Table 1.
Characteristic values of methylene blue and its derivatives MB-1 to MB-6, where λ max describes the maximum of the absorption; the dimerisation was detected in a concentration range between 10–200 μM; the photostability is described with the ratio of the height of the absorption maximum after irradiation to height of the maximum before irradiation with 180000 laser pulses; t R and t D are the rise and decay time of the time resolved singlet oxygen luminescence, respectively; ΦΔ is the quantum yield of singlet oxygen generation relatively to the quantum yield of methylene blue, which is found in literature to be 0.52 [43]; ΦΔ 1.00 is the quantum yield of MB set to 1.00, to simplify the comparison. For the values of the quantum yield an error of 10% in regard to the measurement procedure had to be estimated. “overlap” describes the uptake of the lamp emission spectrum by the different photosensitizers at a concentration of 10 μM. “Eff.Tox.” describes therefore the predicted effective toxicity that was calculated by multiplication of ΦΔ 1.00 (ref. MB) with the value of the overlap.
| PS |
λ abs,max | dimeriz. |
photostab. |
t D (μs) | t R (μs) | ΦΔ 1.00 (ref. MB) | ΦΔ 1.00 (ref. MB) | Overlap [%] | Eff.Tox. [%] |
|---|---|---|---|---|---|---|---|---|---|
| MB | 664 | Yes | 95% | 3.51 | 1.64 | 0.52* | 1.00 | 54.4 | 54 |
| MB-1 | 653.5 | No | 82% | 3.47 | 1.93 | 0.45 ± 0.05 | 0.87 | 43.1 | 37 |
| MB-2 | 650.5 | No | 81% | 3.57 | 1.76 | 0.38 ± 0.04 | 0.73 | 38.7 | 28 |
| MB-3 | 643.5 | No | 95% | 3.44 | 1.92 | 0.47 ± 0.05 | 0.90 | 38.4 | 35 |
| MB-4 | 663.5 | Yes | 97% | 3.51 | 1.78 | 0.51 ± 0.05 | 0.98 | 44.5 | 44 |
| MB-5 | 662 | Yes | 96% | 3.46 | 1.70 | 0.41 ± 0.04 | 0.79 | 45.4 | 36 |
| MB-6 | 649 | No | 95% | 3.47 | 1.76 | 0.35 ± 0.04 | 0.67 | 29.6 | 20 |