Nanoholes for Single-Molecule Experiments

Speaker:      Reuven Gordon (University of Victoria, Canada)

Subject:       Nano-Opto-Bio-Mechanics: Listening to Single Proteins with Light

Location:     TNW-Zuid

Date:            Friday, October 14, 16:00-17:00

Jasper Veerman


Having read the first four words of his presentation, the audience was none the wiser. Fortunately, Reuven Gordon started by explaining how these tie together. Studying  biology at the single-protein level, means we are dealing with nanometer-sized objects of interest. The amazing technique used to study these molecules are optical cavities, with interacting light and sound to study mechanical properties of the molecules. An example of such nanoholes is shown in the figure below. When focusing a laser on the structure, a force field is generated that can trap  polystyrene beads at the place where we see the ‘w’.


Figure 1. Schematic representation of two intersecting circular nanoholes. Holes are 120nm in diameter. Adapted from Reuven Gordon et al., Optics Express, 2015.

If a particle gets trapped inside the nanohole, a difference in the transmitted light can be observed. Effectively, a little bit more light can pass through. Interestingly, these small changes are amplified to the fourth power, making them easy to observe. As an example, the classic biological protein BSA was studied. Trapping the protein can exist in two states, which could be observed from the transmission profiles as two different ‘step heights’ as the particle was trapped inside the nanohole.

There is another practical application of this technique in pharmaceutics. Utilizing the incredible sensitivity of the method, differences in behavior of wildtype and mutant proteins can be observed. In brief, if the addition of a specific drug restores the behavior of the mutant back to the wildtype, the drug has curing potential.

In addition to the research presented above, there were many more fascinating examples of the work done in Reuven Gordon’s lab. This talk was one of the most fascinating ones I attended. Together with the other attendees, I felt highly impressed by the ingenious technique and interesting applications. I look forward to keeping track of his research in the future.


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