From Chemical Gardens to Chemobrionics

To model ion transport across protocell membranes in Hadean hydrothermal vents, we consider both theoretically and experimentally the planar growth of a precipitate membrane formed at the interface between two parallel fluid streams in a 2D microfluidic reactor. The growth rate of the precipitate is found to be proportional to the square root of time, which is characteristic of diffusive transport. However, the dependence of the growth rate on the concentrations of hydroxide and metal ions is approximately linear and quadratic, respectively. We show that such a difference in ionic transport dynamics arises from the enhanced transport of metal ions across a thin gel layer present at the surface of the precipitate. The fluctuations in transverse velocity in this wavy porous gel layer allow an enhanced transport of the cation, so that the effective diffusivity is about one order of magnitude higher than that expected from molecular diffusion alone. Our theoretical predictions are in excellent agreement with our laboratory measurements of the growth of a manganese hydroxide membrane in a microfluidic channel, and this enhanced transport is thought to have been needed to account for the bioenergetics of the first single-celled organisms.

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“…This article is a PNAS Direct Submission. 1 To whom correspondence should be addressed. Email: sssc1@cam.ac.uk.…”

Section: Significancementioning

confidence: 99%

“…Furthermore, the separating membrane or wall enforces its own rules on the evolution of the reaction systems as it controls transmembrane transport according to reactant-specific permeabilities. Prime examples of such phenomena are a class termed chemobrionic systems, which include the so-called chemical gardens (1).…”

mentioning

confidence: 99%

Wavy membranes and the growth rate of a planar chemical garden: Enhanced diffusion and bioenergetics

Ding

Batista

Steinbock

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…First described in 1646 by Johann Glauber, "chemical gardens" are one of chemistry's oldest fascinations, attracting even the curiosity of Isaac Newton. 1 Though not alive, chemical gardens do exhibit certain characteristics, including self-organization and the formation of membranes, reminiscent of biological systems. Indeed, in the 19th and early 20th centuries the self-assembling structures were thought to reveal insights into the mechanism of life emerging from an inorganic setting.…”

Section: The Fertile Physics Of Chemical Gardensmentioning

confidence: 99%

“…Versatile compositionand treatment-dependent applications are being found in areas like catalysis and chemical sensing. 1 For example, tubes can be made of catalytic aluminosilicates, and it is possible to use the tube wall as a platform for trapping various injected components ranging from CdSe/ZnS quantum dots to polymer beads and even biological cells. The wall material can also be transformed after the actual growth process; in a recent study, heating the tubes to 900 °C produced devices such as silicasupported, photocatalytically active ZnO tubes.…”

Section: A Network Of Possibilitiesmentioning

confidence: 99%

“…Beyond chemical changes, heating can also induce a transition from amorphous to crystalline materials that, surprisingly, often leaves the macroscopic tube structure intact. 1 The self-organization of chemical garden formation is a nonequilibrium situation fueled by steep concentration gradients that in most other scenarios would quickly dissipate. That fundamental characteristic is shared with living systems that have mastered the art of controlling and utilizing such far-fromequilibrium conditions for materials synthesis and other engineering feats.…”

Section: A Network Of Possibilitiesmentioning

confidence: 99%

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