Non-equilibrium conditions must have been crucial for the assembly of the first informational polymers of early life-by supporting their formation and continuous enrichment in a long-lasting environment. Here we explored how gas bubbles in water subjected to a thermal gradient, a likely scenario within crustal mafic rocks on the early Earth, drive a complex, continuous enrichment of prebiotic molecules. RNA precursors, monomers, active ribozymes, oligonucleotides, and lipids are shown to (1) cycle between dry and wet states, enabling the central step of RNA phosphorylation, (2) accumulate at the gas-water interface to drastically increase ribozymatic activity, (3) condense into hydrogels, (4) form pure crystals, and (5) encapsulate into protecting vesicle aggregates that subsequently undergo fission. These effects occurred within less than 30 minutes. The findings unite physical conditions in one location which were crucial for the chemical emergence of biopolymers.They suggest that heated microbubbles could have hosted the first cycles of molecular evolution.Life is a non-equilibrium system. By evolution, modern life has created a complex protein machinery to maintain the nonequilibrium of crowded molecules inside dividing vesicles. Based on entropy arguments, equilibrium conditions were unlikely to trigger the evolutionary processes during the origin of life 1 . External non-equilibria had to be provided for the accumulation, encapsulation, and replication of the first informational molecules. They can locally reduce entropy, give rise to patterns 2 , and lean the system towards a continuous, dynamic self-organization 3 . Non-equilibrium dynamics can be found in many fluid systems, including gravity-driven instabilities in the atmosphere 4 , the accumulation of particles in nonlinear flow 5,6 , and shear-dependent platelet activation in blood 7 . Our experiments discuss whether gas-water interfaces in a thermal gradient could have provided such a nonequilibrium setting for the emergence of life on early Earth.Non-equilibrium systems in the form of heat flows were a very common and simplistic setting, found ubiquitously on the planet 8 . Hydrothermal activity is considered abundant on early Earth and intimately linked to volcanic activity 9 . Water is thereby circulating through the pore space of the volcanic rocks, which is formed by magmatic vesiculation (primary origin) and fractures (secondary origin). These systems have been studied as non-equilibrium driving forces for biological molecules in a variety of processes 10-17 .Gases originating from degassing of deeper magma bodies percolate through these water-filled pore networks. At shallow depths bubbles are formed by gases dissolved in water and formation of vapor where sufficient heat is supplied by the hydrothermal system. The bubbles create gas-water interfaces, which previously have been discussed in connection with atmospheric bubble-aerosol-droplet cycles 18 , the adsorption of lipid monolayers and DNA to the interface 19,20 , or the formation of pep...

Supported lipid bilayer (SLB) membranes are key elements to mimic membrane interfaces on a planar surface. Here, we demonstrate that azobenzene photolipids (azo-PC) form fluid, homogeneous SLBs. Diffusion properties of azo-PC within SLBs were probed by fluorescence microscopy and fluorescence recovery after photobleaching. At ambient conditions, we find that the trans-to-cis isomerization causes an increase of the diffusion constant by a factor of two. Simultaneous excitation with two wavelengths and variable intensities furthermore allows to adjust the diffusion constant D continuously. Xray reflectometry and small-angle scattering measurements reveal that membrane photoisomerization results in a bilayer thickness reduction of ∼0.4 nm (or 10%). While thermally induced back-switching is not observed, we find that the trans bilayer fluidity is increasing with higher temperatures. This change in diffusion constant is accompanied by a red-shift in the absorption spectra. Based on these results, we suggest that the reduced diffusivity of trans-azo-PC is controlled by intermolecular interactions that also give rise to Haggregate formation in bilayer membranes.

For the emergence of life, the abiotic synthesis of RNA from its monomers is a central step. We found that in alkaline, drying conditions in bulk and at heated air‐water interfaces, 2′,3′‐cyclic nucleotides oligomerised without additional catalyst, forming up to 10‐mers within a day. The oligomerisation proceeded at a pH range of 7–12, at temperatures between 40–80 °C and was marginally enhanced by K+ ions. Among the canonical ribonucleotides, cGMP oligomerised most efficiently. Quantification was performed using HPLC coupled to ESI‐TOF by fitting the isotope distribution to the mass spectra. Our study suggests a oligomerisation mechanism where cGMP aids the incorporation of the relatively unreactive nucleotides C, A and U. The 2′,3′‐cyclic ribonucleotides are byproducts of prebiotic phosphorylation, nucleotide syntheses and RNA hydrolysis, indicating direct recycling pathways. The simple reaction condition offers a plausible entry point for RNA to the evolution of life on early Earth.

The assembly of ancient informational polymers from nucleotide precursors is the central challenge of life's origin on our planet. Among the possible solutions, dry polymerization of 3’,5’‐cyclic guanosine monophosphate (3’,5’‐cGMP) has been proposed as a candidate to create oligonucleotides of 15–20 units in length. However, the reported sensitivity of the reaction to the presence of cations raised questions of whether this chemistry could be relevant in a geological context. The experiments in this study show that the presence of cations is not restrictive as long as the reaction is conducted in an acidic environment, in contrast to previous reports that suggested optimal conditions at pH 9.