Graphene-enabled electron microscopy and correlated super-resolution microscopy of wet cells.

Michal Wojcik,Margaret Hauser,Ke Xu,Seonah Moon,Wan Li

doi:10.1038/ncomms8384

Abstract

The application of electron microscopy to hydrated biological samples has been limited by high-vacuum operating conditions. Traditional methods utilize harsh and laborious sample dehydration procedures, often leading to structural artefacts and creating difficulties for correlating results with high-resolution fluorescence microscopy. Here, we utilize graphene, a single-atom-thick carbon meshwork, as the thinnest possible impermeable and conductive membrane to protect animal cells from vacuum, thus enabling high-resolution electron microscopy of wet and untreated whole cells with exceptional ease. Our approach further allows for facile correlative super-resolution and electron microscopy of wet cells directly on the culturing substrate. In particular, individual cytoskeletal actin filaments are resolved in hydrated samples through electron microscopy and well correlated with super-resolution results.

Highlights

The application of electron microscopy to hydrated biological samples has been limited by high-vacuum operating conditions
A single-atom-thick honeycomb lattice of carbon atoms[15], as an impermeable and conductive membrane to uniquely enable electron microscopy and correlated super-resolution microscopy of wet and untreated, or fixed mammalian cells cultured on conventional coverglass with exceptional ease
Electron microscopy of multilayer graphene oxide-wrapped bacteria has been achieved via mixing of liquid suspensions of bacteria and micrometre-sized graphene oxide flakes[19,28], but such approaches are difficult to apply to the much larger animal cells, and the sharp edges of graphenic flakes tend to penetrate the cell membrane and lead to internalization[29]

Summary

Introduction

The application of electron microscopy to hydrated biological samples has been limited by high-vacuum operating conditions. A single-atom-thick honeycomb lattice of carbon atoms[15], as an impermeable and conductive membrane to uniquely enable electron microscopy and correlated super-resolution microscopy of wet and untreated, or fixed mammalian cells cultured on conventional coverglass with exceptional ease. We report that monolayer graphene can hermetically seal and protect large areas of mammalian cells, cultured on conventional coverglass, from external environments, including the high vacuum typically encountered in an electron microscope This protection, combined with the high electrical and thermal conductivity of graphene and its ultimate thinness, enables facile electron microscopy of wet and untreated cells with excellent contrast and resolution, as well as correlated super-resolution microscopy directly on the culturing substrate. Individual actin filaments are resolved in wet cells through electron microscopy and well correlated with super-resolution results

Methods

Results

Conclusion