Posted by Researchers at the University of Osaka have developed a compact electrical technique that could help future missions search for extraterrestrial life by detecting a key chemical biosignature – the handedness of amino acids.
Amino acids can exist in two mirror-image forms, known as L- and D-forms. In terrestrial biology, proteins are built almost entirely from L-amino acids, while non-biological chemical processes generally produce both forms in roughly equal amounts. This imbalance, known as chirality, makes the L/D ratio a potentially useful indicator of biological activity.
Current methods for measuring amino-acid chirality typically analyze large numbers of molecules and often require complex laboratory equipment and chemical reagents. The new approach instead detects individual molecules electrically. The researchers used a nanoscale gap between two gold nanowires. As amino-acid molecules passed through the gap, they produced tiny tunneling currents. Because the electrical waveforms generated by L- and D-forms differ slightly, the team could analyze those signals and determine which form had passed through. By combining the nanogap measurements with artificial intelligence, the researchers distinguished between the two forms with more than 80% accuracy. According to the team, this is the first demonstration of amino-acid chirality discrimination at the single-molecule level. They then tested the technique on more realistic astrobiological samples. These included material from the Murchison meteorite, which fell in Australia in 1969, and soil collected from Chile’s Atacama Desert, an environment frequently used as an analogue for extreme extraterrestrial conditions. The electrical method successfully reproduced the main features of amino-acid composition obtained using conventional analytical techniques.
Because the system relies on electrical detection rather than bulky optical equipment or extensive chemical processing, it could eventually be adapted into small instruments for planetary missions. Such sensors could be used to analyze samples on Mars, icy moons, asteroids, or other targets, helping scientists search for chemical patterns that may indicate biological activity beyond Earth.
For more details, read the full article by University of Osaka.
