Direct visualization subcellular liquid-liquid phase separation and the distribution of water and ions are essential for understanding cellular functions. Although techniques such as NMR and Cryo-EM have been successfully utilized to map water and ion content in cells, it remains a challenge to measure these properties at high spatiotemporal resolution. Vibrational imaging methods have long been utilized for environmental sensing. For example, nitriles have proven to be effective to sense the local electric field due to the vibrational Stark effect (VSE) and capable to quantitatively assess the hydrogen bonding interactions. Compared to conventional IR techniques, stimulated Raman scattering (SRS) microscopy has emerged as a superior technique for elucidating the complex structure and dynamics of biological systems with unprecedented acquisition speed, high detection sensitivity, and high spatial resolution. Here, we present our work on vibrational-shift hyperspectral electronic pre-resonance SRS imaging using a near-infrared dye molecule with a conjugated cyano bond. This approach allows us, for the first time, to quantitatively measure the environmental heterogeneities in the degree of water exposure and hydrogen bonding environment at the subcellular level. This advance constitutes a stepping-stone towards a more complete picture of the distribution of water and ions in live cells using coherent Raman microscopy.

Mapping polarity and hydrogen-bonding environments in live cells by hyperspectral stimulated Raman scattering microscopy

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.