We manufacture a wide variety of uniform polystyrene particles, ranging in size from 0.05 um to 500 um. The functionalized particles from Spherotech are provided with a variety of surface functional groups such as carboxyl, amino, and hydroxyl groups for covalent coupling of proteins or other ligands. Besides carboxyl and amino fluctionalized beads, other chemistries can be found below. In addition, whether it's larger functionalized beads or a different surface chemisrty such as epoxy, PEG, NHS or cycloalkane click chemistry we are available to provide your customized needs. See STN-1: Particles Coating Procedures for protocols for attaching biological ligands.