Synthesis of a MnO₂/Fe₃O₄/diatomite nanocomposite as an efficient heterogeneous Fenton-like catalyst for methylene blue degradation

• Zishun Li,
• Xuekun Tang,
• Kun Liu,
• Jing Huang,
• Yueyang Xu,
• Qian Peng and
• Minlin Ao

Beilstein J. Nanotechnol. 2018, 9, 1940–1950, doi:10.3762/bjnano.9.185

• indicates that both of the samples show superparamagnetic behavior at room temperature [31]. The maximum saturation magnetizations of Fe3O4/diatomite and MnO2/Fe3O4/diatomite were measured to be 16.57 and 10.61 emu/g, respectively, which make the composites very easy to be separated by an external magnetic

Magnetic properties of Fe₃O₄ antidot arrays synthesized by AFIR: atomic layer deposition, focused ion beam and thermal reduction

• Juan L. Palma,
• Alejandro Pereira,
• Raquel Álvaro,
• José Miguel García-Martín and
• Juan Escrig

Beilstein J. Nanotechnol. 2018, 9, 1728–1734, doi:10.3762/bjnano.9.164

• -dimensional magnetism and a broad range of applications, such as a new generation of electronic devices [1], sensors [2], ultra-high density recording media – due to the absence of the superparamagnetic limit as there are no isolated magnetic islands – [3], and magnonics and spintronic devices [4][5]. The

Nanocomposites comprised of homogeneously dispersed magnetic iron-oxide nanoparticles and poly(methyl methacrylate)

• Sašo Gyergyek,
• David Pahovnik,
• Ema Žagar,
• Alenka Mertelj,
• Rok Kostanjšek,
• Miloš Beković,
• Marko Jagodič,
• Heinrich Hofmann and
• Darko Makovec

Beilstein J. Nanotechnol. 2018, 9, 1613–1622, doi:10.3762/bjnano.9.153

• chains from the magnetic nanoparticles by the PMMA chains of the matrix. The nanocomposites were superparamagnetic and exhibited large values for the saturation magnetization of up to 36 emu/g. Moreover, the nanocomposite with the largest amount of incorporated nanoparticles exhibited relatively large

• values for the specific power loss when subjected to alternating magnetic fields, giving this material great potential for the magnetically induced hyperthermia-based treatment of cancer. Keywords: magnetic hyperthermia; magnetic properties; nanocomposites; superparamagnetic; Introduction Magnetic iron

• -oxide nanoparticles with a size close to the superparamagnetic limit have been extensively studied because of their unique properties that can be exploited in a variety of applications. When the size of a single-domain ferromagnetic material is reduced below a certain critical value, the transition to

Surface characterization of nanoparticles using near-field light scattering

• Eunsoo Yoo,
• Yizhong Liu,
• Chukwuazam A. Nwasike,
• Sebastian R. Freeman,
• Brian C. DiPaolo,
• Bernardo Cordovez and
• Amber L. Doiron

Beilstein J. Nanotechnol. 2018, 9, 1228–1238, doi:10.3762/bjnano.9.114

• )-coated superparamagnetic iron oxide nanoparticles (PEG-SPIOs) with the synthetic pseudotannin polygallol via interpolymer complexation (IPC). Changes in particle size and zeta potential were indirectly assessed via differences between PEG-SPIOs and IPC-SPIOs in particle velocity and scattering intensity

• reaction kinetics at the particle surface. Keywords: nanoparticle surface properties; nanoparticles; nanophotonic force microscopy; near-field light scattering; superparamagnetic iron oxide; Introduction Nanotechnology is an increasingly integral part of modern medicine, predominantly in the fields of

• the particle surface in varied solvents [7][17][18]. In this work, we present one potential application of near-field light scattering-based nanophotonic force microscopy used to evaluate changes in particle surface and size by examining the self-assembly of interpolymer complexed superparamagnetic

Review on nanoparticles and nanostructured materials: history, sources, toxicity and regulations

• Jaison Jeevanandam,
• Ahmed Barhoum,
• Yen S. Chan,
• Alain Dufresne and
• Michael K. Danquah

Beilstein J. Nanotechnol. 2018, 9, 1050–1074, doi:10.3762/bjnano.9.98

• magnets, so-called ferrofluids, are ultrastable suspensions of small magnetic NPs with superparamagnetic properties [36]. Upon applying a magnetic field, the liquid will macroscopically magnetize, which leads to the alignment of NPs along the magnetic field direction [37]. Recent research has focused on

