Table 1.
CEST properties of I45DC contrast agents synthesized
| Compound | Chemical shifts [δ1, δ2, ppm] |
Detectable pH range |
STratio slope (°) |
KBA (s−1) at 7.7 ppm pH 6.5 |
|---|---|---|---|---|
| Anionic Aliphatic | ||||
| I45DC-diGlu | 4.5, 7.7 | 5.6 – 7.0 | 53 | 5,081 |
| I45DC-GluLys | 3.0, 7.7 | 4.5 – 7.0 | 85 | 3,413 |
| I45DC-GluArg | 2.0, 7.7 | 4.5 – 6.5 | 79 | 3,449 |
| I45DC-GluThr | 4.5, 7.7 | 5.6 – 6.5 | 33 | 2,140 |
| I45DC-GluEa | 2.0, 7.7 | 5.6 – 6.5 | 70 | 3,950 |
| I45DC-GluLeu | 2.0, 7.7 | 5.6 – 6.5 | 78 | 6,767 |
| Anionic Aromatic | ||||
| I45DC-diTrp | 3.5, 7.7 | 5.0 – 6.2 | 26 | 3,416 |
| I45DC-diTyr | 3.0, 7.7 | 5.0 – 6.5 | 74 | 2,628 |
| I45DC-diHis * | - | - | - | - |
| I45DC-GluTrp | 3.5, 7.7 | 5.6 – 6.5 | 32 | 2,499 |
| I45DC-GluTyr | 3.0, 7.7 | 5.6 – 6.5 | 62 | 3,539 |
| Cationic Aliphatic | ||||
| I45DC-diEda ** | 3.0, 5.0 | 4.5 – 7.4 | 60 | 381 |
| Nonionic Aliphatic | ||||
| I45DC-diAp | 4.5, 7.7 | 5.6 – 7.4 | 65 | 9,442 |
| I45DC-diEa | 3.5, 7.7 | 6.2 – 7.4 | 30 | 2,745 |
| I45DC-diPEG | 3.5, 7.7 | 6.2 – 7.4 | 24 | 2,038 |
*
There is no peak at 7.7 ppm or 5 ppm observed.
**
Peak is at 5 ppm instead of 7.7 ppm. Conditions: CEST data were obtained at 25 mM concentration, tsat = 4 sec and 37 ±C.