Research On Mitochondrial Reactive Oxygen Species (ROS) Generation Induced By Femtosecond Laser

Femtosecond lasers have been advancing Biophotonics research in the past two decades with significant progresses including multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, traditionally, laser irradiation was thought to bring photodamage to cells via reactive oxygen species(ROS) generation by unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely in both spatial and temporal dimension, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca2+ release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power breaks over a threshold, ROS are then released to cytosol, indicating photodamage effect overwhelming cellular self-repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging.