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Surface analysis of microorganisms using cryo-XPS

Research project The surface chemical composition of microorganisms can be analyzed using several different methods. We have been developing methodology for cryogenic X-ray photoelectron spectroscopy (cryo-XPS) applications on microorganisms.


Head of project

Madeleine Ramstedt
Associate professor

Project overview

Project period:

Start date: 2010-01-01

Participating departments and units at Umeå University

Department of Chemistry, Department of Molecular Biology

Research area

Chemical sciences, Environmental chemistry, Infection biology, Materials science

Project description

The goal of the method development is to enable XPS surface analyses of biological specimens without dessication that may risk to alter the surface composition of the sample.

This methodology involves analyzing fast-frozen intact microbial cells (i.e. not freeze dried or dehydrated) under liquid nitrogen temperatures. We thereafter use a spectral model to predict the content of lipid, polysaccharide and peptide (protein + peptidoglycan) in the outermost part of the intact microbial cell wall from the C1s spectrum. We have used this approach on bacteria (both Gram-positive and Gram-negative), phages, algae and fungal cells.

This work has been funded through grants from Umeå Center for Microbial Research and the Kempe Foundation. It has been conducted at the XPS platform at Umeå University.

This method development has taken place during several years in collaboration with other researchers at Umeå universitet, e.g. Andrey Shchukarev, Jean-François Boily, Bernt-Erik Uhlin, Sun Nuynt Wai, Christiane Funk, Constantin Urban. Also international colaborators have been important partners in this work e.g. Ryoma Nakao at National Institute of Infectious Diseases, Tokyo, Japan and Stefan Salentinig at University of Fribourg, Schweiz.

In 2022 we also investigated application of this methodology to investigate nanoparticles together with colleagues at the National Physical Laboratory in UK, David Cant, Caterina Minelli and Alex Shard.

For a webinar on the topic (ca 45 min) please visit this recording by the Electrons Spectroscopy Division of the French Vacuum Society (SFV) from November 2022: link



2011, Monitoring Surface Chemical Changes in the Bacterial Cell Wall – Multivariate analysis of X-ray photoelectron spectroscopy data

2014, The cell wall composition of Bacillus subtilis changes as a function of pH and Zn2+ exposure – insights from cryo-XPS measurements

2016, Cryo-XPS: probing intact interfaces in nature and life, perspective article

2016, Analysis of bacterial cell surface chemical composition using cryogenic X-ray photoelectron spectroscopy, Book chapter in Methods in Molecular Biology

2020, Cryo-XPS analysis reveals surface composition of microalgae

2020, Surface Analysis of Bacterial Systems Using Cryo-X-ray Photoelectron Spectroscopy

2021, Comparative study of NAP-XPS and cryo-XPS for the investigation of surface chemistry of the bacterial cell-envelope

2021, Applying cryo-XPS to study the surface chemical composition of fungi and viruses

2022, Cryo-XPS spectra from bacterial reference strain Pseudomonas fluorescens DSM50090
  Highlighted by AIP SciLight on 23rd March 2022

2023, XPS spectra from nucleobases, DNA, and RNA

2023, Cryo-XPS for Surface Characterization of Nanomedicines

Latest update: 2023-10-17