title: Two-dimensional flow nanometry of biological nanoparticles for accurate determination of their size and emission intensity.
abstract: Biological nanoparticles (BNPs) are of high interest due to their key role in various biological processes and use as biomarkers. BNP size and composition are decisive for their functions, but simultaneous determination of both properties with high accuracy remains challenging. Optical microscopy allows precise determination of fluorescence/scattering intensity, but not the size of individual BNPs. The latter is better determined by tracking their random motion in bulk, but the limited illumination volume for tracking this motion impedes reliable intensity determination. Here, we show that by attaching BNPs to a supported lipid bilayer, subjecting them to hydrodynamic flows and tracking their motion via surface-sensitive optical imaging enable determination of their diffusion coefficients and flow-induced drifts, from which accurate quantification of both BNP size and emission intensity can be made. For vesicles, the accuracy of this approach is demonstrated by resolving the expected radius-squared dependence of their fluorescence intensity for radii down to 15 nm.
authors.affiliation: Department of Physics, Division of Biological Physics, Chalmers University of Technology, Gothenburg SE-412 96, Sweden.
authors.forename: Stephan
authors.initials: S
authors.lastname: Block
authors.affiliation: Department of Physics, Division of Biological Physics, Chalmers University of Technology, Gothenburg SE-412 96, Sweden.
authors.forename: Björn Johansson
authors.initials: BJ
authors.lastname: Fast
authors.affiliation: Department of Physics, Division of Biological Physics, Chalmers University of Technology, Gothenburg SE-412 96, Sweden.|Department of Nanobiotechnology, University of Natural Resources and Life Sciences, Vienna 1190, Austria.
authors.forename: Anders
authors.initials: A
authors.lastname: Lundgren
authors.affiliation: Department of Physics, Division of Biological Physics, Chalmers University of Technology, Gothenburg SE-412 96, Sweden.|Boreskov Institute of Catalysis, Russian Academy of Sciences, Novosibirsk 630090, Russia.
authors.forename: Vladimir P
authors.initials: VP
authors.lastname: Zhdanov
authors.affiliation: Department of Physics, Division of Biological Physics, Chalmers University of Technology, Gothenburg SE-412 96, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Höök