As part of the grant, Waggoner's team will develop new fluorescent dyes that bind to the common building blocks of life – DNA, lipids, carbohydrates and proteins. The grant also provides funds to develop an optical system that can spray these fluorescent dyes on a region of soil to detect life forms in the environment. This system is expected to be completed within several years. The Waggoner team is collaborating with researchers at Carnegie Mellon's Robotics Institute; the final life detection system should be versatile enough to couple with different types of rovers used in planetary expeditions.
The scope of the grant includes developing dyes and testing their feasibility in local environments, as well as areas hostile to life, such as the Atacama Desert in northern Chile, where relatively few pockets of life persist. Given its Mars-like terrain, the Atacama is a favorite laboratory testing ground for astrobiologists.
"It's tremendously exciting to extend the work of our team and contribute to interplanetary searches for life," says Waggoner, who directs the Molecular Biosensor and Imaging Center (MBIC) at the Mellon College of Science. "We believe that these methods will provide the most sensitive means of detecting life with a remote device."
The technology has potential beyond Mars, according to Shmuel Weinstein, project manager. "The scientific impact of our work begins on earth, with the ability to detect very low concentrations of living and dead organisms." Once developed, this system could work in circumstances such as biohazardous settings or extreme environments, where an automated, unmanned device would be ideal.
Developing fluorescent markers to detect life in space for this project presents many technical challenges, according to Gregory Fisher, project imaging scientist. Fluorescent markers that bind to their targets must stand out against what could be a blinding background of natural mineral luminescence. Additionally, detecting low levels of light emitted from relatively few organisms could be difficult against reflected light that is originally emitted from the optical instrument. Just as big a challenge is creating a detection system that resembles a good epi-fluorescence microscope used on earth, but one with few, if any, moveable parts. The completed system will need to focus using a camera range finder (like those found in hand-held cameras), in addition to providing some additional processing of its own camera images.
"Other testing methods require considerably more sampling or are less sensitive than what we propose. We don't know of other remote methods capable both of detecting low levels of micro-organisms and visualizing high levels incorporated as biofilms or colonies," adds Fisher.
Additionally, notes Lauren Ernst, project chemist, Martian life forms may contain different structural components than those found on earth. "We want our reagents to visualize any form of life that might be present. We will define fluorescent probes to detect the smallest amounts of DNA, lipids, carbohydrates and proteins."
For example, Ernst will design fluorescent tags to the materials containing peptide bonds, a signature feature of proteins. Other tags will target a variety of sugars that comprise carbohydrates. Moreover, these tags will not be specific for left- or right-handed structures. Such "handedness," or chirality, characterizes proteins and other compounds on earth, but Martian life could exhibit opposite chirality from our own.
Other members of Waggoner's team who will be performing critical research as part of this grant include Christoffer Lagerholm and Byron Ballou.
The fluorescent marker technology proposed is based on the extensive expertise of the MBIC at Carnegie Mellon. Established 17 years ago with a multimillion dollar grant from the National Science Foundation, MBIC combines research on molecular and cellular sensors along with research in imaging and computation to understand biological function. The Waggoner team is world renowned for developing widely commercialized cyanine dye fluorescent labeling reagents that have played a significant role in the human genome project and are the main dyes used to analyze gene activity in the regulation of cells and tissues.
For more information about the grant or MBIC, please contact Lauren Ward at 412-268-7761 or wardle@andrew.cmu.edu. For information about interplanetary research under way at the Robotics Institute, please contact Anne Watzman at 412-268-3830 or aw16@andrew.cmu.edu.