Selective cell killing by microparticle absorption of pulsed laser radiation

The mechanism of interaction between subcellular pigment microparticles and short pulse laser radiation was investigated with nanosecond time-resolved microscopy and fluorescence microscopy. Stroboscopic illumination was used to capture images of transient events induced in cells by laser pulses. Fluorescence microscopy enabled assessment of cell damage using fluorescent probes. Short-lived intracellular cavitation bubbles were directly visualized within nanoseconds after laser irradiation. Microbubble expansion and implosion took place on the timescale of 0.1-1 μs and were confined entirely within pigmented cells with remarkable selectivity. Cells containing particles underwent cavitation and rapidly lost viability, while adjacent cells without particles remained viable. Nonpigmented cells can be targeted by labeling them with absorbing particles. Laser-pumped microparticles provide an efficient means of selective cell targeting