Table 1.
Comparison of synthetic methods for labeling the sdAb 2Rs15d with 18F.
| Parameters | [18F]RL-I-2Rs15d (Ref.37) | [18F]RL-II-2Rs15d (Ref.22) | [18F]AlF-NOTA-Tz-TCO-GK- 2Rs15d |
|---|---|---|---|
| Total time for synthesis | 3.0 h | 2.0 h | 1.5 h |
| Heating cycles | 3 | 1 | 1 |
| Total time for heating | 50 min | 15 min | 15 min |
| Evaporation cycles | 6 | 4 | 1 |
| HPLC required | Yes, Normal phase | Yes, Reversed-phase | No |
| Extraction required | Yes | No | No |
| Cartridge other than QMA | Na2SO4 | C18 SPE | C18 SPE |
| TFA cleavage required | Yes | No | No |
| RCY for intermediate | 8.5 ± 2.8% | 55.9 ± 14.5% | 46.3 ± 4.1% |
| Conjugation yield | 40.8 ± 9.1% | 23.9 ± 6.9% | 52.0 ± 1.8% |
| Overall RCY | 3.5 ± 1.0% | 3.2 ± 0.9% (n = 8) | 17.8 ± 1.5% (n = 5) |