Correlative light electron microscopy using small gold nanoparticles as single probes

TL;DR

This paper introduces a correlative light and electron microscopy method using small gold nanoparticles as single probes, achieving high localization precision and accuracy without additional fiducial markers, suitable for live cell imaging.

Contribution

The study demonstrates a novel FWM-based CLEM technique with gold nanoparticles, enabling nanometric precision in correlating light and electron microscopy images without extra fiducial markers.

Findings

Correlation accuracy below 60 nm over 10 μm areas

Improved accuracy below 40 nm with error reduction

Localization precision below 10 nm

Abstract

Correlative light electron microscopy (CLEM) requires the availability of robust probes which are visible both in light and electron microscopy. Here we demonstrate a CLEM approach using small gold nanoparticles as a single probe. Individual gold nanoparticles bound to the epidermal growth factor protein were located with nanometric precision background-free in human cancer cells by light microscopy using resonant four-wave-mixing (FWM), and were correlatively mapped with high accuracy to the corresponding transmission electron microscopy images. We used nanoparticles of 10 nm and 5 nm radius, and show a correlation accuracy below 60 nm over an area larger than 10 um size, without the need for additional fiducial markers. Correlation accuracy was improved to below 40 nm by reducing systematic errors, while the localisation precision is below 10 nm. Polarisation-resolved FWM correlates with nanoparticle shapes, promising for multiplexing by shape recognition in future applications. Owing to the photostability of gold nanoparticles and the applicability of FWM microscopy to living cells, FWM-CLEM opens up a powerful alternative to fluorescence-based methods.