An efficient recyclable magnetic material for the selective removal of organic pollutants

• Clément Monteil,
• Nathalie Bar,
• Agnès Bee and
• Didier Villemin

Beilstein J. Nanotechnol. 2016, 7, 1447–1453, doi:10.3762/bjnano.7.136

• magnetic core. Polyethylenimine is phosphonated at different percentages by a one-step process and used to coat maghemite nanoparticles. It selectively extracts high amounts of cationic and anionic contaminants over a wide range of pH values, depending on the adjustable number of phosphonate groups

• . Preparation of the phosphonated polyethylenimine–maghemite material Synthesis of nanoparticles Maghemite ionic ferrofluid ([Fe] = 10−2 mol/L) was prepared by wet alkaline coprecipitation according to the Massart protocol [18][19]. Iron(III) chloride and iron(II) chloride were co-precipitated at a molar ratio

• preparation and conditions of the studies The novelty of this contribution consists in the use of PEI with phosphonic groups allowing a solid grafting of PEI on the maghemite nanoparticles, by the formation of strong covalent P–O–Fe bonds. The presence of these negative phosphonic groups ensures the stability

Improved biocompatibility and efficient labeling of neural stem cells with poly(L-lysine)-coated maghemite nanoparticles

• Igor M. Pongrac,
• Marina Dobrivojević,
• Lada Brkić Ahmed,
• Michal Babič,
• Miroslav Šlouf,
• Daniel Horák and
• Srećko Gajović

Beilstein J. Nanotechnol. 2016, 7, 926–936, doi:10.3762/bjnano.7.84

• . Their properties can be modified by coating with different biocompatible polymers. To test if a coating polymer, poly(L-lysine), can improve the biocompatibility of nanoparticles applied to neural stem cells, poly(L-lysine)-coated maghemite nanoparticles were prepared and characterized. We evaluated

• intracellular uptake of iron oxide in neural stem cells. The methyl thiazolyl tetrazolium assay and the calcein acetoxymethyl ester/propidium iodide assay demonstrated that poly(L-lysine)-coated maghemite nanoparticles scored better than nanomag®-D-spio in cell labeling efficiency, viability and proliferation

• -lysine)-coated maghemite and nanomag®-D-spio nanoparticles showed that they preserve their identity as neural stem cells and their potential to differentiate into all three major neural cell types (neurons, astrocytes and oligodendrocytes). Conclusion: Improved biocompatibility and efficient cell

Surface coating affects behavior of metallic nanoparticles in a biological environment

• Darija Domazet Jurašin,
• Marija Ćurlin,
• Ivona Capjak,
• Tea Crnković,
• Marija Lovrić,
• Michal Babič,
• Daniel Horák,
• Ivana Vinković Vrček and
• Srećko Gajović

Beilstein J. Nanotechnol. 2016, 7, 246–262, doi:10.3762/bjnano.7.23

• Republic, Heyrovský Sq. 2, 162 06 Prague 6, Czech Republic Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10 000 Zagreb, Croatia 10.3762/bjnano.7.23 Abstract Silver (AgNPs) and maghemite, i.e., superparamagnetic iron oxide nanoparticles (SPIONs) are promising candidates for new

• of metallic NP transformation. Our results highlight the importance of physicochemical characterization and stability evaluation of metallic NPs in a variety of biological systems including as many NP properties as possible. Keywords: biological fluids; colloidal stability; maghemite; nanoparticles

• study. For PLLSPIONs, the negatively charged surface of the maghemite core was only partially compensated by positive PLL resulting in a ζ-potential value of −5.4 ± 0.4 mV. As expected, the use of negatively charged coating agents CIT, AOT and MAN resulted in NPs bearing an overall negative charge of

Synthesis, characterization and in vitro biocompatibility study of Au/TMC/Fe₃O₄ nanocomposites as a promising, nontoxic system for biomedical applications

• Hanieh Shirazi,
• Maryam Daneshpour,
• Soheila Kashanian and
• Kobra Omidfar

Beilstein J. Nanotechnol. 2015, 6, 1677–1689, doi:10.3762/bjnano.6.170

• ) and maghemite (γ-Fe2O3). The increasing number of studies that report the successful use of Fe3O4 nanoparticles for industrial (e.g., as synthetic pigments or as catalyst), biomedical (in vivo and in vitro), environmental, and analytical applications, demonstrate their versatility. Since it is

