Shedding the light on cell biology by fast label-free Raman imaging

Multimodal non-linear optical microscopy allows the study of tumor liver cells in a non-invasive way and in the total absence of exogenous markers, with an acquisition speed compatible with in-vivo applications (2 min for images 300×300 pixels, pixel size 350nm).

The combination of Epi-CARS, Forward-CARS and SRS vibrational microscopy in the CH-stretching region allows for the chemical-specific visualization of lipid accumulations (2850 cm-1), generic proteins (2920 cm-1) and DNA (2850 cm-1 – 2920 cm-1). In particular, in Epi-CARS the resonant signal from aqueous cytoplasmic regions is suppressed, thus allowing discerning small scatterers in solution. By combining Raman microscopy with 2-photon-excited fluorescence microscopy, it is possible to add information on the areas of active cellular metabolism, thus delineating a chemical map of the entire tumor cell.