AJ-BIND: Functionalized polymer particles

AJ-Bind particles have functional groups covalently bounded to the surface of the particles, offering higher performance in diagnostics and other applications in which it is necessary to bind covalently the ligand to the particle surface. The surface density of the functional groups can be varied in order to modify the response of the reagent.

Carboxyl functionality (-COOH) is the most demanded functionality in diagnostic applications due to its well known coupling chemistry, which requires the use of a carbodiimide as an intermediate.

The advantage of chloromethyl groups (-CH₂Cl) is that the coupling reaction can be achieved directly in one step and no intermediate steps are required (like a simple protein adsorption process on to plain polystyrene particles). Other functional groups like sulfonate (-SO₃^–), amino (-NH⁺) or other groups are available for specific uses upon request.

Variables

Advantages of AJ-Bind particles

• Greater stability of the reagents over time (improvement of the reagents shelf life).
• Greater sensitivity. The covalent coupling avoids the desorption of the proteins in the aqueous phase.
• Greater selectivity. Covalent coupling allows for protein orientation which keeps the active sites accessible. This effect can even be improved by the use of spacers.

Uses

AJ Bind particles are used in turbidimetry, nephelometry or for slide agglutination diagnostic kits in which is necessary to bound covalently the protein to the particle surface. Of course, they can be used too as standards for calibrations, colloidal models…

Examples of reference codes

• AJ20COOH: Mean particle size of 200 nm. Covalently bounded carboxyl groups on the surface.
• AJ30CH₂Cl: Mean particle size of 300 nm. Covalently bounded chloromethyl groups on the surface.
• AJ17COOH-Clean: Precleaned dispersion with a mean size of 170 nm. Covalently bounded carboxyl groups on the surface.