Table 1. Optimization of Synthesis of [64Cu]1 through the Strain-Promoted Catalyst-Free Conjugation between 2 and [64Cu]3.
| entry | 2 (μM) | [64Cu]3a | solvent | temp (°C) | reaction time (min) | radiochem yield (%) |
|---|---|---|---|---|---|---|
| 1 | 228 | 3.7 MBq (1 μM) | H2O | 25 | 15 | >98 |
| 2 | 114 | 3.7 MBq (1 μM) | H2O | 25 | 10 | 92 |
| 3 | 5.7 | 3.7 MBq (1 μM) | H2O | 25 | 10 | 42 |
| 4 | 5.7 | 3.7 MBq (1 μM) | H2O | 45 | 10 | >98 |
| 5 | 1.14 | 3.7 MBq (1 μM) | H2O | 45 | 15 | >98 |
| 6 | 0.29 | 1.85 MBq (0.5 μM) | H2O | 45 | 10 | 16 |
| 7 | 1.14 | 3.7 MBq (1 μM) | PBS buffer | 45 | 15 | >98 |
a
The concentration was estimated based on the specific activity of [64Cu]3 (37 MBq·nmol–1), taking into account a correction of radioactive decay.