophilic iron-oxidizing candidate class Zetaproteobacteria have predominantly been found at sites of microbially mediated iron oxidation in marine environments around the Pacific Ocean. Eighty-four full-length (>1,400-bp) and 48 partial-length Zetaproteobacteria small-subunit (SSU) rRNA gene sequences from five novel clone libraries, one novel Zetaproteobacteria isolate, and the GenBank database were analyzed to assess the biodiversity of this burgeoning class of the Proteobacteria and to investigate its biogeography between three major sampling regions in the Pacific Ocean: Loihi Seamount, the Southern Mariana Trough, and the Tonga Arc. Sequences were grouped into operational taxonomic units (OTUs) on the basis of a 97% minimum similarity. Of the 28 OTUs detected, 13 were found to be endemic to one of the three main sampling regions and 2 were ubiquitous throughout the Pacific Ocean. Additionally, two deeply rooted OTUs that potentially dominate communities of iron oxidizers originating in the deep subsurface were identified. Spatial autocorrelation analysis and analysis of molecular variance (AMOVA) showed that geographic distance played a significant role in the distribution of Zetaproteobacteria biodiversity, whereas environmental parameters, such as temperature, pH, or total Fe concentration, did not have a significant effect. These results, detected using the coarse resolution of the SSU rRNA gene, indicate that the Zetaproteobacteria have a strong biogeographic signal.

  19. Colloidal stability of iron oxide nanocrystals coated with a PEG-based tetra-catechol surfactant

    NASA Astrophysics Data System (ADS)

    Mondini, Sara; Drago, Carmelo; Ferretti, Anna M.; Puglisi, Alessandra; Ponti, Alessandro

    2013-03-01

    Long-term colloidal stability of magnetic iron oxide nanoparticles (NPs) is an important goal that has not yet been fully achieved. To make an advance in our understanding of the colloidal stability of iron oxide NPs in aqueous media, we prepared NPs comprising a monodisperse (13 nm) iron oxide core coated with a PEG-based (PEG: polyethyleneglycol) surfactant. This consists of a methoxy-terminated PEG chain (MW = 5000 Da) bearing four catechol groups via a diethylenetriamine linker. The surfactant was grafted onto the nanocrystals by ligand exchange monitored by infrared spectroscopy. The colloidal stability of these nanoparticles was probed by monitoring the time evolution of the Z-average intensity-weighted radius Rh and volume-weighted size distribution Pv obtained from analysis of dynamic light scattering data. The nanoparticles showed no sign of aggregation for four months in deionized water at room temperature and also when subjected to thermal cycling between 25 and 75 °C. In 0.01 M PBS (phosphate buffered saline), aggregation (if any) is slow and partial; after 66 h, about 50% of NPs have not aggregated. Aggregation is more effective in 0.15 M NH4AcO buffer, where isolated particles are not observed after 66 h, and especially in acidic NH4AcO/AcOH buffer, where aggregation is complete within 1 h and precipitation is observed. The differing stability of the NPs in the above aqueous media is closely related to their ζ potential.

  20. The Modification of Carbon with Iron Oxide Synthesized in Electrolysis Using the Arc Discharge Method

    NASA Astrophysics Data System (ADS)

    Endah Saraswati, Teguh; Dewi Indah Prasiwi, Oktaviana; Masykur, Abu; Handayani, Nestri; Anwar, Miftahul

    2017-02-01

    The modification of carbon-based nanomaterials with metals is widely studied due to its unique properties. Here, the modification of carbon nanomaterial with iron oxide has been successfully carried out. This modification was achieved using arc discharge in 50% ethanol liquid media. The anode used in the arc discharge was prepared from a mixture of carbon and iron oxide that was synthesized in electrolysis and was then calcined at 250°C with silicon binder with a mass ratio of 3:1:1, and the cathode used was graphite rod. Both electrodes were set in the nearest gap that could provide an arc during arc-discharging, leading to carbon-based nanoparticle formation. The diffractogram pattern of the X-ray diffraction of the fabricated nanoparticles confirmed the typical peak of carbon, iron oxide and iron. The magnetization value of the result analysis of the vibrating sample magnetometer was 9.9 emu/g. The bandgap energy measurement using diffuse reflectance ultra violet was estimated to be 2.18 eV. Using the transmission electron microscopy, the structure of the nanomaterial produced was observed as carbon-encapsulated iron compound nanoparticles.

  1. Discovery of the recoverable high-pressure iron oxide Fe4O5.

    PubMed

    Lavina, Barbara; Dera, Przemyslaw; Kim, Eunja; Meng, Yue; Downs, Robert T; Weck, Philippe F; Sutton, Stephen R; Zhao, Yusheng

    2011-10-18

    Phases of the iron-oxygen binary system are significant to most scientific disciplines, directly affecting planetary evolution, life, and technology. Iron oxides have unique electronic properties and strongly interact with the environment, particularly through redox reactions. The iron-oxygen phase diagram therefore has been among the most thoroughly investigated, yet it still holds striking findings. Here, we report the discovery of an iron oxide with formula Fe(4)O(5), synthesized at high pressure and temperature. The previously undescribed phase, stable from 5 to at least 30 GPa, is recoverable to ambient conditions. First-principles calculations confirm that the iron oxide here described is energetically more stable than FeO + Fe(3)O(4) at pressure greater than 10 GPa. The calculated lattice constants, equation of states, and atomic coordinates are in excellent agreement with experimental data, confirming the synthesis of Fe(4)O(5). Given the conditions of stability and its composition, Fe(4)O(5) is a plausible accessory mineral of the Earth's upper mantle. The phase has strong ferrimagnetic character comparable to magnetite. The ability to synthesize the material at accessible conditions and recover it at ambient conditions, along with its physical properties, suggests a potential interest in Fe(4)O(5) for technological applications.

  2. Size and space controlled hexagonal arrays of superparamagnetic iron oxide nanodots: magnetic studies and application

    PubMed Central

    Ghoshal, Tandra; Maity, Tuhin; Senthamaraikannan, Ramsankar; Shaw, Matthew T.; Carolan, Patrick; Holmes, Justin D.; Roy, Saibal; Morris, Michael A.

    2013-01-01

    Highly dense hexagonally arranged iron oxide nanodots array were fabricated using PS-b-PEO self-assembled patterns. The copolymer molecular weight, composition and choice of annealing solvent/s allows dimensional and structural control of the nanopatterns at large scale. A mechanism is proposed to create scaffolds through degradation and/or modification of cylindrical domains. A methodology based on selective metal ion inclusion and subsequent processing was used to create iron oxide nanodots array. The nanodots have uniform size and shape and their placement mimics the original self-assembled nanopatterns. For the first time these precisely defined and size selective systems of ordered nanodots allow careful investigation of magnetic properties in dimensions from 50 nm to 10 nm, which delineate the nanodots are superparamagnetic, well-isolated and size monodispersed. This diameter/spacing controlled iron oxide nanodots systems were demonstrated as a resistant mask over silicon to fabricate densely packed, identical ordered, high aspect ratio silicon nanopillars and nanowire features. PMID:24072037

  3. Iron oxidation in Mops buffer. Effect of EDTA, hydrogen peroxide and FeCl3.

    PubMed

    Tadolini, B

    1987-01-01

    The effect of EDTA and H2O2 on iron autoxidation in Mops buffer depends on the pH of the solution. At acidic pH, EDTA caused the oxidation of a stoichiometric amount of iron. At neutral and alkaline pH, EDTA and H2O2 not only oxidizes a stoichiometric amount of iron but also causes the oxidation of the Fe2+ exceeding the concentration of these compounds. In the presence of EDTA, oxidation of Fe2+ in exceeding the concentration of these compounds has a shorter lag phase and an increased rate compared with that in the absence. The solution develops a yellow colour whose intensity is proportional to the amount of Fe2+ exceeding the concentration of these compounds in solution. When the reaction is conducted in the presence of NBT, formazan formation is greatly reduced compared to the control without EDTA and H2O2. The Fe3+-EDTA complex and Fe3+ affected iron oxidation, development of the yellow colour and NBT reduction in a similar fashion. In all these experimental conditions, iron oxidation is greatly reduced in the presence of mannitol, sorbitol and catalase. In phosphate buffer, EDTA oxidized a stoichiometric amount of iron without affecting free Fe2+ oxidation. Fe3+ has no effect on iron oxidation in this buffer.

  4. Lactoferrin conjugated iron oxide nanoparticles for targeting brain glioma cells in magnetic particle imaging

    NASA Astrophysics Data System (ADS)

    Tomitaka, Asahi; Arami, Hamed; Gandhi, Sonu; Krishnan, Kannan M.

    2015-10-01

    Magnetic Particle Imaging (MPI) is a new real-time imaging modality, which promises high tracer mass sensitivity and spatial resolution directly generated from iron oxide nanoparticles. In this study, monodisperse iron oxide nanoparticles with median core diameters ranging from 14 to 26 nm were synthesized and their surface was conjugated with lactoferrin to convert them into brain glioma targeting agents. The conjugation was confirmed with the increase of the hydrodynamic diameters, change of zeta potential, and Bradford assay. Magnetic particle spectrometry (MPS), performed to evaluate the MPI performance of these nanoparticles, showed no change in signal after lactoferrin conjugation to nanoparticles for all core diameters, suggesting that the MPI signal is dominated by Néel relaxation and thus independent of hydrodynamic size difference or presence of coating molecules before and after conjugations. For this range of core sizes (14-26 nm), both MPS signal intensity and spatial resolution improved with increasing core diameter of nanoparticles. The lactoferrin conjugated iron oxide nanoparticles (Lf-IONPs) showed specific cellular internalization into C6 cells with a 5-fold increase in MPS signal compared to IONPs without lactoferrin, both after 24 h incubation. These results suggest that Lf-IONPs can be used as tracers for targeted brain glioma imaging using MPI.

  5. Iron-oxide colloidal nanoclusters: from fundamental physical properties to diagnosis and therapy

    NASA Astrophysics Data System (ADS)

    Kostopoulou, Athanasia; Brintakis, Konstantinos; Lascialfari, Alessandro; Angelakeris, Mavroeidis; Vasilakaki, Marianna; Trohidou, Kalliopi; Douvalis, Alexios P.; Psycharakis, Stylianos; Ranella, Anthi; Manna, Liberato; Lappas, Alexandros

    2014-03-01

    Research on magnetic nanocrystals attracts wide-spread interest because of their challenging fundamental properties, but it is also driven by problems of practical importance to the society, ranging from electronics (e.g. magnetic recording) to biomedicine. In that respect, iron oxides are model functional materials as they adopt a variety of oxidation states and coordinations that facilitate their use. We show that a promising way to engineer further their technological potential in diagnosis and therapy is the assembly of primary nanocrystals into larger colloidal entities, possibly with increased structural complexity. In this context, elevated-temperature nanochemistry (c.f. based on a polyol approach) permitted us to develop size-tunable, low-cytotoxicity iron-oxide nanoclusters, entailing iso-oriented nanocrystals, with enhanced magnetization. Experimental (magnetometry, electron microscopy, Mössbauer and NMR spectroscopies) results supported by Monte Carlo simulations are reviewed to show that such assemblies of surface-functionalized iron oxide nanocrystals have a strong potential for innovation. The clusters' optimized magnetic anisotropy (including microscopic surface spin disorder) and weak ferrimagnetism at room temperature, while they do not undermine colloidal stability, endow them a profound advantage as efficient MRI contrast agents and hyperthermic mediators with important biomedical potential.

  6. Effects of phase transfer ligands on monodisperse iron oxide magnetic nanoparticles.

    PubMed

    Palma, Susana I C J; Marciello, Marzia; Carvalho, Alexandra; Veintemillas-Verdaguer, Sabino; Morales, Maria del Puerto; Roque, Ana C A

    2015-01-01

    Oleic acid coated iron oxide nanoparticles synthesized by thermal decomposition in organic medium are highly monodisperse but at the same time are unsuitable for biological applications. Ligand-exchange reactions are useful to make their surface hydrophilic. However, these could alter some structural and magnetic properties of the modified particles. Here we present a comprehensive study and comparison of the effects of employing either citric acid (CA) or meso-2,3-dimercaptosuccinic acid (DMSA) ligand-exchange protocols for phase transfer of monodisperse hydrophobic iron oxide nanoparticles produced by thermal decomposition of Fe(acac)3 in benzyl ether. We show the excellent hydrodynamic size distribution and colloidal stability of the hydrophilic particles obtained by the two protocols and confirm that there is a certain degree of oxidation caused by the ligand-exchange. CA revealed to be more aggressive towards the iron oxide surface than DMSA and greatly reduced the saturation magnetization values and initial susceptibility of the resulting particles compared to the native ones. Besides being milder and more straightforward to perform, the DMSA ligand exchange protocol produces MNP chemically more versatile for further functionalization possibilities. This versatility is shown through the covalent linkage of gum Arabic onto MNP-DMSA using carboxyl and thiol based chemical routes and yielding particles with comparable properties.

  7. Oligomerization of Glycine and Alanine Catalyzed by Iron Oxides: Implications for Prebiotic Chemistry

    NASA Astrophysics Data System (ADS)

    Shanker, Uma; Bhushan, Brij; Bhattacharjee, G.; Kamaluddin

    2012-02-01

    Iron oxide minerals are probable constituents of the sediments present in geothermal regions of the primitive earth. They might have adsorbed different organic monomers (amino acids, nucleotides etc.) and catalyzed polymerization processes leading to the formation of the first living cell. In the present work we tested the catalytic activity of three forms of iron oxides (Goethite, Akaganeite and Hematite) in the intermolecular condensation of each of the amino acids glycine and L-alanine. The effect of zinc oxide and titanium dioxide on the oligomerization has also been studied. Oligomerization studies were performed for 35 days at three different temperatures 50, 90 and 120°C without applying drying/wetting cycling. The products formed were characterized by HPLC and ESI-MS techniques. All three forms of iron oxides catalyzed peptide bond formation (23.2% of gly2 and 10.65% of ala2). The reaction was monitored every 7 days. Formation of peptides was observed to start after 7 days at 50°C. Maximum yield of peptides was found after 35 days at 90°C. Reaction at 120°C favors formation of diketopiperazine derivatives. It is also important to note that after 35 days of reaction, goethite produced dimer and trimer with the highest yield among the oxides tested. We suggest that the activity of goethite could probably be due to its high surface area and surface acidity.

  8. Low-crystalline iron oxide hydroxide nanoparticle anode for high-performance supercapacitors

    PubMed Central

    Owusu, Kwadwo Asare; Qu, Longbing; Li, Jiantao; Wang, Zhaoyang; Zhao, Kangning; Yang, Chao; Hercule, Kalele Mulonda; Lin, Chao; Shi, Changwei; Wei, Qiulong; Zhou, Liang; Mai, Liqiang

    2017-01-01

    Carbon materials are generally preferred as anodes in supercapacitors; however, their low capacitance limits the attained energy density of supercapacitor devices with aqueous electrolytes. Here, we report a low-crystalline iron oxide hydroxide nanoparticle anode with comprehensive electrochemical performance at a wide potential window. The iron oxide hydroxide nanoparticles present capacitances of 1,066 and 716 F g−1 at mass loadings of 1.6 and 9.1 mg cm−2, respectively, a rate capability with 74.6% of capacitance retention at 30 A g−1, and cycling stability retaining 91% of capacitance after 10,000 cycles. The performance is attributed to a dominant capacitive charge-storage mechanism. An aqueous hybrid supercapacitor based on the iron oxide hydroxide anode shows stability during float voltage test for 450 h and an energy density of 104 Wh kg−1 at a power density of 1.27 kW kg−1. A packaged device delivers gravimetric and volumetric energy densities of 33.14 Wh kg−1 and 17.24 Wh l−1, respectively. PMID:28262797

  9. Reduced Staphylococcus aureus biofilm formation in the presence of chitosan-coated iron oxide nanoparticles

    PubMed Central

    Shi, Si-feng; Jia, Jing-fu; Guo, Xiao-kui; Zhao, Ya-ping; Chen, De-sheng; Guo, Yong-yuan; Zhang, Xian-long

    2016-01-01

    Staphylococcus aureus can adhere to most foreign materials and form biofilm on the surface of medical devices. Biofilm infections are difficult to resolve. The goal of this in vitro study was to explore the use of chitosan-coated nanoparticles to prevent biofilm formation. For this purpose, S. aureus was seeded in 96-well plates to incubate with chitosan-coated iron oxide nanoparticles in order to study the efficiency of biofilm formation inhibition. The biofilm bacteria count was determined using the spread plate method; biomass formation was measured using the crystal violet staining method. Confocal laser scanning microscopy and scanning electron microscopy were used to study the biofilm formation. The results showed decreased viable bacteria numbers and biomass formation when incubated with chitosan-coated iron oxide nanoparticles at all test concentrations. Confocal laser scanning microscopy showed increased dead bacteria and thinner biofilm when incubated with nanoparticles at a concentration of 500 µg/mL. Scanning electron microscopy revealed that chitosan-coated iron oxide nanoparticles inhibited biofilm formation in polystyrene plates. Future studies should be performed to study these nanoparticles for anti-infective use. PMID:27994455

  10. Thiol-Ene Induced Diphosphonic Acid Functionalization of Superparamagnetic Iron Oxide Nanoparticles

    SciTech Connect

    Rutledge, Ryan D.; Warner, Cynthia L.; Pittman, Jonathan W.; Addleman, Raymond S.; Engelhard, Mark H.; Chouyyok, Wilaiwan; Warner, Marvin G.

    2010-07-20

    Multi-functional organic molecules represent an interesting challenge for nanoparticle functionalization due to the potential for undesirable interactions between the substrate material and the variable functionalities, making it difficult to control the final orientation of the ligand. In the present study, UV-induced thiol-ene click chemistry has been utilized as a means of directed functionalization of bifunctional ligands on an iron oxide nanoparticle surface. Allyl diphosphonic acid ligand was covalently deposited on the surface of thiol-presenting iron oxide nanoparticles via the formation of a UV-induced thioether. This method of thiol-ene click chemistry offers a set of reaction conditions capable of controlling the ligand deposition and circumventing the natural affinity exhibited by the phosphonic acid moiety for the iron oxide surface. These claims are supported via a multimodal characterization platform which includes thermogravimetric analysis, x-ray photoelectron spectroscopy, and metal contact analysis and are consistent with a properly oriented, highly active ligand on the nanoparticle surface. These experiments suggest thiol-ene click chemistry as both a practical and generally applicable strategy for the directed deposition of multi-functional ligands on metal oxide nanoparticle surfaces.

  11. Magnetic Properties of Polyvinyl Alcohol and Doxorubicine Loaded Iron Oxide Nanoparticles for Anticancer Drug Delivery Applications

    PubMed Central

    Nadeem, Muhammad; Ahmad, Munir; Akhtar, Muhammad Saeed; Shaari, Amiruddin; Riaz, Saira; Naseem, Shahzad; Masood, Misbah; Saeed, M. A.

    2016-01-01

    The current study emphasizes the synthesis of iron oxide nanoparticles (IONPs) and impact of hydrophilic polymer polyvinyl alcohol (PVA) coating concentration as well as anticancer drug doxorubicin (DOX) loading on saturation magnetization for target drug delivery applications. Iron oxide nanoparticles particles were synthesized by a reformed version of the co-precipitation method. The coating of polyvinyl alcohol along with doxorubicin loading was carried out by the physical immobilization method. X-ray diffraction confirmed the magnetite (Fe3O4) structure of particles that remained unchanged before and after polyvinyl alcohol coating and drug loading. Microstructure and morphological analysis was carried out by transmission electron microscopy revealing the formation of nanoparticles with an average size of 10 nm with slight variation after coating and drug loading. Transmission electron microscopy, energy dispersive, and Fourier transform infrared spectra further confirmed the conjugation of polymer and doxorubicin with iron oxide nanoparticles. The room temperature superparamagnetic behavior of polymer-coated and drug-loaded magnetite nanoparticles were studied by vibrating sample magnetometer. The variation in saturation magnetization after coating evaluated that a sufficient amount of polyvinyl alcohol would be 3 wt. % regarding the externally controlled movement of IONPs in blood under the influence of applied magnetic field for in-vivo target drug delivery. PMID:27348436

  12. Reduction of iron-oxide-carbon composites: part I. Estimation of the rate constants

    SciTech Connect

    Halder, S.; Fruehan, R.J.

    2008-12-15

    A new ironmaking concept using iron-oxide-carbon composite pellets has been proposed, which involves the combination of a rotary hearth furnace (RHF) and an iron bath smelter. This part of the research focuses on studying the two primary chemical kinetic steps. Efforts have been made to experimentally measure the kinetics of the carbon gasification by CO{sub 2} and wustite reduction by CO by isolating them from the influence of heat- and mass-transport steps. A combined reaction model was used to interpret the experimental data and determine the rate constants. Results showed that the reduction is likely to be influenced by the chemical kinetics of both carbon oxidation and wustite reduction at the temperatures of interest. Devolatilized wood-charcoal was observed to be a far more reactive form of carbon in comparison to coal-char. Sintering of the iron-oxide at the high temperatures of interest was found to exert a considerable influence on the reactivity of wustite by virtue of altering the internal pore surface area available for the reaction. Sintering was found to be predominant for highly porous oxides and less of an influence on the denser ores. It was found using an indirect measurement technique that the rate constants for wustite reduction were higher for the porous iron-oxide than dense hematite ore at higher temperatures (> 1423 K). Such an indirect mode of measurement was used to minimize the influence of sintering of the porous oxide at these temperatures.

  13. Freezing-Enhanced Dissolution of Iron Oxides: Effects of Inorganic Acid Anions.

    PubMed

    Jeong, Daun; Kim, Kitae; Min, Dae Wi; Choi, Wonyong

    2015-11-03

    Dissolution of iron from mineral dust particles greatly depends upon the type and amount of copresent inorganic anions. In this study, we investigated the roles of sulfate, chloride, nitrate, and perchlorate on the dissolution of maghemite and lepidocrocite in ice under both dark and UV irradiation and compared the results with those of their aqueous counterparts. After 96 h of reaction, the total dissolved iron in ice (pH 3 before freezing) was higher than that in the aqueous phase (pH 3) by 6-28 times and 10-20 times under dark and UV irradiation, respectively. Sulfuric acid was the most efficient in producing labile iron under dark condition, whereas hydrochloric acid induced the most dissolution of the total and ferrous iron in the presence of light. This ice-induced dissolution result was also confirmed with Arizona Test Dust (AZTD). In the freeze-thaw cycling test, the iron oxide samples containing chloride, nitrate, or perchlorate showed a similar extent of total dissolved iron after each cycling while the sulfate-containing sample rapidly lost its dissolution activity with repeating the cycle. This unique phenomenon observed in ice might be related to the freeze concentration of protons, iron oxides, and inorganic anions in the liquid-like ice grain boundary region. These results suggest that the ice-enhanced dissolution of iron oxides can be a potential source of bioavailable iron, and the acid anions critically influence this process.

  14. Reduced Staphylococcus aureus biofilm formation in the presence of chitosan-coated iron oxide nanoparticles.

    PubMed

    Shi, Si-Feng; Jia, Jing-Fu; Guo, Xiao-Kui; Zhao, Ya-Ping; Chen, De-Sheng; Guo, Yong-Yuan; Zhang, Xian-Long

    Staphylococcus aureus can adhere to most foreign materials and form biofilm on the surface of medical devices. Biofilm infections are difficult to resolve. The goal of this in vitro study was to explore the use of chitosan-coated nanoparticles to prevent biofilm formation. For this purpose, S. aureus was seeded in 96-well plates to incubate with chitosan-coated iron oxide nanoparticles in order to study the efficiency of biofilm formation inhibition. The biofilm bacteria count was determined using the spread plate method; biomass formation was measured using the crystal violet staining method. Confocal laser scanning microscopy and scanning electron microscopy were used to study the biofilm formation. The results showed decreased viable bacteria numbers and biomass formation when incubated with chitosan-coated iron oxide nanoparticles at all test concentrations. Confocal laser scanning microscopy showed increased dead bacteria and thinner biofilm when incubated with nanoparticles at a concentration of 500 µg/mL. Scanning electron microscopy revealed that chitosan-coated iron oxide nanoparticles inhibited biofilm formation in polystyrene plates. Future studies should be performed to study these nanoparticles for anti-infective use.

