Three-dimensional molecular imaging of living organisms
and cells
plays a significant role in modern biology. Yet, current volumetric
imaging modalities are largely fluorescence-based and thus lack chemical
content information. Mid-infrared photothermal microscopy as a chemical
imaging technology provides infrared spectroscopic information at
submicrometer spatial resolution. Here, by harnessing thermosensitive
fluorescent dyes to sense the mid-infrared photothermal effect, we
demonstrate 3D fluorescence-detected mid-infrared photothermal Fourier
light field (FMIP-FLF) microscopy at the speed of 8 volumes per second
and submicron spatial resolution. Protein contents in bacteria and
lipid droplets in living pancreatic cancer cells are visualized. Altered
lipid metabolism in drug-resistant pancreatic cancer cells is observed
with the FMIP-FLF microscope.