6 Materialchemie
Filtern
Dokumenttyp
- Vortrag (9)
- Posterpräsentation (4)
- Sonstiges (2)
- Beitrag zu einem Tagungsband (1)
- Forschungsdatensatz (1)
Sprache
- Englisch (17)
Referierte Publikation
- nein (17) (entfernen)
Schlagworte
- Biofilms (17) (entfernen)
Organisationseinheit der BAM
- 6 Materialchemie (17)
- 6.1 Oberflächen- und Dünnschichtanalyse (15)
- 4 Material und Umwelt (12)
- 4.1 Biologische Materialschädigung und Referenzorganismen (11)
- 6.2 Material- und Oberflächentechnologien (2)
- 4.0 Abteilungsleitung und andere (1)
- 4.2 Material-Mikrobiom Wechselwirkungen (1)
- 6.6 Physik und chemische Analytik der Polymere (1)
- 9 Komponentensicherheit (1)
- 9.5 Tribologie und Verschleißschutz (1)
Eingeladener Vortrag
- nein (9)
In this contribution the mechanisms of formation and current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, and the improvement of the tribological performance of nanostructured metal surfaces.
Data for the publication "The role of extracellular polymeric substances of fungal biofilms in mineral attachment and weathering" (https://doi.org/10.1038/s41529-022-00253-1). It includes:
- The Summary of the EPS concentration, EPS sugar components and EPS linkages.
- The Summary of the XPS analysis of freeze-dried biofilm samples of all strains.
- The Summary of the pH, Mg, SI and Fe concentration, biomass and olivine dissolution rate for each time point of all dissolution experiments.
This application note presents how EnviroESCA can be used to analyze bacterial samples under near ambient pressure conditions in various states of hydration using different levels of humidity. Such investigations of bacterial cell wall surfaces in their hydrated state are essential for studying biological interfaces at work.
The use of innovative near-ambient pressure (NAP-)XPS instrumentation allows the detailed analysis of irregularly-surfaced biofilms. NAP-XPS enables the surface analysis of bacterial samples in their natural hydrated state without complex sample preparation techniques such as freeze-drying or fast-freezing, which are needed for XPS analysis in ultrahigh vacuum.
Bacterial biofilms have the capacity to develop and thrive in virtually all circumstances and surfaces, even in the most challenging environmental conditions. The pervasive and recalcitrant existence of biofilms renders them to be a significant safety risk and economical encumbrance in a wide array of industries and technologies, and therefore is a priority area of research.
It is essential to develop an improved understanding of the mechanisms implicated during biofilm formation, such as in the case of the diffusion of bacterial-secreted extracellular electron transporters, which are purported to play an important role during biocorrosion by exoelectrogenic bacteria. Hence, a fundamental understanding of electron transfer mechanisms between bacteria and extracellular electron acceptors will contribute insight to our understanding of charge transport and chemistry at the biofilm – external insoluble electron acceptor interface.
In the present work, Attenuated Total Reflection - Fourier transform-infrared (ATR-FTIR) spectroscopy has been coupled to electrochemical techniques for the nondestructive, in situ spectro-electrochemical monitoring of biofilms in real-time. Shewanella sp. have been selected for this investigation due to their adaptable exoelectrogenic respiratory capacities and their notable ability to reduce metals via several different mechanisms of extracellular electron transfer mechanisms, including self-secreted flavin shuttles. Gold-thin film model substrates have been used due to their inert nature and for their ability to permit precise manipulation of the substrate surface polarization. Additionally, hydrogels comprised of calcium cross-linked alginate have been used to mimic the architectural features of extracellular polymeric substances which are integral to a bacterial biofilm, to allow the study of electron-transporting flavin molecules in an artificial biofilm. The results will demonstrate patterns of diffusion, akin to how flavins would diffuse in a naturally occurring biofilm, and how polarization affects this process. Furthermore, insight will be gained on how the redox behavior of flavins can influence the development and evolution of a biofilm.
This interdisciplinary approach should shed light on bacterial electron transfer mechanisms which could contribute towards emerging technologies which seek to better understand such mechanisms for novel antifouling strategies, renewable energies, and bioremediation.
