Fluorine-18 (18F-) is an important isotope in radiotracer synthesis for positron emission tomography (PET). Fluorine-18 possesses many desirable properties such as a strong and stable C-F bond, relatively low energy, and a half-life that provides sufficient time for local shipping. Radiosynthesis of the majority of PET probes involves the concentration of the F18fluoride ion, followed by several cycles of azeotropic distillation to remove all the water. The dried and activated 18F is then transferred to the microfluidic or capillary microreactor for subsequent fluorination steps. These steps have traditionally mandated a scale of production that is much greater than the required amount of isotope, leading to severe limitations in cost, speed of production and reaction efficiency. The inefficient production of the radioisotope is a restriction on further research and clinical study of new radiolabeled compounds. Novel approaches that can efficiently downscale the preparation and synthesis of PET probes have enormous potential in improving research and access to PET imaging.
Dr. Keng and colleagues in UCLA’s Department of Molecular & Medical Pharmacology have developed a system that uses functional polymer monoliths on a flow-through microfluidic platform to perform ion concentration, solvent exchange and activation processes within a single chip with high efficiency. The polymer monolith dually concentrates and activates the [18F] fluoride ion on the microfluidic chip thereby circumventing additional drying steps. The unique polymer monolith is highly suitable for microfluidic applications due to the ease of preparation, high loading capacity, high surface area, tunable pore size, tunable functionalities and high hydrodynamic flow. The researchers have confirmed that the anion exchange monoliths polymerized within the 13 μL serpentine channels of microfluidic chip consisted sufficient surface area to trap [18F]fluoride ion up to 1 Ci in radioactivity. Additionally, they have successfully prepared and demonstrate the fluoride trapping and activation in other micro-volume chambers. The Keng group has successfully demonstrated comparable fluorination efficiencies of several commonly used PET probe intermediates. Thus, this method and apparatus provides a practical and efficient interface for concentrating, drying, and activation non-carrier added 18F-fluoride directly from the cyclotron into the tens to hundreds of microliters volume. This technology platform can also be adapted for conventional macroscale radiosynthesizer to eliminate the time consuming drying processes.
o Ease of preparation
o High loading capacity
o High surface area
o Tunable pore size
o Tunable functionalities
o High hydrodynamic flow
Country | Type | Number | Dated | Case |
United States Of America | Issued Patent | 9,321,866 | 04/26/2016 | 2012-813 |
flow chemistry, microfluidic, positron emission tomography, PET, radiotracer synthesis, PET imaging, solvent exchange, drying, chemical drying, polyer monolith, polymer, chemical separation, on-chip, distillation, microreactor, 18F, 18-fluoride, PET probe, microscale chemistry