Chemistry with [¹⁸F]Fluoride Ion

Abstract

The success of molecular imaging with positron‐emission tomography (PET) depends on the availability of selective molecular probes labeled with positron‐emitters, such asfluorine‐18 (t1/2 = 109.7 min). No‐carrier‐added (NCA) [18F]fluoride ion (18F–) is the primary reagent for the preparation of 18F‐labeled tracers in high specific activity. In this microreview, we survey current and advancing radiochemical methods and technologies for the use of NCA [18F]fluoride ion in the preparation of 18F‐labeled radiotracers for applications with PET. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Biocompatibility of Thermally Hydrocarbonized Porous Silicon Nanoparticles and their Biodistribution in Rats

“…23 In this study, 0.5Ϫ1.0 GBq of no-carrier added [ 18 F]fluoride corresponding to less than 0.1 g in mass was used to label a 10000-fold excess of 1 mg of THCPSi nanoparticles. Therefore, radiolabeling of the THCPSi surface with a trace amount of 18 F is unlikely to result in detectable change in the particle size and surface chemistry and, consequently, alterations in the in vivo behavior of the nanoparticles.…”

Radiolabelling diverse positron emission tomography (PET) tracers using a single digital microfluidic reactor chip

“…Due to the properties of the water-MeCN azeotrope, this is an effective method for removing residual water. Typically, fluorine-18 radiochemistry processes using the macroscale synthesizer include 2-3 successive cycles of azeotropic evaporation with MeCN to obtain the "naked" [ 18 F]fluoride ion for the subsequent fluorination reaction [4]. Multiple azeotropic evaporations were also used in the preliminary devices [21,26] as well as our early work [22,25].…”

“…Although reaction times are typically shorter when performed with microfluidic volumes [4], the overall radiotracer synthesis time (from initial loading to extraction) on the EWOD device was longer than desired and ranged from 31 + 1 min for [ 18 F]fallypride (n=6) to 58 + 8 min for [ 18 F]SFB (n=3). During the developmental period, the synthesis times were longer due to tedious process of manual reagent loading and manual activation of electrodes.…”

“…Reaction efficiency can also be improved with reduced volumes because of increased concentration of the radioisotope, expedited heat transfer, and quicker mass transport [3]. This is important for radiosynthesis reactions that sometimes involve low-yields and short half-life isotopes [4]. While the small amount of product limits the utility of microfluidic chemical synthesis in some cases, it is not an issue for PET imaging, which requires product in only nanogram quantities.…”

18F-Labeling of Mannan for Inflammation Research with Positron Emission Tomography

“…Another favorable physical property of 18 F is its suitably long half-life (109.8 min), although 18 F is a shortlived radionuclide. This enables multistep radiosynthesis feasible 14,15 and distribution to hospitals distanced from production sites possible.…”