Chemistry Weekly Seminar - Ralf Schirrmacher

Title: Silicon-based 18F-radiochemistry: The development of a novel labeling methodology for PET imaging

During 2005 and 2016 we introduced a new radiochemical methodology to label small as well as large organic compounds with the radio-isotope fluorine-18 (18F). The distinguishing feature of this technology is that it uses the labeling concept of isotopic exchange which had previously been deemed as unsuccessful and unfeasible in the contemporary literature. The reason for this is routed in its perceived disability to yield radioactive compounds of high specific activity. Our so called Silicon-Fluoride-Acceptor Chemistry (“SiFA-Chemistry“) invalidated this commonly accepted dogma in radiochemistry by providing evidence for the first time in literature that an isotopic exchange can yield labeled compounds of high specific activity. Furthermore, the conceptual basis of the methodology we introduced breaks with standard concepts of radiolabeling. In contrast to ordinary labeling with 18F, we devised a new chemical skaffold based on silicon as opposed to carbon as a center atom bound to radioactive fluorine. The SiFA chemistry is a one-step radiolabeling reaction that does not require high temperatures, catalysts or accelarants. Particularly valuable is the fact that the purification of the 18F-labeled compound does not require any sophisticated technical procedures such as High Performance Liquid Chromatography (HPLC). The SiFA technology has been confirmed and used by other research groups in Europe, Canada and the US, and it has found entry into current text-book literature, becoming thoroughly accepted.