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Monitoring Conformational Dynamics of Single Unmodified Proteins using Plasmonic Nanotweezers
Published on: March 21, 2025
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Probing protein surface interactions in nanoaperture optical tweezers
Sherin George1,2, Tianyu Zhao1,2, Keiran Letwin1,2
1Department of Electrical Engineering, University of Victoria, Victoria V8W 2Y2, British Columbia, Canada.
Nanotechnology
|November 6, 2025
Summary
Nanoaperture optical tweezers (NOTs) reveal protein surface charge interactions. Negatively charged proteins are attracted to gold surfaces, while positively charged ones are repelled, impacting nanophotonic sensors.
Area of Science:
- Biophysics
- Nanotechnology
- Surface Science
Background:
- Nanoaperture optical tweezers (NOTs) utilize localized electromagnetic field enhancements for single-molecule trapping.
- These trapping mechanisms are influenced by interactions with metal surfaces, particularly for biomolecules like proteins.
Purpose of the Study:
- To investigate the influence of protein surface charge on interactions within nanoaperture optical tweezers.
- To quantify the impact of surface forces on trapping stiffness at zero power.
Main Methods:
- Analyzing the power dependence of trapping stiffness in nanoaperture optical tweezers.
- Studying proteins with varying charges.
- Performing finite-element Poisson equation simulations.
Main Results:
- Observed that negatively charged proteins exhibit attraction to the gold surface.
- Found that positively charged proteins are repelled by the gold surface.
- Interpreted attraction as arising from local image charges at the gold-water interface.
Conclusions:
- Surface charge significantly impacts biomolecule behavior in nanophotonic trapping systems.
- This study provides a method to quantify surface interactions in single-molecule sensors.
- The findings are crucial for understanding and optimizing nanophotonic sensors for biomolecules and nanoparticles.
