Direct Observation of Cell Surface Sialylation by Atomic Force Microscopy Employing Boronic Acid-Sialic Acid Reversible Interaction

Anal Chem. 2020 Sep 1;92(17):11714-11720. doi: 10.1021/acs.analchem.0c01705. Epub 2020 Aug 12.

Abstract

Tracing cell surface sialylation dynamics at a scale of the glycolipoprotein microdomain (lipid rafts) formations remains an intriguing challenge of cellular biology. Here, we demonstrate that this goal is accessible, taking advantage of a boronic acid (BA)-based reversible molecular recognition chemistry. A BA-end-functionalized poly(ethylene glycol) was decorated onto an atomic force microscopy (AFM) cantilever, which provided a dynamic and sialic acid (SA)-specific imaging mode. Using this technique, we were able to heat map the SA expression levels not only on protein-decorated substrates but also directly on the cell surfaces, with a submicrometer scale resolution that may be relevant to that of the lipid rafts formation. The SA specificity and the binding reversibility of the probe were confirmed from its pH-dependent characteristics and an inhibition assay using free state SA. This finding may provide a noninvasive means for assessing a variety of SA-involved glycosylation dynamics spanning from physiology to pathology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Boronic Acids / chemistry*
  • Cell Membrane
  • Humans
  • Microscopy, Atomic Force / methods*
  • N-Acetylneuraminic Acid / chemistry*

Substances

  • Boronic Acids
  • N-Acetylneuraminic Acid