Plasmonic optical trapping for single-molecule conformational dynamics interrogation

Edona Karakaci, BioPhysics, AMI

Conformational dynamics are critical for the function of many proteins. Therefore, studying conformational changes of proteins in response to external stimuli is essential for determining their function in human cells and their contribution to both health and disease. Established approaches to monitor conformational changes of proteins require modification of the target proteins, either by attaching fluorophores (smFRET) or by attaching molecular tethers (smFS). Plasmonic optical tweezers have demonstrated the potential to trap unlabeled nanoscale objects and monitor their behavior over time. Karakaci and colleagues were the first to demonstrate the thermal unfolding and refolding trajectory of a single protein by using the double-nanohole (DNH) plasmonic optical tweezer. They trapped single calmodulin proteins from solution, and monitored the conformational changes of proteins from changes in transmission while tuning the temperature in the trapping site by adjusting the laser power. They were able to show that single apo-calmodulin thermally unfolds and refolds in steps by conformational fluctuations of individual protein domains. The results agree with smFS and suggest general utility for single-molecule protein folding studies.

Bugs to beverages: using structural colours in food colouring

Alessandro Parisotto, Soft Matter Physics, AMI

In this seminar talk, the fundamental concepts of structural colouration is introduced by discussing the unique photonic structures found in nature. Using this fundamental knowledge, curved interfaces can be utilized to create structural colours in emulsions for use as tunable and edible food colouring.