Thermal treatment of magnetite nanoparticles

• Beata Kalska-Szostko,
• Urszula Wykowska,
• Dariusz Satula and
• Per Nordblad

Beilstein J. Nanotechnol. 2015, 6, 1385–1396, doi:10.3762/bjnano.6.143

• maghemite with indexes (hkl) ascribed to (220), (311), (400), (422), (333) and (440) [12][29] are observable. MNP-1 nanoparticles do not show any significant amount of additional structure up to 400 °C and therefore no additional patterns are presented. At 450 °C and 500 °C a small amount of hematite

• °C for the previous series. The MNP-3 particles are also stable only up to 400 °C, and above this temperature the hematite structure can be seen together with the magnetite/maghemite phase and metallic Ag (111), (200), (220) and (311) [31]. This proves that the MNP-2 nanoparticles are less stable

• range from 50 to 500 °C. In Figure 7A we observe the IR spectra of MNP-1 nanoparticles, in Figure 7B for the MNP-2 sample, and in Figure 7C for MNP-3. Heating resulted in oxidation of magnetite firstly to maghemite then to hematite for all types of nanoparticles. When the particles are heated to

Silica micro/nanospheres for theranostics: from bimodal MRI and fluorescent imaging probes to cancer therapy

• Shanka Walia and
• Amitabha Acharya

Beilstein J. Nanotechnol. 2015, 6, 546–558, doi:10.3762/bjnano.6.57

• magnetic NPs doped inside silica was found to be 7.0 emu/g, which was far less than the saturation magnetization of the magnetite/maghemite NPs used for the preparation of these core–shell spheres (54 emu/g). This decrease in magnetic saturation was attributed to the presence of a thick silica shell in the

• maghemite (γ-Fe2O3) NPs were prepared by using 1,2-hydroxydodecanoic acid and then these were coupled with CdSe/ZnS QDs. Finally, silica coating was achieved by using TEOS. The TEM and SEM images confirmed the incorporation of NPs inside silica. The presence of QDs was confirmed by spectrophotometric

• used as MR contrast agent in solution and in cells. Further, Chekina et al. [57] reported the synthesis of bifunctional NPs through a silinazation process. The maghemite (γ-Fe2O3) NPs were prepared by oxidizing pure magnetite NPs with sodium hypochlorite. The magnetic NPs were then coated with silica

Multifunctional layered magnetic composites

• Maria Siglreitmeier,
• Baohu Wu,
• Tina Kollmann,
• Martin Neubauer,
• Gergely Nagy,
• Dietmar Schwahn,
• Vitaliy Pipich,
• Damien Faivre,
• Dirk Zahn,
• Andreas Fery and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2015, 6, 134–148, doi:10.3762/bjnano.6.13

• areas in between the layers show the presence of polycrystalline nanoparticles with no preferred orientation (see Figure S5, Supporting Information File 1). The iron oxides magnetite and maghemite show very similar diffraction patterns and d-spacings, therefore it is not possible to differentiate these

Cathode lens spectromicroscopy: methodology and applications

• T. O. Menteş,
• G. Zamborlini,
• A. Sala and
• A. Locatelli

Beilstein J. Nanotechnol. 2014, 5, 1873–1886, doi:10.3762/bjnano.5.198

• . In the above example of FeOx growth on Ru(0001), further oxidation by using NO2 as atomic oxygen source resulted in the transformation of the FeO wetting layer to hematite (α-Fe2O3) and the triangular Fe3O4 islands to maghemite (γ-Fe2O3) [71]. In an independent study, the real-time observation of

Influence of surface-modified maghemite nanoparticles on in vitro survival of human stem cells

• Michal Babič,
• Daniel Horák,
• Lyubov L. Lukash,
• Tetiana A. Ruban,
• Yurii N. Kolomiets,
• Svitlana P. Shpylova and
• Oksana A. Grypych