  15. Optimization of preparation of chitosan-coated iron oxide nanoparticles for biomedical applications by chemometrics approaches

    NASA Astrophysics Data System (ADS)

    Honary, Soheila; Ebrahimi, Pouneh; Rad, Hossein Asgari; Asgari, Mahsa

    2013-08-01

    Functionalized magnetic nanoparticles are used in several biomedical applications, such as drug delivery, magnetic cell separation, and magnetic resonance imaging. Size and surface properties of iron oxide nanoparticles are the two important factors which could dramatically affect the nanoparticle efficiency as well as their stability. In this study, the chemometrics approach was applied to optimize the coating process of iron oxide nanoparticles. To optimize the size of nanoparticles, the effect of two experimental parameters on size was investigated by means of multivariate analysis. The factors considered were chitosan molecular weight and chitosan-to-tripolyphosphate concentration ratio. The experiments were performed according to face-centered cube central composite response surface design. A second-order regression model was obtained which characterized by both descriptive and predictive abilities. The method was optimized with respect to the percent of Z average diameter's increasing after coating as response. It can be concluded that experimental design provides a suitable means of optimizing and testing the robustness of iron oxide nanoparticle coating method.

  16. Superparamagnetic iron oxide nanoparticles as radiosensitizer via enhanced reactive oxygen species formation

    SciTech Connect

    Klein, Stefanie; Sommer, Anja; Distel, Luitpold V.R.; Neuhuber, Winfried; Kryschi, Carola

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Ultrasmall citrate-coated SPIONs with {gamma}Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} structure were prepared. Black-Right-Pointing-Pointer SPIONs uptaken by MCF-7 cells increase the ROS production for about 240%. Black-Right-Pointing-Pointer The SPION induced ROS production is due to released iron ions and catalytically active surfaces. Black-Right-Pointing-Pointer Released iron ions and SPION surfaces initiate the Fenton and Haber-Weiss reaction. Black-Right-Pointing-Pointer X-ray irradiation of internalized SPIONs leads to an increase of catalytically active surfaces. -- Abstract: Internalization of citrate-coated and uncoated superparamagnetic iron oxide nanoparticles by human breast cancer (MCF-7) cells was verified by transmission electron microscopy imaging. Cytotoxicity studies employing metabolic and trypan blue assays manifested their excellent biocompatibility. The production of reactive oxygen species in iron oxide nanoparticle loaded MCF-7 cells was explained to originate from both, the release of iron ions and their catalytically active surfaces. Both initiate the Fenton and Haber-Weiss reaction. Additional oxidative stress caused by X-ray irradiation of MCF-7 cells was attributed to the increase of catalytically active iron oxide nanoparticle surfaces.

  17. Cold catalytic recovery of loaded activated carbon using iron oxide-based nanoparticles.

    PubMed

    Bach, Altai; Zelmanov, Grigory; Semiat, Raphael

    2008-01-01

    A novel approach for the recovery of spent activated carbon by an advanced oxidation process using iron oxide-based nanocatalysts was proposed and investigated. Model organic contaminants, such as ethylene glycol and phenol, were chosen for this study as water pollutants. It was shown that there are several advantages in using catalytic oxidation recovery of activated carbon with iron oxide-based nanocatalysts: low temperature reactivity of catalytic recovery without heating; and a relatively large number of adsorption-recovery cycles, without a reduction in the adsorptive properties of the virgin activated carbon or without a performance decrease from the first adsorption-recovery cycle of the new modified adsorptive properties of the activated carbon. The catalytic recovery takes place without ultraviolet light or any visible radiation sources. Results show a high efficiency of catalytic recovery of spent activated carbon using iron oxide-based nanocatalysts. A 97-99% efficiency of spent activated carbon catalytic regeneration was achieved under chosen conditions after 15-20 min of reaction. The process may be also considered as cold in situ recovery of active carbon.

  18. Flame synthesis and in vitro biocompatibility assessment of superparamagnetic iron oxide nanoparticles: cellular uptake, toxicity and proliferation studies.

    PubMed

    Buyukhatipoglu, K; Miller, T A; Clyne, A Morss

    2009-12-01

    Superparamagnetic iron oxide nanoparticles are used in diverse applications, such as targeted drug delivery, magnetic resonance imaging and hyperthermic malignant cell therapy. In the current work, superparamagnetic iron oxide nanoparticles were produced by flame synthesis, which has improved nanoparticle property control and is capable of commercial production rates with minimal post-processing. The iron oxide nanoparticle material characteristics were analyzed by electron microscopy and Raman spectroscopy. Finally, flame synthesized iron oxide nanoparticle interaction with endothelial cells was compared to commercially available iron oxide nanoparticles. Flame synthesis produced a heterogeneous mixture of 6-12 nm diameter hematite and magnetite nanoparticles with superparamagnetic properties. Endothelial cell scanning electron microscopy, confirmed by energy dispersive spectroscopy, demonstrated that flame synthesized nanoparticles are ingested into cells in a similar manner to commercially available nanoparticles. The flame synthesized particles showed no statistically significant toxicity difference from commercially available nanoparticles, as measured by Live/Dead assay, Alamar blue, and lactase dehydrogenase release. Neither type of nanoparticle affected cell proliferation induced by fibroblast growth factor-2. These data suggest that combustion synthesized iron oxide nanoparticles are comparable to commercially available nanoparticles for biological applications, yet flame synthesis is a simpler process with higher purity products and lower manufacturing costs. Future work will include functionalizing nanoparticles for specific cell targeting and bioactive factor delivery.

  19. A silica-supported iron oxide catalyst capable of activating hydrogen peroxide at neutral pH values.

    PubMed

    Pham, Anh Le-Tuan; Lee, Changha; Doyle, Fiona M; Sedlak, David L

    2009-12-01

    Iron oxides catalyze the conversion of hydrogen peroxide (H(2)O(2)) into oxidants capable of transforming recalcitrant contaminants. Unfortunately, the process is relatively inefficient at circumneutral pH values because of competing reactions that decompose H(2)O(2) without producing oxidants. Silica- and alumina-containing iron oxides prepared by sol-gel processing of aqueous solutions containing Fe(ClO(4))(3), AlCl(3), and tetraethyl orthosilicate efficiently catalyzed the decomposition of H(2)O(2) into oxidants capable of transforming phenol at circumneutral pH values. Relative to hematite, goethite, and amorphous FeOOH, the silica-iron oxide catalyst exhibited a stoichiometric efficiency, defined as the number of moles of phenol transformed per mole of H(2)O(2) consumed, which was 10-40 times higher than that of the iron oxides. The silica-alumina-iron oxide catalyst had a stoichiometric efficiency that was 50-80 times higher than that of the iron oxides. The significant enhancement in oxidant production is attributable to the interaction of Fe with Al and Si in the mixed oxides, which alters the surface redox processes, favoring the production of strong oxidants during H(2)O(2) decomposition.

  20. A Silica-Supported Iron Oxide Catalyst Capable of Activating Hydrogen Peroxide at Neutral pH Values

    PubMed Central

    Pham, Anh Le-Tuan; Lee, Changha; Doyle, Fiona M.; Sedlak, David L.

    2009-01-01

    Iron oxides catalyze the conversion of hydrogen peroxide (H2O2) into oxidants capable of transforming recalcitrant contaminants. Unfortunately, the process is relatively inefficient at circumneutral pH values due to competing reactions that decompose H2O2 without producing oxidants. Silica- and alumina-containing iron oxides prepared by sol-gel processing of aqueous solutions containing Fe(ClO4)3, AlCl3 and tetraethyl orthosilicate efficiently catalyzed the decomposition of H2O2 into oxidants capable of transforming phenol at circumneutral pH values. Relative to hematite, goethite and amorphous FeOOH, the silica-iron oxide catalyst exhibited a stoichiometric efficiency, defined as the number of moles of phenol transformed per mole of H2O2 consumed, that was 10 to 40 times higher than that of the iron oxides. The silica-alumina-iron oxide catalyst had a stoichiometric efficiency that was 50 to 80 times higher than that of the iron oxides. The significant enhancement in oxidant production is attributable to the interaction of Fe with Al and Si in the mixed oxides, which alters the surface redox processes, favoring the production of strong oxidants during H2O2 decomposition. PMID:19943668

  1. Fractionation of Oxygen Isotopes in Phosphate during its Interactions with Iron Oxides

    SciTech Connect

    Jaisi, Deb P; Blake, Ruth E; Kukkadapu, Ravi K

    2010-02-15

    Iron (III) oxides are ubiquitous in near-surface soils and sediments and interact strongly with dissolved phosphates via sorption, co-precipitation, mineral transformation and redox-cycling reactions. Iron oxide phases are thus, an important reservoir for dissolved phosphate, and phosphate bound to iron oxides should reflect dissolved sources as well as carry a history of the biogeochemical cycling of phosphorus (P). It has recently been demonstrated that dissolved inorganic phosphate (DIP) in rivers, lakes, estuaries and the open ocean can be used to distinguish different P sources and biological reaction pathways in the ratio of 18O/16O (δ18OP) in PO43-. Here we present results of experimental studies aimed at determining whether non-biological interactions between dissolved inorganic phosphate and solid iron-oxides involve fractionation of oxygen isotopes in PO4. Determination of such fractionations is critical to any interpretation of δ18OP values of modern (e.g. hydrothermal iron oxide deposits, marine sediments, soils, groundwater systems) to ancient and extraterrestrial samples (e.g., BIF’s, Martian soils). Batch sorption experiments were performed using varied concentrations of synthetic ferrihydrite and isotopically- labeled dissolved ortho-phosphate at temperatures ranging from 4 to 95 oC. Mineral transformations and morphological changes were determined by X-Ray, Mössbauer spectroscopy and SEM image analyses. Our results reveal that isotopic fractionation between sorbed and aqueous phosphate occurs during the early phase of sorption with isotopically light phosphate preferentially incorporated into sorbed/solid phases. This fractionation showed negligible temperature-dependence and gradually decreased as a result of O-isotopic exchange between sorbed and aqueous phase phosphate, to become insignificant at greater than ~100 hours of reaction. In high-temperature experiments, this exchange was very rapid

  2. Climatic thresholds for pedogenic iron oxides under aerobic conditions: Processes and their significance in paleoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Long, Xiaoyong; Ji, Junfeng; Barrón, Vidal; Torrent, José

    2016-10-01

    Iron oxides are widely distributed across the surface of the Earth as a result of the aerobic weathering of primary Fe-bearing minerals. Pedogenic iron oxides which consist mainly of hematite (Hm), goethite (Gt), maghemite (Mgh), are often concentrated synchronously in aerobic soils under low to moderate rainfall regimes. Magnetic susceptibility (χ) and redness, which respectively reflect the content of Mgh and Hm in soils, are considered reasonable pedogenic and climatic indicators in soil taxonomy and paleorainfall reconstruction. However, under high rainfall regimes, the grain growth of Mgh and transformation to Hm, combined with the prior formation of Gt under conditions of high relative humidity (RH), can result in magnetic reduction and dramatic yellowing of soils and sediments, which explains the existence of rainfall thresholds for Mgh and Hm at a large scale even before the pedogenic environment turns anaerobic. In order to capture the rainfall thresholds for Mgh and Hm occurring under aerobic conditions, we explored a tropical transect across a granitic region where the soil color turned from red to yellow under a wide rainfall range of 900-2200 mm/yr and a corresponding mean annual RH range of 77%-85%. We observed a lower rainfall threshold of ∼1500 mm/yr and a corresponding RH ∼80% for Mgh and Hm along this transect, as well as a higher rainfall threshold of ∼1700 mm/yr and a corresponding RH of ∼81% for Gt and total pedogenic iron oxides (citrate/bicarbonate/dithionite-extractable Fe, Fed). Cross-referencing with comparable studies in temperate and subtropical regions, we noted that the rainfall or RH thresholds for Fed and Hm or Mgh likewise increase with temperature. Moreover, the different thresholds for total and individual iron oxide phase indicates that a negative correlation between chemical weathering intensity and redness or χ in sediment sequences can occur under the prevalent climate regime just between their thresholds. Finally

  3. Iron oxides as pedoenvironmental indicators: state of the art, answers and questions (Philippe Duchaufour Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Torrent, J.

    2012-04-01

    The colour and magnetic properties of soils largely reflect the content and mineralogy of their iron oxides, which in turn relate to the physical, chemical and biological characteristics of the soil environment. For more than 50 years, soil mineralogists and chemists have collected data for iron oxides in soils formed in widely different environments and tried to understand the complex nature of the different suites and formation pathways for these minerals via laboratory experiments. The discovery of ferrihydrite —the poorly crystalline precursor of most Fe oxides— in 1971, and the recognition of its common presence in soils, raised interest in deciphering the environmental factors that affect its transformation into goethite and hematite, the two most abundant crystalline iron oxides in soil. Field observations were consistent with laboratory experiments in which temperature, water activity, pH, foreign ions and organic matter were found to play a key role in the crystallization of ferrihydrite. Thus, the hematite/(hematite + goethite) ratio increased with increasing temperature and also with the likelihood of seasonal soil drying. Exploiting this ratio as a (pedo)environment indicator is, however, not devoid of problems derived from insufficient knowledge of the interactions between the influential chemical variables, difficulties in quantifying the two minerals and changes brought about by reductive dissolution. Soil formation usually leads to magnetic enhancement as a result of the production of magnetite and/or maghemite, which are ferrimagnetic iron oxides, and, possibly, an ordered ferrimagnetic ferrihydrite, as suggested by recent laboratory experiments. The concentration of pedogenic ferrimagnets as estimated via proxies such as magnetic susceptibility or frequency-dependent magnetic susceptibility has been found to relate to climate variables [particularly (paleo)rainfall] in many studies reported over the last 30 years. However, extracting accurate

  4. Regional framework and geology of iron oxide-apatite-rare earth element and iron oxide-copper-gold deposits of the Mesoproterozoic St. Francois Mountains Terrane, southeast Missouri

    USGS Publications Warehouse

    Day, Warren C.; Slack, John F.; Ayuso, Robert A.; Seeger, Cheryl M.

    2016-01-01

    This paper provides an overview on the genesis of Mesoproterozoic igneous rocks and associated iron oxide ± apatite (IOA) ± rare earth element, iron oxide-copper-gold (IOCG), and iron-rich sedimentary deposits in the St. Francois Mountains terrane of southeast Missouri, USA. The St. Francois Mountains terrane lies along the southeastern margin of Laurentia as part of the eastern granite-rhyolite province. The province formed during two major pulses of igneous activity: (1) an older early Mesoproterozoic (ca. 1.50–1.44 Ga) episode of volcanism and granite plutonism, and (2) a younger middle Mesoproterozoic (ca. 1.33–1.30 Ga) episode of bimodal gabbro and granite plutonism. The volcanic rocks are predominantly high-silica rhyolite pyroclastic flows, volcanogenic breccias, and associated volcanogenic sediments with lesser amounts of basaltic to andesitic volcanic and associated subvolcanic intrusive rocks. The iron oxide deposits are all hosted in the early Mesoproterozoic volcanic and volcaniclastic sequences. Previous studies have characterized the St. Francois Mountains terrane as a classic, A-type within-plate granitic terrane. However, our new whole-rock geochemical data indicate that the felsic volcanic rocks are effusive derivatives from multicomponent source types, having compositional similarities to A-type within-plate granites as well as to S- and I-type granites generated in an arc setting. In addition, the volcanic-hosted IOA and IOCG deposits occur within bimodal volcanic sequences, some of which have volcanic arc geochemical affinities, suggesting an extensional tectonic setting during volcanism prior to emplacement of the ore-forming systems.The Missouri iron orebodies are magmatic-related hydrothermal deposits that, when considered in aggregate, display a vertical zonation from high-temperature, magmatic ± hydrothermal IOA deposits emplaced at moderate depths (~1–2 km), to magnetite-dominant IOA veins and IOCG deposits emplaced at shallow

  5. A Description of an Acidophilic, Iron Reducer, Geobacter sp. FeAm09 Isolated from Tropical Soils

    NASA Astrophysics Data System (ADS)

    Healy, O.; Souchek, J.; Heithoff, A.; LaMere, B.; Pan, D.; Hollis, G.; Yang, W. H.; Silver, W. L.; Weber, K. A.

    2014-12-01

    Iron (Fe) is the fourth most abundant element in the Earth's crust and plays a significant role controlling the geochemistry in soils, sediments, and aquatic systems. As part of a study to understand microbially-catalysed iron biogeochemical cycling in tropical soils, an iron reducing isolate, strain FeAm09, was obtained. Strain FeAm09 was isolated from acidic, Fe-rich soils collected from a tropical forest (Luquillo Experimental Forest, Puerto Rico). Strain FeAm09 is a rod-shaped, motile, Gram-negative bacterium. Taxonomic analysis of the near complete 16S rRNA gene sequence revealed that strain FeAm09 is 94.7% similar to Geobacter lovleyi, placing it in the genus Geobacter within the Family Geobacteraceae in the Deltaproteobacteria. Characterization of the optimal growth conditions revealed that strain FeAm09 is a moderate acidophile with an optimal growth pH of 5.0. The optimal growth temperature was 37°C. Growth of FeAm09 was coupled to the reduction of soluble Fe(III), Fe(III)-NTA, with H2, fumarate, ethanol, and various organic acids and sugars serving as the electron donor. Insoluble Fe(III), in the form of synthetic ferrihydrite, was reduced by strain FeAm09 using acetate or H2 as the electron donor. The use of H2 as an electron donor in the presence of CO2 and absence of organic carbon and assimilation of 14C-labelled CO2 into biomass indicate that strain FeAm09 is an autotrophic Fe(III)-reducing bacterium. Together, these data describe the first acidophilic, autotrophic Geobacter species. Iron reducing bacteria were previously shown to be as abundant in tropical soils as in saturated sediments (lake-bottoms) and saturated soils (wetlands) where Fe(III) reduction is more commonly recognized as a dominant mode of microbial respiration. Furthermore, Fe(III) reduction was identified as a primary driver of carbon mineralization in these tropical soils (Dubinsky et al. 2010). In addition to mineralizing organic carbon, Geobacter sp. FeAm09 is likely to also

  6. Colour and toxic characteristics of metakaolinite–hematite pigment for integrally coloured concrete, prepared from iron oxide recovered from a water treatment plant of an abandoned coal mine

    SciTech Connect

    Sadasivam, Sivachidambaram Thomas, Hywel Rhys

    2016-07-15

    A metakaolinite-hematite (KH) red pigment was prepared using an ocherous iron oxide sludge recovered from a water treatment plant of an abandoned coal mine. The KH pigment was prepared by heating the kaolinite and the iron oxide sludge at kaolinite's dehydroxylation temperature. Both the raw sludge and the KH specimen were characterised for their colour properties and toxic characteristics. The KH specimen could serve as a pigment for integrally coloured concrete and offers a potential use for the large volumes of the iron oxide sludge collected from mine water treatment plants. - Graphical abstract: A kaolinite based red pigment was prepared using an ocherous iron oxide sludge recovered from an abandoned coal mine water treatment plant. Display Omitted - Highlights: • A red pigment was prepared by heating a kaolinite and an iron oxide sludge. • The iron oxide and the pigment were characterised for their colour properties. • The red pigment can be a potential element for integrally coloured concrete.

  7. Potential for iron oxides to control metal releases in CO2 sequestration scenarios

    USGS Publications Warehouse

    Berger, P.M.; Roy, W.R.

    2011-01-01

    The potential for the release of metals into groundwater following the injection of carbon dioxide (CO2) into the subsurface during carbon sequestration projects remains an open research question. Changing the chemical composition of even the relatively deep formation brines during CO2 injection and storage may be of concern because of the recognized risks associated with the limited potential for leakage of CO2-impacted brine to the surface. Geochemical modeling allows for proactive evaluation of site geochemistry before CO2 injection takes place to predict whether the release of metals from iron oxides may occur in the reservoir. Geochemical modeling can also help evaluate potential changes in shallow aquifers were CO2 leakage to occur near the surface. In this study, we created three batch-reaction models that simulate chemical changes in groundwater resulting from the introduction of CO2 at two carbon sequestration sites operated by the Midwest Geological Sequestration Consortium (MGSC). In each of these models, we input the chemical composition of groundwater samples into React??, and equilibrated them with selected mineral phases and CO 2 at reservoir pressure and temperature. The model then simulated the kinetic reactions with other mineral phases over a period of up to 100 years. For two of the simulations, the water was also at equilibrium with iron oxide surface complexes. The first model simulated a recently completed enhanced oil recovery (EOR) project in south-central Illinois in which the MGSC injected into, and then produced CO2, from a sandstone oil reservoir. The MGSC afterwards periodically measured the brine chemistry from several wells in the reservoir for approximately two years. The sandstone contains a relatively small amount of iron oxide, and the batch simulation for the injection process showed detectable changes in several aqueous species that were attributable to changes in surface complexation sites. After using the batch reaction

  8. Magnetic labeling of non-phagocytic adherent cells with iron oxide nanoparticles: a comprehensive study.

    PubMed

    Boutry, Sébastien; Brunin, Stéphanie; Mahieu, Isabelle; Laurent, Sophie; Vander Elst, Luce; Muller, Robert N

    2008-01-01

    Small particles of iron oxide (SPIO) and ultrasmall particles of iron oxide (USPIO), inducing a strong negative contrast on T(2) and T(2)*-weighted MR images, are the most commonly used systems for the magnetic labeling of cultured cells and their subsequent detection by magnetic resonance imaging (MRI). The purpose of this work is to study the influence of iron incubation concentration, nanoparticle size and nanoparticle coating on the magnetic labeling and the viability of non-phagocytic adherent cells in culture. The magnetic labeling of 3T6 fibroblasts was studied by T(2)-weighted MRI at 4.7 T and by dosing-or cytochemical revealing-of iron through methods based on Perl's Prussian blue staining. Cells were incubated for 48 h with increasing iron concentrations of SPIO (25-1000 microg Fe/ml Endorem. Sinerem, a USPIO (20-40 nm) coated with neutral dextran, and Resovist (65 nm), a SPIO bearing an anionic carboxydextran coating, were compared with Endorem (dextran-coated, 80-150 nm) as magnetic tags. The iron loading of marrow stromal cell primary cultures (MSCs) isolated from rat femurs was compared with that of 3T6 fibroblasts. The SPIO-labeling of cells with Endorem was found to be dependent on the iron incubation concentration. MSCs, more sparsely distributed in the culture, exhibited higher iron contents than more densely populated 3T6 fibroblast cultures. A larger iron loading was achieved with Resovist than with Endorem, which in turn was more efficient than Sinerem as a magnetic tag. The magnetic labeling of cultured non-phagocytic adherent cells with iron oxide nanoparticles was thus found to be dependent on the relative concentration of the magnetic tag and of the cells in culture, on the nanoparticle size, and on the coating type. The viability of cells, estimated by methods assessing cell membrane permeability, was not affected by magnetic labeling in the conditions used in this work.

