Abstract:
This webinar will show work that we have performed at Umeå University enabling surface analysis of hydrated – but frozen- microorganisms. We have observed that cryo-XPS maintains the structural organization of soft hydrated materials better than if the same samples are analysed at room temperature in dehydrated form. Using cryogenic XPS (cryo-XPS), we have analysed the surface chemical composition for a range of microbial cells. I will show examples from bacterial cells, algal cells, fungi and viruses (bacteriophages). To support in data analysis, we have also analysed a large range of standard substances that form building blocks of microbial cell wall. We have also developed a methodology for using the C1s spectrum of a sample to predict the relative content of C atoms in substances with a character resembling lipids, polysaccharide or peptide (protein or peptidoglycan). I will present comparative studies between cryo-XPS and near ambient pressure XPS on bacterial cells. Overall, I hope to illustrate that cryo-XPS can play a very important role in surface characterization of soft hydrated materials such as biological systems, polymers and drug delivery platforms.