Label-free biomedical imaging of hydrodynamics in single human cells.

Intracellular hydrodynamics is of considerable importance to regulate cellular functions. Using Raman microspectroscopy and imaging, we visualized the time-dependent changes of water concentration in single human acute promyelocytic leukemia HL-60 cells, and also showed the labelfree biomedical imaging of water molecules, lipids and proteins for analyzing molecular distribution. Taken together, our results demonstrated that we can distinguish between intracellular water and other major cell components, and that when the physiological status of cells changes with time, the Raman spectral intensities for intracellular water concentration also changes. Therefore, this biospectroscopic analysis of intracellular hydrodynamics can provide biomarkers to examine activities in dynamic living systems, and has significant potential in determining cell specificity for novel therapeutic approaches.