Cell-bead hybrids

Interesting studies were also performed based on a suspension of beads in conjunction with flow cytometry measurements [23,24], Flow cytometry, which was the standard methodology for cell population study during the last 20 years, has now begun to serve for in vitro microspheres analysis [25]. Such systems were described as multiplex microsphere bead assays and were used to detect different nucleic acid sequences hybridized on beads having different properties (size, fluorescent label). 

Each sample was diluted in decimal stages to ensure the reliability of the end result. The dilute solutions were seeded evenly on the surface of the Petri dishes with sterile beads. This technique is necessary if the cells are to be identified by DNA/DNA hybridization (Volume 1, Section 4.3.5) on colonies or PCR (Volume 1, Section 4.3.6). If the wine contains very few microorganisms, it is filtered onto a 0.45-tim membrane, which is then deposited on the specific... 

Fig. 3. Examples of the analysis of cultured explants. A Appearance of an explant in the stereomicroscope. The epithelium as well as the TGF(i-1-releasing bead have induced a translucent zone in dental mesenchyme. B Localization of cell proliferation with BrdU incorporation under the epithelium as well as around an FGF-4-releasing bead. C Whole-mount in-situ hybridization analysis of Msx-1 gene expression indicating induction by the epithelium in the mesenchyme. D Whole-mount immunohistochemical staining showing stimulation of tenascin expression in the mesenchyme around an FGF-4-releasing bead. E Section of an explant of dental mesenchyme and a TGF 3-1-releasing bead (the filter has been detached during processing). F Dark-field illumination of the explant in E showing the induction of tenascin-C transcripts by in-situ hybridization analysis e, dental epithelium m, dental mesenchyme b, bead.

Multilayers may also be used for their permeation properties. Accordingly, membranes covered by multilayers have been employed for gas permeability measurements and for pervaporation studies [88,181,185,333-335]. These measurements showed, for example, 02/H20,C02/02, or toluene/ heptane selectivity. The permeation properties of polyelectrolyte multilayers are also important when they are used for the encapsulation of enzymes [210] or living cells [336,337]. The deposition of polyelectrolyte multilayers or of hybrid polyelectrolyte/inorganic multilayers on latex particles, and the subsequent dissolution or calcination of the latex beads leads to the fabrication of hollow spheres [94-96,338-340]. Potential applications of such hollow spheres are numerous, for example, for the controlled release and targeting of drugs. 

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