Fluorescent carboxyl microspheres are created by diffusion or entrapment of the dye into the polymer matrix, followed by functionalization of the surface. Therefore, the full surface is available for covalent attachment of your biomolecule of interest.nnFluorophore embedded, carboxyl-coated microspheres with europium (III) chelate are used for time resolved fluorescence in lateral flow assays, and our product has a strong fluorescence for clear readings. We also offer the PolyLink Protein Coupling Kit with the properly prepared reagents for coupling to our carboxylated beads.