About the speaker:

Prof. Aleksandra Radenovic is a full professor of biological engineering at the École Polytechnique Fédérale de Lausanne (EPFL) and head of the Laboratory of Nanoscale Biology.

Her lab works in the research field that can be termed single-molecule biophysics. She has received her Ph.D. in Biophysics from the University of Lausanne (Switzerland.) in 2003 and a Msc. in Physics from the University of Zagreb (Croatia) in 2000. In 2010. she received a European Research Council (ERC) Starting Grant in 2010 and SNF Backup scheme Consolidator Grant (2015). She is also the recipient of the CCMX materials challenge award in 2016 and the Advanced ERC (2020) grant.

She develops techniques and methodologies based on optical imaging, bio-sensing and single-molecule manipulation with the aim to monitor the behavior of individual biological molecules and complexes in vitro and in live cells.

Abstract:

From the plethora of correlative imaging modalities, SR techniques were most frequently combined with electron microscopy to provide protein-ultrastructure relationships at nanometer-scale resolution. At the other forefront of methods development, scanning probe microscopy techniques aim to capture nanoscale topographical dynamic changes of cells under physiological conditions. To avoid membrane deformation and to provide a method that could unlock long-term monitoring of the biological processes, we recently implemented SICM. The method currently experiences vast leaps in performance due to instrument developments and the ability to fabricate capillaries below tens of nanometers reliably.

In contrast to AFM, SICM is truly non-contact, and represents the soft cell surface much more faithfully. In addition to providing accurate topographic imaging with nanometer resolution, SICM can be used to measure membrane stiffness surface charges and allows local delivery of material (e.g. fluorescent probes). The use of self-blinking dyes in SR microscopy permitted imaging conditions such as low laser excitation intensities and negligible bleaching that are ideal for live-cell imaging. In addition, the high SNR and photophysical properties of self-blinking dyes allow us to extend multiplane cross-correlation analysis to the 4th order using 8-plane volumetric imaging, achieving up to 29 planes. Finally, with a combined SICM-SR setup we demonstrate long-term correlated live-cell imaging.