  9. The Preparation and Reduction Behavior of Charcoal Composite Iron Oxide Pellets

    NASA Astrophysics Data System (ADS)

    Konishi, Hirokazu; Usui, Tateo; Harada, Takeshi

    In the energy conversion, biomass has novel advantage, i.e., no CO2 emission, because of carbon neutral. Charcoal composite iron oxide pellets were proposed to decrease CO2 emission for the ironmaking. These pellets were promising to decrease the initial temperature for reduction reaction of carbon composite iron ore agglomerate under a rising temperature condition, such as in a blast furnace shaft. In order to obtain charcoal, Japanese cedar and cypress were carbonized from room temperature to maximum carbonization temperature (TC, max = 1273 K) at a heating rate of 200 K/h, and kept at TC, max until arrival time of 6 h. Reducing gases of CO and CH4 started releasing from relatively low temperature (500 K). In the total gas volume of carbonization, H2 gas of Japanese cedar was more than that of Japanese cypress. These woods have more CO gas volume than Newcastle blend coal has. The obtained charcoal was mixed with reagent grade hematite in the mass ratio of one to four. Then, a small amount of Bentonite was added to the mixture as a binder, and the charcoal composite iron oxide pellets were prepared and reduced at 1273, 1373 and 1473 K in nitrogen gas atmosphere. It was conirmed by the generated gas analysis during reduction reaction that charcoal composite iron oxide pellets had higher reducibility than char composite pellets using Newcastle blend coal. From the XRD analysis of the reduced pellets, it was found that the original Fe2O3 was almost reduced to Fe for 60 min at 1273 K, 20 min at 1373 K and 5~15 min at 1473 K.

  10. Competitive adsorption, displacement, and transport of organic matter on iron oxide: II. Displacement and transport

    SciTech Connect

    Gu, B; Mehlhorn, T.L.; Liang, Liyuan

    1996-08-01

    The competitive interactions between organic matter compounds and mineral surfaces are poorly understood, yet these interactions may play a significant role in the stability and co-transport of mineral colloids and/or environmental contaminants. In this study, the processes of competitive adsorption, displacement, and transport of Suwannee River natural organic matter (SR-NOM) are investigated with several model organic compounds in packed beds of iron oxide-coated quartz columns. Results demonstrated that strongly-binding organic compounds are competitively adsorbed and displace those weakly-bound organic compounds along the flow path. Among the four organic compounds studied, polyacrylic acid (PAA) appeared to be the most competitive, whereas SR-NOM was more competitive than phthalic and salicylic acids. A diffuse adsorption and sharp desorption front (giving an appearance of irreversible adsorption) of the SR-NOM breakthrough curves are explained as being a result of the competitive time-dependent adsorption and displacement processes between different organic components within the SR-NOM. The stability and transport of iron oxide colloids varied as one organic component competitively displaces another. Relatively large quantities of iron oxide colloids are transported when the more strongly-binding PAA competitively displaces the weakly-binding SR-NOM or when SR-NOM competitively displaces phthalic and salicylic acids. Results of this study suggest that the chemical composition and hence the functional behavior of NOM (e.g., in stabilizing mineral colloids and in complexing contaminants) can change along its flow path as a result of the dynamic competitive interactions between heterogeneous NOM subcomponents. Further studies are needed to better define and quantify these NOM components as well as their roles in contaminant partitioning and transport. 37 refs., 10 figs.

  11. Different effect of hydrogelation on antifouling and circulation properties of dextran-iron oxide nanoparticles.

    PubMed

    Karmali, Priya Prakash; Chao, Ying; Park, Ji-Ho; Sailor, Michael J; Ruoslahti, Erkki; Esener, Sadik C; Simberg, Dmitri

    2012-03-05

    Premature recognition and clearance of nanoparticulate imaging and therapeutic agents by macrophages in the tissues can dramatically reduce both the nanoparticle half-life and delivery to the diseased tissue. Grafting nanoparticles with hydrogels prevents nanoparticulate recognition by liver and spleen macrophages and greatly prolongs circulation times in vivo. Understanding the mechanisms by which hydrogels achieve this "stealth" effect has implications for the design of long-circulating nanoparticles. Thus, the role of plasma protein absorption in the hydrogel effect is not yet understood. Short-circulating dextran-coated iron oxide nanoparticles could be converted into stealth hydrogel nanoparticles by cross-linking with 1-chloro-2,3-epoxypropane. We show that hydrogelation did not affect the size, shape and zeta potential, but completely prevented the recognition and clearance by liver macrophages in vivo. Hydrogelation decreased the number of hydroxyl groups on the nanoparticle surface and reduced the binding of the anti-dextran antibody. At the same time, hydrogelation did not reduce the absorption of cationic proteins on the nanoparticle surface. Specifically, there was no effect on the binding of kininogen, histidine-rich glycoprotein, and protamine sulfate to the anionic nanoparticle surface. In addition, hydrogelation did not prevent activation of plasma kallikrein on the metal oxide surface. These data suggest that (a) a stealth hydrogel coating does not mask charge interactions with iron oxide surface and (b) the total blockade of plasma protein absorption is not required for maintaining iron oxide nanoparticles' long-circulating stealth properties. These data illustrate a novel, clinically promising property of long-circulating stealth nanoparticles.

  12. Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps

    PubMed Central

    Sivan, Orit; Antler, Gilad; Turchyn, Alexandra V.; Marlow, Jeffrey J.; Orphan, Victoria J.

    2014-01-01

    Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with 13C-labeled methane showed co-occurring sulfate reduction, AOM, and methanogenesis. The isotope fractionation factors for sulfur and oxygen isotopes in sulfate were about 40‰ and 22‰, respectively, reinforcing the difference between microbial sulfate reduction in methane seeps versus other sedimentary environments (for example, sulfur isotope fractionation above 60‰ in sulfate reduction coupled to organic carbon oxidation or in diffusive sedimentary sulfate–methane transition zone). The addition of hematite to these microcosm experiments resulted in significant microbial iron reduction as well as enhancing sulfate-driven AOM. The magnitude of the isotope fractionation of sulfur and oxygen isotopes in sulfate from these incubations was lowered by about 50%, indicating the involvement of iron oxides during sulfate reduction in methane seeps. The similar relative change between the oxygen versus sulfur isotopes of sulfate in all experiments (with and without hematite addition) suggests that oxidized forms of iron, naturally present in the sediment incubations, were involved in sulfate reduction, with hematite addition increasing the sulfate recycling or the activity of sulfur-cycling microorganisms by about 40%. These results highlight a role for natural iron oxides during bacterial sulfate reduction in methane seeps not only as nutrient but also as stimulator of sulfur recycling. PMID:25246590

  13. Constraining Paleo-Hydrologic Flow Fields from Iron Oxide Cementation Patterns

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Chan, M. A.

    2013-12-01

    Fine-grained sandstone in Mesozoic sedimentary red beds of the Colorado Plateau (southwestern United States) contain iron oxides cements (e.g., hematite and goethite) that display spectacular pattern formation, including evenly spaced nodule formation and banding with nested scales spanning about two to three orders of magnitude (Fig. 1). These nodules are commonly referred to as concretions, which are cemented mineral masses. The size of concretions typically ranges from millimeters to centimeters, while the spacing of bands ranges from millimeters to sub-meters. Spatial transition of one pattern to another or one pattern superimposed on another is also observed. Such patterns may embed important information about paleo-environments of sediment diagenesis, especially regarding the fluid migration and geochemical conditions involved. Field evidence indicates that the formation of iron oxide bands in sandstone seems closely related to groundwater flows. Here we show that such patterns can autonomously emerge from a previously unrecognized Ostwald ripening mechanism and they capture rich information regarding ancient chemical and hydrologic environments. Using a linear stability analysis, we demonstrate that the pattern transition from nodules to bands results from symmetry breaking triggered by groundwater advection. Nodules tend to develop under nearly stagnant hydrologic conditions, while repetitive bands tend to form in the presence of persistent water flows. The banding is formed perpendicularly to the flow direction, and the flow rate is expected to be proportional to the square of banding spacing. Therefore, careful mapping of cementation patterns and banding spacing over rock outcrops will allow us to reconstruct a detail map of water flow field for a sandstone aquifer. Concretion nodules formed in Jurassic Navajo Sandstone have been proposed as a terrestrial analogue to hematite spherules detected by the rover Opportunity at the Meridiani Planum site on the

  14. Electrochemical reduction of nitroaromatic compounds by single sheet iron oxide coated electrodes.

    PubMed

    Huang, Li-Zhi; Hansen, Hans Christian B; Bjerrum, Morten Jannik

    2016-04-05

    Nitroaromatic compounds are substantial hazard to the environment and to the supply of clean drinking water. We report here the successful reduction of nitroaromatic compounds by use of iron oxide coated electrodes, and demonstrate that single sheet iron oxides formed from layered iron(II)-iron(III) hydroxides have unusual electrocatalytic reactivity. Electrodes were produced by coating of single sheet iron oxides on indium tin oxide electrodes. A reduction current density of 10 to 30μAcm(-2) was observed in stirred aqueous solution at pH 7 with concentrations of 25 to 400μM of the nitroaromatic compound at a potential of -0.7V vs. SHE. Fast mass transfer favors the initial reduction of the nitroaromatic compound which is well explained by a diffusion layer model. Reduction was found to comprise two consecutive reactions: a fast four-electron first-order reduction of the nitro-group to the hydroxylamine-intermediate (rate constant=0.28h(-1)) followed by a slower two-electron zero-order reduction resulting in the final amino product (rate constant=6.9μM h(-1)). The zero-order of the latter reduction was attributed to saturation of the electrode surface with hydroxylamine-intermediates which have a more negative half-wave potential than the parent compound. For reduction of nitroaromatic compounds, the SSI electrode is found superior to metal electrodes due to low cost and high stability, and superior to carbon-based electrodes in terms of high coulombic efficiency and low over potential.

  15. Iron Oxides

    SciTech Connect

    Qafoku, Nikolla; Amonette, James E.

    2016-09-19

    Abstract: Fe oxides are common clay-sized oxide, oxyhydroxide and hydroxide soil minerals. They are compounds of Fe, O, and H that have structures based on close-packed arrays of O. The octahedral and tetrahedral cavities within these arrays are filled with either Fe3+ or Fe2+ to form Fe(O/OH)6, FeO6, or FeO4 structural units. All of the naturally occurring Fe oxide minerals usually undergo some degree of isomorphous substitution of other metal ions for Fe in their structures. Relatively simple techniques may be used to identify Fe oxides in the field based on their typical colors and magnetic properties. In the laboratory, a variety of instrumental techniques can be used to confirm phase identity and to quantify amount. Of these, X-ray diffraction, infrared spectroscopy, electron microscopy, thermal analysis, and Mössbauer spectroscopy are the most commonly used techniques. As oxides, the functional groups on their surfaces may have positive, negative, or no charge depending on pH and on the concentration and nature of other ions in the contact solution. A net positive surface charge usually is observed in soils because Fe oxides have a point-of-zero-charge in the neutral or slightly basic pHs. The functional groups on the surface form complexes with cations and anions from the aqueous phase. Their sorption and electron-buffering properties significantly affect the geochemical cycles of almost all elements having agronomic or environmental significance.

  16. Thermally modulated photoacoustic imaging with super-paramagnetic iron oxide nanoparticles.

    PubMed

    Feng, Xiaohua; Gao, Fei; Zheng, Yuanjin

    2014-06-15

    Thermally modulated photoacoustic imaging (TMPI) is reported here for contrast enhancement when using nanoparticles as contrast agents. Exploiting the excellent sensitivity of the photoacoustic (PA) process on temperature and the highly selective heating capability of nanoparticles under electromagnetic field, the PA signals stemming from the nanoparticles labeled region can be efficiently modulated whereas those from highly light absorptive backgrounds are minimally affected. A coherent difference imaging procedure reduces the background signal and thus improves the imaging contrast. Phantom experiments with super-paramagnetic iron oxide nanoparticles (SPIONs) as contrast agents and alternating magnetic fields for heating are demonstrated. Further improvements toward clinical applications are also discussed.

  17. Silica-coated super paramagnetic iron oxide nanoparticles (SPION) as biocompatible contrast agent in biomedical photoacoustics.

    PubMed

    Alwi, Rudolf; Telenkov, Sergey; Mandelis, Andreas; Leshuk, Timothy; Gu, Frank; Oladepo, Sulayman; Michaelian, Kirk

    2012-10-01

    In this study, we report for the first time the use of silica-coated superparamagnetic iron oxide nanoparticles (SPION) as contrast agents in biomedical photoacoustic imaging. Using frequency-domain photoacoustic correlation (the photoacoustic radar), we investigated the effects of nanoparticle size, concentration and biological media (e.g. serum, sheep blood) on the photoacoustic response in turbid media. Maximum detection depth and the minimum measurable SPION concentration were determined experimentally. The nanoparticle-induced optical contrast ex vivo in dense muscular tissues (avian pectus and murine quadricept) was evaluated and the strong potential of silica-coated SPION as a possible photoacoustic contrast agents was demonstrated.

  18. Superparamagnetic Iron Oxide Nanoparticles: Promises for Diagnosis and Treatment of Multiple Sclerosis

    PubMed Central

    2011-01-01

    Smart superparamagnetic iron oxide nanoparticles (SPIONs) are the most promising candidate for theragnosis (i.e., diagnosis and treatment) of multiple sclerosis. A deep understanding of the dynamics of the in vivo neuropathology of multiple sclerosis can be achieved by improving the efficiency of various medical techniques (e.g., positron emission tomography and magnetic resonance imaging) using multimodal SPIONs. In this Review, recent advances and challenges in the development of smart SPIONs for theragnostic applications are comprehensively described. In addition, critical outlines of emerging developments are provided from the points of view of both clinicians and nanotechnologists. PMID:22778862

  19. Characterization and Functionalization of Iron-Oxide Nanoparticles for Use as Potential Agents for Cancer Thermotherapy

    NASA Astrophysics Data System (ADS)

    O'Reilly, Nora

    This thesis presents experimental studies of iron oxide nanoparticle synthesis, functionalization, and intracellular hyperthermal effects on murine macrophages as a model in vitro system. Colloidal suspensions of magnetic nanoparticles (MNPs) are of particular interest in Magnetic Fluid Hyperthermia (MFH). Iron oxide nanoparticles (IONPs) have garnered great interest as economical, biocompatible hyperthermia agents due to their superparamagnetic activity. Here we seek to optimize the synthetic reproducibility and in vitro utilization of IONPs for application in MFH. We compared aqueous synthetic protocols and various protective coating techniques using various analytical techniques and in vitro assays to assess the biocompatibility and feasibility of the various preparations of nanoparticles. Using a co-precipitation of iron salts methodology, iron oxide nanoparticles (IONPs) with an average diameter of 6-8nm were synthesized and stabilized with carboxylates. By performing calorimetry measurements in an oscillating magnetic field (OMF) with a frequency of 500 kHz and field strength of 0.008Tesla the superparamagnetic behavior of these particles was confirmed. To further investigate these IONPs in a biological application, citric acid-stabilized particles, in conjunction with heat generated by these IONPs when exposed to an OMF, were assessed to determine their effects on cell viability in a RAW 267.4 murine macrophage model system. Our results show that 91.5-97% of cells that have ingested IONPs die follow exposure to an OMF. Importantly, neither the IONPs (at applicable concentrations) nor the OMF show cytotoxic effects. These particular particles have promising preliminary results as hyperthermic agents in both the current literature and simple, proof-of-concept experiments in our laboratory setting. We present experimental results for the synthesis, characterization, and utilization of iron oxide nanoparticles in MFH. Our results show that while IONPs have

  20. Superparamagnetic iron oxide nanoparticles for in vivo molecular and cellular imaging.

    PubMed

    Sharifi, Shahriar; Seyednejad, Hajar; Laurent, Sophie; Atyabi, Fatemeh; Saei, Amir Ata; Mahmoudi, Morteza

    2015-01-01

    In the last decade, the biomedical applications of nanoparticles (NPs) (e.g. cell tracking, biosensing, magnetic resonance imaging (MRI), targeted drug delivery, and tissue engineering) have been increasingly developed. Among the various NP types, superparamagnetic iron oxide NPs (SPIONs) have attracted considerable attention for early detection of diseases due to their specific physicochemical properties and their molecular imaging capabilities. A comprehensive review is presented on the recent advances in the development of in vitro and in vivo SPION applications for molecular imaging, along with opportunities and challenges.

  1. Recent advances in synthesis and surface modification of superparamagnetic iron oxide nanoparticles with silica

    NASA Astrophysics Data System (ADS)

    Sodipo, Bashiru Kayode; Aziz, Azlan Abdul

    2016-10-01

    Research on synthesis of superparamagnetic iron oxide nanoparticles (SPION) and its surface modification for biomedical applications is of intense interest. Due to superparamagnetic property of SPION, the nanoparticles have large magnetic susceptibility, single magnetic domain and controllable magnetic behaviour. However, owing to easy agglomeration of SPION, surface modification of the magnetic particles with biocompatible materials such as silica nanoparticle has gained much attention in the last decade. In this review, we present recent advances in synthesis of SPION and various routes of producing silica coated SPION.

  2. Photo-fluorescent and magnetic properties of iron oxide nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Shi, Donglu; Sadat, M. E.; Dunn, Andrew W.; Mast, David B.

    2015-04-01

    Iron oxide exhibits fascinating physical properties especially in the nanometer range, not only from the standpoint of basic science, but also for a variety of engineering, particularly biomedical applications. For instance, Fe3O4 behaves as superparamagnetic as the particle size is reduced to a few nanometers in the single-domain region depending on the type of the material. The superparamagnetism is an important property for biomedical applications such as magnetic hyperthermia therapy of cancer. In this review article, we report on some of the most recent experimental and theoretical studies on magnetic heating mechanisms under an alternating (AC) magnetic field. The heating mechanisms are interpreted based on Néel and Brownian relaxations, and hysteresis loss. We also report on the recently discovered photoluminescence of Fe3O4 and explain the emission mechanisms in terms of the electronic band structures. Both optical and magnetic properties are correlated to the materials parameters of particle size, distribution, and physical confinement. By adjusting these parameters, both optical and magnetic properties are optimized. An important motivation to study iron oxide is due to its high potential in biomedical applications. Iron oxide nanoparticles can be used for MRI/optical multimodal imaging as well as the therapeutic mediator in cancer treatment. Both magnetic hyperthermia and photothermal effect has been utilized to kill cancer cells and inhibit tumor growth. Once the iron oxide nanoparticles are up taken by the tumor with sufficient concentration, greater localization provides enhanced effects over disseminated delivery while simultaneously requiring less therapeutic mass to elicit an equal response. Multi-modality provides highly beneficial co-localization. For magnetite (Fe3O4) nanoparticles the co-localization of diagnostics and therapeutics is achieved through magnetic based imaging and local hyperthermia generation through magnetic field or photon

  3. Photo-fluorescent and magnetic properties of iron oxide nanoparticles for biomedical applications.

    PubMed

    Shi, Donglu; Sadat, M E; Dunn, Andrew W; Mast, David B

    2015-05-14

    Iron oxide exhibits fascinating physical properties especially in the nanometer range, not only from the standpoint of basic science, but also for a variety of engineering, particularly biomedical applications. For instance, Fe3O4 behaves as superparamagnetic as the particle size is reduced to a few nanometers in the single-domain region depending on the type of the material. The superparamagnetism is an important property for biomedical applications such as magnetic hyperthermia therapy of cancer. In this review article, we report on some of the most recent experimental and theoretical studies on magnetic heating mechanisms under an alternating (AC) magnetic field. The heating mechanisms are interpreted based on Néel and Brownian relaxations, and hysteresis loss. We also report on the recently discovered photoluminescence of Fe3O4 and explain the emission mechanisms in terms of the electronic band structures. Both optical and magnetic properties are correlated to the materials parameters of particle size, distribution, and physical confinement. By adjusting these parameters, both optical and magnetic properties are optimized. An important motivation to study iron oxide is due to its high potential in biomedical applications. Iron oxide nanoparticles can be used for MRI/optical multimodal imaging as well as the therapeutic mediator in cancer treatment. Both magnetic hyperthermia and photothermal effect has been utilized to kill cancer cells and inhibit tumor growth. Once the iron oxide nanoparticles are up taken by the tumor with sufficient concentration, greater localization provides enhanced effects over disseminated delivery while simultaneously requiring less therapeutic mass to elicit an equal response. Multi-modality provides highly beneficial co-localization. For magnetite (Fe3O4) nanoparticles the co-localization of diagnostics and therapeutics is achieved through magnetic based imaging and local hyperthermia generation through magnetic field or photon

  4. Mössbauer, magnetization and X-ray diffraction characterization methods for iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Gabbasov, Raul; Polikarpov, Michael; Cherepanov, Valery; Chuev, Michael; Mischenko, Iliya; Lomov, Andrey; Wang, Andrew; Panchenko, Vladislav

    2015-04-01

    Water soluble magnetite iron oxide nanoparticles with oleic polymer coating and average diameters in the range of 5-25 nm, previously determined by TEM, were characterized using Mössbauer, magnetization and X-ray diffraction measurements. Comparative analysis of the results demonstrated a large diversity of magnetic relaxation regimes. Analysis showed the presence of an additional impurity component in the 25 nm nanoparticles, with principally different magnetic nature at the magnetite core. In some cases, X-ray diffraction measurements were unable to estimate the size of the magnetic core and Mössbauer data were necessary for the correct interpretation of the experimental results.

  5. Synthesis and assembly of barium-doped iron oxide nanoparticles and nanomagnets.

    PubMed

    Wu, Liheng; Shen, Bo; Sun, Shouheng

    2015-10-21

    A facile organic-phase synthesis of monodisperse barium-doped iron oxide (Ba-Fe-O) nanoparticles (NPs) is reported. The Ba-Fe-O NPs can be converted into hexagonal barium ferrite NPs at 700 °C, showing strong ferromagnetic properties with H(c) reaching 5260 Oe and M(s) at 54 emu g(-1). Moreover, the Ba-Fe-O NPs can be assembled into densely packed magnetic arrays, providing a unique model system for studying nanomagnetism and for nanomagnetic applications.

  6. Cellular Precipitates Of Iron Oxide in Olivine in a Stratospheric Interplanetary Dust Particle

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.

    1996-01-01

    The petrology of a massive olivine-sulphide interplanetary dust particle shows melting of Fe,Ni-sulphide plus complete loss of sulphur and subsequent quenching to a mixture of iron-oxides and Fe,Ni-metal. Oxidation of the fayalite component in olivine produced maghemite discs and cellular intergrowths with olivine and rare andradite-rich garnet. Cellular reactions require no long-range solid-state diffusion and are kinetically favourable during pyrometamorphic oxidation. Local melting of the cellular intergrowths resulted in three dimensional symplectic textures. Dynamic pyrometamorphism of this asteroidal particle occurred at approx. 1100 C during atmospheric entry flash (5-15 s) heating.

  7. Surface chemical heterogeneity of bacteriogenic iron oxides from a subterranean environment.

    PubMed

    Martinez, Raul E; Smith, D Scott; Pedersen, Karsten; Ferris, F Grant

    2003-12-15

    This study quantifies the surface chemical heterogeneity of bacteriogenic iron oxides (BIOS) and its end-members (2-line ferrihydrite and intermixed intact and fragmented bacteria). On a dry weight basis, BIOS consisted of 64.5 +/- 1.8% ferrihydrite and 34.5 +/- 1.8% organic matter. Enrichment of Al, Cu, Cr, Mn, Sr, and Zn was shown in the solid versus the aqueous phase (1.9 < log Kd < 4.2). Within the solid-phase Al (69.5%), Cu (78.7%), and Zn (77.9%) were associated with the bacteria, whereas Cr (59.8%), Mn (99.8%), and Sr (79.4%) preferred ferrihydrite. Acid-base titration data from the BIOS and bacteria were fitted using FOCUS pKa spectroscopy. The bacteria spectrum with pKa's of 4.18 +/- 0.37, 4.80 +/- 0.54, 6.98 +/- 0.45, and 9.75 +/- 0.68 was similar to discrete and continuous spectra for intact and fragmented bacteria. The BIOS spectrum recorded pKa's of 4.27 +/- 0.51, 6.61 +/- 0.51, 7.89 +/- 1.10, and 9.65 +/- 0.66 and was deconvoluted to remove overlapping binding site contributions from the bacteria. The resulting residual iron oxide spectrum coincided with discrete MUSIC spectra for goethite and lepidocrocite with pKa values of 4.10 +/- 0.43, 6.53 +/- 0.45, 7.81 +/- 0.76, and 9.51 +/- 0.68. Surface site density analysis showed that acidic sites (pKa < 6) were contributed by the bacteria (37%), whereas neutral sites (6 < pKa < 8) were characteristic of the iron oxide fraction (35%). Basic sites (8 < pKa) were higher in the bacteria (57%), than in the BIOS (44%) or iron oxide fractions (47%). This analysis suggested a high degree of bacterial group masking and a similarity between the BIOS and goethite surface reactivity. An understanding of the BIOS surface chemical heterogeneity and inherent proton and metal binding capacity was obtained through the use of FOCUS apparent pKa spectroscopy.

