Magnetic particle is also known as magnetic beads, magnetic microspheres, nano magnetic beads, and etc., which is a kind of super paramagnetic microspheres with small particle size. It is made of magnetic material, such as iron oxide and organic or inorganic composite materials and functional materials with special structure and properties.

Zeesan magnetic particle is a kind of new macromolecule material composed of iron oxide and silicon dioxide, which can be applied to nucleic acid extraction of biological samples. The basic principle is that the nucleic acid can combine with SiO₂ specificity in certain conditions. Based on the characteristics of magnetic particle can be quickly gathered in the magnetic field, and dispersed when leaved the magnetic field, Zeesan also developed nucleic acid extraction systems with the use of magnetic beads, to achieve the automation of nucleic acid extraction.