Super-resolved FRET imaging by confocal fluorescence-lifetime single-molecule localization microscopy

TL;DR

This paper introduces a super-resolution FRET imaging technique using confocal fluorescence-lifetime single-molecule localization microscopy, enabling detailed visualization of molecular interactions beyond diffraction limits.

Contribution

It presents a novel method combining FRET, FLIM, and single-molecule localization microscopy for super-resolved imaging of molecular interactions.

Findings

Achieved super-resolved FRET imaging with a confocal microscope.

Utilized DNA-PAINT with fluorogenic probes for background reduction.

Detected FRET events from lifetime information.

Abstract

FRET-based approaches are a unique tool for sensing the immediate surroundings and interactions of (bio)molecules. FRET imaging and FLIM (Fluorescence Lifetime Imaging Microscopy) enable the visualization of the spatial distribution of molecular interactions and functional states. However, conventional FLIM and FRET imaging provide average information over an ensemble of molecules within a diffraction-limited volume, which limits the spatial information, accuracy, and dynamic range of the observed signals. Here, we demonstrate an approach to obtain super-resolved FRET imaging based on single-molecule localization microscopy using an early prototype of a commercial time-resolved confocal microscope. DNA Points Accumulation for Imaging in Nanoscale Topography (DNA-PAINT) with fluorogenic probes provides a suitable combination of background reduction and blinking kinetics compatible with the scanning speed of usual confocal microscopes. A single laser is used to excite the donor, a broad detection band is employed to retrieve both donor and acceptor emission, and FRET events are detected from lifetime information.