  8. Characterization of magnetization-induced second harmonic generation in iron oxide polymer nanocomposites.

    PubMed

    Vandendriessche, Stefaan; Valev, Ventsislav K; Verbiest, Thierry

    2012-01-10

    We have measured the magnetization-induced second harmonic generation (MSHG) of a nanocomposite consisting of iron oxide nanoparticles in a polymer film. The existing theoretical framework is extended to include DC magnetic fields in order to characterize the MSHG signal and analyze the measurements. Additionally, magnetic hysteresis loops are measured for four principal polarizer-analyzer configurations, revealing the P(IN)-P(OUT) and S(IN)-P(OUT) polarizer-analyzer configurations to be sensitive to the transverse magnetic field. These results demonstrate the use of MSHG and the applied formalism as a tool to study magnetic nanoparticles and their magnetic properties.

  9. Method of minimizing energy consumption when reducing iron oxide with reducing gases

    SciTech Connect

    Mathisson, G.; Santen, S.

    1984-02-21

    Energy consumption may be minimized when reducing iron oxide with reducing gases which are at least partially re-circulated in the process and where the re-circulation gas is washed to remove the reaction product CO/sub 2/ in what is known as a CO/sub 2/ wash to enable it to be re-used, by the heat requirement necessary for regenerating the washing liquid in the CO/sub 2/ wash being entirely or partially covered by the physical heat content in top gas from the shaft furnace and/or gas leaving the sponge-iron cooler of the shaft furnace.

  10. Chelator free gallium-68 radiolabelling of silica coated iron oxide nanorods via surface interactions

    NASA Astrophysics Data System (ADS)

    Burke, Benjamin P.; Baghdadi, Neazar; Kownacka, Alicja E.; Nigam, Shubhanchi; Clemente, Gonçalo S.; Al-Yassiry, Mustafa M.; Domarkas, Juozas; Lorch, Mark; Pickles, Martin; Gibbs, Peter; Tripier, Raphaël; Cawthorne, Christopher; Archibald, Stephen J.

    2015-09-01

    The commercial availability of combined magnetic resonance imaging (MRI)/positron emission tomography (PET) scanners for clinical use has increased demand for easily prepared agents which offer signal or contrast in both modalities. Herein we describe a new class of silica coated iron-oxide nanorods (NRs) coated with polyethylene glycol (PEG) and/or a tetraazamacrocyclic chelator (DO3A). Studies of the coated NRs validate their composition and confirm their properties as in vivo T2 MRI contrast agents. Radiolabelling studies with the positron emitting radioisotope gallium-68 (t1/2 = 68 min) demonstrate that, in the presence of the silica coating, the macrocyclic chelator was not required for preparation of highly stable radiometal-NR constructs. In vivo PET-CT and MR imaging studies show the expected high liver uptake of gallium-68 radiolabelled nanorods with no significant release of gallium-68 metal ions, validating our innovation to provide a novel simple method for labelling of iron oxide NRs with a radiometal in the absence of a chelating unit that can be used for high sensitivity liver imaging.The commercial availability of combined magnetic resonance imaging (MRI)/positron emission tomography (PET) scanners for clinical use has increased demand for easily prepared agents which offer signal or contrast in both modalities. Herein we describe a new class of silica coated iron-oxide nanorods (NRs) coated with polyethylene glycol (PEG) and/or a tetraazamacrocyclic chelator (DO3A). Studies of the coated NRs validate their composition and confirm their properties as in vivo T2 MRI contrast agents. Radiolabelling studies with the positron emitting radioisotope gallium-68 (t1/2 = 68 min) demonstrate that, in the presence of the silica coating, the macrocyclic chelator was not required for preparation of highly stable radiometal-NR constructs. In vivo PET-CT and MR imaging studies show the expected high liver uptake of gallium-68 radiolabelled nanorods with no

  11. Nanoencapsulation of ultra-small superparamagnetic particles of iron oxide into human serum albumin nanoparticles

    PubMed Central

    Altinok, Mahmut; Urfels, Stephan; Bauer, Johann

    2014-01-01

    Summary Human serum albumin nanoparticles have been utilized as drug delivery systems for a variety of medical applications. Since ultra-small superparamagnetic particles of iron oxide (USPIO) are used as contrast agents in magnetic resonance imaging, their encapsulation into the protein matrix enables the synthesis of diagnostic and theranostic agents by surface modification and co-encapsulation of active pharmaceutical ingredients. The present investigation deals with the surface modification and nanoencapsulation of USPIO into an albumin matrix by using ethanolic desolvation. Particles of narrow size distribution and with a defined particle structure have been achieved. PMID:25551054

  12. Magneto-inductive heating of water-based iron oxide ferrofluids

    NASA Astrophysics Data System (ADS)

    Novoselova, Iu. P.; Safronov, A. P.; Samatov, O. M.; Kurlyandskaya, G. V.

    2016-09-01

    Spherical magnetic nanoparticles (MNPs) of iron oxide were fabricated by laser target evaporation technique. Water-based ferrofluids were prepared on the basis of obtained MNPs. Their structure and magnetic properties were studied by a number of methods including transmission electron microscopy, X-ray diffraction, SQUID-magnetometry and magnetic relaxation losses measurements. Magneto-inductive heating experiment showed the specific power loss value of 2 W/g for 1.8 kA/m alternating magnetic field of 214 kHz frequency. These parameters indicate that LTE MNPs are perspective materials for biomedical applications such as hyperthermia.

  13. Carbon-11 radiolabeling of iron-oxide nanoparticles for dual-modality PET/MR imaging

    NASA Astrophysics Data System (ADS)

    Sharma, Ramesh; Xu, Youwen; Kim, Sung Won; Schueller, Michael J.; Alexoff, David; Smith, S. David; Wang, Wei; Schlyer, David

    2013-07-01

    Dual-modality imaging, using Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) simultaneously, is a powerful tool to gain valuable information correlating structure with function in biomedicine. The advantage of this dual approach is that the strengths of one modality can balance the weaknesses of the other. However, success of this technique requires developing imaging probes suitable for both. Here, we report on the development of a nanoparticle labeling procedure via covalent bonding with carbon-11 PET isotope. Carbon-11 in the form of [11C]methyl iodide was used as a methylation agent to react with carboxylic acid (-COOH) and amine (-NH2) functional groups of ligands bound to the nanoparticles (NPs). The surface coating ligands present on superparamagnetic iron-oxide nanoparticles (SPIO NPs) were radiolabeled to achieve dual-modality PET/MR imaging capabilities. The proof-of-concept dual-modality PET/MR imaging using the radiolabeled SPIO NPs was demonstrated in an in vivo experiment.Dual-modality imaging, using Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) simultaneously, is a powerful tool to gain valuable information correlating structure with function in biomedicine. The advantage of this dual approach is that the strengths of one modality can balance the weaknesses of the other. However, success of this technique requires developing imaging probes suitable for both. Here, we report on the development of a nanoparticle labeling procedure via covalent bonding with carbon-11 PET isotope. Carbon-11 in the form of [11C]methyl iodide was used as a methylation agent to react with carboxylic acid (-COOH) and amine (-NH2) functional groups of ligands bound to the nanoparticles (NPs). The surface coating ligands present on superparamagnetic iron-oxide nanoparticles (SPIO NPs) were radiolabeled to achieve dual-modality PET/MR imaging capabilities. The proof-of-concept dual-modality PET/MR imaging using the radiolabeled

  14. Dendrimer-based magnetic iron oxide nanoparticles: their synthesis and biomedical applications.

    PubMed

    Sun, Wenjie; Mignani, Serge; Shen, Mingwu; Shi, Xiangyang

    2016-12-01

    Magnetic iron oxide nanoparticles (MIO NPs) bearing different appropriate surface modifications can be prepared using diverse physical and chemical methods. As an ideal macromolecule, dendrimers have attracted considerable attention because of their unique properties, including their three 3D architecture, monodispersity, highly branched macromolecular characteristics, and tunable terminal functionalities. These properties make dendrimers a powerful nanoplatform for the creation of functional organic and/or inorganic hybrid NPs, in particular dendrimer-based MIO NPs. Here, we report on recent advances in the preparation of dendrimer-based MIO NPs for different biomedical applications, such as magnetic resonance (MR) imaging, drug and gene delivery, and protein immobilization.

  15. Size-dependant heating rates of iron oxide nanoparticles for magnetic fluid hyperthermia.

    PubMed

    Gonzales-Weimuller, Marcela; Zeisberger, Matthias; Krishnan, Kannan M

    2009-07-01

    Using the thermal decomposition of organometallics method we have synthesized high-quality, iron oxide nanoparticles of tailorable size up to ~15nm and transferred them to a water phase by coating with a biocompatible polymer. The magnetic behavior of these particles was measured and fit to a log-normal distribution using the Chantrell method and their polydispersity was confirmed to be very narrow. By performing calorimetry measurements with these monodisperse particles we have unambiguously demonstrated, for the first time, that at a given frequency, heating rates of superparamagnetic particles are dependent on particle size, in agreement with earlier theoretical predictions.

  16. Tracking Injectable Microspheres in Dynamic Tissues With Encapsulated Superparamagnetic Iron Oxide Nanoparticlesa

    PubMed Central

    Franklin-Ford, Travelle; Shah, Nehal; Leiferman, Ellen; Chamberlain, Connie S.; Raval, Amish; Vanderby, Ray

    2013-01-01

    Trackable spheres of similar size to those typically used for sustained protein delivery are prepared by incorporating superparamagnetic iron oxide (SPIO) nanoparticles into the core of poly(lactide-co-glycolide) microspheres. The visibility of injections in static and temporally in dynamic tissue systems is demonstrated. This method improves upon other, less sensitive imaging modalities in their ability to track injectable delivery systems. The results obtained confirm the localization of microspheres to the injected target area and highlight the novelty of tracking delivery vehicles for other applications. PMID:23124987

  17. Self-assembled patterns of iron oxide nanoparticles by hydrothermal chemical-vapor deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengjun; Wei, B. Q.; Ajayan, P. M.

    2001-12-01

    Here, we report a hydrothermal chemical-vapor deposition process, which produces self-assembled patterns of iron oxide nanoparticles. By exposing a planar silica substrate to a prevaporized mixture of water, ferrocene [Fe(C5H5)2] and xylene (C8H10), at temperatures of ˜1000 °C, Fe2O3 nanoparticles are deposited on the substrate surface, in regular circular patterns. The particle sizes are less than 100 nm, and are organized into submicron-size patterns. The same process without water produces arrays of carbon nanotubes catalyzed by iron nanoparticles that are formed by the decomposition of ferrocene molecules.

  18. Sulfates and iron oxides in Ophir Chasma, Mars, based on OMEGA and CRISM observations

    NASA Astrophysics Data System (ADS)

    Wendt, Lorenz; Gross, Christoph; Kneissl, Thomas; Sowe, Mariam; Combe, Jean-Philippe; LeDeit, Laetitia; McGuire, Patrick C.; Neukum, Gerhard

    2011-05-01

    We investigate the sulfate and iron oxide deposits in Ophir Chasma, Mars, based on short-wave infrared data from the Compact Reconnaissance Imaging Spectrometer for Mars - CRISM and from the Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité - OMEGA. Sulfates are detected mainly in two locations. In the valley between Ophir Mensa and the southern wall of Ophir Chasma, kieserite is found both within the slope of Ophir Mensa, and superposed on the basaltic wall of the chasm. Here, kieserite is unconformably overlain by polyhydrated sulfate deposits and iron oxides. Locally, jarosite and unidentified phases with absorptions at 2.21 μm or 2.23 μm are detected, which could be mixtures of jarosite and amorphous silica or other poorly crystalline phases. The second large sulfate-rich outcrop is found on the floor of the central valley. Although the same minerals are found here, polyhydrated sulfates, kieserite, iron oxides, and locally a possibly jarosite-bearing phase, this deposit is very distinct. It is not layered, almost horizontal, and located at a much lower elevation of below -4250 m. Kieserite superposes polyhydrated sulfate-rich deposits, and iron oxides form lags. The facies of sulfate formation remains unclear, and could be different for the two locations. A formation in a lake, playa or under a glacier is consistent with the mineralogy of the central valley and its flat, low-lying topography. This is not conceivable for the kieserite deposits observed south of Ophir Mensa. These deposits are observed over several thousands of meters of elevation, which would require a standing body of water several thousands of meters deep. This would have lead to much more pervasive sulfate deposits than observed. These deposits are therefore more consistent with evaporation of groundwater infiltrating into previously sulfate-free light-toned deposits. The overlying polyhydrated sulfates and other mineral phases are observed in outcrops on ridges along the

  19. Structural investigations on differently sized monodisperse iron oxide nanoparticles synthesized by remineralization of apoferritin molecules

    NASA Astrophysics Data System (ADS)

    Ullrich, Aladin; Horn, Siegfried

    2013-08-01

    We have investigated the structure of iron oxide nanoparticles produced by remineralization and thermal treatment of horse spleen apoferritin molecules. The described procedure allows to synthesize particles with diameters ranging from 4 to 7 nm in size. Atomic force microscopy and transmission electron microscopy (TEM) investigations were performed for shape and size determination, whereas energy-dispersive X-ray (TEM-EDX), high-resolution TEM, and electron diffraction measurements revealed the chemical composition and crystal structure of the particles. We found predominantly single crystalline nanoparticles with a hematite-like (α-Fe2O3) structure.

  20. Transport and viability of Escherichia coli cells in clean and iron oxide coated sand following coating with silver nanoparticles.

    PubMed

    Ngwenya, Bryne T; Curry, Philip; Kapetas, Leon

    2015-08-01

    A mechanistic understanding of processes controlling the transport and viability of bacteria in porous media is critical for designing in situ bioremediation and microbiological water decontamination programs. We investigated the combined influence of coating sand with iron oxide and silver nanoparticles on the transport and viability of Escherichia coli cells under saturated conditions. Results showed that iron oxide coatings increase cell deposition which was generally reversed by silver nanoparticle coatings in the early stages of injection. These observations are consistent with short-term, particle surface charge controls on bacteria transport, where a negatively charged surface induced by silver nanoparticles reverses the positive charge due to iron oxide coatings, but columns eventually recovered irreversible cell deposition. Silver nanoparticle coatings significantly increased cell inactivation during transit through the columns. However, when viability data is normalised to volume throughput, only a small improvement in cell inactivation is observed for silver nanoparticle coated sands relative to iron oxide coating alone. This counterintuitive result underscores the importance of net surface charge in controlling cell transport and inactivation and implies that the extra cost for implementing silver nanoparticle coatings on porous beds coated with iron oxides may not be justified in designing point of use water filters in low income countries.

  1. Bench-scale study of the effect of phosphate on an aerobic iron oxidation plant for mine water treatment.

    PubMed

    Tischler, Judith S; Wiacek, Claudia; Janneck, Eberhard; Schlömann, Michael

    2014-01-01

    At the opencast pit Nochten acidic iron- and sulfate-rich mine waters are treated biotechnologically in a mine-water treatment plant by microbial iron oxidation. Due to the low phosphate concentration in such waters the treatment plant was simulated in bench-scale to investigate the influence of addition of potassium dihydrogen phosphate on chemical and biological parameters of the mine-water treatment. As a result of the phosphate addition the number of cells increased, which resulted in an increase of the iron oxidation rate in the reactor with phosphate addition by a factor of 1.7 compared to a reference approach without phosphate addition. Terminal restriction fragment length polymorphism (T-RFLP) analysis during the cultivation revealed a shift of the microbial community depending on the phosphate addition. While almost exclusively iron-oxidizing bacteria related to "Ferrovum" sp. were detected with phosphate addition, the microbial community was more diverse without phosphate addition. In the latter case, iron-oxidizing bacteria ("Ferrovum" sp., Acidithiobacillus spp.) as well as non-iron-oxidizing bacteria (Acidiphilium sp.) were identified.

  2. Effect of temperature on the kinetics of acetylene decomposition over reduced iron oxide catalyst for the production of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Khedr, M. H.; Abdel Halim, K. S.; Soliman, N. K.

    2008-12-01

    Carbon nanotubes (CNTs) were synthesized by the catalytic decomposition of acetylene over nanosized metallic iron. A high metal loading was chosen in order to obtain a longer catalytic activity. Different nanosized iron oxides were prepared using chemical methods. A catalyst of the composition 40% Fe 2O 3:60% Al 2O 3 is prepared by wet impregnation method. The prepared samples of iron oxides supported in alumina were completely reduced by hydrogen gas at 500 °C and then constant rate of acetylene gas was passed over the freshly reduced samples at different reaction conditions. The kinetics of CNTs synthesis on reduced nanosized Fe 2O 3 supported on alumina was investigated as a function of crystal size of iron oxide catalyst (35-150 nm) and decomposition temperature (400-700 °C). The microstructure and morphology of the synthesized catalyst and CNTs were characterized using scanning electron microscope (SEM), high-resolution transmission electron microscope (HR-TEM) and XRD analysis. The results revealed that both the crystal size of iron oxide and decomposition temperature have a significant effect on the percentage yield of carbon deposited. It increased by decreasing crystal size of the catalyst and increasing decomposition temperature to certain limit. The maximum yield of carbon deposited (426%) was obtained at decomposition temperature 600 °C and over nanosized iron oxide catalyst with crystal size of average 35 nm.

  3. Phosphate dynamics in an acidic mountain stream: Interactions involving algal uptake, sorption by iron oxide, and photoreduction

    USGS Publications Warehouse

    Tate, Cathy M.; Broshears, Robert E.; McKnight, Diane M.

    1995-01-01

    Acid mine drainage streams in the Rocky Mountains typically have few algal species and abundant iron oxide deposits which can sorb phosphate. An instream injection of radiolabeled phosphate (32P0,) into St. Kevin Gulch, an acid mine drainage stream, was used to test the ability of a dominant algal species, Ulothrix sp., to rapidly assimilate phosphate. Approximately 90% of the injected phosphate was removed from the water column in the 175-m stream reach. When shaded stream reaches were exposed to full sunlight after the injection ended, photoreductive dissolution of iron oxide released sorbed 32P, which was then also removed downstream. The removal from the stream was modeled as a first-order process by using a reactive solute transport transient storage model. Concentrations of 32P mass-’ of algae were typically lo-fold greater than concentrations in hydrous iron oxides. During the injection, concentrations of 32P increased in the cellular P pool containing soluble, low-molecular-weight compounds and confirmed direct algal uptake of 32P0, from water. Mass balance calculations indicated that algal uptake and sorption on iron oxides were significant in removing phosphate. We conclude that in stream ecosystems, PO, sorbed by iron oxides can act as a dynamic nutrient reservoir regulated by photoreduction.

  4. Formation of indigoidine derived-pigments contributes to the adaptation of Vogesella sp. strain EB to cold aquatic iron-oxidizing environments.

    PubMed

    Day, Paula Arrúa; Villalba, María S; Herrero, O Marisa; Arancibia, Luz Alejandra; Alvarez, Héctor M

    2017-03-01

    We investigated previously under explored cold aquatic environments of Andean Patagonia, Argentina. Oily sheens similar to an oil spill are frequently observed at the surface of water in creeks and small ponds in these places. Chemical analysis of a water sample revealed the occurrence of high concentrations of iron and the presence of a free insoluble indigoidine-derived pigment. A blue pigment-producing bacterium (strain EB) was isolated from the water sample and identified as Vogesella sp. by molecular analysis. The isolate was able to produce indigoidine and another derived-pigment (here called cryoindigoidine) with strong antifreeze properties. The production of the pigments depended on the cell growth at cold temperatures (below 15 °C), as well as on the attachment of cells to solid surfaces, and iron limitation in the media. The pigments produced by strain EB showed an inhibitory effect on the growth of diverse microorganisms such as Candida albicans, Escherichia coli and Staphylococcus aureus. In addition, pigmented cells were more tolerant to freezing than non-pigmented cells, suggesting a role of cryoindigoidine/indigoidine as a cold-protectant molecule. The possible roles of the pigments in strain EB physiology and its interactions with the iron-rich environment from which the isolate was obtained are discussed. Results of this study suggested an active role of strain EB in the investigated iron-oxidizing ecosystem.

  5. Biodegradable Magnetic Silica@Iron Oxide Nanovectors with Ultra-Large Mesopores for High Protein Loading, Magnetothermal Release, and Delivery.

    PubMed

    Omar, Haneen; Croissant, Jonas G; Alamoudi, Kholod; Alsaiari, Shahad; Alradwan, Ibrahim; Majrashi, Majed A; Anjum, Dalaver H; Martins, Patricia; Moosa, Basem; Almalik, Abdulaziz; Khashab, Niveen M

    2016-11-29

    The delivery of large cargos of diameter above 15nm for biomedical applications has proved challenging since it requires biocompatible, stably-loaded, and biodegradable nanomaterials. In this study, we describe the design of biodegradable silica-iron oxide hybrid nanovectors with large mesopores for large protein delivery in cancer cells. The mesopores of the nanomaterials spanned from 20 to 60nm in diameter and post-functionalization allowed the electrostatic immobilization of large proteins (e.g. mTFP-Ferritin, ~534kDa). Half of the content of the nanovectors was based with iron oxide nanophases which allowed the rapid biodegradation of the carrier in fetal bovine serum and a magnetic responsiveness. The nanovectors released large protein cargos in aqueous solution under acidic pH or magnetic stimuli. The delivery of large proteins was then autonomously achieved in cancer cells via the silica-iron oxide nanovectors, which is thus a promising for biomedical applications.

  6. Preparation of composite with silica-coated nanoparticles of iron oxide spinels for applications based on magnetically induced hyperthermia

    NASA Astrophysics Data System (ADS)

    Andrade, Angela L.; Fabris, José D.; Pereira, Márcio C.; Domingues, Rosana Z.; Ardisson, José D.

    2013-04-01

    It is reported a novel method to prepare magnetic core (iron oxide spinels)-shell (silica) composites containing well-dispersed magnetic nanoparticles in aqueous solution. The synthetic process consists of two steps. In a first step, iron oxide nanoparticles obtained through co-precipitation are dispersed in an aqueous solution containing tetramethylammonium hydroxide; in a second step, particles of this sample are coated with silica, through hydrolyzation of tetraethyl orthosilicate. The intrinsic atomic structure and essential properties of the core-shell system were assessed with powder X-ray diffraction, Fourier transform infrared spectrometry, Mössbauer spectroscopy and transmission electron microscopy. The heat released by this ferrofluid under an AC-generated magnetic field was evaluated by following the temperature evolution under increasing magnetic field strengths. Results strongly indicate that this ferrofluid based on silica-coated iron oxide spinels is technologically a very promising material to be used in medical practices, in oncology.

