Carboxyl Magnetic Beads is magnetic bead with surface functional group -COOH. The magnetic bead consists of a single-crystal Fe₃O₄ sphere core and dextran coating layer. Through chemical modification of dextran, the carboxyl groups (-COOH) are joined to the magnetic beads through a short hydrophilic linker. The hydrophilic surface ensures the magnetic beads excellent dispersion ability and easy handling property in a wide variety of buffers.

Through activation of Carboxyl Magnetic Beads with EDC, the ligands could be conjugated to the magnetic beads through primary amine groups such as antibody, protein, or peptide.