Search results for "Magnetic Nanoparticle"
showing 10 items of 128 documents
Cover Picture: Nanoscale Deposition of Single-Molecule Magnets onto SiO2 Patterns (Adv. Mater. 2/2007)
2007
The cover shows a schematic of scanning probe nanolithography based on the spatial confinement of an oxidation reaction within a water meniscus, and its application for fabricating ordered arrays of cationic Mn12 single-molecule magnets. Romero, Coronado, Garcia, and co-workers report on p. 291 that electrostatic interactions between the molecules and trapped charges within the nanodots drive the positioning of the molecules at the nanoscale.
Manganese iron oxide superparamagnetic powder by mechanochemical processing. Nanoparticles functionalization and dispersion in a nanofluid
2012
Manganese ferrite nanoparticles were synthesized using a High-Energy Ball-Milling mechanochemical method. After 1 h of milling, the process produces a material consisting of single crystalline domain nanoparticles having a diameter of about 8 nm. Chemical properties of the synthesized powders allow an easy functionalization with citric acid. Both as-obtained and functionalized samples show superparamagnetic behaviour at room temperature, and the functionalized powder is stably dispersible in aqueous media at physiological pH. The average hydrodynamic diameter is equal to similar to 60 nm. Nanoparticles obtained by the reported High-Energy Ball-Milling method can be synthesized with high yie…
Nanomaterials and phase sensitive based signal enhancment in surface plasmon resonance
2018
Measurement of small molecules in extremely dilute concentrations of analyte play an important role in different issues ranging from food industry to biological, pharmaceutical and therapeutical applications. Surface plasmon resonance (SPR) sensors can be a suitable choice for detection of small molecules based on interactions with biomolecules. However, sensitivity of the system for detection of these molecules is very low. Improving sensitivity has been a challenge for years. Therefore, different methods have been used to enhance SPR signals. The SPR signal enhancement using numerous nanomaterials has provided exciting results. Among various nanomaterials, metal nanoparticles (for instanc…
Contactless Nanoparticle-Based Guiding of Cells by Controllable Magnetic Fields
2021
Peter Blümler,1 Ralf P Friedrich,2 Jorge Pereira,3 Olga Baun,1 Christoph Alexiou,2 Volker Mailänder3,4 1Institute of Physics, Johannes Gutenberg-University Mainz, Mainz, 55128, Germany; 2Department of Otorhinolaryngology, Head and Neck Surgery, Section of Experimental Oncology and Nanomedicine (SEON), Else Kröner-Fresenius-Stiftung-Professorship, Universitätsklinikum Erlangen, Erlangen, 91054, Germany; 3Department of Physical Chemistry, Max Planck Institute for Polymer Research, Mainz, 55128, Germany; 4Department of Dermatology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, 55131, GermanyCorrespondence: Peter Blümle…
Effect of precursor concentration on size evolution of iron oxide nanoparticles
2017
Thermal decomposition is a promising route for the synthesis of magnetic nanoparticles. The simplicity of the synthesis method is counterbalanced by the complex chemistry of the system such as precursor decomposition and surfactant–reducing agent interactions. Control over nanoparticle size is achieved by adjusting the reaction parameters, namely, the precursor concentration. The results, however, are conflicting as both an increase and a decrease in nanoparticle size, as a function of increasing concentration, have been reported. Here, we address the issue of size-controlled synthesis via the precursor concentration. We synthesized iron oxide nanoparticles with sizes from 6 nm to 24 nm wit…
Silica-coated superparamagnetic nanoparticles as contrast agent for magnetic resonance imaging: Synthesis and physicological charaterizations
2015
Superparamagnetic iron oxide nanoparticles (SPIONs) have received a growing interest for various biomedical applications due to their interesting magnetic properties. Herein, we report a method for facile synthesis of colloidal silica-coated superparamagnetic iron oxide nanoparticles (Si-SPIONs). The polyvinyl alcohol (PVA)-SPIONs were successfully prepared and then coated with silica by the modified Stober method. The obtained Si-SPIONs are highly monodisperse with uniform morphology. Notably, comparing to uncoated SPIONs, silica coated ones show colloidal stability region at physiological pH which is applicable in biomedical applications and synthesis at the scale of grams was easily obta…
Magnetic molecularly imprinted polymer for the simultaneous selective extraction of phenoxy acid herbicides from environmental water samples
2022
[EN] A selective magnetic molecularly imprinted polymer (MMIP) was synthetized with 4-chloro-2-methylphenoxyacetic acid as template and 4-vinylpiridine as monomer in presence of vinylized magnetite nanoparticles. Scanning electron microscopy, nitrogen adsorption-desorption isotherms, Fourier transform infrared spectrometry and vibrating sample magnetometry were applied to characterize the resulting material. The synthesized MMIP was applied as sorbent in magnetic molecularly imprinted solid-phase extraction (MMISPE) for selective extraction of a mixture of the five herbicides 4-chloro-2-methylphenoxyacetic acid (MCPA), 4-(4-chloro-2-methylphenoxy)butyric acid (MCPB), mecoprop (MCPP), fenoxa…
Elastic torsion effects in magnetic nanoparticle diblock-copolymer structures
2011
Magnetic properties of thin composite films, consisting of non-interacting polystyrene-coated γ-Fe(2)O(3) (maghemite) nanoparticles embedded into polystyrene-block-polyisoprene P(S-b-I) diblock-copolymer films are investigated. Different particle concentrations, ranging from 0.7 to 43 wt%, have been used. The magnetization measured as a function of external field and temperature shows typical features of anisotropic superparamagnets including a hysteresis at low temperatures and blocking phenomena. However, the data cannot be reconciled with the unmodified Stoner-Wohlfarth-Néel theory. Applying an appropriate generalization we find evidence for either an elastic torque being exerted on the …
The zero field self-organization of cobalt/surfactant nanocomposite thin films
2009
Cobalt nanostructures have been prepared by a chemical route based on the Co(II) reduction in the confined space of cobalt bis(2-ethylhexyl)sulfosuccinate (Co(DEHSS)(2)) reverse micelles dispersed in n-heptane. This procedure involves the rapid formation of surfactant softly coated Co nanostructures followed by a slow separation process of the magnetic-field responsive Co/surfactant nanocomposites from the liquid phase. The detailed structure of thin films of the Co/surfactant nanocomposites has been investigated by scanning force microscopy (SFM). The thin films were characterized by different anisotropic features. Micrometric long domains of self-aligned ellipsoidal NPs (tens of nanometer…
Nanoscale Deposition of Single-Molecule Magnets onto SiO2 Patterns
2007
bet on a silicon oxide template while the rest ofthe macroscopic surface remains free of molecules. Local oxi-dation was used to fabricate silicon oxide nanopatterns, eitherdots or stripes, over a Si (100) surface coated with a SAM.Their width ranged from 30 to 500 nm whereas the lengthcould be modified from a few nanometers up to several mi-crometers. Nanoscale direct assembly arose from a combina-tion of three factors: i) the strength of the attractive electro-static interactions between the molecules and the local oxides;ii) the weak repulsive interaction between the molecules andthe unpatternedsurface; and iii) the size of the nanopattern.Local oxidation nanolithography (LON) allows the…