A New Path to Nanoscale Cellular Analysis with Monochromated Electron Energy-Loss Spectroscopy

TL;DR

This paper introduces a novel nanoscale vibrational EELS method using monochromated electron microscopy, enabling detailed chemical mapping of biological cells with high spatial and spectral resolution.

Contribution

The study develops and demonstrates a new monochromated EELS technique for nanoscale biological analysis, combining first-principles calculations with experimental data.

Findings

Successfully mapped cellular regions in cucumber stem with high spatial resolution.

Identified vibrational signatures corresponding to specific cellular components.

Unraveled physical mechanisms behind vibrational signatures in biological tissues.

Abstract

High-spatial-resolution vibrational spectroscopy is one of the principal techniques for nanoscale compositional analysis in biological materials. Here, we present a new method for the analysis of whole-cell biological specimens through nanoscale vibrational electron energy-loss spectroscopy (EELS) in the monochromated scanning transmission electron microscope. Using the combined spatial and spectral resolution of the technique, we examine the vascular system of a cucumber stem and identify clear physical and vibrational signatures from the different cellular regions with high spatial resolution. Furthermore, using first-principles calculations combined with optical and EELS spectroscopy on the individual components that make up the cucumber stem, we unravel the physical mechanisms of the vibrational signatures and directly assign compositional origins to the cell walls and bodies of different cellular regions. These results demonstrate that monochromated electron energy-loss spectroscopy is a promising technique for nanoscale spatial mapping of the chemical composition of biological materials.