Super-resolution Imaging of the Fluorescent Dipole Assembly with Polarized Structured Illumination Microscopy

TL;DR

This paper introduces polarized structured illumination microscopy (pSIM), a novel super-resolution technique that images fluorescent dipole orientations and dynamics in biological systems with high spatial and angular resolution.

Contribution

The paper presents pSIM, a new method that decouples spatial and angular structured illumination, enabling detailed super-resolution imaging of dipole assemblies in live cells.

Findings

Resolved subcellular dipole structures in biological filaments.

Visualized actin dynamics and organization in live neurons.

Demonstrated compatibility with existing SIM systems.

Abstract

Fluorescence polarization microscopy images both the intensity and orientation of fluorescent dipoles, which plays a vital role in studying the molecular structure and dynamics of bio-complex. However, it is difficult to resolve the dipole assemblies on the subcellular structure and their dynamics in living cells with super-resolution. Here we report polarized structured illumination microscopy (pSIM), which decouples the entangled spatial and angular structured illumination through interpreting the dipoles in spatio-angular hyperspace. We demonstrate its application on a series of biological filamentous systems such as cytoskeleton networks and lambda-DNA, and report the dynamics of short actin sliding through myosin-coated surface. Further, pSIM reveals "side-by-side" organization of the actin ring structure in the membrane-associated periodic skeleton in hippocampal neurons. It also images the dipole dynamics of green fluorescent proteins labeled to the microtubules in live U2OS cells. pSIM can be applied directly to a large variety of commercial or home-built SIM systems.