Microspheres (also called latex beads or latex particles) are spherical particles in the colloidal size range that are formed from an amorphous polymer such as polystyrene. Our Molecular Probes® FluoSpheres® beads are manufactured using high-quality, ultraclean polystyrene and are loaded with a variety of our proprietary dyes to create intensely fluorescent beads that typically show little or no photobleaching, even when excited with the intense illumination required for fluorescence microscopy. Different surface modifications are available to facilitate the coupling of various molecules and proteins to the surface of the bead.

FluoSpheres® Microsphere Specifications

• Label (Ex/Em): Yellow-green fluorescent (505 / 515)
• Nominal bead diameter: 1.0 µm
• Surface modification: NeutrAvidin®
• Solids: 1%

Characteristics of the Various FluoSpheres® Coupling Surfaces

• Carboxylate-modified FluoSpheres® beads have a high density of pendent carboxylic acids on their surface, making them suitable for covalent coupling of proteins and other amine-containing biomolecules using water-soluble carbodiimide reagents such as EDAC
• Sulfate FluoSpheres® beads are relatively hydrophobic particles that will passively and nearly irreversibly adsorb almost any protein, including albumin, IgG, avidin, and streptavidin
• Aldehyde—sulfate FluoSpheres® beads have surface aldehyde groups added, designed to react with proteins and other amines under very mild conditions.
• Amine-modified FluoSpheres® beads can be coupled to a wide variety of amine-reactive molecules, including the succinimidyl esters and isothiocyanates of haptens and drugs or the carboxylic acids of proteins, using a water-soluble carbodiimide

Key Applications of Microspheres

• Instrument calibration (flow cytometry, microscopy, HTS, HCS)
• Flow testing (microfluidics, blood flow, water flow, and air flow)
• Cell biology tracers (cell differentiation and cell tracing)
• Immunoassays (agglutination tests, ELISA, particle capture, and contrast reagents)

Choices for FluoSpheres® Fluorescent Microspheres
Among our complete offering of fluorescent microspheres products, you’ll find beads with these variations:

• Ten fluorescent colors
• Ten nominal bead diameters: 0.02 µm, 0.04 µm, 0.1 µm, 0.2 µm, 0.5 µm, 1.0 µm, 2.0 µm, 4.0 µm, 10.0 µm, and 15.0 µm
• Four surface modifications for protein coupling: carboxylate, sulfate, aldehyde-sulfate, amine
• Microspheres that are additionally precoupled with streptavidin, NeutrAvidin, biotin, europium, and platinum

Choices for Unstained Microspheres
We also offer hundreds of choices for UltraClean™ surfactant-free microspheres for research and commercial applications.

We’ll Make a Custom Microsphere Product for You
We will prepare custom orders upon request. For example, FluoSpheres® beads can be prepared with intensities that are lower than those of our regular selection, a desirable feature in some multicolor applications. Our custom conjugation service is efficient and confidential, and we guarantee the quality of our work. We are ISO 9001:2000 certified.

For Research Use Only. Not intended for animal or human therapeutic or diagnostic use.