• -distributed magnetic iron-sulfide particles [159], 12 nm magnetic octahedral NPs [160], modified iron NPs [161] and superparamagnetic NPs [162][163] were produced by using magnetotactic bacteria. Bacterial magnetic particle (BacMPs) [164] produced via bacterium are suggested to perform as a bio-needle in a

Heavy-metal detectors based on modified ferrite nanoparticles

• Urszula Klekotka,
• Ewelina Wińska,
• Elżbieta Zambrzycka-Szelewa,
• Dariusz Satuła and
• Beata Kalska-Szostko

Beilstein J. Nanotechnol. 2018, 9, 762–770, doi:10.3762/bjnano.9.69

• presence of a doublet in the central part of the spectrum, which is connected to the superparamagnetic behavior of Fe magnetic moments in the studied samples. The relative intensity of the doubles depends on the kind of dopant. The most intensive doublet is observed for magnetite doped by Ca (more than 50

• %) and the smallest one in the case of Co dopant. These results show that the superparamagnetic blocking temperature for the Ca doping is below room temperature whereas for the other cases it is slightly above. Taking both features of the measured spectra into account, the mean values of the hyperfine

• field are equal to 43 T, 44 T, 39 T, 30 T and 20 T for pure magnetite and Co-, Ni-, Mn- and Ca-doped magnetite, respectively. This value strongly depends on the ferrite composition, particle size, surface modification and proximity to superparamagnetic blocking temperature. Attachment of Cu2+, Cd2+ and

Anchoring Fe₃O₄ nanoparticles in a reduced graphene oxide aerogel matrix via polydopamine coating

• Błażej Scheibe,
• Radosław Mrówczyński,
• Natalia Michalak,
• Karol Załęski,
• Michał Matczak,
• Mateusz Kempiński,
• Zuzanna Pietralik,
• Mikołaj Lewandowski,
• Stefan Jurga and
• Feliks Stobiecki

Beilstein J. Nanotechnol. 2018, 9, 591–601, doi:10.3762/bjnano.9.55

• ][34], gas sensors [18] or even nanoswitches/actuators [22]. The magnetic properties of hybrid aerogels are related to the presence of magnetic nanoparticles (MNPs) which can be in ferromagnetic or superparamagnetic state and are embedded in aerogel matrix. Iron oxide nanoparticles, such as magnetite

• . It can be noticed that all the M–H curves have non-hysteretic, superparamagnetic-like character. The saturation magnetization was found to be 38.2 emu/g, 30.5 emu/g and 36.9 emu/g for rGO-Fe3O4, rGO-PDA@Fe3O4 and c-rGO-PDA@Fe3O4 aerogel samples, respectively. It was generally expected that covering

• susceptibility curves coincide at high temperatures and separate as the temperature is decreasing. The maximum of the ZFC curve is defined as the blocking temperature (TB) of the superparamagnetic nanoparticles and the width of the ZFC curve maximum is related to the size distribution or agglomeration process of

Alternating current magnetic susceptibility of a ferronematic

• Natália Tomašovičová,
• Jozef Kováč,
• Veronika Gdovinová,
• Nándor Éber,
• Tibor Tóth-Katona,
• Jan Jadżyn and
• Peter Kopčanský

Beilstein J. Nanotechnol. 2017, 8, 2515–2520, doi:10.3762/bjnano.8.251

• particles are superparamagnetic. The temperature of the phase transition of the samples was detected by independent capacitance measurements in a capacitor made of ITO-coated glass electrodes (AWAT). The capacitor with an electrode area of approximately 5 mm × 5 mm was placed into a regulated thermostat

Methionine-mediated synthesis of magnetic nanoparticles and functionalization with gold quantum dots for theranostic applications

• Arūnas Jagminas,
• Agnė Mikalauskaitė,
• Vitalijus Karabanovas and
• Jūrate Vaičiūnienė

Beilstein J. Nanotechnol. 2017, 8, 1734–1741, doi:10.3762/bjnano.8.174

• Biocompatible superparamagnetic iron oxide nanoparticles (NPs) through smart chemical functionalization of their surface with fluorescent species, therapeutic proteins, antibiotics, and aptamers offer remarkable potential for diagnosis and therapy of disease sites at their initial stage of growth. Such NPs can

• application of Fe3O4@Met NPs for the adsorption of water pollutants. In this study, we report a novel synthesis protocol for superparamagnetic cobalt ferrite NPs capped with a biocompatible methionine shell (CoFe2O4@Met), which in turn is capable to reduce and attach the gold species. In this way, hybrid

