Seeing signals in noise: molecular specific microscope images reconstructed from the random light scattering of unlabeled live cells

Chia-Lung Hsieh^1*

¹IAMS, Academia Sinica, Taipei, Taiwan

* Presenter:Chia-Lung Hsieh, email:clh@gate.sinica.edu.tw

Optical microscopy has been the unique tool to measure the structures and dynamics of live biological samples at a high spatial resolution. To acquire a molecular specific microscope image, it is almost mandatory to label the target of interest with an image probe. Unfortunately, probe labeling inevitably affects the biological processes and some labeling schemes are not compatible with live sample observation. Moreover, the optical properties of the imaging probes are often unsatisfactory; for example, the fluorescence microscopy suffers from the photobleaching effect of the fluorophores. In this talk, a scattering-based optical microscope technique, the interferometric scattering (iSCAT) microscopy, will be introduced. By detecting the linear scattering signal through interference, the iSCAT microscopy can be extremely sensitive at a very high speed (up to 500,000 frames per second). The iSCAT microscopy offers the opportunity to directly visualize the unlabeled biological macromolecules in live cells. As linear scattering is ubiquitous where all biomolecules scatter light, the conventional scattering-based imaging has been lacking the molecular specificity. To enhance the molecular specificity of iSCAT imaging, a novel approach will be presented where the temporal fluctuation of the iSCAT signal is analyzed for the estimation of the distribution of a specific type of biomolecule. I will showcase the results of DYNAMICS imaging for live cell nucleus imaging and present its applications to biophysical studies of chromatin conformation and dynamics. The opportunities and challenges of label-free iSCAT microscopy for bioimaging will be discussed.

Keywords: label-free cell imaging, dynamic light scattering, interferometric scattering microscopy, cell nucleus, chromatin