Beilstein J. Nanotechnol. 2014, 5, 1732–1737, doi:10.3762/bjnano.5.183

• Molecular Biology and Genetics, NAS of Ukraine, Zabolotnogo 150, 03143 Kiev, Ukraine 10.3762/bjnano.5.183 Abstract Surface-modified maghemite (γ-Fe2O3) nanoparticles were obtained by using a conventional precipitation method and coated with D-mannose and poly(N,N-dimethylacrylamide). Both the initial and

• -mannose- and poly(N,N-dimethylacrylamide)-coated γ-Fe2O3 particles exhibit much lower level of cytotoxicity than the non-coated γ-Fe2O3. Keywords: maghemite; magnetic; MTT assay; nanoparticles; stem cells; Introduction One of the most important applications of nanoparticles in biomedicine is the direct

• (magnetite Fe3O4 or maghemite γ-Fe2O3) are their simple preparation and their magnetic properties, which are necessary for detection. Moreover, it is convenient that iron oxides are readily metabolized in the body. From this point of view, quantum dots are disqualified due to their toxicity. Like in every

A sonochemical approach to the direct surface functionalization of superparamagnetic iron oxide nanoparticles with (3-aminopropyl)triethoxysilane

• Bashiru Kayode Sodipo and
• Azlan Abdul Aziz

Beilstein J. Nanotechnol. 2014, 5, 1472–1476, doi:10.3762/bjnano.5.160

• standard of either magnetite or maghemite (cubic phase) XRD spectrum. However, the assignment to one of these phases on the basis of the XRD is difficult owing to their related structures. The absence of peaks at 110 and 104 corresponding to goethite and hematite in the spectrum indicate that the co

• maghemite compared with JCPDS 5-0664. (a) TEM micrograph of the APTES–SPION (b) Magnetization curves of the APTES-functionalised SPION at 300 K. Schematic representation of the sonochemical synthesis of APTES-functionalized SPION. Comparing the conventional methods of grafting APTES on SPION. Supporting

PEGylated versus non-PEGylated magnetic nanoparticles as camptothecin delivery system

• Paula M. Castillo,
• Mario de la Mata,
• Maria F. Casula,
• José A. Sánchez-Alcázar and
• Ana P. Zaderenko

Beilstein J. Nanotechnol. 2014, 5, 1312–1319, doi:10.3762/bjnano.5.144

• for USM nanoparticles to magnetite rather than to the isostructural spinel ferric iron oxide (maghemite), the XRD sample of the USM nanoparticles is consistent with the formation of magnetite. The peak broadening of the XRD pattern of the USM sample is in agreement with its nanocrystalline form. In

• at 5 K was measured to be around 72 emu·g−1 which is close to the value of bulk magnetite and maghemite (ca. 90 and 80 emu·g−1, respectively). A decrease in saturation magnetisation values is often observed in nanoparticles and ascribed both to the effect of surface atoms and to a reduced

Manipulation of isolated brain nerve terminals by an external magnetic field using D-mannose-coated γ-Fe₂O₃ nano-sized particles and assessment of their effects on glutamate transport

• Tatiana Borisova,
• Natalia Krisanova,
• Arsenii Borуsov,
• Roman Sivko,
• Ludmila Ostapchenko,
• Michal Babic and
• Daniel Horak

Beilstein J. Nanotechnol. 2014, 5, 778–788, doi:10.3762/bjnano.5.90

• in nano-neurotechnology. D-Mannose-coated superparamagnetic nanoparticles were synthesized by coprecipitation of Fe(II) and Fe(III) salts followed by oxidation with sodium hypochlorite and addition of D-mannose. Effects of D-mannose-coated superparamagnetic maghemite (γ-Fe2O3) nanoparticles on key

• of iron salts, namely FeCl2 and FeCl3, by rapid increase of pH by ammonia. Similarly as described in [12], this was followed by the oxidation of the resulting magnetite (Fe3O4) with sodium hypochlorite producing maghemite (γ-Fe2O3), which is chemically more stable than Fe3O4. This is in contrast to

• magnetite, which undergoes spontaneous oxidation by air. Proof of the maghemite by Mössbauer spectroscopy and powder X-ray diffraction, as well as its magnetic properties were described in our previous reports [15][16]. The neat γ-Fe2O3 nanoparticles were used in control experiments with cells or were used

Thermal stability and reduction of iron oxide nanowires at moderate temperatures

• Annalisa Paolone,
• Marco Angelucci,
• Stefania Panero,
• Maria Grazia Betti and
• Carlo Mariani

