# AFM on glutaraldehyde-coated glass images live bacterial envelopes at nanometer resolution across species

- Published: 2026-11-11 07:39 UTC
- Section: Science › Instruments & experiments
- Tags: atomic force microscopy, live bacteria imaging, bacterial immobilization, glutaraldehyde-functionalized glass, bacterial cell envelope, outer membrane, lipopolysaccharide, O-antigen, Pseudomonas aeruginosa, Acinetobacter baumannii
- URL: https://realtech.media/news/rt-3d448e2b3cbe329c28f8804f_afm_on_glutaraldehyde/

**Authors report reversible covalent attachment of live bacteria for atomic force microscopy. Cells stay viable and grow, including smooth E. coli and Pseudomonas aeruginosa.**

![AFM on glutaraldehyde-coated glass images live bacterial envelopes at nanometer resolution across species](https://realtech.media/media/2026/11/31141d67e0571b64.png)
*Nature Communications*

A study in Nature Communications describes a way to immobilize live bacteria on glass for atomic force microscopy (AFM). It gives nanometer-resolution images of the cell envelope across several species and cellular orientations, including the cell poles [1]. The method uses glutaraldehyde-functionalized glass coverslips for reversible covalent attachment. According to the authors, it preserves cell viability and growth [1].

## Why immobilization limits AFM

AFM has produced the highest-resolution images of native bacterial cell envelopes, but it requires rigid attachment of cells that does not harm them. Earlier approaches included physical trapping in grids or trenches, chemical coupling, hydrophobic attachment, and electrostatic adhesion on gelatin, poly-L-lysine, Cell-Tak or Vectabond [1]. Results varied between strains. There were no high-resolution AFM data on smooth E. coli with full-length O-antigen, and AFM of live Pseudomonas aeruginosa had been unsuccessful [1].

The authors compared Vectabond (electrostatic attachment), glutaraldehyde, and lectins that bind LPS sugars. Smooth E. coli K-12 MG1655, in which O-antigen was restored by repairing the wbbL mutation, adsorbed poorly to Vectabond [1]. Glutaraldehyde on glass forms a Schiff base with primary amines of surface lysines, and this bond is reversible in the presence of water [1]. Viability was assessed with SYTOX staining in a combined AFM and fluorescence microscopy setup. On the glutaraldehyde coverslip, a growing E. coli cell was imaged in LB medium over 24 min, followed by division between 27 and 33 min [1].

## What the images showed

The authors imaged E. coli both expressing O-antigen and fully lacking LPS oligosaccharides. They report that AFM contrast depends on LPS complexity, and that outer membrane domains seen earlier are LPS-enriched islands [1].

The outer membranes of Pseudomonas aeruginosa and Acinetobacter baumannii were also imaged. They lack the characteristic protein trimers observed in model E. coli [1].

The authors also describe growth-phase dependent changes at E. coli poles. Trimer networks typical of exponential-phase cells were unresolved, and morphological defects appeared [1]. All experiments were performed on laboratory bacterial cultures.

## Sources

1. [Nature Communications](https://doi.org/10.1038/s41467-026-78975-y)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-3d448e2b3cbe329c28f8804f_afm_on_glutaraldehyde/