Label-free histopathological assessment of tissues with photoacoustic remote sensing (PARS) microscopy

Here we explore the use of Photoacoustic Remote Sensing (PARS™) microscopy, a recently developed non-contact photoacoustic imaging modality, for visualizing subcellular structures label-free in tissues. Operating in an all-optical reflection-mode architecture PARS captures optical absorption contrast within bulk tissue samples. Presented here, by visualizing endogenous optical absorption of DNA and cytochromes, cellular morphology is captured with contrast analogous to the industry standard hematoxylin and eosin (H&E) staining. Subcellular features are recovered from human and murine, brain and gastrointestinal tissues. This work represents a significant step towards the development of a real-time microscopy system for label-free histopathological assessment of tissues in-situ.