Tiny Gold Nanogaps Could Crack the Chirality Puzzle

Looking for biosignatures across the solar system requires looking for asymmetry. Amino acids, the building blocks of proteins, are famously either “left-handed” (L) or “right-handed” (D). We know abiotic processes (i.e. those that create amino acids but don’t involve life) create a 50/50 mixture of the two types, which is called a racemic mixture. But life as we know it almost exclusively relies on left-handed amino acids to fold proteins and right-handed ones to construct nucleic acids. So if we find an imbalance in the types of amino acids we analyze from somewhere in the solar system, it's a good indication that life is behind that imbalance. Differentiating between the two “chiralities”, as they’re called, is possible, but typically requires advanced equipment and chemical disposables that make them burdensome for spaceflight applications. But a new paper in Nature Communications from researchers led by Takahito Ohshiro and Masateru Taniguchi of Osaka University offers an alternative - a solid-state quantum tunneling sensor that can read the chirality of a single amino acid molecule using basically just some gold wire.