Fluorescent Estapor^® Microspheres
for Lateral Flow

As the top choice in microspheres for many IVD manufacturers, Estapor^® offers proven success with a recognized and established portfolio of fluorescent microspheres.

The Estapor^® Advantage

Made with polystyrene (PS), our fluorescent Estapor^® microspheres are monodisperse and uniform. They are easily dispersed allowing for efficient washing, reduced background, and low non-specific binding. They do not experience dye leaching, display maximum color brilliance, and exhibit stable surface properties so you get the performance you expect, every time.

See our full list of Fluorescent microspheres offerings here:

New! Estapor^® Europium Microspheres

We are proud to announce the launch of the new Estapor^® Europium Microspheres as the latest part of our comprehensive lateral flow portfolio. As a key partner and supplier to rapid diagnostics manufacturers, we’ve developed these beads in order to provide several advantages over traditional fluorescent microspheres.

Benefits of Estapor^® Europium Microspheres

• Significantly improved quantitative lateral flow assay sensitivity
• Reduced background fluorescence
• Simplified assay readability and easier to quantify
• Longer Stokes shift than traditional fluorescent labels
• Enhanced fluorescent quantum yield facilitating a low detection limit
• Functionalized with a carboxylated surface for easy protein conjugation
• Range of sizes available; choose the best for the desired target analyte

Fig. 1 Qualitative image of myoglobin lateral flow test strips with Estapor® Europium microspheres viewed under UV light.

Fig. 2 Myoglobin lateral flow test strips utilizing 300nm Europium microspheres viewed under UV light.

Just Released

Download the new application note
Development of a Quantitative Lateral Flow Test Using Estapor^® Europium Microspheres

Best in Class: Estapor^® XC Microspheres

Our tried and trusted XC fluorescent microspheres are used in millions of rapid diagnostic assays worldwide. Offering consistency and ease of use in quantitative lateral flow assays, our XC microspheres are a convenient and reliable choice.

Fig. 3 Qualitative image of Human Chorionic Gonadotropin (hCG) lateral flow test strips utilizing XC fluorescent microspheres viewed under UV light.

Fig. 4 Schematic of the Excitation and Emission profile of 'XC'. Max excitation and emission wavelengths indicated on each peak. Note; XC is well suited to the 488nm and 515nm of the Argon laser.

Fluorescent Microsphere Technical Considerations

Surface Chemistry

Our fluorescent microspheres are pre-functionalized with carboxyl (-COOH) groups at the microsphere surface. This allows for quick and efficient covalent binding of polyclonal or monoclonal antibodies, proteins and haptens. Moreover, the -COOH groups increase polystyrene stability and thus overall assay performance.

Microsphere Size and Membrane Pore Size

In lateral flow assays, microspheres move through the porous structure of the lateral flow membrane. The size of the microspheres and membrane pores affect microsphere mobility. Smaller microspheres will move faster than larger microspheres and a more open membrane pore structure will also promote faster movement of microspheres. Thus, microsphere size as well as the membrane pore size should be carefully chosen to maximize assay sensitivity. Larger beads (300 – 500 nm diameter) flow through the membrane at a slower rate, thereby offering greater sensitivity, whilst smaller microspheres (100 – 200 nm diameter) may allow a faster run time but with lower sensitivity.

Compatibility of the Reader

The lateral flow test reader must be compatible with the excitation and emission properties of the fluorescent microspheres. The strips must also have dimensions that are compatible with the scanning system inside the reader.

View our full list of Fluorescent microspheres offerings here.