ASTID

Robust Biosensors for the Measurement of Biomarkers in Extraterrestrial Environments with Stereochemical Specificity (2)

PI: Chad Paavola

The search for signs of life is the next step in the exploration of extraterrestrial environments where there is evidence for the presence of water. It is accepted that abiotic and prebiotic environments can be distinguished from extinct or extant life by examining complex organic molecules such as carbohydrates and amino acids. Based on the identity
and stereochmistry of these molecules we can determine the likelihood of abiotic vs. biotic vs. terrestrial origin. The existing technologies for this application are gas chromatography mass spectroscopy, an improved version of the instrument used on the Viking missions, and capillary electrophoresis, which is the basis for the Mars Organic Detector. However, both of these sensor systems require volatilization of the analyte and are therefore not well suited to detection of a variety of compounds, including carbohydrates and nutrients such as phosphate and nitrate. For definitive identification of
a wider range of compounds associated with astrobiology objectives, a method for detecting specific volatile and non-volatile molecules in complex mixtures, including their stereochemistry, is required The objective of this proposal is to develop a new sensing technology for biomarkers that is specific for a wider range of relevant organic molecules and nutrients using bacterial binding proteins. These sensors could also detect a pattern of
compounds consistent with a prebiotic environment, and thus help confirm or refute current theories on the origin of life. The long-term goal of this research is to develop the methods by which biosensors that use shared optical and electronic hardware can be produced for any desired small molecule analyte. Improvement of technology for detecting biomarkers is an important part of the goals of the ASTID program. The proposed sensors would support goal 2 of the Astrobiology Roadmap, “explore for past or
present habitable environments, prebiotic chemistry and signs of life elsewhere in our Solar System.” The proposed sensing technology is based on the binding affinity of a family of proteins derived from bacteria. These proteins are highly selective and sensitive, each binding a specific molecule. Fluorescent biosensors can be produced by attaching fluorophores to carefully selected positions on the binding proteins. We are using binding
proteins derived from thermophilic bacteria to produce biosensors that are sufficiently robust for planetary exploration and have already created two sensors of this type. Instruments using this technology could be built using off-the-shelf optical and electronic hardware and would require minimal hardware mass and power consumption. We are well prepared to carry out the proposed research, having assembled a team of researchers with
expertise in areas of protein biosensors, nanostructured templates and protein chemistry. We maintain state of the art laboratory for molecular biology and protein chemistry. Furthermore, we have already produced biosensors based on this technology, using proteins derived from both mesophilic and thermophilic organisms. We will accomplish the objective of this research by pursuing the following specific aims, which are described in detail in subsequent sections: 1. Obtain binding proteins for analytes from thermophilic
bacteria. 2. Incorporate fluorophores and characterize resulting biosensors. 3. Immobilize biosensors and incorporate into optical flow cell. 4. Construct a laboratory-scale prototype. This research will exploit the latest advances in bionanotechnology to create a family of biosensors that can detect compounds characteristic of extinct or extant living organisms. At the end of this three-year effort, we will have a working laboratory prototype that will detect a set of carbohydrates, amino acids, organic amines, and nutrients with minimal sample preparation at parts per trillion levels. This would represent a significant addition to available analytical tools for planetary exploration.