Diagnostic and / or therapeutic agent, process for its preparation and use

The invention relates to the field of materials science and medicine and relates to an agent which can be used for example as a contrast agent for the localization of cancer cells. The object of the present invention is to provide an agent which recognizes sensitive and selective the location and the type of the assayed molecules or cells. The object is achieved by an agent which consists of at least BioShuttle molecules to the above peptide-based molecules endohedral fullerenes are coupled, wherein the endohedral fullerenes are hydrophobic and of the formula correspond, with x = 0 to 3, n ≧ 34, A rare earths and / or transuranics, M metals, non-metals Z and C represent carbon. The object is further achieved are coupled by a process wherein the hydrophobic endohedral fullerenes BioShuttle molecules via an irreversibly running Diels-Alder reaction with inverse electron demand (DAR