Uncovering solvation heterogeneity in live cells via hyperspectral stimulated Raman scattering microscopy

The structure and dynamics of intracellular water constitute the cornerstone for understanding all aspects of cellular function. However, direct visualization of subcellular solvation heterogeneity has remained elusive. To explore this question, we have demonstrated a vibrational-shift imaging approach to probe solvation at the microscopic level by combining spectral-focusing hyperspectral stimulated Raman scattering (hsSRS) with an environmentally-sensitive nitrile probe. When applied to quantitatively measure the spatial variation of solvation in live cells, this new method reveals significantly reduced solvation in the cytoplasm compared to the nuclear compartment and bulk water! This work sheds light on heterogenous solvation at the subcellular level and opens up new avenues to explore solvation variance in complex systems.