Electronic Single Molecule Identification of Carbohydrate Isomers by Recognition Tunneling

TL;DR

This paper introduces a label-free electron tunneling technique capable of identifying carbohydrate isomers at the single-molecule level, surpassing traditional methods in sensitivity, resolution, and potential for sequencing oligosaccharides.

Contribution

It presents a novel recognition tunneling method for single-molecule carbohydrate identification, enabling analysis of isomers with high sensitivity and direct sequencing capabilities.

Findings

Able to analyze sub-picomole quantities of samples

Can distinguish epimers better than ion-mobility methods

Provides a potential platform for single-molecule carbohydrate sequencing

Abstract

Glycans play a central role as mediators in most biological processes, but their structures are complicated by isomerism. Epimers and anomers, regioisomers, and branched sequences contribute to a structural variability that dwarfs those of nucleic acids and proteins, challenging even the most sophisticated analytical tools, such as NMR and mass spectrometry. Here, we introduce an electron tunneling technique that is label-free and can identify carbohydrates at the single-molecule level, offering significant benefits over existing technology. It is capable of analyzing sub-picomole quantities of sample, counting the number of individual molecules in each subset in a population of coexisting isomers, and is quantitative over more than four orders of magnitude of concentration. It resolves epimers not well separated by ion-mobility and can be implemented on a silicon chip. It also provides a readout mechanism for direct single-molecule sequencing of linear oligosaccharides.