Microbubble dynamics around laser heated microparticles

Selective tissue damage on the cellular level can be achieved due to microbubble formation around laser heated intracellular pigments. To get an estimate on damage ranges we investigated microbubble dynamics (lifetime, size) around isolated melanosomes of the retinal pigment epithelium in aqueous suspensions by fast flash photography and probe laser transmission. For short pulsed laser irradiation (12ns@532nm) an increasing radiant exposure results in larger bubble sizes. Bubble diameters ranging from 1μm to 10μm were observed. Applying longer pulses (1.8μs@527nm), increasing radiant exposure leads to an earlier onset of bubble growth relative to the pulse. In this case, the diameter of the bubble is nearly independent of the radiant exposure, whereas the number of bubbles during the pulse increases towards higher radiant exposures.

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