Non-equilibrium composition of mixed metal hydroxide membranes grown in flow systems

Maggie A. Cooper, Bruno C. Batista, Oliver Steinbock

Florida State University

It is likely that life on Earth did not arise organically but, rather, inorganically. The earliest iterations of cellular membranes may have formed as inorganic precipitates in hydrothermal environments, as we observe in the walls of deep-sea hydrothermal vent chimneys. Albeit complex, these precipitates and their capacity to support prebiotic synthesis are accessible to us by means of systematic investigations into chemical garden systems. We have utilized microfluidic methods to grow two-dimensional inorganic membranes composed of magnesium and nickel hydroxides – common mineral species in low-temperature alkaline vent chimneys – and characterize their resulting structural and compositional features. With a more thorough understanding of the underlying physical attributes of these precipitates, we now aim to assess their capabilities in the context of prebiotic synthesis. The presence of metal-ion gradients, significant Ni-enrichment, and the precipitation of unstable alpha-nickel hydroxides in all mixed-metal precipitates studied is noteworthy, especially when we consider these results alongside preliminary organic dye adsorption data which show preferential partitioning of large organic molecules into the membrane by factors of hundreds to thousands.