Researchers have successfully applied nano-infrared (nano-IR) spectroscopy to image the molecular composition of living animal cells in their native aqueous environment, paving the way for nanoscale infrared tomography in biology.
Published in Small, the study demonstrates the first use of infrared scattering-type near-field optical microscopy (s-SNOM) on fibroblast cells immersed in liquid, enabled by the IRIS beamline at the BESSY II synchrotron source.
Infrared spectroscopy is already valued as a non-destructive technique for biological samples, but nano-IR typically struggles with hydrated systems due to sample fragility and IR attenuation. This new setup overcomes those limitations.
The key was an ultra-thin, highly transparent silicon carbide (SiC) membrane, which acts as a biocompatible interface between the cell and the probing s-SNOM tip. “Not only were we able to visualize the nucleus and cell organelles, but we succeeded too in reading the individual contributions of proteins, nucleic acids, carbohydrates and membrane lipids based on the detected vibrational spectra,” said Alexander Veber, lead author from Helmholtz-Zentrum Berlin (HZB), Germany, in a press release.
The broadband infrared light from BESSY II enables acquisition of rich vibrational spectra with spatial resolution below 10 nm. By adjusting the measurement parameters, the team was also able to control sampling depth and capture layered signals – offering a foundation for future 3D IR nano-tomography.
The data revealed the expected heterogeneity of cellular composition at the nanoscale, supporting the method’s reliability. “This method offers the possibility of analyzing biological samples and liquid-solid interfaces much more accurately than was previously possible,” Veber added.
Accessible to national and international user groups of the IRIS beamline, the technique opens new doors for studying diverse biological questions, including the molecular dynamics of cancer and disease processes, under more native-like conditions.
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