Mapping the phonon dispersion in biological matter using angle-resolved Brillouin light scattering microspectroscopy

Biological matter is usually structurally anisotropic. As such the speed of acoustic phonons, which can be probed using Brillouin spectroscopy, depends on the angular-direction. Using a novel spectrometer-setup, which simultaneously probes the acoustic-velocity from different azimuthal angles, we quantify this anisotropy in different biological structures. By point-scanning the sample we render spatial-maps of parts of the phonon dispersion relation and find different regions in live cells have distinct anisotropic properties in their phonon velocity, with variations related to cell-health and phase. I will discuss the physical/biological interpretation of our results, their relevance for understanding/modelling cellular mechanics, and potential diagnostic applications.