Microsphere

This article largely refers to micropheres or protein protocells as small spherical units postulated by some scientists as a key stage in the origin of life. The term microsphere is otherwise widely being used in various areas, such as, materials and pharmaceutical sciences, for spherical particles composed of various natural and synthetic materials with diameters in the micrometer range.

In 1953, Stanley Miller and Harold Urey demonstrated that many simple biomolecules could be formed spontaneously from inorganic precursor compounds under laboratory conditions designed to mimic those found on Earth before the evolution of life. Of particular interest was the substantial yield of amino acids obtained, since amino acids are the building blocks for proteins.

In 1957, Sidney Fox demonstrated that amino acids could be encouraged to polymerize upon exposure to moderate heat. These polypeptides formed spherical shells&mdash;microspheres. Under appropriate conditions, microspheres will bud new spheres at their surfaces.

Although roughly cellular in appearance, microspheres in and of themselves are not alive. They do not reproduce or pass on any type of genetic material. However they may have been important in the development of life, providing a membrane-enclosed volume which is similar to that of a cell.

One useful discovery made from the research of microspheres is a way to fight cancer on a molecular level. According to Wake Oncologists, "SIR-Spheres micropheres are radioactive polymer spheres that emit beta radiation. Physicians insert a catheter through the groin into the hepatic artery and deliver millions of micropheres directly to the tumor site. The SIR-Spheres microspheres target the liver tumors sparing healthy liver tissue. Approximately 55 physicians in the United States use Sirtex’s SIR-Spheres micropheres in more than 60 medical centers."