Nanoparticle bead

Surface Plasmon Resonance Light Scatter Nanoparticle-Bead Probes... 

Scientists also have learned how to mimic the surface of a butterfly wing. Polystyrene beads and smaller silica nanoparticles are suspended in water and mixed thoroughly using ultrasound. When a glass slide is dipped into the suspension and slowly withdrawn, a thin film forms on the glass surface. This film is a regular array of beads encased in a matrix of nanoparticles. Heating the film destroys the polystyrene beads but leaves the silica web intact. The result is a silica inverse opal film. 

Recently, the immobilisation of indicators in tiny beads rather than in polymer layers has provided nanoparticles which can be inserted into cells and allow the measurement of various analytes (oxygen, sodium, potassium) within a living cell16. 

Apart from polymers and indicators, the beads can contain a variety of other components that improve their properties or provide additional functionalities. For example, addition of titanium dioxide nanoparticles significantly increases the brightness of the beads due to light scattering [5]. The plasmonic enhancement... 

Micro- and nanobeads with magnetic properties have recently become popular since these tools can be manipulated, e.g., collected in the region of interest. Magnetite nanoparticles are introduced in order to render the polymeric beads magnetic. Preparation and application of magnetic beads will be discussed in more detail in Sect 5.5. 

Whenever the commercially available particles do not match the operator s requirements, a variety of possibilities exist in order to modify the particles from company suppliers. Similarly to other doped beads the dyes [92] or quantum dots [107, 108] can be physically entrapped into magnetic beads by swelling or are covalently bound to the surface of the particles. If localization of the dye on the particle surface is desired or if the polarity of dye and/or matrix polymer does not allow the irreversible entrapment of the dye in the bulk polymer, a covalent attachment of the dye is preferable [109, 110]. Even the covalent binding of whole fluorescent nanoparticles to magnetic microparticles is possible, as shown by Kinosita and co-workers who investigated the rotation of molecular motors [111]. 

Zhu, Y., et al., Multiwalled carbon nanotubes beaded with ZnO Nanoparticles for ultrafast nonlinear optical switching. Advanced Materials, 2006.18(5) p.587-592. 

Chromatographic approaches have been also used to separate nanoparticles from samples coupled to different detectors, such as ICP-MS, MS, DLS. The best known technique for size separation is size exclusion chromatography (SEC). A size exclusion column is packed with porous beads, as the stationary phase, which retain particles, depending on their size and shape. This method has been applied to the size characterization of quantum dots, single-walled carbon nanotubes, and polystyrene nanoparticles [168, 169]. Another approach is hydro-dynamic chromatography (HDC), which separates particles based on their hydro-dynamic radius. HDC has been connected to the most common UV-Vis detector for the size characterization of nanoparticles, colloidal suspensions, and biomolecules [170-172]. 

The MARTINI model effectively replaces three to four heavy atoms with a bead, parameterized to reproduce condensed-phase thermodynamic data of small molecules [23]. The MARTINI model has been used to investigate many biological processes, such as lung surfactant collapse [24], nanoparticle permeation in bilayers [25], large domain motion of integral membrane proteins [26], vesicle fusion [27,28], and lateral domain formation in membranes [29]. 

The first field of application for SdFFF were latex beads, which were used either to test the channels or to produce separation results alternative to other separation techniques. PS nanoparticles used as model surfaces for bioanalytical work have been analyzed by SdFFF [39]. The appealing feature of SdFFF is its ability to characterize particle adlayers—by direct determination of the mass increase performed by observing the differences in retention between the bare and coated particles—with high precision and few error sources the mass of the coating is determined advantageously on a per particle basis. 

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