Beilstein J. Nanotechnol. 2014, 5, 323–328, doi:10.3762/bjnano.5.36

• transmittance between 500 and 650 cm−1 and the broad phonon band centered around 950 cm−1. However, we can observe a minimum of the transmittance around 700 cm−1, which is a fingerprint of maghemite (γ-Fe2O3) [27]. Thus, the clean sample 2 presents features that are typical of a mixture of α- and γ-Fe2O3. The

Magnetic interactions between nanoparticles

• Steen Mørup,
• Mikkel Fougt Hansen and
• Cathrine Frandsen

Beilstein J. Nanotechnol. 2010, 1, 182–190, doi:10.3762/bjnano.1.22

• , however, remarkable that weak dipole interactions can result in faster superparamagnetic relaxation. This has been observed in Mössbauer studies of maghemite (γ-Fe2O3) nanoparticles [12][28], and the effect has been explained by a lowering of the energy barriers between the two minima of the magnetic

Magnetic nanoparticles for biomedical NMR-based diagnostics

• Huilin Shao,
• Tae-Jong Yoon,
• Monty Liong,
• Ralph Weissleder and
• Hakho Lee

Beilstein J. Nanotechnol. 2010, 1, 142–154, doi:10.3762/bjnano.1.17

• ][37][38][39][40][41][42]. CLIO nanoparticles contain a superparamagnetic iron oxide core (3–5 nm monocrystalline iron oxide) composed of ferrimagnetic magnetite (Fe3O4) and/or maghemite (γ-Fe2O3). The metallic core is subsequently coated with biocompatible dextran, before being cross-linked with

Magnetic coupling mechanisms in particle/thin film composite systems

• Giovanni A. Badini Confalonieri,
• Philipp Szary,
• Durgamadhab Mishra,
• Maria J. Benitez,
• Mathias Feyen,
• An Hui Lu,
• Leonardo Agudo,
• Gunther Eggeler,
• Oleg Petracic and
• Hartmut Zabel

Beilstein J. Nanotechnol. 2010, 1, 101–107, doi:10.3762/bjnano.1.12

• characterization Magnetization hysteresis loops of a monolayer film, consisting of single phased maghemite NPs as detailed in the experimental section, are shown in Figure 3a. Hysteresis loops taken at 330 K and 15 K show the expected behavior of nanosized ferrimagnetic particles, i.e., symmetric loops, with a

• ferrimagnetic maghemite NPs and a ferromagnetic Co thin film, it is necessary to account for the presence of an extra AF component. A possible explanation is that the Co layer is partially oxidized to AF CoO. The Co layer is capped with a protective Cu layer, and therefore, oxidation is more likely to occur at

• samples were annealed at 170 °C for 20 min in air in order to obtain mainly single phase maghemite (γ-Fe2O3) NPs as reported in Ref. [41]. After heat treatment, the NP monolayer was ion-milled with neutralized Ar-ions for 4 min in order to flatten the NP array and remove the oleic acid layer. Finally, a

Uniform excitations in magnetic nanoparticles

• Steen Mørup,
• Cathrine Frandsen and
• Mikkel Fougt Hansen

Beilstein J. Nanotechnol. 2010, 1, 48–54, doi:10.3762/bjnano.1.6

• magnetic anisotropy [14]. A similar size dependence of the magnetic anisotropy constant has been found by Mössbauer studies in other nanoparticles, for example, maghemite (γ-Fe2O3) [15], hematite (α-Fe2O3) [16] and metallic iron (α-Fe) [17]. If a sufficiently large magnetic field B is applied, such that B

• maghemite particles [20] is shown. Figure 4a demonstrates that the energy of the satellite peaks varies almost linearly with the magnitude of the applied magnetic field, indicating that the anisotropy field is almost negligible for B > 1 T. By a detailed analysis of the data, BA was estimated to be on the

• Figure 6b shows data obtained in different applied magnetic fields at 200 K. In Figure 6a, inelastic satellite peaks at energies ±ε0 ≈ ±1.1 meV are seen on both sides of the intense quasielastic peak. As in the data for ferrimagnetic maghemite (Figure 4) the relative area of the inelastic peaks increases