Single-Molecule Identification of the Isomers of a Lipidic Antibody Activator

TL;DR

This paper shows how a new imaging technique can visualize sensitive molecules that are hard to study with traditional methods.

Contribution

The study demonstrates the use of STM with ESD to characterize isomers of a labile molecule relevant in molecular biology.

Findings

The technique successfully characterized two isomers of rhamnopolyene.

The method is suitable for inspecting non-crystallizable and sensitive compounds.

Theoretical calculations supported the experimental findings.

Abstract

Molecular structural elucidation can be accomplished
by different
techniques, such as nuclear magnetic resonance or X-ray diffraction.
However, the former does not give information about the three-dimensional
atomic arrangement, and the latter needs crystallizable solid samples.
An alternative is direct, real-space visualization of the molecules
by cryogenic scanning tunneling microscopy (STM). This technique is
usually limited to thermally robust molecules because an annealing
step is required for sample deposition. A landmark development has
been the coupling of STM with electrospray deposition (ESD), which
smooths the process and widens the scope of the visualization technique.
In this work, we present the on-surface characterization of air-,
light-, and temperature-sensitive rhamnopolyene with relevance in
molecular biology. Supported by theoretical calculations, we characterize
two isomers of this flexible molecule, confirming the potential of
the technique to inspect labile, non-crystallizable compounds.

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