Energy-filtered transmission electron microscopy of biological samples on highly transparent carbon nanomembranes

TL;DR

This paper demonstrates the use of ultrathin carbon nanomembranes as highly transparent support films for advanced electron microscopy techniques, enabling improved elemental mapping and contrast in biological samples.

Contribution

It introduces ultrathin carbon nanomembranes as novel support substrates for EFTEM and cryoEM, enhancing imaging quality and elemental analysis of biological specimens.

Findings

Background-free elemental maps of TMV and ferritin achieved

Enhanced contrast of ice-embedded TMV on conductive CNM

Developed method for vitrified specimen preparation using ultrathin cCNM

Abstract

Ultrathin carbon nanomembranes (CNM) comprising crosslinked biphenyl precursors have been tested as support films for energy-filtered transmission electron microscopy (EFTEM) of biological specimens. Due to their high transparency CNM are ideal substrates for electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) of stained and unstained biological samples. Virtually background-free elemental maps of tobacco mosaic virus (TMV) and ferritin have been obtained from samples supported by ~ 1 nm thin CNM. Furthermore, we have tested conductive carbon nanomembranes (cCNM) comprising nanocrystalline graphene, obtained by thermal treatment of CNM, as supports for cryoEM of ice-embedded biological samples. We imaged ice-embedded TMV on cCNM and compared the results with images of ice-embedded TMV on conventional carbon film (CC), thus analyzing the gain in contrast for TMV on cCNM in a quantitative manner. In addition we have developed a method for the preparation of vitrified specimens, suspended over the holes of a conventional holey carbon film, while backed by ultrathin cCNM.