Fully automated radiosynthesis of [1-(2-[18F]fluoroethyl),1H[1,2,3]triazole 4-ethylene] triphenylphosphonium bromide as a potential positron emission tomography tracer for imaging apoptosis

A novel phosphonium salt bearing a fluorine-18 labelled triazole has been designed as a potential imaging agent for apoptosis. The radiosynthesis of [1-(2-[18F]fluoroethyl),1H[1,2,3]triazole 4-ethylene] triphenylphosphonium bromide ([18F]MitoPhos_01) has been carried out on a fully automated system in a two-step reaction. Radiolabelling an ethyl azide and then carrying out a copper-mediated 1,3-cycloaddition reaction has allowed for total synthesis time to be slightly more than 1h from aqueous [18F]fluoride. After purification by HPLC, the average radiochemical yield was determined to be 9% (not decay corrected); the specific activity was on average 70GBq/mu mol at the end of synthesis, and the radiochemical purity was >99%.