BPS2026 – Multimodal characterization of cells through scanning Mueller matrix and fluorescence microscopy

Label-free imaging systems can provide structural information of an unstained specimen exploiting changes in the optical properties of light. The polarization of light, for example, can change upon the interaction with the sample. Mueller matrix microscope harnesses this property to obtain a characterization of the anisotropies of the sample. If this information is coupled to the one obtained with fluorescence imaging systems, a deeper characterization of the sample is achieved. We implemented a Mueller matrix microscope based on scanning architecture, in which the polarization of the illumination light is varied by means of a photoelastic modulator. Multiple images are obtained in this way, each one corresponding to a single component of the Mueller matrix. In our case, we are interested in some specific components among the 16 elements of the full Mueller matrix. Specifically, our main interest is on element m14, which characterizes chiral structures by describing the different scattering of left and right circularly polarized light and is thus on birefringence. This label-free information is combined with a high-resolution fluorescence image of the sample. This multimodal approach represents a powerful tool to characterize chromatin organization.