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| Characteristics |
|---|
| Chemically pure and specific composition. |
| Stability at room temperature. |
| Minimal dark toxicity. |
| Only be cytotoxic in the presence of light at defined wavelength. |
| Preferential retention by target tissues. |
| Excellent photochemical reactivity with high triplet state yields and long triplet state life times. |
| Be inexpensive and commercially available. |
| Be easy to dissolve in the body's tissue fluids. |
