Labeling G-rich oligonucleotides (GROs) with N-succinimidyl 4-[18F]fluorobenzoate (S18FB)

Three G-rich oligonucleotides (GROs) were conjugated with N-succinimidyl 4-[F-18]fluorobenzoate ((SFB)-F-18). The yields for GRO5, the shortest sequence among those three GROs being tested, were 42, 70, 84, and 99% at GRO5 concentration of 59, 118, 236, and 472 nmol/100 mu l, respectively. Reaction temperature (22 and 40 degrees C), reaction time (15 and 30 min), and borate buffer concentration (25 and 50 mM) showed no noticeable effects on the labeling results. Two longer sequences of GROs, GRO15A and GRO26A, were also labeled with the same procedures and the corresponding yields were 80 +/- 2% at 93 nmol/100 mu l (n = 3) and 47 +/- 3% at 98 nmol/100 mu l (n = 3), respectively. Finally, CROa was conjugated with (SFB)-F-18 to further confirm our results. The radiochemical yields were 13.7 +/- 2.5, 40.9 +/- 3.5, 70.1 +/- 2.0, 93.4 +/- 1.4% at 8.7, 17.5, 35 and 52.5 OD of CROa (non-isolated, decay-corrected and based on (SFB)-F-18, n = 3) in comparison to 7, 17, 22 and 28% at 5, 10, 20 and 40 OD of CROa, respectively, as reported by Hedberg et al. (Acta Chem Scand 1998; 52: 1034-1039). Copyright (c) 2006 John Wiley & Sons, Ltd.