Magnetic particles/nanoparticles

Particularly attractive for numerous bioanalytical applications are colloidal metal (e.g., gold) and semiconductor quantum dot nanoparticles. The conductivity and catalytic properties of such systems have been employed for developing electrochemical gas sensors, electrochemical sensors based on molecular- or polymer-functionalized nanoparticle sensing interfaces, and for the construction of different biosensors including enzyme-based electrodes, immunosensors, and DNA sensors. Advances in the application of molecular and biomolecular functionalized metal, semiconductor, and magnetic particles for electroanalytical and bio-electroanalytical applications have been reviewed by Katz et al. [142]. 

Small magnetic particles exist in nature or are produced artificially (Chs. 6 to 8). Nanoparticles have sizes ranging from a few nanometers to submicron dimensions (Ch. 7), whereas molecular magnets (Ch. 6) contain a few magnetic atoms in well-defined atomic environments. Clusters are intermediate structures, with less well-defined atomic environments but exhibiting atomic features such as facets (Ch. 8). 

Even below TB, the magnetization of nanoparticles may be strongly affected by thermal activation. Very small Co particles showing coherent rotation allowed thermal activation effects to be analyzed quantitatively [110]. From 40 mK up to 12 K, the coercive field was found to be a function of the expression theoretically expected for thermal activation, Tln(T/T0]213. 

Cationic PNIPAM-covered magnetic particles Hetero coagulation of iron oxide nanoparticles onto cationic particles. Encapsulation of preformed particles by polymerization of NIPAM, BAM and AEMH 300-1000 nm Superparamag-netic, bioreactive particles. Temperature, salinity and pH sensitive [10,18,19]... 

For instance, ligand protected 8nm Au and 5nm Ag particles form perfect bimodal 2D arrays of the AB2 type. Magnetic CoPts nanoparticles of different size (4.5 and 2.6 nm) even form AB5 structures, whereas identical species... 

Magnetic metal nanoparticles tend to self-assemble not only for reasons known from nomnagnetic species, namely, van der Waals forces, but especially owing to their intrinsic magnetic nature. Solutions of 4.8mn CoPts particles, spread onto a substrate, organize spontaneously when the solvent is evaporated.Higher concentrations of the solutions easily result in formation of double and triple layers as is indicated in Figure IS. ... 

Hergt R, Dutz S, Miiller R, Zeisberger M (2006) Magnetic particle hyperthermia, nanoparticle magnetism and materials development for cancer therapy. J Phys Condens Matter 18 S2919-S2934... 

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