  7. High specificity targeting and detection of human neuroblastoma using multifunctional anti-GD2 iron-oxide nanoparticles

    PubMed Central

    Baiu, Dana C.; Artz, Nathan S.; McElreath, Meghan R.; Menapace, Bryan D.; Hernando, Diego; Reeder, Scott B.; Grüttner, Cordula; Otto, Mario

    2015-01-01

    Aim To develop biocompatible, tumor-specific multifunctional iron oxide nanoconstructs targeting neuroblastoma, an aggressive pediatric malignancy. Materials & methods Clinical-grade humanized monoclonal antibody (hu14.18K322A), designed to target GD2 antigen on neuroblastoma with reduced non-specific immune interactions, was conjugated to hydroxyethyl starch-coated iron oxide nanoparticles. Targeting capability in vitro and in vivo was assessed by immunofluorescence, electron microscopy, analytical spectrophotometry, histochemistry and magnetic resonance R2* relaxometry. Results The biocompatible nanoconstructs demonstrated high tumor-specificity in vitro and in vivo, and low background uptake in a mouse flank xenograft model. Specific accumulation in tumors enabled particle visualization and quantification by magnetic resonance R2* mapping. Conclusions Our findings support the further development towards clinical application of this anti-GD2 iron-oxide nanoconstruct as diagnostic and therapeutic scaffold for neuroblastoma and potentially other GD2 positive malignancies. PMID:26420448

  8. Comparison study of ferrofluid and powder iron oxide nanoparticle permeability across the blood-brain barrier.

    PubMed

    Hoff, Dan; Sheikh, Lubna; Bhattacharya, Soumya; Nayar, Suprabha; Webster, Thomas J

    2013-01-01

    In the present study, the permeability of 11 different iron oxide nanoparticle (IONP) samples (eight fluids and three powders) was determined using an in vitro blood-brain barrier model. Importantly, the results showed that the ferrofluid formulations were statistically more permeable than the IONP powder formulations at the blood-brain barrier, suggesting a role for the presently studied in situ synthesized ferrofluid formulations using poly(vinyl) alcohol, bovine serum albumin, collagen, glutamic acid, graphene, and their combinations as materials which can cross the blood-brain barrier to deliver drugs or have other neurological therapeutic efficacy. Conversely, the results showed the least permeability across the blood-brain barrier for the IONP with collagen formulation, suggesting a role as a magnetic resonance imaging contrast agent but limiting IONP passage across the blood-brain barrier. Further analysis of the data yielded several trends of note, with little correlation between permeability and fluid zeta potential, but a larger correlation between permeability and fluid particle size (with the smaller particle sizes having larger permeability). Such results lay the foundation for simple modification of iron oxide nanoparticle formulations to either promote or inhibit passage across the blood-brain barrier, and deserve further investigation for a wide range of applications.

  9. SAXS analysis of single- and multi-core iron oxide magnetic nanoparticles

    PubMed Central

    Szczerba, Wojciech; Costo, Rocio; Morales, Maria del Puerto; Thünemann, Andreas F.

    2017-01-01

    This article reports on the characterization of four superparamagnetic iron oxide nanoparticles stabilized with dimercaptosuccinic acid, which are suitable candidates for reference materials for magnetic properties. Particles p1 and p2 are single-core particles, while p3 and p4 are multi-core particles. Small-angle X-ray scattering analysis reveals a lognormal type of size distribution for the iron oxide cores of the particles. Their mean radii are 6.9 nm (p1), 10.6 nm (p2), 5.5 nm (p3) and 4.1 nm (p4), with narrow relative distribution widths of 0.08, 0.13, 0.08 and 0.12. The cores are arranged as a clustered network in the form of dense mass fractals with a fractal dimension of 2.9 in the multi-core particles p3 and p4, but the cores are well separated from each other by a protecting organic shell. The radii of gyration of the mass fractals are 48 and 44 nm, and each network contains 117 and 186 primary particles, respectively. The radius distributions of the primary particle were confirmed with transmission electron microscopy. All particles contain purely maghemite, as shown by X-ray absorption fine structure spectroscopy. PMID:28381973

  10. Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation.

    PubMed

    Zhuang, Li; Tang, Jia; Wang, Yueqiang; Hu, Min; Zhou, Shungui

    2015-08-15

    Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89-94% of the electrons released from benzoate oxidation were recovered in CH4 production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments.

  11. In-situ synthesis of magnetic iron-oxide nanoparticle-nanofibre composites using electrospinning.

    PubMed

    Burke, Luke; Mortimer, Chris J; Curtis, Daniel J; Lewis, Aled R; Williams, Rhodri; Hawkins, Karl; Maffeis, Thierry G G; Wright, Chris J

    2017-01-01

    We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125±18nm (PEO) and 1.58±0.28μm (PVP); Free-surface electrospun: 155±31nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8±3nm to 27±5nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique.

  12. Biocompatible and fluorescent superparamagnetic iron oxide nanoparticles with superior magnetic properties coated with charged polysaccharide derivatives.

    PubMed

    Lachowicz, Dorota; Szpak, Agnieszka; Malek-Zietek, Katarzyna E; Kepczynski, Mariusz; Muller, Robert N; Laurent, Sophie; Nowakowska, Maria; Zapotoczny, Szczepan

    2017-02-01

    Syntheses and characterizations of biocompatible superparamagnetic iron oxide nanoparticles with embedded curcumin and coated with ultrathin layer of hyaluronic acid-curcumin (HA-Cur) conjugate have been reported. Zeta potential measurements confirmed effective coating of native iron oxide nanoparticles stabilized by cationic derivative of chitosan (SPION-CCh) with the synthesized HA-Cur conjugate. Both SPIONs with embedded curcumin and the ones coated with HA-Cur (SPION-CCh/HA-Cur) revealed desired magnetic characteristics while fluorescent properties were much better for the coated nanoparticles. SPION-CCh/HA-Cur nanoparticles were shown to be very promising candidates for T2 MRI contrast agents as they can easily penetrate cell membrane and their relaxivity is exceptionally high (ca. 470mM(-1)s(-1)). They may be also tracked using confocal fluorescence microscopy due to the presence of fluorescent curcumin in the coating. In vitro studies indicated that the obtained SPIONs-CCh/HA-Cur were non-toxic for EA.hy926 endothelial cells.

  13. Magnetic tumor targeting of β-glucosidase immobilized iron oxide nanoparticles.

    PubMed

    Zhou, Jie; Zhang, Jian; David, Allan E; Yang, Victor C

    2013-09-20

    Directed enzyme/prodrug therapy (DEPT) has promising application for cancer therapy. However, most current DEPT strategies face shortcomings such as the loss of enzyme activity during preparation, low delivery and transduction efficiency in vivo and difficultly of monitoring. In this study, a novel magnetic directed enzyme/prodrug therapy (MDEPT) was set up by conjugating β-glucosidase (β-Glu) to aminated, starch-coated, iron oxide magnetic iron oxide nanoparticles (MNPs), abbreviated as β-Glu-MNP, using glutaraldehyde as the crosslinker. This β-Glu-MNP was then characterized in detail by size distribution, zeta potential, FTIR spectra, TEM, SQUID and magnetophoretic mobility analysis. Compared to free enzyme, the conjugated β-Glu on MNPs retained 85.54% ± 6.9% relative activity and showed much better temperature stability. The animal study results showed that β-Glu-MNP displays preferable pharmacokinetics characteristics in relation to MNPs. With an adscititious magnetic field on the surface of a tumor, a significant quantity of β-Glu-MNP was selectively delivered into a subcutaneous tumor of a glioma-bearing mouse. Remarkably, the enzyme activity of the delivered β-Glu in tumor lesions showed as high as 20.123±5.022 mU g(-1) tissue with 2.14 of tumor/non-tumor β-Glu activity.

  14. TREG coated iron oxide nanoparticles as contrast agent for MRI in-vivo use

    NASA Astrophysics Data System (ADS)

    Gutierrez-Garcia, Eric; Hidalgo-Tobon, Silvia; Lopez, Ciro; Gonzalez-Rodriguez, Roberto; Coffer, Jeffery; De Celis Alonso, Benito; Dies Suarez, Pilar; Obregon, Manuel; Perez-Pena, Mario; Platas-Neri, Diana; Mendez-Rojas, Miguel

    2014-11-01

    Super-paramagnetic iron oxide nanoparticles (SPIONs) are of interest due to their great potential applications in diverse fields such as biomedicine. In this work we have prepared SPION nanoparticles using the polyol technique and characterized the magnetic properties of them for MRI in-vivo use. Nanoparticle preparation: All reagents were purchased from commercial sources (Sigma-Aldrich, St. Louis, USA) Iron (III) acetylacetonate, [Fe(acac)3], was used as the iron oxide precursor and thermally decomposed at high temperatures in triethyleneglycol (TREG). Nano-sized magnetite particles were prepared by an adaptation of the method proposed by Wei Cai et al[1-3]. A healthy rabbit was scanned on a clinical 1.5 T Philips MR scanner. Images were taken in 2D mode with a mFFE sequence. Relaxation time T2 was obtained from the MR images using a Matlab algorithm where the signal intensity decay was calculated at each image and then adjusted to a mono-exponential curve. Images were obtained before contrast injection, 24 hours and 36 hours following SPIONs administration. Signal decay at different Echo times for the prepared magnetic SPIONs, before and after contrast injection was measured. It was visualized a concentration of the agent contrast in brain and liver and the results were compared with images obtained from histopathology.

  15. Electric-field controlled liposome formation with embedded superparamagnetic iron oxide nanoparticles.

    PubMed

    Eleršič, Kristina; Pavlič, Janez I; Iglič, Aleš; Vesel, Alenka; Mozetič, Miran

    2012-01-01

    Liposomes are one of the most promising biomaterial carriers to deliver DNA,(1) proteins, drugs and medicine in human bodies. However, artificially formed liposomes have to satisfy some crucial functions such as: (i) to efficiently carry drugs to targeted systems, (ii) to be biologically stable until they are removed from human body, (iii) to be biodegradable, and (iv) to be sufficiently small in size for effective drug delivery. Here, we report an efficient and novel method to simultaneously manufacture and incorporate super-paramagnetic iron-oxide nanoparticles (efficient target finder in the presence of external magnetic field) into the liposome's interior and its bilayer. In this technique, we use electric field to control the formation of liposomes and the incorporation of iron oxide nanoparticles. Our preparation procedure does not require any chemical or ultrasound treatments. Apart from that, we also provide further experimental investigations on the role of electric fields on the formation of liposomes using XPS(2) and the magnetic-optical microscope.

  16. The Irony of Iron – Biogenic Iron Oxides as an Iron Source to the Ocean

    PubMed Central

    Emerson, David

    2016-01-01

    Primary productivity in at least a third of the sunlit open ocean is thought to be iron-limited. Primary sources of dissolved iron (dFe) to the ocean are hydrothermal venting, flux from the sediments along continental margins, and airborne dust. This article provides a general review of sources of hydrothermal and sedimentary iron to the ocean, and speculates upon the role that iron-cycling microbes play in controlling iron dynamics from these sources. Special attention is paid to iron-oxidizing bacteria (FeOB) that live by oxidizing iron and producing biogenic iron oxides as waste products. The presence and ubiquity of FeOB both at hydrothermal systems and in sediments is only beginning to be appreciated. The biogenic oxides they produce have unique properties that could contribute significantly to the dynamics of dFe in the ocean. Changes in the physical and chemical characteristics of the ocean due to climate change and ocean acidification will undoubtedly impact the microbial iron cycle. A better understanding of the contemporary role of microbes in the iron cycle will help in predicting how these changes could ultimately influence marine primary productivity. PMID:26779157

  17. Magnetically triggered clustering of biotinylated iron oxide nanoparticles in the presence of streptavidinylated enzymes

    NASA Astrophysics Data System (ADS)

    Hodenius, Michael; Hieronymus, Thomas; Zenke, Martin; Becker, Christiane; Elling, Lothar; Bornemann, Jörg; Wong, John E.; Richtering, Walter; Himmelreich, Uwe; De Cuyper, Marcel

    2012-09-01

    This work deals with the production and characterization of water-compatible, iron oxide based nanoparticles covered with functional poly(ethylene glycol) (PEG)-biotin surface groups (SPIO-PEG-biotin). Synthesis of the functionalized colloids occurred by incubating the oleate coated particles used as precursor magnetic fluid with anionic liposomes containing 14 mol% of a phospholipid-PEG-biotin conjugate. The latter was prepared by coupling dimyristoylphosphatidylethanolamine (DC14:0PE) to activated α-biotinylamido-ω -N-hydroxy-succinimidcarbonyl-PEG (NHS-PEG-biotin). Physical characterization of the oleate and PEG-biotin iron oxide nanocolloids revealed that they appear as colloidal stable clusters with a hydrodynamic diameter of 160 nm and zeta potentials of - 39 mV (oleate coated particles) and - 14 mV (PEG-biotin covered particles), respectively, as measured by light scattering techniques. Superconducting quantum interference device (SQUID) measurements revealed specific saturation magnetizations of 62-73 emu g-1 Fe3O4 and no hysteresis was observed at 300 K. MR relaxometry at 3 T revealed very high r2 relaxivities and moderately high r1 values. Thus, both nanocolloids can be classified as small, superparamagnetic, negative MR contrast agents. The capacity to functionalize the particles was illustrated by binding streptavidin alkaline phosphatase (SAP). It was found, however, that these complexes become highly aggregated after capturing them on the magnetic filter device during high-gradient magnetophoresis, thereby reducing the accessibility of the SAP.

  18. Recent advances in surface chemistry strategies for the fabrication of functional iron oxide based magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Turcheniuk, Kostiantyn; Tarasevych, Arkadii V.; Kukhar, Valeriy P.; Boukherroub, Rabah; Szunerits, Sabine

    2013-10-01

    The synthesis of superparamagnetic nanostructures, especially iron-oxide based nanoparticles (IONPs), with appropriate surface functional groups has been intensively researched for many high-technological applications, including high density data storage, biosensing and biomedicine. In medicine, IONPs are nowadays widely used as contrast agents for magnetic resonance imaging (MRI), in hyperthermia therapy, but are also exploited for drug and gene delivery, detoxification of biological fluids or immunoassays, as they are relatively non-toxic. The use of magnetic particles in vivo requires IONPs to have high magnetization values, diameters below 100 nm with overall narrow size distribution and long time stability in biological fluids. Due to the high surface energies of IONPs agglomeration over time is often encountered. It is thus of prime importance to modify their surface to prevent aggregation and to limit non-specific adsorption of biomolecules onto their surface. Such chemical modifications result in IONPs being well-dispersed and biocompatible, and allow for targeted delivery and specific interactions. The chemical nature of IONPs thus determines not only the overall size of the colloid, but also plays a significant role for in vivo and in vitro applications. This review discusses the different concepts currently used for the surface functionalization and coating of iron oxide nanoparticles. The diverse strategies for the covalent linking of drugs, proteins, enzymes, antibodies, and nucleotides will be discussed and the chemically relevant steps will be explained in detail.

  19. Characterization, Quantification, and Determination of the Toxicity of Iron Oxide Nanoparticles to the Bone Marrow Cells

    PubMed Central

    Paik, Sae-Yeol-Rim; Kim, Jong-Seok; Shin, Sung Jae; Ko, Sanghoon

    2015-01-01

    Iron oxide nanoparticles (IONPs) have been used to develop iron supplements for improving the bioavailability of iron in patients with iron deficiency, which is one of the most serious nutritional deficiencies in the world. Accurate information about the characteristics, concentration, and cytotoxicity of IONPs to the developmental and reproductive cells enables safe use of IONPs in the supplement industry. The objective of this study was to analyze the physicochemical properties and cytotoxicity of IONPs in bone marrow cells. We prepared three different types of iron samples (surface-modified iron oxide nanoparticles (SMNPs), IONPs, and iron citrate) and analyzed their physicochemical properties such as particle size distribution, zeta potential, and morphology. In addition, we examined the cytotoxicity of the IONPs in various kinds of bone marrow cells. We analyzed particle size distribution, zeta potential, iron levels, and subcellular localization of the iron samples in bone marrow cells. Our results showed that the iron samples were not cytotoxic to the bone marrow cells and did not affect the expression of cell surface markers and lipopolysaccharide (LPS)-induced the secretion of cytokines by murine bone marrow-derived dendritic cells (BMDCs). Our results may be used to investigate the interactions between nanoparticles and cells and tissues and the developmental toxicity of nanoparticles. PMID:26389886

  20. Molecular photoacoustic tomography of breast cancer using receptor targeted magnetic iron oxide nanoparticles as contrast agents.

    PubMed

    Xi, Lei; Grobmyer, Stephen R; Zhou, Guangyin; Qian, Weiping; Yang, Lily; Jiang, Huabei

    2014-06-01

    In this report, we present a breast imaging technique combining high-resolution near-infrared (NIR) light induced photoacoustic tomography (PAT) with NIR dye-labeled amino-terminal fragments of urokinase plasminogen activator receptor (uPAR) targeted magnetic iron oxide nanoparticles (NIR830-ATF-IONP) for breast cancer imaging using an orthotopic mouse mammary tumor model. We show that accumulation of the targeted nanoparticles in the tumor led to photoacoustic contrast enhancement due to the high absorption of iron oxide nanoparticles (IONP). NIR fluorescence images were used to validate specific delivery of NIR830-ATF-IONP to mouse mammary tumors. We found that systemic delivery of the targeted IONP produced 4- and 10-fold enhancement in photoacoustic signals in the tumor, compared to the tumor of the mice that received non-targeted IONP or control mice. The use of targeted nanoparticles allowed imaging of tumors located as deep as 3.1 cm beneath the normal tissues. Our study indicates the potential of the combination of photoacoustic tomography and receptor-targeted NIR830-ATF-IONP as a clinical tool that can provide improved specificity and sensitivity for breast cancer detection.

  1. Effective delivery of immunosuppressive drug molecules by silica coated iron oxide nanoparticles.

    PubMed

    Hwang, Jangsun; Lee, Eunwon; Kim, Jieun; Seo, Youngmin; Lee, Kwan Hong; Hong, Jong Wook; Gilad, Assaf A; Park, Hansoo; Choi, Jonghoon

    2016-06-01

    Iron oxide nanoparticles have been used in a wide range of biomedical applications, including drug delivery, molecular imaging, and cellular imaging. Various surface modifications have been applied to the particles to stabilize their surface and to give them a moiety for anchoring tags and/or drug molecules. Conventional methods of delivering immunosuppressant drugs often require a high dose of drugs to ensure therapeutic effects, but this can lead to toxic side effects. In this study, we used silica-coated iron oxide nanoparticles (IOSs) for a drug delivery application in which the nanoparticles carry the minimum amount of drug required to be effective to the target cells. IOSs could be loaded with water-insoluble immunosuppressive drug molecules (MPA: mycophenolic acid) and be used as a contrast agent for MRI. We characterized the IOSs for their physicochemical properties and found their average hydrodynamic diameter and core size to be 40.5nm and 5nm, respectively. Following the introduction of MPA-loaded IOSs (IOS/M), we evaluated the secretion dynamics of cytokines from peripheral blood mononuclear cells stimulated with phytohemagglutinin (PHA). The results showed that IOS/M effectively inhibited the secretion of the cytokines interleukin-2 and tumor necrosis factor α, with a minimal concentration of MPA. In conclusion, IOS/M may have potential applications in both efficient drug delivery and MRI.

  2. The effect of nanocrystalline silicon host on magnetic properties of encapsulated iron oxide nanoparticles.

    PubMed

    Granitzer, P; Rumpf, K; Gonzalez-Rodriguez, R; Coffer, J L; Reissner, M

    2015-12-21

    The purpose of this work is a detailed comparison of the fundamental magnetic properties of nanocomposite systems consisting of Fe3O4 nanoparticle-loaded porous silicon as well as silicon nanotubes. Such composite structures are of potential merit in the area of magnetically guided drug delivery. For magnetic systems to be utilized in biomedical applications, there are certain magnetic properties that must be fulfilled. Therefore magnetic properties of embedded Fe3O4-nanoparticles in these nanostructured silicon host matrices, porous silicon and silicon nanotubes, are investigated. Temperature-dependent magnetic investigations have been carried out for four types of iron oxide particle sizes (4, 5, 8 and 10 nm). The silicon host, in interplay with the iron oxide nanoparticle size, plays a sensitive role. It is shown that Fe3O4 loaded porous silicon and SiNTs differ significantly in their magnetic behavior, especially the transition between superparamagnetic behavior and blocked state, due to host morphology-dependent magnetic interactions. Importantly, it is found that all investigated samples meet the magnetic precondition of possible biomedical applications of exhibiting a negligible magnetic remanence at room temperature.

  3. The Irony of Iron - Biogenic Iron Oxides as an Iron Source to the Ocean.

    PubMed

    Emerson, David

    2015-01-01

    Primary productivity in at least a third of the sunlit open ocean is thought to be iron-limited. Primary sources of dissolved iron (dFe) to the ocean are hydrothermal venting, flux from the sediments along continental margins, and airborne dust. This article provides a general review of sources of hydrothermal and sedimentary iron to the ocean, and speculates upon the role that iron-cycling microbes play in controlling iron dynamics from these sources. Special attention is paid to iron-oxidizing bacteria (FeOB) that live by oxidizing iron and producing biogenic iron oxides as waste products. The presence and ubiquity of FeOB both at hydrothermal systems and in sediments is only beginning to be appreciated. The biogenic oxides they produce have unique properties that could contribute significantly to the dynamics of dFe in the ocean. Changes in the physical and chemical characteristics of the ocean due to climate change and ocean acidification will undoubtedly impact the microbial iron cycle. A better understanding of the contemporary role of microbes in the iron cycle will help in predicting how these changes could ultimately influence marine primary productivity.

  4. Self-organized iron-oxide cementation geometry as an indicator of paleo-flows

    DOE PAGES

    Wang, Yifeng; Chan, Marjorie A.; Merino, Enrique

    2015-06-30

    Widespread iron oxide precipitation from groundwater in fine-grained red beds displays various patterns, including nodulation, banding and scallops and fingers. Hematite nodules have been reported also from the Meridiani Planum site on Mars and interpreted as evidence for the ancient presence of water on the red planet. Here we show that such patterns can autonomously emerge from a previously unrecognized Ostwald ripening mechanism and they capture rich information regarding ancient chemical and hydrologic environments. A linear instability analysis of the reaction-transport equations suggests that a pattern transition from nodules to bands may result from a symmetry breaking of mineral dissolutionmore » and precipitation triggered by groundwater advection. Round nodules tend to develop under nearly stagnant hydrologic conditions, while repetitive bands form in the presence of persistent water flows. Since water circulation is a prerequisite for a sustainable subsurface life, a Martian site with iron oxide precipitation bands, if one were found, may offer a better chance for detecting extraterrestrial biosignatures on Mars than would sites with nodules.« less

  5. Self-organized iron-oxide cementation geometry as an indicator of paleo-flows

    SciTech Connect

    Wang, Yifeng; Chan, Marjorie A.; Merino, Enrique

    2015-06-30

    Widespread iron oxide precipitation from groundwater in fine-grained red beds displays various patterns, including nodulation, banding and scallops and fingers. Hematite nodules have been reported also from the Meridiani Planum site on Mars and interpreted as evidence for the ancient presence of water on the red planet. Here we show that such patterns can autonomously emerge from a previously unrecognized Ostwald ripening mechanism and they capture rich information regarding ancient chemical and hydrologic environments. A linear instability analysis of the reaction-transport equations suggests that a pattern transition from nodules to bands may result from a symmetry breaking of mineral dissolution and precipitation triggered by groundwater advection. Round nodules tend to develop under nearly stagnant hydrologic conditions, while repetitive bands form in the presence of persistent water flows. Since water circulation is a prerequisite for a sustainable subsurface life, a Martian site with iron oxide precipitation bands, if one were found, may offer a better chance for detecting extraterrestrial biosignatures on Mars than would sites with nodules.