• methionine-functionalized cobalt ferrite nanoparticles A hydrothermal approach was applied to synthesize the superparamagnetic cobalt ferrite NPs stabilized with methionine. The proposed approach differs from the reported one [19] in the nature of magnetic NPs, the composition of the aqueous solution applied

Near-infrared-responsive, superparamagnetic Au@Co nanochains

• Varadee Vittur,
• Arati G. Kolhatkar,
• Shreya Shah,
• Irene Rusakova,
• Dmitri Litvinov and
• T. Randall Lee

Beilstein J. Nanotechnol. 2017, 8, 1680–1687, doi:10.3762/bjnano.8.168

• , University of Houston, 4800 Calhoun Road, Houston, TX 77204, USA Department of Electrical and Computer Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204, USA 10.3762/bjnano.8.168 Abstract This manuscript describes a new type of nanomaterial, namely superparamagnetic Au@Co nanochains

• (superparamagnetism) and provide a potentially useful new nanoarchitecture for biomedical or catalytic applications that can benefit from both activation by light and manipulation using an external magnetic field. Keywords: Au@Co; magneto-optical; nanochains; near-IR-active; superparamagnetic; Introduction The

• nanoparticles [25] by reducing an organo-gold compound onto a cobalt seed with a weak reducing agent in toluene. These particles showed superparamagnetic behavior and a strong optical extinction at ca. 680 nm. Similarly, Wetz and co-workers prepared hybrid Co–Au nanorods via decomposition of an organometallic

Characterization of ferrite nanoparticles for preparation of biocomposites

• Urszula Klekotka,
• Magdalena Rogowska,
• Dariusz Satuła and
• Beata Kalska-Szostko

Beilstein J. Nanotechnol. 2017, 8, 1257–1265, doi:10.3762/bjnano.8.127

• doping material. At RT, magnetite and Co0.5Fe2.5O4 are almost totally below the superparamagnetic blocking temperature. Especially in case of Co it is seen that even when the average particle size decreases, the mean hyperfine field increases. This phenomenon can only be caused by the influence of Co on

• Fe in a way that the Fe magnetic moment increases when Co is in the nearest surrounding of the Fe nuclei. Such a scenario is in good agreement with the observation in other systems [26]. Particles substituted with Mn are very close to superparamagnetic TB, which is estimated to occur when the

• external magnetic field while the size of the particles is a critical parameter. It was observed that superparamagnetic fluctuations are blocked (or not blocked) at RT for nanoparticles with a diameter smaller than the reference magnetite due to elemental substitution. Therefore, at any stage of the

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

• Arpita Jana,
• Elke Scheer and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2017, 8, 688–714, doi:10.3762/bjnano.8.74

Formation and shape-control of hierarchical cobalt nanostructures using quaternary ammonium salts in aqueous media

• Ruchi Deshmukh,
• Anurag Mehra and
• Rochish Thaokar

Beilstein J. Nanotechnol. 2017, 8, 494–505, doi:10.3762/bjnano.8.53

• further to 8–10 nm over 15 min. The size reduction is attributed to etching by TMAH [35], which exposes favorable crystal planes. The (002) plane is possibly exposed because of this etching. Cobalt nanoparticles in the size range of 8–10 nm are superparamagnetic. Magnetic interactions are therefore absent

• spherical nanoparticles 150 nm, compared to 8 nm particles under ambient conditions, at initial time suggests that the effectiveness of TMAH to cleave and twin the seeds is lost. The aggregation of untwinned uncoated superparamagnetic nanoparticles results in large spherical nanoclusters, which then

Methods for preparing polymer-decorated single exchange-biased magnetic nanoparticles for application in flexible polymer-based films

• Laurence Ourry,
• Delphine Toulemon,
• Souad Ammar and
• Fayna Mammeri

Beilstein J. Nanotechnol. 2017, 8, 408–417, doi:10.3762/bjnano.8.43

• coupling at the F–AF interface (see for instance [16][17][18]), leading to an enhanced effective magnetic anisotropy constant (Keff) and a higher temperature of transition from a magnetically blocked state to a superparamagnetic one (TB) [19][20]. Focusing on such particles, in this work, we propose

• -decorated ENP assemblies, a net decrease of the blocking temperature value, defined as the critical temperature at the relaxed/blocked magnetic states transition, was observed when the ENP dilution ratio was increased (Figure 11). Such behaviour is quite common for superparamagnetic single-domain

From iron coordination compounds to metal oxide nanoparticles

• Mihail Iacob,
• Carmen Racles,
• Codrin Tugui,
• George Stiubianu,
• Adrian Bele,
• Liviu Sacarescu,
• Daniel Timpu and
• Maria Cazacu

