Label-free quantification of protein binding to lipid vesicles using transparent waveguide evanescent-field scattering microscopy with liquid control
Journal article, 2023

Recent innovations in microscopy techniques are paving the way for label-free studies of single nanoscopic biological entities such as viruses, lipid-nanoparticle drug carriers, and even proteins. One such technique is waveguide evanescent-field microscopy, which offers a relatively simple, yet sensitive, way of achieving label-free light scattering-based imaging of nanoparticles on surfaces. Herein, we extend the application of this technique by incorporating microfluidic liquid control and adapting the design for use with inverted microscopes by fabricating a waveguide on a transparent substrate. We furthermore formulate analytical models describing scattering and fluorescence intensities from single spherical and shell-like objects interacting with evanescent fields. The models are then applied to analyze scattering and fluorescence intensities from adsorbed polystyrene beads and to temporally resolve cholera-toxin B (CTB) binding to individual surface-immobilized glycosphingolipid GM1 containing vesicles. We also propose a self-consistent means to quantify the thickness of the CTB layer, revealing that protein-binding to individual vesicles can be characterized with sub-nm precision in a time-resolved manner.


Mokhtar Mapar

Chalmers, Physics, Nano and Biophysics

Mattias Sjöberg

Chalmers, Physics, Nano and Biophysics

Nanolyze AB

Vladimir Zhdanov

Chalmers, Physics

Russian Academy of Sciences

Björn Agnarsson

Nanolyze AB

Chalmers, Physics, Nano and Biophysics

Fredrik Höök

Chalmers, Physics, Nano and Biophysics

Biomedical Optics Express

21567085 (eISSN)

Vol. 14 8 4003-4016

Two-dimensional flow nanometry for single nanoparticle analytics

Swedish Research Council (VR) (2018-04900), 2018-12-01 -- 2021-12-31.

Subject Categories

Physical Chemistry

Atom and Molecular Physics and Optics


Condensed Matter Physics



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9/7/2023 2