Label-free microscopy enables the possibility of measuring biological samples noninvasively and purely based on endogenous contrast. In particular, quantitative phase microscopy (QPM) can provide signals proportional to the intracellular refractive index with high-throughput. To improve the specificity of these measurements, we coupled QPM with Raman spectroscopy, another label-free modality that provides a signal related to the molecular content of the sample. We then developed a hybrid imaging approach where imaging is restricted to QPM to maintain a high-throughput despite the inherent slow acquisition time of Raman signals, while ensuring that the measured spectrum is representative of the whole cellular content.

This approach provides signals for both the morphology, related to the phenotype, and the intracellular molecular content at single-cell level, that we employed to study cell populations under different stimuli. In particular, we studied macrophage cells and their response to a simulated bacterial infection upon exposure to lipopolysaccharide, and show how this approach is able to noninvasively detect the activation state at single-cell level by coupling it with multivariate analysis and machine learning algorithms.

Date Published: 4 March 2019
PDF: 6 pages
Proc. SPIE 10887, Quantitative Phase Imaging V, 1088714 (4 March 2019); doi: 10.1117/12.2512665

Published in SPIE Proceedings Vol. 10887:
Quantitative Phase Imaging V
Gabriel Popescu; YongKeun Park, Editor(s)