Beilstein J. Nanotechnol. 2016, 7, 2074–2087, doi:10.3762/bjnano.7.198

• , magnetite is ferromagnetic when the particle diameter is larger than 15 nm and superparamagnetic when smaller [8]. Zhen et al. demonstrate that cubic nanoparticles have higher saturation magnetization and T2 relaxation than spherical nanoparticles of the same size [9]. Magnetic nanoparticles with flat

A novel electrochemical nanobiosensor for the ultrasensitive and specific detection of femtomolar-level gastric cancer biomarker miRNA-106a

• Maryam Daneshpour,
• Kobra Omidfar and
• Hossein Ghanbarian

Beilstein J. Nanotechnol. 2016, 7, 2023–2036, doi:10.3762/bjnano.7.193

• with TMC polymer and gold NPs. However, the zero remanence and coercivity values indicated the superparamagnetic nature of gold–magnetic NPs with an acceptable VSM value (59.05 emu/g) [20]. Preparation of gold–magnetic nanoprobes The oligonucleotides can be immobilized on the gold NPs through various

Cubic chemically ordered FeRh and FeCo nanomagnets prepared by mass-selected low-energy cluster-beam deposition: a comparative study

• Veronique Dupuis,
• Anthony Robert,
• Arnaud Hillion,
• Ghassan Khadra,
• Nils Blanc,
• Damien Le Roy,
• Florent Tournus,
• Clement Albin,
• Olivier Boisron and
• Alexandre Tamion

Beilstein J. Nanotechnol. 2016, 7, 1850–1860, doi:10.3762/bjnano.7.177

• -field-cooling (ZFC) and field-cooling (FC) susceptibility curves show a transition from the superparamagnetic to the blocked regime for the as-prepared NPs with a maximum ZFC temperature (Tmax). Tmax is connected to the energy barrier (ΔE = KeffV, with Keff the effective anisotropy constant and V the

Antitumor magnetic hyperthermia induced by RGD-functionalized Fe₃O₄ nanoparticles, in an experimental model of colorectal liver metastases

• Oihane K. Arriortua,
• Eneko Garaio,
• Borja Herrero de la Parte,
• Maite Insausti,
• Luis Lezama,
• Fernando Plazaola,
• Jose Angel García,
• Jesús M. Aizpurua,
• Maialen Sagartzazu,
• Mireia Irazola,
• Nestor Etxebarria,
• Ignacio García-Alonso,
• Alberto Saiz-López and
• José Javier Echevarria-Uraga

Beilstein J. Nanotechnol. 2016, 7, 1532–1542, doi:10.3762/bjnano.7.147

• achieved. The nanoparticles were characterized by transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), electron magnetic resonance (EMR) spectroscopy and magnetic hyperthermia. The nanoparticles present superparamagnetic behavior with very high magnetization values, which yield

• of the Fe3O4@OA sample (Figure 2). The absence of a coercive field or remanence in the hysteresis loop recorded at 300 K is indicative of a superparamagnetic behavior of the sample. The saturation magnetization value obtained from the hysteresis loops at 300 K is 78.4 emu/g Fe3O4, which slightly

• (ZFC) and field-cooled (FC) for a colloidal sample dispersed in toluene is represented in Figure 2b. The evolution of the curves shows the usual characteristics of a superparamagnetic system, with a blocking temperature (TB) of 177 K and a progressive decrease of magnetization above TB. This high value

Microwave synthesis of high-quality and uniform 4 nm ZnFe₂O₄ nanocrystals for application in energy storage and nanomagnetics

• Christian Suchomski,
• Ben Breitung,
• Ralf Witte,
• Michael Knapp,
• Sondes Bauer,
• Tilo Baumbach,
• Christian Reitz and
• Torsten Brezesinski

Beilstein J. Nanotechnol. 2016, 7, 1350–1360, doi:10.3762/bjnano.7.126

• . Upon further cooling, the FC curve diverges from the ZFC curve and the material exhibits ferrimagnetic behavior. To determine whether Tmax can be associated with either a freezing temperature, Tf, for spin glasses or a blocking temperature, TB, for superparamagnetic particles, frequency-dependent AC

• superparamagnetic particle ensembles, where K is the effective uniaxial magnetic anisotropy, V is the particle volume and kB is the Boltzmann’s constant [43]. As shown in Supporting Information File 1, Figure S7, the frequency dependence of the peak temperature does not follow Néel–Brown model, which is supported

