Multivalency as an interaction principle is widely utilized in nature. It enables specific and strong binding by multiple weak interactions through enhanced avidity and is a core process in immune recognition and cellular signaling. Multivalent interactions are inherently heterogenous and require a single-molecule approach to understand the underlying dynamic behavior during binding that drives the avidity.

In this work researchers from iNANO and TU/e have developed a method that use the high signals from plasmon enhanced fluorescence of nanoparticles to extract binding kinetics and dynamics of multivalent interactions on single-molecule level and in real-time. They study mono-, bi- and trivalent binding interactions using a DNA Holliday Junction (HJ) as a model construct with programmable valency and used this approach to explore how length and flexibility of the DNA ligands affect binding restriction and binding strength. By systematically changing the receptor density they explored the binding super selectivity of the multivalent HJs at the single-molecule level that clearly shows receptor-density dependent selective binding. Furthermore, they could exploit the rapidly decaying near fields of the plasmon that induce a strong dependence of the signal to the position of the dye, to observe binding dynamics during single multivalent binding events.

The research paves the way for better understanding of multivalent interactions that can be used to inform drug design and develop molecular imaging agents and functional materials.

Study type:
Nanotechnology, Experimental physics

External funding:
This work acknowledges funding from the Danish National Research Foundation Center grant CellPAT (DNRF135) and the Novo Nordisk Foundation (NNF21OC0071574) (K.R.O, D.S.S). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Program (grant agreement No 864772). V.L. and P.Z. acknowledge funding from the European Union’s Horizon 2020 Research and Innovation Program under the Marie Skłodowska-Curie program (ITN SuperCol, Grant Agreement 860914).

Conflicts of interest:
The authors declare no competing financial interest.

Link to the scientific article:
Single-Molecule Multivalent Interactions Revealed by Plasmon-Enhanced Fluorescence

Kasper R. Okholm, Sjoerd W. Nooteboom, Johan Nygaard Vinther, Vincenzo Lamberti, Swayandipta Dey, Ebbe Sloth Andersen, Peter Zijlstra, Duncan S. Sutherland

Contact information:
Professor Duncan S. Sutherland
Aarhus University
Interdisciplinary Nanoscience Center (iNANO)
Email: duncan@inano.au.dk

Associate Professor Peter Zijlstra
Eindhoven University of Technology
Applied Physics and Science Education
Email: p.zijlstra@tue.nl