Nanoscale Effects within Biological Membranes caused by Radiation

Membranes are an essential part of life as we know it. All forms of life depend on membranes, which form a boundary between the surrounding environment and the biological interior. The project NanoMemR investigates the interaction of radiation and biological membranes via advanced infrared spectroscopic and microscopic techniques. This allows to study what effect radiation has on the ultrastructural level of biological membranes.
The prime scientific objective of NanoMembR is to elucidate the large spectrum of effects of electromagnetic radiation on membranes and membrane components, including short and longer-chain fatty acids, isoprenoids, phospholipids, hopanoids, sterols and pigments. Since membranes are an integral part of all life, membrane stability has far reaching implications for various research fields. For example, membrane stability is crucial for the understanding of the formation of first compartments, which then led to the first cellular structures. In the early stages of the evolution of life, membrane stability played an important role when life started to conquer the top surface of the young Earth, where radiation exposure presented an important environmental challenge. Furthermore, life detection missions to other planets, such as Mars, aim to find so called biosignatures indicative for extinct or possibly extant life. A main challenge however is to determine which molecules are “good” biomarkers in terms of stability and unambiguousness. Since membranes are common to all life, they and their components are prime candidates as biomarkers. Assessing in detail their stability and preservation potential will allow to narrow down a suitable list of organic (biogenic) molecules for planetary exploration missions.
The research project NanoMembR could demonstrate that biological membranes are, although only a few nanometres thick, very robust structures and promising candidates as search targets for life detection mission to other planets due to their supramolecular structure highly specific and due its molecular composition robust and stable against environmental influences, radiation in particular.

Within the frame of the NanoMembR project, biological membranes in the form of supported lipid bilayers as well as natural microbial membranes were studied. Via self-assembly processes, vesicle formation and vesicle fusion on suitable substrates, model membranes were constructed and characterised before their exposition to UV radiation and simulated planetary and atmospheric conditions. Model membranes composed of specific lipids (e.g. fatty acids, phospholipids) were enriched with membrane stabilizers (e.g. cholesterol) and modifiers (e.g. pigments). Atomic force microscopy and infrared spectroscopy were the main tools of analysis. The combination of these two techniques in the form of scattering-type scanning near field optical microscopy coupled with Fourier Transform infrared spectroscopy (s-SNOM/FTIR) was employed for structural and chemical investigation of the membrane morphology, composition and stability on the nanoscale. The membranes under investigation showed a remarkable robustness against radiation and environmental influences, especially in anoxic atmospheric conditions. Such conditions were studied in the context of planetary simulation experiments and investigations into the suitability of membranes as biomarkers for life detection. Furthermore, membranes of biological organisms were studied and characterised to study the impact of simulated planetary conditions on living organisms.
In addition to experiments in the laboratory, NanoMembR supported activities to design and develop space exposure platforms to study the photochemistry and stability of organic molecules in low Earth orbit. One of these projects, SpectroCube, consists of a new European nanosatellite platform with an onboard in-situ FTIR spectrometer. Another project, Exocube, will be installed on the International Space Station to monitor photodegradation and the influence of the space environment on organic samples and biological organisms.

The NanoMembR project succeeded in applying advanced spectroscopic and microscopic techniques for nanoscale imaging combined with the capability of spatial chemical mapping to the study of biological model membranes and microorganisms. This allowed to study in detail the effect of environmental conditions, radiation in particular, on biological structure and supramolecular assemblies. With the development of in-situ spectroscopic instrumentation for nanosatellites and other exposure platforms, the NanoMembR projects space missions to investigate suitable organic molecules as search targets for the search of life on other planets such as Mars. Data and results from the NanoMembR project feed into the definition of priority biomarkers for current and future life detection missions, which aim to address the long-standing question whether life arose only on Earth or somewhere else in our solar system, or even beyond.

Periodic Reporting for period 1 - NanoMembR (Nanoscale Effects within Biological Membranes caused by Radiation)

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