• by the finding that the Néel–Arrhenius relation gave an unphysically large value of Ea/kB (1365 K). This has also been observed for other materials with (super)spin glass behavior and thus confirms the conclusion of spin glass freezing rather than superparamagnetic blocking [44][45]. For slightly

Multiwalled carbon nanotube hybrids as MRI contrast agents

• Nikodem Kuźnik and
• Mateusz M. Tomczyk

Beilstein J. Nanotechnol. 2016, 7, 1086–1103, doi:10.3762/bjnano.7.102

• character, the high spatial resolution and the possibility of soft tissue imaging. Contrast agents, such as gadolinium complexes and superparamagnetic iron oxides, are administered to spotlight certain organs and their pathologies. Many new models have been proposed that reduce side effects and required

• introduced in the form of diethylene triamine pentaacetic acid (DTPA) complexes (classical CAs) on SWCNTs [16], superparamagnetic iron oxides (SPIOs) were anchored on SWCNTs [6] and, on the contrary, iron-deficient SWCNTs [17] were found to exhibit good properties for potential MRI CAs. These first works in

• presence of oleic acid [37]. All of these approaches led to the formation of iron oxides with superparamagnetic properties, as determined by superconducting quantum interference device (SQUID) measurements. Only in a few cases was the real composition proven by X-ray techniques. Nevertheless, these

Synthesis of cobalt nanowires in aqueous solution under an external magnetic field

• Xiaoyu Li,
• Lijuan Sun,
• Hu Wang,
• Kenan Xie,
• Qin Long,
• Xuefei Lai and
• Li Liao

Beilstein J. Nanotechnol. 2016, 7, 990–994, doi:10.3762/bjnano.7.91

• the superparamagnetic property exhibited in the previous report [13]. The coercivity (Hc) of the cobalt nanowires were 352.87 Oe, and the saturation magnetization (Ms) were 112.00 emu g−1, which was lower than the corresponding value of bulk cobalt (162.5 emu g−1) [11]. In summary, uniform linear

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

• track stem cells by magnetic resonance imaging (MRI) [11], and superparamagnetic iron oxide nanoparticles are particularly used for this purpose [12][13][14][15]. The efficient cellular uptake of nanoparticles, which would not interfere with the labeled cell activities is crucial for reliable cell

Hemolysin coregulated protein 1 as a molecular gluing unit for the assembly of nanoparticle hybrid structures

• Tuan Anh Pham,
• Andreas Schreiber,
• Elena V. Sturm (née Rosseeva),
• Stefan Schiller and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2016, 7, 351–363, doi:10.3762/bjnano.7.32

• magnetic field and connected by utilization of cysteine-modified Hcp1. After lyophilization, a fiber-like material of micrometer scale length can be observed. The Fe3O4 Hcp1_cys3 fibers show superparamagnetic behavior with a decreasing blocking temperature and an increasing remanent magnetization leading

• conducted under an external magnetic field. After lyophilization of the reaction mixture, fiber-like structures in the micrometer range are obtained. The TEM investigation demonstrates networked structures of Fe3O4 and CoFe2O4 NPs. The magnetic measurements reveal a superparamagnetic character for the Fe3O4

• orientation perpendicular to the fiber elongation. Finally, magnetic measurements of the hybrid material were conducted. In Figure 10A, results of a superconducting quantum interference device (SQUID) measurement show that the hybrid material is superparamagnetic at room temperature with saturation

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

• currently in use for medical purposes [3], for example silver nanoparticles (AgNPs) and superparamagnetic iron oxide nanoparticles (SPIONs). AgNPs are exploited in medicine for biocidal therapy owing to their antibacterial, antifungal, antiviral, and anti-inflammatory properties. In addition, they attract

• silver and superparamagnetic iron oxide NPs [46] in different biological environments was investigated in adherence to the experimental scheme presented in Figure 1. Characteristics of prepared AgNPs and SPIONs As the first step, the physicochemical properties of freshly synthesized NPs were carefully

Green and energy-efficient methods for the production of metallic nanoparticles

• Mitra Naghdi,
• Mehrdad Taheran,
• Satinder K. Brar,
• M. Verma,
• R. Y. Surampalli and
• J. R. Valero

Beilstein J. Nanotechnol. 2015, 6, 2354–2376, doi:10.3762/bjnano.6.243

• Ag NPs were 21 and 39 nm respectively [38]. Carboxylic acids Lai et al. produced superparamagnetic Fe3O4 NPs from FeCl3 using a mixture of water and glycerol as solvent and L-arginine as stabilizing agent. L-arginine is an amino acid that is naturally produced and therefore it is considered to be a