Laser-induced micro-bubbles in cells

We report experimental study and detection of laser-induced micro-bubbles in individual live cells and in confined micro-volumes of solutions. Using pulsed laser radiation (532 nm, 10 ns) as the source of local heating we detected micro-bubbles in light-absorbing media that were caused at least by two mechanisms-heating of the media above (more than 300 °C) critical temperature (referred as 'hot' bubbles) and action of rarefaction pressure waves (referred as 'cold' bubbles) at much lower temperatures (30-150 °C). Bubble generation thresholds, probabilities of bubble forming and bubble lifetimes were experimentally studied with two photothermal (PT) methods-thermal lensing and PT-time-resolved imaging for human red blood cells, homogeneous solutions of haemoglobin, neutral red dye and for suspension of polystyrene nano-particles.