Fluorescent Estapor® Microspheres

Merck 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.

Preparation of Our Fluorescent Microspheres Involves:

• Swelling the polymeric microsphere so that fluorescent dyes may enter the microsphere's pores
• Unswelling the poIymeric microspheres so that the fluorescent dyes become physically entrapped in the pores
• Made in polystyrene (PS) or in polyvinyltoluene (PVT), our fluorescent microspheres are monodisperse and uniform

Plain or functionalized Estapor® Microspheres from 0.250 to 1.0 µm are the recommended size references for this application.

Estapor® Advice

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.

Unfunctionalized Fluorescent Estapor® Microspheres

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.

Carboxylated Fluorescent Estapor® Microspheres (–COOH)

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).