Microscopic beads

The optical trapping method uses a highly focused laser beam to trap and manipulate particles of interest in a medium (illustrated in Figure 3). The laser is focused on a dielectric particle (e.g., a silica microscopic bead), the refractive index of which is higher than the suspension medium. This produces a light pressure (or gradient force), which moves the particle towards the focal point of the beam, that is, the beam waist (Lim et al., 2006). 

Also contains microscopic beads to control the surface. 

Sephadex. TM for a dry, insoluble powder composed of microscopic beads that are synthetic organ-... 

Thorpe, D. S. and Walle, S. (2000) Combinatorial chemistry defines general properties of Hnkers for the optimal display of peptide ligands for binding soluble protein targets to tentagel microscopic beads. Biochem. Biophys. Res. Commun. 269,591-595. 

Many of the mesoscale techniques have grown out of the polymer SCF mean field computation of microphase diagrams. Mesoscale calculations are able to predict microscopic features such as the formation of capsules, rods, droplets, mazes, cells, coils, shells, rod clusters, and droplet clusters. With enough work, an entire phase diagram can be mapped out. In order to predict these features, the simulation must incorporate shape, dynamics, shear, and interactions between beads. 

Fig. 4. Scanning electron microscope (SEM) image of FeCl3-intercalated CNTs assuming a bead-string structure with partially intercalated and swelled portions.

If chromatin is swelled suddenly in water and prepared for viewing in the electron microscope, the nucleosomes are evident as beads on a string, dsDNA being the string (Figure 12.28). The structure of the histone octamer core has been determined by X-ray crystallography without DNA by E. N. Moudrianakis s laboratory (Figure 12.29) and wrapped with DNA by T. J. 

Fig. 3-5. Schematic of the visual screening of colored beads in the field of optical microscope. Open circles red beads, close circles blue beads, dashed circles brown beads.

For on-bead analysis vibrational spectroscopy (IR-spectroscopy) can be employed attenuated total reflection is a method allowing fast and nondestructive on-bead analysis of small samples (single bead analysis) without significant sample preparation. Solid phase NMR is the method of choice if complex structural analysis is intended on the support. Spatially resolved analysis on the resin is possible with microscopic techniques. 

Fig 25 Comparison of microscopic particle size distribution with the average distribution of four identical runs made with the Coulter Counter (Sharpies standard glass bead sample, type XC-3)... 

Sugiura, T., Okada, T., Inouye, Y Nakamura, O. and Kawata, S. (1997) Gold-bead scanning near-field optical microscope with laser-force position control. Opt. Lett., 22, 1663-1665. 

Although several types of fluorescent beads were proposed as a microscopic fluorescence standard 30 years ago,2 beads have not been used as a proteinembedding matrix for routine IHC on FFPE tissue. We recently tested primary coated beads ( Dynabeads, Dynal, New York) that are coated with a goat anti-mouse antibody on the surface of the beads. In the first experiment, a monoclonal antibody to cytokeratin 7 (DAKO, 50pL/34.5pg) was bound to the beads by incubating with the beads (150 pL at a concentration of 109 beads/1 pL) at 4°C in a cold room with an automatic shaker for overnight. Incubation was followed by three phosphate-buffered saline (PBS) washes,... 

Size measurements have also been collected for film thicknesses and bead sizes on the electron microscope [79-81]. One example is the study of the relationship between film thickness and the size and mass of a bead in a fluidized-bed unit [79]. The bead diameter and film thickness were determined by SEM and correlated to dissolution data. It was found that larger beads received thicker coatings and exhibited slower release rates than the smaller beads. 

Scientists have also since demonstrated that DNA (coated on microscopic gold beads) propelled into the epidermis of test animals with a gene gun , is expressed in the animal s skin cells. Furthermore, the introduction in this fashion of DNA coding for human influenza viral antigens... 

Fig. 9. Magnified Pd EnCat catalysts bead and high-resolution electron microscope image of the surface of the polyurea matrix...

Fig. 6 (a) Schematic illustration of a flow cytometer used in a suspension array. The sample microspheres are hydrodynamically focused in a fluidic system and read-out by two laser beams. Laser 1 excites the encoding dyes and the fluorescence is detected at two wavelengths. Laser 2 is used to quantify the analyte, (b) Scheme of randomly ordered bead array concept. Beads are pooled and adsorbed into the etched wells of an optical fiber, (c) Scheme of randomly-ordered sedimentation array. A set of encoded microspheres is added to the analyte solution. Subsequent to binding of the analyte, microparticles sediment and assemble at the transparent bottom of a sample tube generating a randomly ordered array. This array is evaluated by microscope optics and a CCD-camera. Reproduced with permission from Refs. [85] and [101]. Copyright 1999, 2008 American Chemical Society... 

A new suspension array concept based on sedimentation and microscopic imaging was introduced by Moser et al. [98], Magnetic microbeads settle to the bottom of a microplate well by magnetic forces and form randomly ordered arrays, which are examined by fluorescence microscopy and automated imaging analysis. Each bead carries specific capture molecules and can be identified by a defined luminescent code. 

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