Label-Free Imaging of Lysosomes in Living Cells by Photothermal Microscopy

Photothermal microscopy is an optical imaging technique used to visualize the distribution of trace amounts of endogenous dyes in living cells. This technique facilitates lysosomal observation and functional analysis by detecting and identifying accumulated substances within them, eliminating the need for molecular labeling. Here, we describe the fundamental principles and system configuration of a photothermal microscope. We also present a detailed procedure for performing photothermal measurements in living cells.