Microparticles

In physics and biology, microparticles are the smallest particles with a diameter of less than one millimeter.

Microparticles occur in living nature e.g. B. as constrictions of biomembranes inside the cell. Depending on their function, these are called lysosomes , endosomes , micro-bodies , peroxisomes or microsomes . Microparticles released to the outside by constriction of the cell membrane, e.g. B. the endothelial microparticles .

As non-biological microparticles u. a. also describes certain aerosols (sand and dust particles), which are of great interest as fine dust as part of the air . The microparticles in the size range from 0.5 to 5 µm are able to penetrate the alveoli of the lungs particularly efficiently , while smaller nanoparticles are more likely to be exhaled and larger particles are retained by the nasal mucous membrane and the ciliated epithelium of the bronchi .

Microparticles can also be artificially produced for technical and pharmaceutical applications. If these are surrounded by a lipid-containing membrane, one speaks z. B. of liposomes . Solid microparticles made of rubber , polystyrene , glass and various metals such as gold , silver and copper are widely used in technical processes and in medical diagnostics. The specific surface properties of the microparticles are used to bind certain substances to the particle surface (e.g. antibodies ). This broad application is also due to the fact that microparticles, compared to particles in the millimeter range, have a very large surface with a small volume of material and are technically easy to manufacture.

Microplastics are used in various cosmetics to improve cleanability; it is also produced in nature from plastic waste, tire abrasion or z. B. from synthetic fiber clothing.