Physical and Photophysical Characteristics of PSMA-Targeted Hybrid Tracers
| Compound | λex,max/λem,max in H2O/PBS (nm) | ΦF (% in PBS) | Brightness (×104 M−1 × cm−1 in PBS)† | Lipophilicity (logP(o/w); n = 6)* | PPB (n = 3) | Serum stability after 24 h (% remaining; n = 2) |
| EuK-Cy5-mas3 | 644/663 (18)‡ | 12 | 1.1 | −2.13 ± 0.10 | 88.3 ± 1.6 | Abs: 80 ± 6/Flu: 86 ± 5 |
| EuK-(SO3)Cy5-mas3 | 648/664 (16)‡ | 15 | 1.4 | −2.86 ± 0.05 | 85.0 ± 2.3 | Abs: 97 ± 2/Flu: 89 ± 6 |
| EuK-Cy5(SO3)-mas3 | 648/664 (16)‡ | 10 | 1.5 | −2.70 ± 0.01 | 87.4 ± 2.0 | Abs: 82 ± 7/Flu: 85 ± 1 |
| EuK-(Ar)Cy5-mas3 | 664/682 (18)‡ | 9 | 0.3 | −1.75 ± 0.10 | 90.7 ± 1.3 | Abs: 85 ± 3/Flu: 79 ± 1 |
| EuK-Cy5(Ar)-mas3 | 663/680 (17)‡ | 12 | 0.7 | −1.84 ± 0.06 | 89.0 ± 2.5 | Abs: 75 ± 0/Flu: 76 ± 0 |
↵† Calculated using molecular extinction coefficient of free fluorophore.
↵* Measured using 99mTc-labeled hybrid tracers.
↵‡ Parenthetic numbers are Stokes shift.
λex,max/λem,max = maximum λex/λem; ΦF = quantum yield; logP(o/w) = the partition coefficient in octanol/water; PBS = phosphate-buffered saline; Abs = absorbance; Flu = fluorescence.