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Project Progress

The goal of the Microarray Assay for Solar System Exploration (MASSE) project (formally known as MILDI) is to develop detection and quantification methods for a large number of organic compounds, many of which may be associated with life. The methods will be built into a small instrument designed for robotic missions to Mars, Titan, and other NASA targets.

The NASA Fundamental Biology Program has supported early development, but the project is transitioning over to an Astrobiology Institute project. Other NASA research announcements (NRAs) are also appropriate for future funding of this project. Other acronyms used by us for the same general concept include MIDI (Mars Immunoassay Detection Instrument), PASO, Protein Array Sensor for Organics, and one or two others. The general principle is that using antibodies developed to react with them on either a specific or a class basis can do detection of organic compounds. The reaction triggers a fluorescence dye, and ultraviolet (UV) or near UV laser light can be used to trigger the fluorescence; the glow can be detected by a small charged coupled device (CCD) camera and the brightness can be calibrated to the abundance of the target antigen. An array can be made by borrowing current DNA array technology so that a thousand or more different antibodies can be deposited at indexed locations on a small chip. Up to 10,000 different test sites on a single 2-3cm chip have already been demonstrated for this technology. Soil, rock, or water containing unknown compounds can be extracted and the concentrated extract deposited on the chip. Examples of sought compounds include a large variety of proteins, polysaccharides, amino acids, polycyclic aromatic hydrocarbons (PAHs), and hopenoids (for searching for remains of fossil life). The technique has potential picomole sensitivity for many compounds. Activation of the fluorescence component or dye associated with the antibody is automatic and readout can proceed after an appropriate time interval. This technique, which has been demonstrated on a number of antibodies, is the basis of clinical detection for many types of tissue, bacteria, viruses, and organic compounds. The antibody-antigen technique is used in the drugstore over-the-counter pregnancy test. It is very reliable and very cheap. A large number of normal fluorescence stains or dyes can also be included in the array in addition to the antibodies.

Progress during this past year includes adding to and coordinating the team, enlisting an experienced project manager, identification of several dozen initial appropriate antibodies, acquisition of some of the antibodies, outlining of a testing protocol, and engineering design of the instrument. We intend to propose it for the 2009 Mars lander mission. The technology effort is currently transitioning from standard tubing and pumps to a microfluidics design that may reduce the mass and size by an order of magnitude or more.

The basic concept and instrument design is also adaptable to laboratory use for Mars sample return testing for organics and for life. It may also have spinoff use in clinical laboratories, home health care, and biohazard detection.