Multimodal label-free imaging of unprocessed biological tissues using ultraviolet photoacoustic elastography and optical coherence microscopy.

Histological visualizations of tissues are critical to disease diagnosis. Conventional histopathology requires labor-intensive and time-consuming tissue preparation, leading to diagnostic delays of days or even weeks. Here, we developed a label-free histological imaging method based on a reflection-mode ultraviolet photoacoustic elastography (UV-PAE) and near-infrared optical coherence microscopy (NIR-OCM). With the mechanical elasticity and optical scattering contrasts, the proposed multimodal microscopy can reveal multi-parametric structural and morphological details of a mouse brain tissue section without extensive sample preparation. Furthermore, by analyzing both cellular- and extracellular matrix-related information, the technique can identify the pathological features of mouse breast tumor specimens, which were consistent with those observed in the conventional histological staining images. The proposed UV-PAE/NIR-OCM represents an advancement towards a fast and effective intraoperative histopathology method with minimal tissue preparation.