Carboxyl magnetic particles are magnetic beads coated with a high density of carboxyl functional groups on the surface. Carboxyl magnetic particles are designed for the covalent binding of proteins, antibodies or other molecules by carbodiimide chemistry. Fluorescent particles are also available. They can be used as fluorescent tracers for cell surface markers in fluorescence microscopy and flow cytometry. CD Bioparticles is the leading manufacturer and supplier of Carboxyl Magnetic Particles for R&D and commercialization in a wide variety of application areas. carboxylated beads https://www.cd-bioparticles.com/product/carboxyl-list-119.html