Label-free virtual Hematoxylin and Eosin (H&E) staining using second generation Photoacoustic Remote Sensing (PARS)

TL;DR

This paper introduces a novel all-optical, non-contact photoacoustic remote sensing microscope that visualizes biomolecules in tissues, mimicking traditional H&E staining without labels by capturing radiative and non-radiative absorption effects.

Contribution

The study presents the first all-optical, non-contact TA-PARS microscope capable of label-free histological imaging by measuring the quantum efficiency ratio of biomolecular absorption.

Findings

Enables label-free visualization of tissue structures.

Provides H&E-like images without chemical staining.

Captures both radiative and non-radiative absorption effects.

Abstract

In the past decades, absorption modalities have emerged as powerful tools for label-free functional and structural imaging of cells and tissues. Many biomolecules present unique absorption spectra providing chromophore-specific information on properties such as chemical bonding, and sample composition. As chromophores absorb photons the absorbed energy is emitted as photons (radiative relaxation) or converted to heat and under specific conditions pressure (non-radiative relaxation). Modalities like fluorescence microscopy may capture radiative relaxation to provide contrast, while modalities like photoacoustic microscopy may leverage non-radiative heat and pressures. Here we show an all-optical non-contact total-absorption photoacoustic remote sensing (TA-PARS) microscope, which can capture both radiative and non-radiative absorption effects in a single acquisition. The TA-PARS yields an absorption metric proposed as the quantum efficiency ratio (QER), which visualizes a biomolecules proportional radiative and non-radiative absorption response. The TA-PARS provides label-free visualization of a range of biomolecules enabling convincing analogues to traditional histochemical staining of tissues, effectively providing label-free Hematoxylin and Eosin (H&E)-like visualizations. These findings represent the establishment of an effective all-optical non-contact total-absorption microscope for label-free inspection of biological media.