Surface characterisation of biofilms by nearambient pressure X-ray photoelectron spectroscopy
(2018)
The XPS information depth of approximately 10 nm is in the same size range as the outer membrane of the gram-negative bacteria, which makes XPS a suitable tool for determining the elemental composition of the bacterial surface and monitor changes caused by outer stress like dehydration or exposure to antimicrobials. However, bacteria are inherently in a hydrated state, and therefore only compatible to ultra-high vacuum after extensive sample preparation, which may degrade the sample constituents. This issue is addressed by the development of near-ambient pressure (NAP)-XPS, which enables bacteria and biofilms to be characterised in their native wet state. Artificial biofilms, bacteria and biofilms of Escherichia coli have been characterised with the laboratory NAP-XPS instrument EnviroESCA from SPECS GmbH, at pressures ranging from high vacuum to 12 mbar, and in both humid and dry environment. By studying biological samples in their native wet state, new insight about composition and transport of drugs through cell membranes and the extracellular polymeric substance (EPS) of biofilms can be obtained.
The XPS information depth of approximately 10 nm is in the same size range as the outer membrane of the gram-negative bacteria, which makes XPS a suitable tool for determining the elemental composition of the bacterial surface and monitor changes caused by outer stress like dehydration or exposure to antimicrobials. However, bacteria are inherently in a hydrated state, and therefore only compatible to ultra-high vacuum after extensive sample preparation, which may degrade the sample constituents. This issue is addressed by the development of near-ambient pressure (NAP)-XPS, which enables bacteria and biofilms to be characterised in their native wet state. Artificial biofilms, bacteria and biofilms of Escherichia coli have been characterised with the laboratory NAP-XPS instrument EnviroESCA from SPECS GmbH, at pressures ranging from high vacuum to 12 mbar, and in both humid and dry environment. By studying biological samples in their native wet state, new insight about composition and transport of drugs through cell membranes and the extracellular polymeric substance (EPS) of biofilms can be obtained. In this contribution, the latest progress on biofilm characterisation by NAP-XPS will be presented, and measurement capabilities and limitations will be discussed.
A presentation held for the seminar "Ausgewählte analytische Methoden der Physik" hosted by Prof. Birgit Kanngießer at TU Berlin. The first part focus on depth-dependent XPS-measurements (XPS, synchrotron HAXPES) to obtain a concentration profile of iodine in an artificial biofilm. In the second part, NAP-XPS measurements of various bacterial samples are presented.
INTRODUCTION: X-ray photoelectron spectroscopy (XPS) provides elemental and chemical information from the outermost ~10 nm of the sample surface. This is in the same order of magnitude as the thickness of the outer bacterial membrane of gram-negative bacteria, as well as outer membrane molecules as exopolysaccharides and lipopolysaccharides, commonly attached to the cell surface. With the development of near-ambient pressure (NAP)-XPS, bacteria can be analysed with minimal sample preparation. This is in contrast to ultra-high vacuum XPS, where complex sample preparation including freeze-drying or fast-freezing is required, a treatment that may introduce artefacts or degrade the biological constituents.
METHODS: EnviroESCA is a laboratory based NAP-XPS instrument, equipped with a monochromated Al Kα radiation source and a differentially pumped energy analyser connected to an exchangeable sample environment, a basic build-up is displayed in Figure 1c. It allows for measurements in various gas-atmospheres, including water vapor, which makes it possible to characterise bacteria and other biological samples close to their natural, hydrated state. Artificial model-biofilms of exopolysaccharides, planktonic Pseudomonas Fluorescens and biofilms of Escherichia Coli have been characterised in hydrated and dried state.
RESULTS: High-resolution XPS-spectra from carbon, oxygen, nitrogen and phosphorous can be assigned to carbohydrates, lipids and proteins in general agreement with litterature2,3. Especially the carbon 1s peak is of interest (see Figure 1a and b), which reveal components originating from aliphatic carbon, single bounded carbon and double bounded/acetal carbon. A series of measurements of an E. coli biofilm from 11 mbar in humid environment to 1 mbar air reveal changes in the C1s peak, which suggests that the bacterial surface undergo substantial change.
DISCUSSION & CONCLUSIONS:
Bacterial samples can be analysed under near-ambient pressure conditions in various states of hydration with minimal sample preparation. Such investigations of bacterial cell wall surfaces are essential for studying biological interfaces at work.