Label-Free, Real-Time Measurement of Metabolism of Adherent and Suspended Single Cells by In-Cell Fourier Transform Infrared Microspectroscopy

We used infrared (IR) microscopy to monitor in real-time the metabolic turnover of individual mammalian cells in morphologically different states. By relying on the intrinsic absorption of mid-IR light by molecular components, we could discriminate the metabolism of adherent cells as compared to suspended cells. We identified major biochemical differences between the two cellular states, whereby only adherent cells appeared to rely heavily on glycolytic turnover and lactic fermentation. We also report spectroscopic variations that appear as spectral oscillations in the IR domain, observed only when using synchrotron infrared radiation. We propose that this effect could be used as a reporter of the cellular conditions. Our results are instrumental in establishing IR microscopy as a label-free method for real-time metabolic studies of individual cells in different morphological states, and in more complex cellular ensembles.

Automated summary

In this study, infrared microscopy was used to monitor the metabolic turnover of individual mammalian cells in real time, revealing major biochemical differences between adherent cells and suspended cells. Spectroscopic variations and spectral oscillations in the infrared domain were observed when using synchrotron infrared radiation, suggesting a potential application as a reporter of cellular conditions. These findings establish IR microscopy as a valuable label-free method for studying real-time metabolism in cells with distinct morphological states.