Spontaneous formation of autocatalytic sets with self replicating inorganic metal oxide clusters
Significance Self replication is an important property of life, yet no one knows how it arose, and the machinery found in modern cells is far too complex to have formed by chance. One suggestion is that simple networks may become able to cooperate and hence replicate together forming autocatalytic sets, but no simple systems have been found. Here we present an inorganic autocatalytic, based on molybdenum blue, that is formed spontaneously when a simple inorganic salt of sodium molybdate is reduced under acidic conditions. This study demonstrates how autocatalytic sets, based on simple inorganic salts, can lead to the spontaneous emergence of self replicating systems and solves the mystery of how gigantic molecular nanostructures of molybdenum blue can form in the first place. Here we show how a simple inorganic salt can spontaneously form autocatalytic sets of replicating inorganic molecules that work via molecular recognition based on the {PMo12} [PMo12O40]3 Keggin ion, and {Mo36} [H3Mo57M6(NO)6O183(H2O)18]22 cluster. These small clusters are able to catalyze their own formation via an autocatalytic network, which subsequently template the assembly of gigantic molybdenum blue wheel {Mo154} [Mo154O462H14(H2O)70]14 {Mo132} [MoVI72MoV60O372(CH3COO)30(H2O)72]42 ball shaped species containing 154 and 132 molybdenum atoms, and a {PMo12}{Mo124Ce4} [H16MoVI100MoV24Ce4O376(H2O)56 (PMoVI10MoV2O40)(C6H12N2O4S2)4]5 nanostructure. Kinetic investigations revealed key traits of autocatalytic systems including molecular recognition and kinetic saturation. A stochastic model confirms the presence of an autocatalytic network involving molecular recognition and assembly processes, where the larger clusters are the only products stabilized by the cycle, isolated due to a critical transition in the network.
Proceedings of the National Academy of Sciences