Prebiotic nanoscale cavity formation: GABA-induced exfoliation in Ca-montmorillonite

We present exfoliation of a crystalline clay induced by the small carbon-chain amino acid, gamma-aminobutyric acid (GABA), upon adsorption-desorption interaction. We experimentally investigated the interaction between Ca-montmorillonite clay (Ca-Mt) and GABA, a non-proteinogenic amino acid commonly found in carbonaceous meteorites. Despite evidence of only transient adsorption onto the clay surfaces, GABA exhibits the capacity to act as an exfoliator. ATR-FTIR spectroscopy reveals a non-reversible structural change of the Ca-Mt aluminosilicate network induced by GABA. Powder XRD analysis and TEM imaging reveal that localised, partial exfoliation of the clay layers occurrs after interaction with GABA, creating internal nanoscale cavities in-between adjacent clay layers. These results demonstrate that an elementary, monomeric species can act as an exfoliating agent in a prebiotically-relevant scenario, and that in this process, nanoscale confined environments are formed. This work may have far-reaching implications for the role of non-proteinogenic species in proteinogenesis (non-enzymatic formation of proteins) and for the role of clays in processes leading to the origin of life on rocky (exo)planets.