AN EFFICIENT OXYGEN INDEPENDENT 2-PHOTON PHOTOSENSITIZATION MECHANISM

A novel oxygen-independent photosensitization mechanism from the upper triplet state (T-n) of rose bengal has been demonstrated by selective ly populating T-n by sequential two-color laser excitation. Products f ormed from T-n inhibit red blood cell acetylcholinesterase and decreas e viability of P388D(1) mouse macrophage monocyte cells as measured by trypan blue exclusion assay. Laser flash photolysis studies indicate that T-n reacts efficiently, as evidenced by permanent photobleaching of T-1 absorption, with chemical yields approaching unit efficiency. T his mechanism may have application for oxygen deficient photosensitiza tion under high intensity, pulsed laser irradiation.