Issue 23, 2019

Imaging live bacteria at the nanoscale: comparison of immobilisation strategies

Abstract

Atomic force microscopy (AFM) provides an effective, label-free technique enabling the imaging of live bacteria under physiological conditions with nanometre precision. However, AFM is a surface scanning technique, and the accuracy of its performance requires the effective and reliable immobilisation of bacterial cells onto substrates. Here, we compare the effectiveness of various chemical approaches to facilitate the immobilisation of Escherichia coli onto glass cover slips in terms of bacterial adsorption, viability and compatibility with correlative imaging by fluorescence microscopy. We assess surface functionalisation using gelatin, poly-L-lysine, Cell-Tak™, and Vectabond®. We describe how bacterial immobilisation, viability and suitability for AFM experiments depend on bacterial strain, buffer conditions and surface functionalisation. We demonstrate the use of such immobilisation by AFM images that resolve the porin lattice on the bacterial surface; local degradation of the bacterial cell envelope by an antimicrobial peptide (Cecropin B); and the formation of membrane attack complexes on the bacterial membrane.

Graphical abstract: Imaging live bacteria at the nanoscale: comparison of immobilisation strategies

Article information

Article type
Paper
Submitted
27 Jun 2019
Accepted
10 Oct 2019
First published
10 Oct 2019
This article is Open Access
Creative Commons BY license

Analyst, 2019,144, 6944-6952

Imaging live bacteria at the nanoscale: comparison of immobilisation strategies

G. Benn, A. L. B. Pyne, M. G. Ryadnov and B. W. Hoogenboom, Analyst, 2019, 144, 6944 DOI: 10.1039/C9AN01185D

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