  6. Formation of biomineral iron oxides compounds in a Fe hyperaccumulator plant: Imperata cylindrica (L.) P. Beauv.

    PubMed

    Fuente, V; Rufo, L; Juárez, B H; Menéndez, N; García-Hernández, M; Salas-Colera, E; Espinosa, A

    2016-01-01

    We report a detailed work of composition and location of naturally formed iron biominerals in plant cells tissues grown in iron rich environments as Imperata cylindrica. This perennial grass grows on the Tinto River banks (Iberian Pyritic Belt) in an extreme acidic ecosystem (pH∼2.3) with high concentration of dissolved iron, sulphate and heavy metals. Iron biominerals were found at the cellular level in tissues of root, stem and leaf both in collected and laboratory-cultivated plants. Iron accumulated in this plant as a mix of iron compounds (mainly as jarosite, ferrihydrite, hematite and spinel phases) was characterized by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), Mössbauer spectroscopy (MS), magnetometry (SQUID), electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX; TEM-EDX; HRSTEM). A low fraction of phosphorous was detected in this iron hyperaccumulator plant. Root and rhizomes tissues present a high proportion of ferromagnetic iron oxide compounds. Iron oxides-rich zones are localized in electron dense intra and inter-cellular aggregates that appear as dark deposits covering the inner membrane and organelles of the cell. This study aims to contribute to a better understanding of the mechanisms of accumulation, transport, distribution of iron in Imperata cylindrica.

  7. Biological properties of iron oxide nanoparticles for cellular and molecular magnetic resonance imaging.

    PubMed

    Schlorf, Thomas; Meincke, Manuela; Kossel, Elke; Glüer, Claus-Christian; Jansen, Olav; Mentlein, Rolf

    2010-12-23

    Superparamagnetic iron-oxide particles (SPIO) are used in different ways as contrast agents for magnetic resonance imaging (MRI): Particles with high nonspecific uptake are required for unspecific labeling of phagocytic cells whereas those that target specific molecules need to have very low unspecific cellular uptake. We compared iron-oxide particles with different core materials (magnetite, maghemite), different coatings (none, dextran, carboxydextran, polystyrene) and different hydrodynamic diameters (20-850 nm) for internalization kinetics, release of internalized particles, toxicity, localization of particles and ability to generate contrast in MRI. Particle uptake was investigated with U118 glioma cells und human umbilical vein endothelial cells (HUVEC), which exhibit different phagocytic properties. In both cell types, the contrast agents Resovist, B102, non-coated Fe(3)O(4) particles and microspheres were better internalized than dextran-coated Nanomag particles. SPIO uptake into the cells increased with particle/iron concentrations. Maximum intracellular accumulation of iron particles was observed between 24 h to 36 h of exposure. Most particles were retained in the cells for at least two weeks, were deeply internalized, and only few remained adsorbed at the cell surface. Internalized particles clustered in the cytosol of the cells. Furthermore, all particles showed a low toxicity. By MRI, monolayers consisting of 5000 Resovist-labeled cells could easily be visualized. Thus, for unspecific cell labeling, Resovist and microspheres show the highest potential, whereas Nanomag particles are promising contrast agents for target-specific labeling.

  8. Synthesis and in vacuo deposition of iron oxide nanoparticles by microplasma-assisted decomposition of ferrocene

    SciTech Connect

    Schaefer, Michael E-mail: axk650@case.edu E-mail: schlaf@mail.usf.edu; Kumar, Ajay E-mail: axk650@case.edu E-mail: schlaf@mail.usf.edu; Mohan Sankaran, R. E-mail: axk650@case.edu E-mail: schlaf@mail.usf.edu; Schlaf, Rudy E-mail: axk650@case.edu E-mail: schlaf@mail.usf.edu

    2014-10-07

    Microplasma-assisted gas-phase nucleation has emerged as an important new approach to produce high-purity, nanometer-sized, and narrowly dispersed particles. This study aims to integrate this technique with vacuum conditions to enable synthesis and deposition in an ultrahigh vacuum compatible environment. The ultimate goal is to combine nanoparticle synthesis with photoemission spectroscopy-based electronic structure analysis. Such measurements require in vacuo deposition to prevent surface contamination from sample transfer, which can be deleterious for nanoscale materials. A homebuilt microplasma reactor was integrated into an existing atomic layer deposition system attached to a surface science multi-chamber system equipped with photoemission spectroscopy. As proof-of-concept, we studied the decomposition of ferrocene vapor in the microplasma to synthesize iron oxide nanoparticles. The injection parameters were optimized to achieve complete precursor decomposition under vacuum conditions, and nanoparticles were successfully deposited. The stoichiometry of the deposited samples was characterized in situ using X-ray photoelectron spectroscopy indicating that iron oxide was formed. Additional transmission electron spectroscopy characterization allowed the determination of the size, shape, and crystal lattice of the particles, confirming their structural properties.

  9. Iron Oxide Surface Chemistry: Effect of Chemical Structure on Binding in Benzoic Acid and Catechol Derivatives.

    PubMed

    Korpany, Katalin V; Majewski, Dorothy D; Chiu, Cindy T; Cross, Shoronia N; Blum, Amy Szuchmacher

    2017-03-13

    The excellent performance of functionalized iron oxide nanoparticles (IONPs) in nanomaterial and biomedical applications often relies on achieving the attachment of ligands to the iron oxide surface both in sufficient number and with proper orientation. Toward this end, we determine relationships between the ligand chemical structure and surface binding on magnetic IONPs for a series of related benzoic acid and catechol derivatives. Ligand exchange was used to introduce the model ligands, and the resultant nanoparticles were characterized using Fourier transform infrared-attenuated internal reflectance spectroscopy, transmission electron microscopy, and nanoparticle solubility behavior. An in-depth analysis of ligand electronic effects and reaction conditions reveals that the nature of ligand binding does not solely depend on the presence of functional groups known to bind to IONPs. The structure of the resultant ligand-surface complex was primarily influenced by the relative positioning of hydroxyl and carboxylic acid groups within the ligand and whether or not HCl(aq) was added to the ligand-exchange reaction. Overall, this study will help guide future ligand-design and ligand-exchange strategies toward realizing truly custom-built IONPs.

  10. Controlled Phase and Tunable Magnetism in Ordered Iron Oxide Nanotube Arrays Prepared by Atomic Layer Deposition.

    PubMed

    Zhang, Yijun; Liu, Ming; Peng, Bin; Zhou, Ziyao; Chen, Xing; Yang, Shu-Ming; Jiang, Zhuang-De; Zhang, Jie; Ren, Wei; Ye, Zuo-Guang

    2016-01-27

    Highly-ordered and conformal iron oxide nanotube arrays on an atomic scale are successfully prepared by atomic layer deposition (ALD) with controlled oxidization states and tunable magnetic properties between superparamagnetism and ferrimagnetism. Non-magnetic α-Fe2O3 and superparamagnetic Fe3O4 with a blocking temperature of 120 K are in-situ obtained by finely controlling the oxidation reaction. Both of them exhibit a very small grain size of only several nanometers due to the nature of atom-by-atom growth of the ALD technique. Post-annealing α-Fe2O3 in a reducing atmosphere leads to the formation of the spinel Fe3O4 phase which displays a distinct ferrimagnetic anisotropy and the Verwey metal-insulator transition that usually takes place only in single crystal magnetite or thick epitaxial films at low temperatures. The ALD deposition of iron oxide with well-controlled phase and tunable magnetism demonstrated in this work provides a promising opportunity for the fabrication of 3D nano-devices to be used in catalysis, spintronics, microelectronics, data storages and bio-applications.

  11. Controlled Phase and Tunable Magnetism in Ordered Iron Oxide Nanotube Arrays Prepared by Atomic Layer Deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Yijun; Liu, Ming; Peng, Bin; Zhou, Ziyao; Chen, Xing; Yang, Shu-Ming; Jiang, Zhuang-De; Zhang, Jie; Ren, Wei; Ye, Zuo-Guang

    2016-01-01

    Highly-ordered and conformal iron oxide nanotube arrays on an atomic scale are successfully prepared by atomic layer deposition (ALD) with controlled oxidization states and tunable magnetic properties between superparamagnetism and ferrimagnetism. Non-magnetic α-Fe2O3 and superparamagnetic Fe3O4 with a blocking temperature of 120 K are in-situ obtained by finely controlling the oxidation reaction. Both of them exhibit a very small grain size of only several nanometers due to the nature of atom-by-atom growth of the ALD technique. Post-annealing α-Fe2O3 in a reducing atmosphere leads to the formation of the spinel Fe3O4 phase which displays a distinct ferrimagnetic anisotropy and the Verwey metal-insulator transition that usually takes place only in single crystal magnetite or thick epitaxial films at low temperatures. The ALD deposition of iron oxide with well-controlled phase and tunable magnetism demonstrated in this work provides a promising opportunity for the fabrication of 3D nano-devices to be used in catalysis, spintronics, microelectronics, data storages and bio-applications.

  12. Unraveling the Stratification of an Iron-Oxidizing Microbial Mat by Metatranscriptomics

    PubMed Central

    Quaiser, Achim; Bodi, Xavier; Dufresne, Alexis; Naquin, Delphine; Francez, André-Jean; Dheilly, Alexandra; Coudouel, Sophie; Pedrot, Mathieu; Vandenkoornhuyse, Philippe

    2014-01-01

    A metatranscriptomic approach was used to study community gene expression in a naturally occurring iron-rich microbial mat. Total microbial community RNA was reversely transcribed and sequenced by pyrosequencing. Characterization of expressed gene sequences provided accurate and detailed information of the composition of the transcriptionally active community and revealed phylogenetic and functional stratifications within the mat. Comparison of 16S rRNA reads and delineation of OTUs showed significantly lower values of metatranscriptomic-based richness and diversity in the upper parts of the mat than in the deeper regions. Taxonomic affiliation of rRNA sequences and mRNA genome recruitments indicated that iron-oxidizing bacteria affiliated to the genus Leptothrix, dominated the community in the upper layers of the mat. Surprisingly, type I methanotrophs contributed to the majority of the sequences in the deep layers of the mat. Analysis of mRNA expression patterns showed that genes encoding the three subunits of the particulate methane monooxygenase (pmoCAB) were the most highly expressed in our dataset. These results provide strong hints that iron-oxidation and methane-oxidation occur simultaneously in microbial mats and that both groups of microorganisms are major players in the functioning of this ecosystem. PMID:25033299

  13. Erlotinib-Conjugated Iron Oxide Nanoparticles as a Smart Cancer-Targeted Theranostic Probe for MRI

    NASA Astrophysics Data System (ADS)

    Ali, Ahmed Atef Ahmed; Hsu, Fei-Ting; Hsieh, Chia-Ling; Shiau, Chia-Yang; Chiang, Chiao-Hsi; Wei, Zung-Hang; Chen, Cheng-Yu; Huang, Hsu-Shan

    2016-11-01

    We designed and synthesized novel theranostic nanoparticles that showed the considerable potential for clinical use in targeted therapy, and non-invasive real-time monitoring of tumors by MRI. Our nanoparticles were ultra-small with superparamagnetic iron oxide cores, conjugated to erlotinib (FeDC-E NPs). Such smart targeted nanoparticles have the preference to release the drug intracellularly rather than into the bloodstream, and specifically recognize and kill cancer cells that overexpress EGFR while being non-toxic to EGFR-negative cells. MRI, transmission electron microscopy and Prussian blue staining results indicated that cellular uptake and intracellular accumulation of FeDC-E NPs in the EGFR overexpressing cells was significantly higher than those of the non-erlotinib-conjugated nanoparticles. FeDC-E NPs inhibited the EGFR–ERK–NF-κB signaling pathways, and subsequently suppressed the migration and invasion capabilities of the highly invasive and migrative CL1-5-F4 cancer cells. In vivo tumor xenograft experiments using BALB/c nude mice showed that FeDC-E NPs could effectively inhibit the growth of tumors. T2-weighted MRI images of the mice showed significant decrease in the normalized signal within the tumor post-treatment with FeDC-E NPs compared to the non-targeted control iron oxide nanoparticles. This is the first study to use erlotinib as a small-molecule targeting agent for nanoparticles.

  14. Magmatic origin of giant ‘Kiruna-type’ apatite-iron-oxide ores in Central Sweden

    PubMed Central

    Jonsson, Erik; Troll, Valentin R.; Högdahl, Karin; Harris, Chris; Weis, Franz; Nilsson, Katarina P.; Skelton, Alasdair

    2013-01-01

    Iron is the most important metal for modern industry and Sweden is by far the largest iron-producer in Europe, yet the genesis of Sweden's main iron-source, the ‘Kiruna-type’ apatite-iron-oxide ores, remains enigmatic. We show that magnetites from the largest central Swedish ‘Kiruna-type’ deposit at Grängesberg have δ18O values between −0.4 and +3.7‰, while the 1.90−1.88 Ga meta-volcanic host rocks have δ18O values between +4.9 and +9‰. Over 90% of the magnetite data are consistent with direct precipitation from intermediate to felsic magmas or magmatic fluids at high-temperature (δ18Omgt > +0.9‰, i.e. ortho-magmatic). A smaller group of magnetites (δ18Omgt ≤ +0.9‰), in turn, equilibrated with high-δ18O, likely meteoric, hydrothermal fluids at low temperatures. The central Swedish ‘Kiruna-type’ ores thus formed dominantly through magmatic iron-oxide precipitation within a larger volcanic superstructure, while local hydrothermal activity resulted from low-temperature fluid circulation in the shallower parts of this system. PMID:23571605

  15. Expeditious organic-free assembly: morphologically controlled synthesis of iron oxides using microwaves

    NASA Astrophysics Data System (ADS)

    Kou, Jiahui; Varma, Rajender S.

    2013-08-01

    A microwave hydrothermal method is developed for the synthesis of iron oxides, α-Fe2O3, β-FeOOH, and the junction of α-Fe2O3-β-FeOOH. This method is absolutely organic-free, and various structures could be obtained simply by changing the use of the iron source and NaOH. The as-prepared sea urchin-like β-FeOOH exhibits excellent catalytic performance for the degradation of methylene blue (MB) in the presence of H2O2.A microwave hydrothermal method is developed for the synthesis of iron oxides, α-Fe2O3, β-FeOOH, and the junction of α-Fe2O3-β-FeOOH. This method is absolutely organic-free, and various structures could be obtained simply by changing the use of the iron source and NaOH. The as-prepared sea urchin-like β-FeOOH exhibits excellent catalytic performance for the degradation of methylene blue (MB) in the presence of H2O2. Electronic supplementary information (ESI) available: XRD patterns and the reaction profile of the microwave system. See DOI: 10.1039/c3nr02663a

  16. Infrared nanosecond pulsed laser irradiation of stainless steel: Micro iron-oxide zones generation

    NASA Astrophysics Data System (ADS)

    Ortiz-Morales, M.; Frausto-Reyes, C.; Soto-Bernal, J. J.; Acosta-Ortiz, S. E.; Gonzalez-Mota, R.; Rosales-Candelas, I.

    2014-07-01

    Nanosecond-pulsed, infrared (1064 nm) laser irradiation was used to create periodic metal oxide coatings on the surface of two samples of commercial stainless steel at ambient conditions. A pattern of four different metal oxide zones was created using a galvanometer scanning head and a focused laser beam over each sample. This pattern is related to traverse direction of the laser beam scanning. Energy-dispersive X-ray spectroscopy (EDS) was used to find the elemental composition and Raman spectroscopy to characterize each oxide zone. Pulsed laser irradiation modified the composition of the stainless steel samples, affecting the concentration of the main components within each heat affected zone. The Raman spectra of the generated oxides have different intensity profiles, which suggest different oxide phases such as magnetite and maghemite. In addition, these oxides are not sensible to the laser power of the Raman system, as are the iron oxide powders reported in the literature. These experiments show that it is possible to generate periodic patterns of various iron oxide zones by laser irradiation, of stainless steel at ambient conditions, and that Raman spectroscopy is a useful punctual technique for the analysis and inspection of small oxide areas.

  17. Prediction of erodibility in Oxisols using iron oxides, soil color and diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Arantes Camargo, Livia; Marques, José, Jr.

    2015-04-01

    The prediction of erodibility using indirect methods such as diffuse reflectance spectroscopy could facilitate the characterization of the spatial variability in large areas and optimize implementation of conservation practices. The aim of this study was to evaluate the prediction of interrill erodibility (Ki) and rill erodibility (Kr) by means of iron oxides content and soil color using multiple linear regression and diffuse reflectance spectroscopy (DRS) using regression analysis by least squares partial (PLSR). The soils were collected from three geomorphic surfaces and analyzed for chemical, physical and mineralogical properties, plus scanned in the spectral range from the visible and infrared. Maps of spatial distribution of Ki and Kr were built with the values calculated by the calibrated models that obtained the best accuracy using geostatistics. Interrill-rill erodibility presented negative correlation with iron extracted by dithionite-citrate-bicarbonate, hematite, and chroma, confirming the influence of iron oxides in soil structural stability. Hematite and hue were the attributes that most contributed in calibration models by multiple linear regression for the prediction of Ki (R2 = 0.55) and Kr (R2 = 0.53). The diffuse reflectance spectroscopy via PLSR allowed to predict Interrill-rill erodibility with high accuracy (R2adj = 0.76, 0.81 respectively and RPD> 2.0) in the range of the visible spectrum (380-800 nm) and the characterization of the spatial variability of these attributes by geostatistics.

  18. Iron oxide nanoparticle-mediated hyperthermia stimulates dispersal in bacterial biofilms and enhances antibiotic efficacy

    PubMed Central

    Nguyen, Thuy-Khanh; Duong, Hien T. T.; Selvanayagam, Ramona; Boyer, Cyrille; Barraud, Nicolas

    2015-01-01

    The dispersal phase that completes the biofilm lifecycle is of particular interest for its potential to remove recalcitrant, antimicrobial tolerant biofilm infections. Here we found that temperature is a cue for biofilm dispersal and a rise by 5 °C or more can induce the detachment of Pseudomonas aeruginosa biofilms. Temperature upshifts were found to decrease biofilm biomass and increase the number of viable freely suspended cells. The dispersal response appeared to involve the secondary messenger cyclic di-GMP, which is central to a genetic network governing motile to sessile transitions in bacteria. Furthermore, we used poly((oligo(ethylene glycol) methyl ether acrylate)-block-poly(monoacryloxy ethyl phosphate)-stabilized iron oxide nanoparticles (POEGA-b-PMAEP@IONPs) to induce local hyperthermia in established biofilms upon exposure to a magnetic field. POEGA-b-PMAEP@IONPs were non-toxic to bacteria and when heated induced the detachment of biofilm cells. Finally, combined treatments of POEGA-b-PMAEP@IONPs and the antibiotic gentamicin reduced by 2-log the number of colony-forming units in both biofilm and planktonic phases after 20 min, which represent a 3.2- and 4.1-fold increase in the efficacy against planktonic and biofilm cells, respectively, compared to gentamicin alone. The use of iron oxide nanoparticles to disperse biofilms may find broad applications across a range of clinical and industrial settings. PMID:26681339

  19. Reduction phases of thin iron-oxide nanowires upon thermal treatment and Li exposure

    SciTech Connect

    Angelucci, Marco Frau, Eleonora; Grazia Betti, Maria; Hassoun, Jusef; Hong, Inchul; Panero, Stefania; Scrosati, Bruno; Mariani, Carlo

    2014-04-28

    Iron oxide nanostructures, a promising alternative to carbon-based anode in lithium-ion batteries, can be produced using a hard template route. This procedure guarantees the formation of Fe{sub 2}O{sub 3} nanowires with comparable diameter and size (average diameter 8 nm) with a dominant cubic γ-phase at the surface. Lithium exposure of the iron oxide nanowires in ultra-high-vacuum (UHV) conditions induces reduction of the Fe ion, leading to a Fe{sub 3}O{sub 4} and then to a Fe{sup 2+} phase, as determined by means of core-level photoemission spectroscopy. Mild annealing of Fe{sub 2}O{sub 3} in UHV determines an oxygen content reduction for the nanowires at lower temperature with respect to the bulk phase. The morphology and the evolution of the electronic properties upon reduction have been compared to those of micro-sized bulk-like grains, to unravel the role of the reduced size and surface-volume ratio.

  20. Mechanisms of enhanced osteoblast gene expression in the presence of hydroxyapatite coated iron oxide magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Tran, Nhiem; Hall, Douglas; Webster, Thomas J.

    2012-11-01

    Hydroxyapatite (HA) coated iron oxide (Fe3O4) magnetic nanoparticles have been shown to enhance osteoblast (bone forming cells) proliferation and osteoblast differentiation into calcium depositing cells (through increased secretion of alkaline phosphatase, collagen and calcium deposition) compared to control samples without nanoparticles. Such nanoparticles are, thus, very promising for numerous orthopedic applications including magnetically directed osteoporosis treatment. The objective of the current study was to elucidate the mechanisms of the aforementioned improved osteoblast responses in the presence of HA coated Fe3O4 nanoparticles. Results demonstrated large amounts of fibronectin (a protein known to increase osteoblast functions) adsorption on HA coated Fe3O4 nanoparticles. Specifically, fibronectin adsorption almost doubled when HA coated Fe3O4 nanoparticle concentrations increased from 12.5 to 100 μg ml-1, and from 12.5 to 200 μg ml-1, a four fold increase was observed. Results also showed greater osteoblast gene regulation (specifically, osteocalcin, type I collagen and cbfa-1) in the presence of HA coated Fe3O4 nanoparticles. Collectively, these results provide a mechanism for the observed enhanced osteoblast functions in the presence of HA coated iron oxide nanoparticles, allowing their further investigation for a number of orthopedic applications.

  1. Magnetic tumor targeting of β-Glucosidase immobilized iron oxide nanoparticles

    PubMed Central

    Zhou, Jie; Zhang, Jian; David, Allan E.; Yang, Victor C.

