NEWS Researchers at Umeå University have developed a methodology to study the surface chemistry of frozen, intact microorganisms – from bacteria, algae and fungi to viruses – without losing water. This is important for understanding how these organisms interact with their environment, for example how they adhere to surfaces.
Madeleine Ramstedt, together with her colleague Andrey Shchukarev, head of the XPS platform, has developed and refined this methodology for nearly ten years.
ImageMattias PetterssonWater is very important for biological samples because it maintains surface structure
Chemists at the Department of Chemistry have long worked to develop methods for surface analysis of various microorganisms using cryogenic XPS, that is, measurements performed with liquid nitrogen at around −170 °C. The unique method they now present in detail in a new publication describes how to analyze the surface chemistry of frozen biological samples in an ultra-high vacuum XPS spectrometer, without loss of water.
“Water is very important for biological samples because it maintains surface structure. Being able to analyze samples while hydrated means we can correctly study their surface chemistry and gain clues about how they interact with their environment,” says associate professor Madeleine Ramstedt at the Department of Chemistry .
Madeleine Ramstedt and her colleague, XPS platform head Andrey Shchukarev, have developed and refined the methodology over nearly ten years. Originating at Umeå University, it has since spread – but currently only a few laboratories in the world can perform comparable cryogenic XPS analyses. Staff at the XPS platform have noted growing interest, with several researchers traveling to Umeå to learn the Umeå team’s methodology on site.
To further disseminate information about the method, the researchers recently published reference data and detailed experimental protocols for surface analysis of bacterial cells in Surface Science Spectra. This journal serves as a reference collection of surface analysis data and is published by the American Institute of Physics (AIP).
“Our publication is part of a large set of reference spectra that others can use to identify what they have in their samples or interpret their data. Also, our contribution is highlighted in a special article, and we think that’s very exciting!” says Andrey Shchukarev.
The research was funded by the Kempe Foundation.
Madeleine Ramstedt and Andrey Shchukarev by the XPS instrument.
ImageMattias PetterssonCryo-XPS spectra from bacterial reference strain Pseudomonas fluorescens DSM50090
Madeleine Ramstedt, Andrey Shchukarev
https://doi.org/10.1116/6.0001575
Freezing instead of freeze-drying before spectroscopy preserves sample surface structure
Chris Patrick
https://doi.org/10.1063/10.0010048
