Radio analysis - Definitions and techniques

The development of biology in the 20th century was largely based on the exploitation of the properties of the atomic nucleus and radiation. The different isotopes of an atom have the same electronic structure, and consequently the same chemical and therefore biological properties. What's more, radioactive atoms can be detected, located and even measured at a distance by the radiation they emit.

As early as 1944, Frédéric Joliot, Robert Courrier, Alain Horeau and Pierre Sue at the Collège de France achieved the first synthesis of a hormone labeled with an artificial radioelement, thyroxine labeled with iodine-131.

Only artificial radioactivity has made it possible to follow these molecules, present in very low concentrations, from their place of production to their place of action, to isolate the receptors and study message transmission within cells.

The invention of the cyclotron and the discovery of artificial radioactivity considerably extended the possibilities for labelling organic molecules with other radioisotopes (iodine 125, tritium, carbon 14, sulphur 35, phosphorus 32...).

In this article, the authors set out the various steps to be followed by a biologist wishing to radiolabel a molecule for two applications: radioimmunoassay or autoradiography.