Interfaces play a deciding role in many aspects of modern chemistry and material science – catalysis, adhesion, sensing, nucleation are all processes driven by interfaces.
We use methods based on static and time-resolved sum frequency generation to probe the orientation, structure and dynamics of molecules at interfaces. Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and microscopy are used as complementary tools to probe binding chemistry, surface distribution and molecular structure.
An important part of our research are protein structures at interfaces. Specific proteins can act as Nature’s engineers of both hard and soft tissue. Proteins can ‘sculpture’ biogenic minerals and shape cell membranes. The control interfacial proteins exert over biological surfaces has relevance for disciplines as diverse as cell biology, bio-sensor research, biomimetics and material science. We ask how proteins fold and move at surfaces and how energy flows through protein interfaces.
For technical applications we use chemical modification of surfaces to prevent biofouling and scaling and to reduce friction. The approaches we use are inspired by our studies of the surface chemistry of animals. Can we fabricate self-cleaning surfaces like plants? Stick to walls like a spider? Glue like a frog tongue?
The goal of our research is to understand how molecules operate at surfaces and how we can control interfacial processes at the molecular level.
SurfLab researchers, together with an international team of collaborators, have published a paper in Journal of Physical Chemistry entitled “Umbrella-Like Helical Structure of Alpha-Synuclein at the Air-Water Interface Observed with Experimental and Theoretical Sum Frequency Generation Spectroscopy”.
In the paper, the researchers derive the structure of α-synuclein at the air-water interface by combining molecular dynamics with surface specific vibrational spectroscopy. Results show that the structure resembles an umbrella, which could help explain the α-synuclein aggregation associated with Parkinson's Disease.
SurfLab researchers, together with the Biomodelling group and Daniel E. Otzen from iNANO, have published a paper in Nature Communications entitled “Elevated concentrations cause upright alpha-synuclein conformation at lipid interfaces”. In the paper, the researchers show that the structure of α-synuclein changes conformation and promotes protein aggregation when the concentration exceeds normal physiological levels at a lipid membrane. α-synuclein aggregation in the human brain is associated with the development of neurodegenerative diseases such as Parkinson's Disease.
SurfLab researchers, together with collaborators from the NSLS-II from Brookhaven National Laboratory have published a paper in Journal of Electron Spectroscopy and Related Phenomena entitled “A library of calcium mineral reference spectra recorded by parallel imaging using NEXAFS spectromicroscopy”. In the paper, the researchers created a calcium mineral array relevant for studying biomineralization in nature.
SurfLab Researchers in collaboration with the École Polytechnique Fédérale de Lausanne (EPFL) in Lausanne, Switzerland have for the first time probed the structure of globular protein lysozyme binding to phospholipid-coated nanoemulsions in situ. This article was published in Langmuir.
SurfLab researchers augmented by Frank Jensen have published a paper in Journal of the Chemical Society of America entitled “Peptide bond of aqueous di-peptides is resilient to deep UV radiation”.
The paper shows that the vast majority of the excited di-peptides withstand the deep ultraviolet excitation. In those relatively few cases, where excitation leads to dissociation, the measurements show that deep ultraviolet irradiation breaks the Ca-C bond rather than the peptide bond. The peptide bond is thereby left intact and the decarboxylated di-peptide moiety is open to subsequent reactions.
SurfLab researchers augmented by Frank Jensen have published a paper in Journal of the Chemical Society of America entitled “The primary photolysis of aqueous di-carbonate”.
The paper shows that when di-carbonate (CO32-) is excited at 200 nm, 82 +/- 5% of the excited di-anions either detach an electron or dissociate. The electron detachment takes place from the excited state in t < 1 ps and forms ground state CO3- and e(aq)-. Dissociation occurs from both the electronic ground and excited states of CO32-. Dissociation from the CO32- excited state is assisted by water molecules and forms CO2-, OH and OH-.
Tobias Weidner has co-authored an article about bacterial dynamin-like proteins in Nature Communications.
The work, entitled “SynDLP is a dynamin-like protein of Synechocystis sp. PCC 6803 with eukaryotic features” has been a collaboration with several research groups including the University of Mainz and the Forschungszentrum Jülich.