Syntheses of 11C- and 18F-labeled carboxylic esters within a hydrodynamically-driven micro-reactor.
Carboxylic esters were successfully labeled with one of two short-lived positron-emitters, carbon-11 or fluorine-18, within a hydrodynamically-driven micro-reactor. The non-radioactive methyl ester was obtained at room temperature; its yield increased with higher substrate concentration and with reduced infusion rate. Radioactive methyl ester was obtained from the reaction of (10 mM) with in 56% decay-corrected radiochemical yield (RCY) at an infusion rate of 10 microL min(-1), and when the infusion rate was reduced to 1 microL min(-1), the RCY increased to 88%. The synthesis of the non-radioactive fluoroethyl ester from and required heating of the micro-reactor on a heating block at 80 degrees C (14-17% RCY), whilst the corresponding radioactive from and was obtained in 10% RCY. The radioactive 'peripheral' benzodiazepine receptor ligand was obtained from the reaction of acid with labeling agent in 45% RCY at an infusion rate of 10 microL min(-1). When the infusion rate was reduced to 1 microL min(-1), the RCY increased to 65%. The results exemplify a new methodology for producing radiotracers for imaging with positron emission tomography that has many potential advantages, including a requirement for small quantities of substrates, enhanced reaction, rapid reaction optimisation and easy product purification.
Lu
Shui-Yu
SY
PET Radiopharmaceutical Sciences, Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-1003, USA. Shuiyu.Lu@mail.nih.gov
Watts
Paul
P
Chin
Frederick T
FT
Hong
Jinsoo
J
Musachio
John L
JL
Briard
Emmanuelle
E
Pike
Victor W
VW
D002245:Carbon Dioxide; D002250:Carbon Radioisotopes / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D004952:Esters; D005462:Fluorine Radioisotopes / Q000737:chemistry*; D007553:Isotope Labeling / Q000379:methods*; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D008904:Miniaturization; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*
D002250:Carbon Radioisotopes; D002264:Carboxylic Acids; D004952:Esters; D005462:Fluorine Radioisotopes; D019275:Radiopharmaceuticals; D002245:Carbon Dioxide; C041069:carboxyl radical