Browsing by Author "Rix, Catherine S."

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    CASS•E: Cranfield astrobiological stratospheric sampling experiment
    (2010-12-31T00:00:00Z) Naicker, L.; Grama, V. V.; Juanes-Vallejo, Clara M.; Katramados, Ioannis; Rato, Carla Cristina Pereira Salgueiro Catarino; Rix, Catherine S.; Sanchez, E.; Cullen, David C.
    CASS•E is a life detectionexperimentthat aims to be capable of collecting microorganisms in Earth's Stratosphere. Theexperiment will be launched on astratosphericballoon in collaboration with Eurolaunch through the BEXUS (Balloon-borneExperimentsfor Universitv Students) program from Esrange Sweden in October 2010. It essentially consists of a pump which draws air from the Stratosphere through a collection filter mechanism. Due to the low number density of microbes in the Stratosphere compared to the known levels of contamination at ground level, theexperimentincorporated Planetary Protection and Contamination Control (PP&CC) protocols in its design and construction in order to confirm that any microbes detected are trulyStratosphericin origin. Space qualified cleaning and sterilisation techniques were employed throughout Assembly Integration and Testing (AIT) as well as biobarriers which were designed to open only in the stratosphere and so prevent recontamination of the instrument alter sterilisation. The material presented here covers the design and AIT of CASS•E. Copyright ©2010 by the International Astronautical Federation. All rights rese
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    Detecting life on Mars and the life marker chip : antibody assays for detecting organic molecules in liquid extracts of Martian samples
    (Cranfield University, 2012-01) Rix, Catherine S.; Cullen, David C.
    The Life Marker Chip instrument, which has been selected to fly as part of the 2018 ExoMars rover mission payload, aims to detect up to 25 organic molecules in martian rocks and regolith, as markers of extant life, extinct life, meteoritic in-fall and spacecraft contamination. Martian samples will be extracted with a solvent and the resulting liquid extracts will be analysed using multiplexed microarray-format immunoassays. The LMC is under development by an international consortium led by the University of Leicester and the work described within this thesis was carried out at Cranfield University as part of the consortium’s broader program of work preparing the LMC instrument for flight in 2018. Within this thesis four specific areas of LMC instrument development are addressed: the investigation of immunoassay compatible liquid extraction solvents, the study of likely interactions of martian sample matrix with immunoassays, the development of antibodies for the detection of markers of extinct life and demonstration of solvent extraction and immunoassay detection in a flight representative format. Cont/d.
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    Extraction of polar and nonpolar biomarkers from the martian soil using aqueous surfactant solutions
    (Elsevier Science B.V., Amsterdam., 2012-12-31T00:00:00Z) Court, Richard W.; Rix, Catherine S.; Sims, Mark R.; Cullen, David C.; Sephton, Mark A.
    The Life Marker Chip intends to use an aqueous surfactant solution to extract both polar AND nonpolar biomarkers from the martian soil for transport to an antibody-based detection system. Currently, a solution of 1.5 g l-1 polysorbate 80 in 20:80 (vol:vol) methanol:water is being considered and appears to be suitable. However, should this solution be shown to be unsuitable for the LMC or the martian environment, it will be necessary to use a different surfactant. Here, we have investigated the ability of a range of other surfactant solutions to extract a suite of eight standards spiked on the surfaces of the martian soil simulant JSC Mars-1 and tested the compatibility of the best two surfactants with a representative antibody assay for the detection of pyrene. The results show that using 20:80 (vol:vol) methanol:water as the solvent leads to greater recoveries of standards than using water alone. The poloxamer surfactants Pluronic® F-68 and F-108 are not effective at extracting the standards from JSC Mars-1 at any of the concentrations tested here. The fluorosurfactant Zonyl® FS- 300 is able to extract the standards, but not as efficiently as polysorbate 80 solutions. Most successful of the alternative surfactants was the siloxane-based surfactant poly[dimethylsiloxane-co-[3-(2-(2- hydroxyethoxy)ethoxy)propyl]methylsiloxane] (PDMSHEPMS) which is able to extract the standards from JSC Mars-1 about as efficiently as polysorbate 80 solutions. Enhanced recovery of the standards using polysorbate 80 solutions can be achieved by increasing the concentration of polysorbate 80, from 1.5 g l-1 to 10 g l-1, leading to an increase in the recovery of standards of about 50%; a similar increase in effectiveness is also apparent for PDMSHEPMS. Polysorbate 80 at concentrations of 1.5 g l-1 and 10 g l-1 and Zonyl® FS-300 and PDMSHEPMS (both at a concentration of 10 g l-1) are also compatible with the representative pyrene antibody ass
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    Immunological detection of small organic molecules in the presence of perchlorates: relevance to the life marker chip and life detection on Mars.
    (Mary Ann Leibert, 2011-11-17T00:00:00Z) Rix, Catherine S.; Sims, Mark R.; Cullen, David C.
    The proposed ExoMars mission, due to launch in 2018, aims to look for evidence of extant and extinct life in martian rocks and regolith. Previous attempts to detect organic molecules of biological or abiotic origin on Mars have been unsuccessful, which may be attributable to destruction of these molecules by perchlorate salts during pyrolysis sample extraction techniques. Organic molecules can also be extracted and measured with solvent-based systems. The ExoMars payload includes the Life Marker Chip (LMC) instrument, capable of detecting biomarker molecules of extant and extinct Earth-like life in liquid extracts of martian samples with an antibody microarray assay. The aim of the work reported here was to investigate whether the presence of perchlorate salts, at levels similar to those at the NASA Phoenix landing site, would compromise the LMC extraction and detection method. To test this, we implemented an LMC- representative sample extraction process with an LMC-representative antibody assay and used these to extract and analyze a model sample that consisted of a Mars analog sample matrix (JSC Mars-1) spiked with a representative organic molecular target (pyrene, an example of abiotic meteoritic infall targets) in the presence of perchlorate salts. We found no significant change in immunoassay function when using pyrene standards with added perchlorate salts. When model samples spiked with perchlorate salts were subjected to an LMC-representative liquid extraction, immunoassays functioned in a liquid extract and detected extracted pyrene. For the same model sample matrix without perchlorate salts, we observed anomalous assay signals that coincided with yellow coloration of the extracts. This unexpected observation is being studied further. This initial study indicates that the presence of perchlorate salts, at levels similar to those detected at the NASA Phoenix landing site, is unlikely to prevent the LMC from extracting and detecting organic molecules from martian samples.