Fluorescent Estapor® Microspheres
MilliporeSigma offers photostable fluorescent microspheres that have been specifically developed and patented by Estapor®. To prevent dye leaching and to provide the maximum of active surface, the fluorescent dyes are physically and irreversibly entrapped inside the microspheres.
Plain or functionalized Estapor® Microspheres from 0.250 to 1.0 µm are the recommended size references for this application.
Use of fluorescent Estapor® Microspheres in agglutination tests can offer an important advantage over white or dyed beads classically use in this test. In fact, thanks to a simple light, UV for example, it is possible to easily detect some agglutinates, invisible without microscopic tools, offering a more sensitive method.
Our Fluorescent Microspheres are available as plain for passive adsorption. The plain microspheres do not have any functional groups onto their surfaces, and they are dedicated to hydrophobic or passive immobilization of biomolecules onto their surface.
This coupling passive procedure works perfectly well for biomolecules with a molecular weight of 10 kDa and more. For biomolecules with a molecular weight under 10 kDa, we recommend a covalent coupling procedure.
Highly polar or ionisable chemical groups increase latex stability and facilitate covalent protein coupling to the microsphere surface.
The groups –COOH are produced by copolymerisation of the corresponding functional monomers. For carboxylated latexes, eliminating surfactant and lowering of the pH decreases latex stability and may trigger partial flocculation. In this case, we recommend diluting the latex further and slowing the stirring. If the result is still unsatisfactory, a non-ionic emulsifier may be added (0.1 to 0.5 g/L of TWEEN 20).