Magnetic beads are devices composed of superparamagnetic iron oxide particles, typically ranging from 20 to 30 nanometers in size. These particles have a functional carboxylic group covering an iron-oxide core, allowing them to bind to biomolecules such as DNA and RNA, enabling quick and effective separation. The main types of magnetic beads include cells, nucleic acids, peptides, proteins, and others. Protein magnetic beads, for example, are utilized in the purification of epitope-tagged proteins.