Observation of the dynamics of live cardiomyocytes through a free-running scanning near-field optical microscopy setup

We report the observation of live-cell dynamics by noncontact scanning near-field optical microscopy (SNOM) modified to work with living biological samples that are fully immersed in liquid. We did not use the SNOM setup in strictly near-field conditions (we used 1-mm constant-height mode); however, we could examine the dynamics of rhythmically beating cardiac myocytes in culture with extremely high vertical sensitivity below the nanometric range. We could halt scans at any point to record localized contraction profiles of the cell membrane. We show that the contractions of the organisms changed shape dramatically within adjacent areas. We believe that the spatial dependency of the contractions arises because of the measurement system’s ability to resolve the behavior of individual submembrane actin bundles. Our results, combining imaging and real-time recording in localized areas, reveal a new, to our knowledge, noninvasive method for using SNOM setups for studying the dynamics of live biological samples.