    2014-01-01

    Directed enzyme/prodrug therapy (DEPT) has promising application for cancer therapy. However, most current DEPT strategies face shortcomings such as the loss of enzyme activity during preparation, low delivery and transduction efficiency in vivo, difficult to be monitored. In current study, a novel magnetic directed enzyme/prodrug therapy (MDEPT) was set up by conjugating β-Glucosidase (β-Glu) to aminated, starch-coated, iron oxide magnetic iron oxide nanoparticles (MNP), abbreviated as β-Glu-MNP, using glutaraldehyde as the crosslinker. This β-Glu-MNP was then characterized in detail by size distribution, zeta potential, FTIR spectra, TEM, SQUID and magnetophoretic mobility analysis. Compared to free enzyme, the conjugated β-Glu on MNP remained 85.54%±6.9% relative activity and showed much better temperature stability. relative activity and showed much better temperature stability. The animal study results showed that β-Glu-MNP display preferable pharmacokinetics characteristic in relation to MNP. With adscititious magnetic field on the surface of tumor, a significant quantity of β-Glu-MNP was selectively delivered into a subcutaneous tumor of glioma-bearing mice. Remarkably, the enzyme activity of the delivered β-Glu in tumor lesions showed as high as 20.123 ± 5.022 mU/g tissue with 2.14 of tumor/non-turmor of β-Glu activity. PMID:23974977

  2. Erlotinib-Conjugated Iron Oxide Nanoparticles as a Smart Cancer-Targeted Theranostic Probe for MRI

    PubMed Central

    Ali, Ahmed Atef Ahmed; Hsu, Fei-Ting; Hsieh, Chia-Ling; Shiau, Chia-Yang; Chiang, Chiao-Hsi; Wei, Zung-Hang; Chen, Cheng-Yu; Huang, Hsu-Shan

    2016-01-01

    We designed and synthesized novel theranostic nanoparticles that showed the considerable potential for clinical use in targeted therapy, and non-invasive real-time monitoring of tumors by MRI. Our nanoparticles were ultra-small with superparamagnetic iron oxide cores, conjugated to erlotinib (FeDC-E NPs). Such smart targeted nanoparticles have the preference to release the drug intracellularly rather than into the bloodstream, and specifically recognize and kill cancer cells that overexpress EGFR while being non-toxic to EGFR-negative cells. MRI, transmission electron microscopy and Prussian blue staining results indicated that cellular uptake and intracellular accumulation of FeDC-E NPs in the EGFR overexpressing cells was significantly higher than those of the non-erlotinib-conjugated nanoparticles. FeDC-E NPs inhibited the EGFR–ERK–NF-κB signaling pathways, and subsequently suppressed the migration and invasion capabilities of the highly invasive and migrative CL1-5-F4 cancer cells. In vivo tumor xenograft experiments using BALB/c nude mice showed that FeDC-E NPs could effectively inhibit the growth of tumors. T2-weighted MRI images of the mice showed significant decrease in the normalized signal within the tumor post-treatment with FeDC-E NPs compared to the non-targeted control iron oxide nanoparticles. This is the first study to use erlotinib as a small-molecule targeting agent for nanoparticles. PMID:27833124

  3. Removal of Trace Arsenic to Meet Drinking Water Standards Using Iron Oxide Coated Multiwall Carbon Nanotubes.

    PubMed

    Ntim, Susana Addo; Mitra, Somenath

    2011-05-12

    This study presents the removal of trace level arsenic to meet drinking water standards using an iron oxide-multi-walled carbon nanotube (Fe-MWCNT) hybrid as a sorbent. The synthesis was facilitated by the high degree of nanotube functionalization using a microwave assisted process, and a controlled assembly of iron oxide was possible where the MWCNT served as an effective support for the oxide. In the final product, 11 % of the carbon atoms were attached to Fe. The Fe-MWCNT was effective in arsenic removal to below the drinking water standard levels of 10 µg L(-1). The absorption capacity of the composite was 1723 µg g(-1) and 189 µg g(-1) for As(III) and As(V) respectively. The adsorption of As(V) on Fe-MWCNT was faster than that of As(III). The pseudo-second order rate equation was found to effectively describe the kinetics of arsenic adsorption. The adsorption isotherms for As(III) and As(V) fitted both the Langmuir and Freundlich models.

  4. Toxic effects of iron oxide nanoparticles on human umbilical vein endothelial cells

    PubMed Central

    Wu, Xinying; Tan, Yanbin; Mao, Hui; Zhang, Minming

    2010-01-01

    Iron oxide nanoparticles (IONPs) have been employed for hyperthermia treatments, stem cell therapies, cell labeling, and imaging modalities. The biocompatibility and cytotoxic effects of iron oxide nanoparticles when used in biomedical applications, however, are an ongoing concern. Endothelial cells have a critical role in this research dealing with tumors, cardiovascular disease and inflammation. However, there is little information dealing with the biologic effects of IONPs on the endothelial cell. This paper deals with the influence of dextran and citric acid coated IONPs on the behavior and function of human umbilical vein endothelial cells (HUVECs). After exposing endothelial cells to IONPs, dose-dependent effects on HUVECs viability, cytoskeleton and function were determined. Both citric acid and dextran coated particles appeared to be largely internalized by HUVECs through endocytosis and contribute to eventual cell death possibly by apoptosis. Cytoskeletal structures were greatly disrupted, as evidenced by diminished vinculin spots, and disorganized actin fiber and tubulin networks. The capacity of HUVECs to form a vascular network on Matrigel™ diminished after exposure to IONPs. Cell migration/invasion were inhibited significantly even at very low iron concentrations (0.1 mM). The results of this study indicate the great importance of thoroughly understanding nanoparticle-cell interactions, and the potential to exploit this understanding in tumor therapy applications involving IONPs as thermo/chemoembolization agents. PMID:20957160

  5. Magnetically triggered clustering of biotinylated iron oxide nanoparticles in the presence of streptavidinylated enzymes.

    PubMed

    Hodenius, Michael; Hieronymus, Thomas; Zenke, Martin; Becker, Christiane; Elling, Lothar; Bornemann, Jörg; Wong, John E; Richtering, Walter; Himmelreich, Uwe; De Cuyper, Marcel

    2012-09-07

    This work deals with the production and characterization of water-compatible, iron oxide based nanoparticles covered with functional poly(ethylene glycol) (PEG)-biotin surface groups (SPIO-PEG-biotin). Synthesis of the functionalized colloids occurred by incubating the oleate coated particles used as precursor magnetic fluid with anionic liposomes containing 14 mol% of a phospholipid-PEG-biotin conjugate. The latter was prepared by coupling dimyristoylphosphatidylethanolamine (DC(14:0)PE) to activated α-biotinylamido-ω -N-hydroxy-succinimidcarbonyl-PEG (NHS-PEG-biotin). Physical characterization of the oleate and PEG-biotin iron oxide nanocolloids revealed that they appear as colloidal stable clusters with a hydrodynamic diameter of 160 nm and zeta potentials of - 39 mV (oleate coated particles) and - 14 mV (PEG-biotin covered particles), respectively, as measured by light scattering techniques. Superconducting quantum interference device (SQUID) measurements revealed specific saturation magnetizations of 62-73 emu g(-1) Fe(3)O(4) and no hysteresis was observed at 300 K. MR relaxometry at 3 T revealed very high r(2) relaxivities and moderately high r(1) values. Thus, both nanocolloids can be classified as small, superparamagnetic, negative MR contrast agents. The capacity to functionalize the particles was illustrated by binding streptavidin alkaline phosphatase (SAP). It was found, however, that these complexes become highly aggregated after capturing them on the magnetic filter device during high-gradient magnetophoresis, thereby reducing the accessibility of the SAP.

  6. Polyaspartic acid coated iron oxide nanoprobes for PET/MRI imaging.

    PubMed

    Cowger, Taku; Xie, Jin

    2013-01-01

    Iron oxide nanoparticles, due to their exceptional magnetic property, biocompatibility, and biodegradability, have long been studied as contrast agents for magnetic resonance imaging (Xie et al., Curr Med Chem 16(10):1278-1294, 2009; Xie et al., Adv Drug deliv Rev 62(11):1064-1079, 2010). While previous applications mostly target reticuloendothelial system (RES) organs such as liver and lymph nodes, recent efforts have been made to impart targeting peptides or antibodies onto particle surface to enable site-specific targeting after systemic administration (Xie et al., Adv Drug Deliv Rev 62(11):1064-1079, 2010; Cai and Chen, Small 3(11):1840-1854, 2007; Corot et al., Adv Drug Deliv Rev 58 (14):1471-1504, 2006; Xie et al., Acc Chem Res 44(10):883-892). Moreover, other imaging functionalities can be loaded onto nanoparticles to achieve multimodality imaging probes (Cai and Chen, Small 3(11):1840-1854, 2007; Lee et al., J Nucl Med Soc Nucl Med 49(8):1371-1379, 2008). In this protocol, we describe the procedure of constructing an iron oxide nanoparticle (IONP)-based probe with high affinity towards integrin αvβ3 for positron emission tomography (PET) and magnetic resonance imaging (MRI) dual modality imaging. The related characterizations and validation experiments, including particle concentration determination, Prussian blue staining, animal model preparation, and in vivo PET/MRI imaging will also be discussed.

  7. pH sensitive CdS-iron oxide fluorescent-magnetic nanocomposites.

    PubMed

    Thakur, Dhananjay; Deng, Shuang; Baldet, Thierno; Winter, Jessica O

    2009-12-02

    There has been great interest in the use of nanoparticles for imaging, particularly in multimodal applications (e.g., combination of MRI and fluorescence). Yet creating particles with multiple functionalities has been challenging. Here, we report the synthesis of pH sensitive, fluorescent-magnetic, nanocomposites created through a simple aqueous procedure. Separately synthesized superparamagnetic iron oxide nanoparticles and mercaptopropionic acid (MPA)-coated CdS quantum dots were crosslinked using 3-mercaptopropyl trimethoxysilane (MPS) as a bifunctional linker to yield CdS-iron oxide conjugates. Conjugates formed clusters of 0.1-1.0 microm diameter, with the smallest observed particle diameter approximately 50 nm. Particle solubility and photoluminescent (PL) intensity were sensitive to solution pH, with the highest PL intensity and stability obtained at pH values < 3.0 and MPS:Cd:Fe ratios of 1:10:1. pH sensitivity is believed to result from changes in nanoparticle solubility within the silica-based matrix. Given these unique properties, this material might find application in separation, pH sensitive detection (e.g., endosomal tracking) and biosensing.

  8. A portable Hall magnetometer probe for characterization of magnetic iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Araujo, Jefferson F. D. F.; Costa, Mateus C.; Louro, Sonia R. W.; Bruno, Antonio C.

    2017-03-01

    We have built a portable Hall magnetometer probe, for measuring magnetic properties of iron oxide nanoparticles, that can be used for bulk materials and liquid samples as well. The magnetometer probe consists of four voltage-programmable commercial Hall sensors and a thin acrylic plate for positioning the sensors. In order to operate, it needs to be attached to a pole of an electromagnet and connected to an AD converter and a computer. It acquires a complete magnetization curve in a couple of minutes and has a magnetic moment sensitivity of 3.5×10-7 Am2. We tested its performance with magnetic nanoparticles containing an iron oxide core and having coating layers with different sizes. The magnetization results obtained were compared with measurements performed on commercial stand-alone magnetometers, and exhibited errors of about ±0.2 Am2/kg (i.e 0.4%) at saturation and below 0.5 Am2/kg (i.e. 10%) at remanence.

  9. Synthesis, characterization, and electrochemical response of iron oxide nanoparticles for sensing acetaminophen

    NASA Astrophysics Data System (ADS)

    Pal Singh, Beer; Kumar, Arun; Duarte, Armando P.; Rojas, Segundo J.; Crespo-Medina, Marielys; Areizaga-Martinez, Hector I.; Vega-Olivencia, Carmen A.; Tomar, M. S.

    2016-10-01

    Magnetite (Fe3O4) and hematite (α-Fe2O3) iron oxide nanoparticles were synthesized using the co-precipitation method via subsequent heat treatment using ferrous chloride (FeCl2.4H2O) as a source of iron. The synthesized powder was annealed at high temperature in an air atmosphere to promote the formation of the hematite (α-Fe2O3) phase. Both oxide phases of iron oxide were characterized using x-ray diffraction, thermogravimetric, and differential scanning calorimetric analysis, and Raman spectroscopy. The phases of as-synthesized nanoparticles were confirmed by XRD and Raman studies. The thermal behavior and weight loss of the initial powdered Fe3O4 to α-Fe2O3 was studied using TG-DSC analysis. In the present case, the Fe3O4 and α-Fe2O3 nanoparticles were used for the electrochemical sensing of acetaminophen (C6H9NO2). The sensing of acetaminophen was performed by Fe3O4 and α-Fe2O3 modified glassy carbon electrode, using a potential controlled cyclic voltammetric technique. The Fe3O4 and α-Fe2O3 nanoparticles exhibited electrocatalytic ability for sensing acetaminophen. Detailed results are included.

  10. Influence of alpha and gamma-iron oxide nanoparticles on marine microalgae species

    PubMed Central

    Demir, Veysel; Ates, Mehmet; Arslan, Zikri; Camas, Mustafa; Celik, Fatih; Bogatu, Corneliu; Can, Şafak Seyhaneyildiz

    2015-01-01

    The effects of alpha-iron oxide (α-Fe2O3) and gamma-iron oxide (γ-Fe2O3) nanoparticles (NPs) on marine microalgae species (Nannochloropsis sp. and Isochrysis sp.) were investigated in this study. Both Fe2O3 NPs covered the surface of algae with the agglomerates of the nanoparticles. This form of physical NP toxicity significantly decreased the sizes of phytoplankton. Both NPs were toxic to the tested algal species, while α-Fe2O3 showed less toxicity than γ-Fe2O3 NPs for both algal species. A comparative analysis of growth data of the two algal species treated with α-Fe2O3 or γ-Fe2O3 NPs revealed that Isochrysis sp. are more sensitive than Nannochloropsis sp. Toxicity of these widely used NPs to primary producers forming the base of the food chain in aquatic environments might result in widespread adverse effects on aquatic environmental health. PMID:26276558

  11. Infrared nanosecond pulsed laser irradiation of stainless steel: micro iron-oxide zones generation.

    PubMed

    Ortiz-Morales, M; Frausto-Reyes, C; Soto-Bernal, J J; Acosta-Ortiz, S E; Gonzalez-Mota, R; Rosales-Candelas, I

    2014-07-15

    Nanosecond-pulsed, infrared (1064 nm) laser irradiation was used to create periodic metal oxide coatings on the surface of two samples of commercial stainless steel at ambient conditions. A pattern of four different metal oxide zones was created using a galvanometer scanning head and a focused laser beam over each sample. This pattern is related to traverse direction of the laser beam scanning. Energy-dispersive X-ray spectroscopy (EDS) was used to find the elemental composition and Raman spectroscopy to characterize each oxide zone. Pulsed laser irradiation modified the composition of the stainless steel samples, affecting the concentration of the main components within each heat affected zone. The Raman spectra of the generated oxides have different intensity profiles, which suggest different oxide phases such as magnetite and maghemite. In addition, these oxides are not sensible to the laser power of the Raman system, as are the iron oxide powders reported in the literature. These experiments show that it is possible to generate periodic patterns of various iron oxide zones by laser irradiation, of stainless steel at ambient conditions, and that Raman spectroscopy is a useful punctual technique for the analysis and inspection of small oxide areas.

  12. Hybrid gold-iron oxide nanoparticles as a multifunctional platform for biomedical application

    PubMed Central

    2012-01-01

    Background Iron oxide nanoparticles (IONPs) have increasing applications in biomedicine, however fears over long term stability of polymer coated particles have arisen. Gold coating IONPs results in particles of increased stability and robustness. The unique properties of both the iron oxide (magnetic) and gold (surface plasmon resonance) result in a multimodal platform for use as MRI contrast agents and as a nano-heater. Results Here we synthesize IONPs of core diameter 30 nm and gold coat using the seeding method with a poly(ethylenimine) intermediate layer. The final particles were coated in poly(ethylene glycol) to ensure biocompatibility and increase retention times in vivo. The particle coating was monitored using FTIR, PCS, UV–vis absorption, TEM, and EDX. The particles appeared to have little cytotoxic effect when incubated with A375M cells. The resultant hybrid nanoparticles (HNPs) possessed a maximal absorbance at 600 nm. After laser irradiation in agar phantom a ΔT of 32°C was achieved after only 90 s exposure (50 μgmL-1). The HNPs appeared to decrease T2 values in line with previously clinically used MRI contrast agent Feridex®. Conclusions The data highlights the potential of these HNPs as dual function MRI contrast agents and nano-heaters for therapies such as cellular hyperthermia or thermo-responsive drug delivery. PMID:22731703

  13. Photoacoustic intra-operative nodal staging using clinically approved superparamagnetic iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Grootendorst, Diederik J.; Fratila, Raluca M.; Visscher, Martijn; Ten Haken, Bennie; van Wezel, Richard; Steenbergen, Wiendelt; Manohar, Srirang; Ruers, Theo J. M.

    2013-02-01

    Detection of tumor metastases in the lymphatic system is essential for accurate staging of various malignancies, however fast, accurate and cost-effective intra-operative evaluation of the nodal status remains difficult to perform with common available medical imaging techniques. In recent years, numerous studies have confirmed the additional value of superparamagnetic iron oxide dispersions (SPIOs) for nodal staging purposes, prompting the clearance of different SPIO dispersions for clinical practice. We evaluate whether a combination of photoacoustic (PA) imaging and a clinically approved SPIO dispersion, could be applied for intra-operative nodal staging. Metastatic adenocarcinoma was inoculated in Copenhagen rats for 5 or 8 days. After SPIO injection, the lymph nodes were photoacoustically imaged both in vivo and ex vivo whereafter imaging results were correlated with MR and histology. Results were compared to a control group without tumor inoculation. In the tumor groups clear irregularities, as small as 1 mm, were observed in the PA contrast pattern of the nodes together with an decrease of PA response. These irregularities could be correlated to the absence of contrast in the MR images and could be linked to metastatic deposits seen in the histological slides. The PA and MR images of the control animals did not show these features. We conclude that the combination of photoacoustic imaging with a clinically approved iron oxide nanoparticle dispersion is able to detect lymph node metastases in an animal model. This approach opens up new possibilities for fast intra-operative nodal staging in a clinical setting.

  14. Specific ion effects on the electrokinetic properties of iron oxide nanoparticles: experiments and simulations.

    PubMed

    Vereda, Fernando; Martín-Molina, Alberto; Hidalgo-Alvarez, Roque; Quesada-Pérez, Manuel

    2015-07-14

    We report experimental and simulation studies on ion specificity in aqueous colloidal suspensions of positively charged, bare magnetite nanoparticles. Magnetite has the largest saturation magnetization among iron oxides and relatively low toxicity, which explain why it has been used in multiple biomedical applications. Bare magnetite is hydrophilic and the sign of the surface charge can be changed by adjusting the pH, its isoelectric point being in the vicinity of pH = 7. Electrophoretic mobility of our nanoparticles in the presence of increasing concentrations of different anions showed that anions regarded as kosmotropic are more efficient in decreasing, and even reversing, the mobility of the particles. If the anions were ordered according to the extent to which they reduced the particle mobility, a classical Hofmeister series was obtained with the exception of thiocyanate, whose position was altered. Monte Carlo simulations were used to predict the diffuse potential of magnetite in the presence of the same anions. The simulations took into account the ion volume, and the electrostatic and dispersion forces among the ions and between the ions and the solid surface. Even though no fitting parameters were introduced and all input data were estimated using Lifshitz theory of van der Waals forces or obtained from the literature, the predicted diffusion potentials of different anions followed the same order as the mobility curves. The results suggest that ionic polarizabilities and ion sizes are to a great extent responsible for the specific ion effects on the electrokinetic potential of iron oxide particles.

  15. Influence of Alpha and Gamma-Iron Oxide Nanoparticles on Marine Microalgae Species.

    PubMed

    Demir, Veysel; Ates, Mehmet; Arslan, Zikri; Camas, Mustafa; Celik, Fatih; Bogatu, Corneliu; Can, Şafak Seyhaneyildiz

    2015-12-01

    The effects of alpha-iron oxide (α-Fe2O3) and gamma-iron oxide (γ-Fe2O3) nanoparticles (NPs) on marine microalgae species (Nannochloropsis sp. and Isochrysis sp.) were investigated in this study. Both Fe2O3 NPs covered the surface of algae with the agglomerates of the nanoparticles. This form of physical NP toxicity significantly decreased the sizes of phytoplankton. Both NPs were toxic to the tested algal species, while α-Fe2O3 showed less toxicity than γ-Fe2O3 NPs for both algal species. A comparative analysis of growth data of the two algal species treated with α-Fe2O3 or γ-Fe2O3 NPs revealed that Isochrysis sp. are more sensitive than Nannochloropsis sp. Toxicity of these widely used NPs to primary producers forming the base of the food chain in aquatic environments might result in widespread adverse effects on aquatic environmental health.

  16. How to assess cytotoxicity of (iron oxide-based) nanoparticles: a technical note using cationic magnetoliposomes.

    PubMed

    Soenen, Stefaan J H; De Cuyper, Marcel

    2011-01-01

    The range of different types of nanoparticles and their biomedical applications is rapidly growing, creating a need to thoroughly examine the effects these particles have on biological entities. One of the most commonly used nanoparticle types is iron oxide nanoparticles, which can be used as MRI contrast agents. The main research topic is the in vitro labeling of cells with iron oxide nanoparticles to render the cells detectable for MRI upon in vivo transplantation. For the correct evaluation of cell function and behavior in vivo, any effects of the nanoparticles on the cells must be completely ruled out. The present work provides a technical note where a detailed overview is given of several assays that could be useful to determine nanoparticle toxicity. The assays described focus on (i) nanoparticle internalization, (ii) immediate cell toxicity, (iii) cell proliferation, (iv) cell morphology, (v) cell functionality and (vi) cell physiology. Potential pitfalls, appropriate controls and advantages/disadvantages of the different assays are given. The main focus of this work is to provide a detailed guide to help other researchers in the field interested in setting up nanoparticle-toxicity studies.

  17. Toxicity of bare and surfaced functionalized iron oxide nanoparticles towards microalgae.

    PubMed

    Toh, Pey Yi; Tai, Wan Yii; Ahmad, Abdul Latif; Lim, Jit Kang; Chan, Derek Juinn Chieh

    2016-01-01

    This study investigates the toxicity of bare iron oxide nanoparticles (IONPs) and surface functionalization iron oxide nanoparticles (SF-IONPs) to the growth of freshwater microalgae Chlorella sp. This study is important due to the increased interest on the application of the magnetic responsive IONPs in various fields, such as biomedical, wastewater treatment, and microalgae harvesting. This study demonstrated that the toxicity of IONPs was mainly contributed by the indirect light shading effect from the suspending nanoparticles which is nanoparticles concentration-dependent, direct light shading effect caused by the attachment of IONPs on cell and the cell aggregation, and the oxidative stress from the internalization of IONPs into the cells. The results showed that the layer of poly(diallyldimethylammonium chloride) (PDDA) tended to mask the IONPs and hence eliminated oxidative stress toward the protein yield but it in turn tended to enhance the toxicity of IONPs by enabling the IONPs to attach on cell surfaces and cause cell aggregation. Therefore, the choice of the polymer that used for surface functionalize the IONPs is the key factor to determine the toxicity of the IONPs.

  18. Synthesis and characterization of superparamagnetic iron oxide nanoparticles as calcium-responsive MRI contrast agents

    NASA Astrophysics Data System (ADS)

    Xu, Pengfei; Shen, Zhiwei; Zhang, Baolin; Wang, Jun; Wu, Renhua

    2016-12-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) as T2 contrast agents have great potential to sense calcium ion (Ca2+) using magnetic resonance imaging (MRI). Here we prepared calcium-responsive SPIONs for MRI, formed by combining poly(ethylene glycol) (PEG) and polyethylenimine (PEI) coated iron oxide nanoparticle (PEI/PEG-SPIONs) contrast agents with the straightforward calcium-sensing compound EGTA (ethylene glycol tetraacetic acid). EGTA was conjugated onto PEI/PEG-SPIONs using EDC/sulfo-NHS method. EGTA-SPIONs were characterized using TEM, XPS, DSL, TGA and SQUIID. DSL results show that the SPIONs aggregate in the presence of Ca2+. MRI analyses indicate that the water proton T2 relaxation rates in HEPES suspensions of the EGTA-SPIONs significantly increase with the calcium concentration because the SPIONs aggregate in the presence of Ca2+. The T2 values decreased 25% when Ca2+ concentration decreased from 1.2 to 0.8 mM. The aggregation of EGTA-SPIONs could be reversed by EDTA. EGTA-SPIONs have potential as smart contrast agents for Ca2+-sensitive MRI.

  19. Interactions of human hemoglobin with charged ligand-functionalized iron oxide nanoparticles and effect of counterions

    NASA Astrophysics Data System (ADS)

    Ghosh, Goutam; Panicker, Lata

    2014-12-01

    Human hemoglobin is an important metalloprotein. It has tetrameric structure with each subunit containing a `heme' group which carries oxygen and carbon dioxide in blood. In this work, we have investigated the interactions of human hemoglobin (Hb) with charged ligand-functionalized iron oxide nanoparticles and the effect of counterions, in aqueous medium. Several techniques like DLS and ζ-potential measurements, UV-vis, fluorescence, and CD spectroscopy have been used to characterize the interaction. The nanoparticle size was measured to be in the range of 20-30 nm. Our results indicated the binding of Hb with both positively as well as negatively charged ligand-functionalized iron oxide nanoparticles in neutral aqueous medium which was driven by the electrostatic and the hydrophobic interactions. The electrostatic binding interaction was not seen in phosphate buffer at pH 7.4. We have also observed that the `heme' groups of Hb remained unaffected on binding with charged nanoparticles, suggesting the utility of the charged ligand-functionalized nanoparticles in biomedical applications.

