Nanometer-Scale Resolution Achieved with Nonradiative Excitation

Lina Riachy (1) , Dalia El Arawi (1) , Rodolphe Jaffiol (1) , Cyrille Vézy (1)

1 L2n - Lumière, nanomatériaux et nanotechnologies

Nonradiative Excitation Fluorescence Microscopy (NEFM) is a promising technique allowing the observation of biological samples beyond the diraction limit. By coating a substrate with an homogeneous monolayer of quantum dots (QDs), NEFM is achieved through a nonradiative energy transfer from QDs (donors) to dye molecules located in the sample (acceptors). The excitation depth of the sample is then given by the För-ster radius, which corresponds to few nanometers above the surface. The powerful axial resolution of NEFM is highlighted by observing the adhesion of Giant Unilamellar Vesi-cles (GUVs) on strong interaction with coated surfaces. In this paper, we demonstrate that the QD-quenching level is valuable to calculate and map the distance between the membrane and the surface with a high precision along the optical axis. By tuning the electrostatic interactions between the membrane and the substrate, we have been able to measure a height displacement of ≈ 1 nm of the lipid membrane. The experimental results were discussed according to simulations, which take into account all the common forces appearing between lipid membranes and surfaces.

Keywords: biophotonics; membrane; Förster resonance energy transfer; nanoscopy

Domains: Biological Physics [physics.bio-ph]; Optics / Photonic; Condensed Matter [cond-mat]

Lina Riachy, Dalia El Arawi, Rodolphe Jaffiol, Cyrille Vézy. Nanometer-Scale Resolution Achieved with Nonradiative Excitation. ACS photonics, 2018, 5 (6), pp.2217-2224. ⟨10.1021/acsphotonics.8b00063⟩. ⟨hal-02363346⟩