  20. Reduction of iron-oxide-carbon composites: part III. Shrinkage of composite pellets during reduction

    SciTech Connect

    Halder, S.; Fruehan, R.J.

    2008-12-15

    This article involves the evaluation of the volume change of iron-oxide-carbon composite pellets and its implications on reduction kinetics under conditions prevalent in a rotary hearth furnace (RHF) that were simulated in the laboratory. The pellets, in general, were found to shrink considerably during the reduction due to the loss of carbon and oxygen from the system, sintering of the iron-oxide, and formation of a molten slag phase at localized regions inside the pellets due to the presence of binder and coal/wood-charcoal ash at the reduction temperatures. One of the shortcomings of the RHF ironmaking process has been the inability to use multiple layers of composite pellets because of the impediment in heat transport to the lower layers of a multilayer bed. However, pellet shrinkage was found to have a strong effect on the reduction kinetics by virtue of enhancing the external heat transport to the lower layers. The volume change of the different kinds of composite pellets was studied as a function of reduction temperature and time. The estimation of the change in the amount of external heat transport with varying pellet sizes for a particular layer of a multilayer bed was obtained by conducting heat-transfer tests using inert low-carbon steel spheres. It was found that if the pellets of the top layer of the bed shrink by 30 pct, the external heat transfer to the second layer increases by nearly 6 times.

  1. Synthesis, characterization, and in vitro biological evaluation of highly stable diversely functionalized superparamagnetic iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Dipsikha; Sahu, Sumanta K.; Banerjee, Indranil; Das, Manasmita; Mishra, Debashish; Maiti, Tapas K.; Pramanik, Panchanan

    2011-09-01

    In this article, we report the design and synthesis of a series of well-dispersed superparamagnetic iron oxide nanoparticles (SPIONs) using chitosan as a surface modifying agent to develop a potential T 2 contrast probe for magnetic resonance imaging (MRI). The amine, carboxyl, hydroxyl, and thiol functionalities were introduced on chitosan-coated magnetic probe via simple reactions with small reactive organic molecules to afford a series of biofunctionalized nanoparticles. Physico-chemical characterizations of these functionalized nanoparticles were performed by TEM, XRD, DLS, FTIR, and VSM. The colloidal stability of these functionalized iron oxide nanoparticles was investigated in presence of phosphate buffer saline, high salt concentrations and different cell media for 1 week. MRI analysis of human cervical carcinoma (HeLa) cell lines treated with nanoparticles elucidated that the amine-functionalized nanoparticles exhibited higher amount of signal darkening and lower T 2 relaxation in comparison to the others. The cellular internalization efficacy of these functionalized SPIONs was also investigated with HeLa cancer cell line by magnetically activated cell sorting (MACS) and fluorescence microscopy and results established selectively higher internalization efficacy of amine-functionalized nanoparticles to cancer cells. These positive attributes demonstrated that these nanoconjugates can be used as a promising platform for further in vitro and in vivo biological evaluations.

  2. Magnetic tumor targeting of β-glucosidase immobilized iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhou, Jie; Zhang, Jian; David, Allan E.; Yang, Victor C.

    2013-09-01

    Directed enzyme/prodrug therapy (DEPT) has promising application for cancer therapy. However, most current DEPT strategies face shortcomings such as the loss of enzyme activity during preparation, low delivery and transduction efficiency in vivo and difficultly of monitoring. In this study, a novel magnetic directed enzyme/prodrug therapy (MDEPT) was set up by conjugating β-glucosidase (β-Glu) to aminated, starch-coated, iron oxide magnetic iron oxide nanoparticles (MNPs), abbreviated as β-Glu-MNP, using glutaraldehyde as the crosslinker. This β-Glu-MNP was then characterized in detail by size distribution, zeta potential, FTIR spectra, TEM, SQUID and magnetophoretic mobility analysis. Compared to free enzyme, the conjugated β-Glu on MNPs retained 85.54% ± 6.9% relative activity and showed much better temperature stability. The animal study results showed that β-Glu-MNP displays preferable pharmacokinetics characteristics in relation to MNPs. With an adscititious magnetic field on the surface of a tumor, a significant quantity of β-Glu-MNP was selectively delivered into a subcutaneous tumor of a glioma-bearing mouse. Remarkably, the enzyme activity of the delivered β-Glu in tumor lesions showed as high as 20.123±5.022 mU g-1 tissue with 2.14 of tumor/non-tumor β-Glu activity.

  3. Effect of interfacial iron oxidation on the exchange bias in CoO/Fe bilayers

    NASA Astrophysics Data System (ADS)

    Młyńczak, E.; Gurgul, J.; Przewoźnik, J.; Wilgocka-Ślęzak, D.; Freindl, K.; Spiridis, N.; Korecki, J.

    2014-06-01

    The relation between the interface structure and the exchange bias was studied in the epitaxial CoO/Fe(0 0 1) bilayers that were grown on MgO(0 0 1) using molecular beam epitaxy. Three samples with different interface structures were prepared. The CoO/Fe bilayer, which was prepared using the reactive evaporation of CoO, served as the reference sample. In the other two samples, the CoO/Fe interfaces were modified prior to the CoO growth using either (i) the deposition of a 2 Å thick Co layer or (ii) an exposure to molecular oxygen, which resulted in under- and over-oxidized CoO/Fe interfaces, respectively. The actual structures of the resulting interfaces were revealed using conversion electron Mössbauer spectroscopy. For each sample, an iron oxide was found at the interface, and its amount depended on the sample preparation recipe. The exchange bias effect (EB), as a function of the temperature, was experimentally studied in detail using VSM magnetometry. The coercivity showed a distinct peak near the blocking temperature for all samples; however, the peak's location and its width were diverse. The obtained EB values depended on the interface structure. The largest hysteresis loop shift (HEB = 180 Oe at 4 K) was obtained for the sample with the thickest interfacial iron oxide layer.

  4. Toxicity assessment and comparison between two types of iron oxide nanoparticles in Mytilus galloprovincialis.

    PubMed

    Taze, Chrysa; Panetas, Ioannis; Kalogiannis, Stavros; Feidantsis, Konstantinos; Gallios, George P; Kastrinaki, Georgia; Konstandopoulos, Athanasios G; Václavíková, Miroslava; Ivanicova, Lucia; Kaloyianni, Martha

    2016-03-01

    Nanoparticles (NPs), due to their increased application and production, are being released into the environment with unpredictable impact on the physiology of marine organisms, as well as on entire ecosystems and upcoming effects on human health. The aim of the present study was to evaluate and compare the oxidative responses of the mussel Mytilus galloprovincialis after exposure to iron oxide NPs and to iron oxide NPs incorporated into zeolite for 1, 3 and 7 days. Our results showed that both effectors induced changes on animal physiology by causing oxidative stress in hemocytes of exposed mussels compared to control animals. This was shown by the significant increase in reactive oxygen species (ROS) production, protein carbonylation, lipid peroxidation, ubiquitin conjugates and DNA damage. In addition an increase in prooxidant levels as measured by the prooxidant-antioxidant balance (PAB) assay was observed in exposed mussels' hemolymph. The results show that ROS, DNA damage, protein and lipid oxidation, ubiquitin conjugates and PAB could constitute, after further investigation, reliable biomarkers for the evaluation of pollution or other environmental stressors. In addition, more studies are needed in order to ensure the safety of these NPs on various biomedical applications, since it is critical to design NPs that they meet the demands of application without causing cellular toxicity.

  5. Magmatic origin of giant 'Kiruna-type' apatite-iron-oxide ores in central Sweden.

    PubMed

    Jonsson, Erik; Troll, Valentin R; Högdahl, Karin; Harris, Chris; Weis, Franz; Nilsson, Katarina P; Skelton, Alasdair

    2013-01-01

    Iron is the most important metal for modern industry and Sweden is by far the largest iron-producer in Europe, yet the genesis of Sweden's main iron-source, the 'Kiruna-type' apatite-iron-oxide ores, remains enigmatic. We show that magnetites from the largest central Swedish 'Kiruna-type' deposit at Grängesberg have δ(18)O values between -0.4 and +3.7‰, while the 1.90-1.88 Ga meta-volcanic host rocks have δ(18)O values between +4.9 and +9‰. Over 90% of the magnetite data are consistent with direct precipitation from intermediate to felsic magmas or magmatic fluids at high-temperature (δ(18)Omgt > +0.9‰, i.e. ortho-magmatic). A smaller group of magnetites (δ(18)Omgt ≤ +0.9‰), in turn, equilibrated with high-δ(18)O, likely meteoric, hydrothermal fluids at low temperatures. The central Swedish 'Kiruna-type' ores thus formed dominantly through magmatic iron-oxide precipitation within a larger volcanic superstructure, while local hydrothermal activity resulted from low-temperature fluid circulation in the shallower parts of this system.

  6. Developmental and Reproductive Effects of Iron Oxide Nanoparticles in Arabidopsis thaliana.

    PubMed

    Bombin, Sergey; LeFebvre, Mitchell; Sherwood, Jennifer; Xu, Yaolin; Bao, Yuping; Ramonell, Katrina M

    2015-10-13

    Increasing use of iron oxide nanoparticles in medicine and environmental remediation has led to concerns regarding exposure of these nanoparticles to the public. However, limited studies are available to evaluate their effects on the environment, in particular on plants and food crops. Here, we investigated the effects of positive (PC) and negative (NC) charged iron oxide (Fe₂O₃) nanoparticles (IONPs) on the physiology and reproductive capacity of Arabidopsis thaliana at concentrations of 3 and 25 mg/L. The 3 mg/L treated plants did not show evident effects on seeding and root length. However, the 25 mg/L treatment resulted in reduced seedling (positive-20% and negative-3.6%) and root (positive-48% and negative-negligible) length. Interestingly, treatment with polyethylenimine (PEI; IONP-PC coating) also resulted in reduced root length (39%) but no change was observed with polyacrylic acid (PAA; IONP-NC coating) treatment alone. However, treatment with IONPs at 3 mg/L did lead to an almost 5% increase in aborted pollen, a 2%-6% reduction in pollen viability and up to an 11% reduction in seed yield depending on the number of treatments. Interestingly, the treated plants did not show any observable phenotypic changes in overall size or general plant structure, indicating that environmental nanoparticle contamination could go dangerously unnoticed.

  7. Controlled Phase and Tunable Magnetism in Ordered Iron Oxide Nanotube Arrays Prepared by Atomic Layer Deposition

    DOE PAGES

    Zhang, Yijun; Liu, Ming; Peng, Bin; ...

    2016-01-27

    Highly-ordered and conformal iron oxide nanotube arrays on an atomic scale are successfully prepared by atomic layer deposition (ALD) with controlled oxidization states and tunable magnetic properties between superparamagnetism and ferrimagnetism. Non-magnetic α-Fe2O3 and superparamagnetic Fe2O3with a blocking temperature of 120 K are in-situ obtained by finely controlling the oxidation reaction. Both of them exhibit a very small grain size of only several nanometers due to the nature of atom-by-atom growth of the ALD technique. Post-annealing α-Fe2O3 in a reducing atmosphere leads to the formation of the spinel Fe3O4 phase which displays a distinct ferrimagnetic anisotropy and the Verwey metal-insulatormore » transition that usually takes place only in single crystal magnetite or thick epitaxial films at low temperatures. Finally, the ALD deposition of iron oxide with well-controlled phase and tunable magnetism demonstrated in this work provides a promising opportunity for the fabrication of 3D nano-devices to be used in catalysis, spintronics, microelectronics, data storages and bio-applications.« less

  8. Controlled Phase and Tunable Magnetism in Ordered Iron Oxide Nanotube Arrays Prepared by Atomic Layer Deposition

    SciTech Connect

    Zhang, Yijun; Liu, Ming; Peng, Bin; Zhou, Ziyao; Chen, Xing; Yang, Shu-Ming; Jiang, Zhuang-De; Zhang, Jie; Ren, Wei; Ye, Zuo-Guang

    2016-01-27

    Highly-ordered and conformal iron oxide nanotube arrays on an atomic scale are successfully prepared by atomic layer deposition (ALD) with controlled oxidization states and tunable magnetic properties between superparamagnetism and ferrimagnetism. Non-magnetic α-Fe2O3 and superparamagnetic Fe2O3with a blocking temperature of 120 K are in-situ obtained by finely controlling the oxidation reaction. Both of them exhibit a very small grain size of only several nanometers due to the nature of atom-by-atom growth of the ALD technique. Post-annealing α-Fe2O3 in a reducing atmosphere leads to the formation of the spinel Fe3O4 phase which displays a distinct ferrimagnetic anisotropy and the Verwey metal-insulator transition that usually takes place only in single crystal magnetite or thick epitaxial films at low temperatures. Finally, the ALD deposition of iron oxide with well-controlled phase and tunable magnetism demonstrated in this work provides a promising opportunity for the fabrication of 3D nano-devices to be used in catalysis, spintronics, microelectronics, data storages and bio-applications.

  9. Photoactive nanocomplex formed from chlorophyll assembly on TMA-coated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Barbaros, Sibel; Meray, Zeynep; Tecim, Tuğba; Genç, Rükan

    2016-07-01

    In this study, hierarchical self-assembly of photocatalytic nanodisks through non-covalent interactions between spinach-extracted chlorophyll molecules and trimethylammonium hydroxide-coated magnetic iron oxide nanoparticles was discussed. Combination of chlorophyll molecules with iron oxide nanoparticles generated an alteration in light absorption at both visible and near-IR region with accompanying enhancement in fluorescence emission. Further, photocatalytic role of resulting molecular assembly was studied by means of the photoinduced degradation of methylene blue dye under UV light and direct sun irradiation at neutral pH. In order to enhance the long-term stability of the hybrid nanocatalyst, commercially available cellulose membrane was used as a support and magnetic recovery and reusability was achieved where the nanocatalyst retained more than 90 % of its efficiency even after four cycles. This simple strategy could initiate the development of new materials for wastewater treatment including membrane-based technologies. On the other hand, their sunlight-induced photocatalytic activity could easily be conducted to dye-synthesized solar cells or their enhanced photoluminescence can provide a strong basis for future bioimaging tools.

  10. Rapid Size- Controlled Synthesis of Dextran-Coated, Copper-Doped Iron Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Wong, Ray M.

    2011-12-01

    Development of dual modality probes enabled for magnetic resonance imaging (MRI) and positron emission tomography (PET) has been on the rise in recent years due to the potential for these probes to facilitate combining the complementary high resolution of MRI and the high sensitivity of PET. The efficient synthesis of multimodal probes that include the radiolabels for PET can be hindered due to prolonged reaction times during radioisotope incorporation, and the resulting decay of the radiolabel. Along with a time-efficient synthesis, one also needs an optimal synthesis that yields products in a desirable size range (between 20-100 nm) to increase blood retention time. In this work, we describe a novel, rapid, microwave-based synthesis of dextran-coated iron oxide nanoparticles doped with copper (DIO/Cu). Traditional methods for synthesizing dextran-coated iron oxide particles require refluxing for 2 hours and result in approximately 50 nm particles. We demonstrate that microwave synthesis can produce 50 nm nanoparticles in 5 minutes of heating. We discuss the various parameters used in the microwave synthesis protocol to vary the size distribution of DIO/Cu, and demonstrate the successful incorporation of copper into these particles with the aim of future use for rapid 64Cu incorporation.

  11. Self-organized iron-oxide cementation geometry as an indicator of paleo-flows

    PubMed Central

    Wang, Yifeng; Chan, Marjorie A.; Merino, Enrique

    2015-01-01

    Widespread iron oxide precipitation from groundwater in fine-grained red beds displays various patterns, including nodulation, banding and scallops and fingers. Hematite nodules have been reported also from the Meridiani Planum site on Mars and interpreted as evidence for the ancient presence of water on the red planet. Here we show that such patterns can autonomously emerge from a previously unrecognized Ostwald ripening mechanism and they capture rich information regarding ancient chemical and hydrologic environments. A linear instability analysis of the reaction-transport equations suggests that a pattern transition from nodules to bands may result from a symmetry breaking of mineral dissolution and precipitation triggered by groundwater advection. Round nodules tend to develop under nearly stagnant hydrologic conditions, while repetitive bands form in the presence of persistent water flows. Since water circulation is a prerequisite for a sustainable subsurface life, a Martian site with iron oxide precipitation bands, if one were found, may offer a better chance for detecting extraterrestrial biosignatures on Mars than would sites with nodules. PMID:26123788

  12. A general approach towards carbon nanotube and iron oxide coaxial architecture and its lithium storage capability

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Ni, Jiangfeng; Wang, Wencong; Li, Liang

    2015-12-01

    Coaxial architectures consisting of metal oxide and carbon nanotube are promising for many energy applications due to their synergetic interaction. The engineering and development of coaxial structures through a simple approach are highly desirable but remain a challenge. Herein, we present a general and facile ethylene glycol bath approach to fabricate coaxial architectures in which the metal oxide component is sandwiched by carbon nanotube and amorphous carbon. These unique architectures can serve as efficient electrode for lithium storage. The internal carbon nanotube allows rapid electron transport, while the external amorphous carbon acts as flexible buffer to accommodate volume variation upon lithium uptake. When evaluated in lithium cells, the carbon nanotube and iron oxide coaxial material exhibits a remarkable electrochemical lithium storage. It affords a capacity of 1083 mAh g-1 over 60 cycles, and retains 529 mAh g-1 at a high rate of 5 A g-1, drastically outperforming the pure iron oxide counterpart. This facile approach is in principle applicable to constructing other coaxial electrodes, and thus holds great potential in the manipulation of battery materials for lithium storage application.

  13. Developmental and Reproductive Effects of Iron Oxide Nanoparticles in Arabidopsis thaliana

    PubMed Central

    Bombin, Sergey; LeFebvre, Mitchell; Sherwood, Jennifer; Xu, Yaolin; Bao, Yuping; Ramonell, Katrina M.

    2015-01-01

    Increasing use of iron oxide nanoparticles in medicine and environmental remediation has led to concerns regarding exposure of these nanoparticles to the public. However, limited studies are available to evaluate their effects on the environment, in particular on plants and food crops. Here, we investigated the effects of positive (PC) and negative (NC) charged iron oxide (Fe2O3) nanoparticles (IONPs) on the physiology and reproductive capacity of Arabidopsis thaliana at concentrations of 3 and 25 mg/L. The 3 mg/L treated plants did not show evident effects on seeding and root length. However, the 25 mg/L treatment resulted in reduced seedling (positive-20% and negative-3.6%) and root (positive-48% and negative-negligible) length. Interestingly, treatment with polyethylenimine (PEI; IONP-PC coating) also resulted in reduced root length (39%) but no change was observed with polyacrylic acid (PAA; IONP-NC coating) treatment alone. However, treatment with IONPs at 3 mg/L did lead to an almost 5% increase in aborted pollen, a 2%–6% reduction in pollen viability and up to an 11% reduction in seed yield depending on the number of treatments. Interestingly, the treated plants did not show any observable phenotypic changes in overall size or general plant structure, indicating that environmental nanoparticle contamination could go dangerously unnoticed. PMID:26473847

  14. Deep reduction behavior of iron oxide and its effect on direct CO oxidation

    NASA Astrophysics Data System (ADS)

    Dong, Changqing; Liu, Xinglei; Qin, Wu; Lu, Qiang; Wang, Xiaoqiang; Shi, Simo; Yang, Yongping

    2012-01-01

    Reduction of metal oxide oxygen carrier has been attractive for direct CO oxidation and CO2 separation. To investigate the reduction behaviors of iron oxide prepared by supporting Fe2O3 on γ-Al2O3 and its effect on CO oxidation, fluidized-bed combustion experiments, thermogravimetric analyzer (TGA) experiments, and density functional theory (DFT) calculations were carried out. Gas yield (γCO2) increases significantly with the increase of temperature from 693 K to 1203 K, while carbon deposition decreases with the increase of temperature from 743 K to 1203 K, where temperature is a very important factor for CO oxidation by iron oxide. Further, it were quantitatively detected that the interaction between CO and Fe2O3, breakage of O-Fe bonds and formation of new C-O bonds, and effect of reduction degree were quantitatively detected. Based on adsorptions under different temperatures and reducing processes from Fe3+ into Fe2+, Fe+ and then into Fe, it was found that Fe2+ → Fe+ was the reaction-controlling step and the high oxidation state of iron is active for CO oxidation, where efficient partial reduction of Fe2O3 into FeO rather than complete reduction into iron may be more energy-saving for CO oxidation.

  15. Controlled Phase and Tunable Magnetism in Ordered Iron Oxide Nanotube Arrays Prepared by Atomic Layer Deposition

    PubMed Central

    Zhang, Yijun; Liu, Ming; Peng, Bin; Zhou, Ziyao; Chen, Xing; Yang, Shu-Ming; Jiang, Zhuang-De; Zhang, Jie; Ren, Wei; Ye, Zuo-Guang

    2016-01-01

    Highly-ordered and conformal iron oxide nanotube arrays on an atomic scale are successfully prepared by atomic layer deposition (ALD) with controlled oxidization states and tunable magnetic properties between superparamagnetism and ferrimagnetism. Non-magnetic α-Fe2O3 and superparamagnetic Fe3O4 with a blocking temperature of 120 K are in-situ obtained by finely controlling the oxidation reaction. Both of them exhibit a very small grain size of only several nanometers due to the nature of atom-by-atom growth of the ALD technique. Post-annealing α-Fe2O3 in a reducing atmosphere leads to the formation of the spinel Fe3O4 phase which displays a distinct ferrimagnetic anisotropy and the Verwey metal-insulator transition that usually takes place only in single crystal magnetite or thick epitaxial films at low temperatures. The ALD deposition of iron oxide with well-controlled phase and tunable magnetism demonstrated in this work provides a promising opportunity for the fabrication of 3D nano-devices to be used in catalysis, spintronics, microelectronics, data storages and bio-applications. PMID:26813143

  16. Organization and regulation of the arsenite oxidase operon of the moderately acidophilic and facultative chemoautotrophic Thiomonas arsenitoxydans.

    PubMed

    Slyemi, Djamila; Moinier, Danielle; Talla, Emmanuel; Bonnefoy, Violaine

    2013-11-01

    Thiomonas arsenitoxydans is an acidophilic and facultatively autotrophic bacterium that can grow by oxidizing arsenite to arsenate. A comparative genomic analysis showed that the T. arsenitoxydans aioBA cluster encoding the two subunits of arsenite oxidase is distinct from the other clusters, with two specific genes encoding a cytochrome c and a metalloregulator belonging to the ArsR/SmtB family. These genes are cotranscribed with aioBA, suggesting that these cytochromes c are involved in arsenite oxidation and that this operon is controlled by the metalloregulator. The growth of T. arsenitoxydans in the presence of thiosulfate and arsenite, or arsenate, is biphasic. Real-time PCR experiments showed that the operon is transcribed during the second growth phase in the presence of arsenite or arsenate, whereas antimonite had no effect. These results suggest that the expression of the aioBA operon of T. arsenitoxydans is regulated by the electron donor present in the medium, i.e., is induced in the presence of arsenic but is repressed by more energetic substrates. Our data indicate that the genetic organization and regulation of the aioBA operon of T. arsenitoxydans differ from those of the other arsenite oxidizers.