Synchronized chaotic targeting and acceleration of surface chemistry in prebiotic hydrothermal microenvironments
Aashish Priye a, Yuncheng Yu a, Yassin A. Hassan b,c, and Victor M. Ugaz a,d,1
Author Affiliations
aArtie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843;
bDepartment of Mechanical Engineering, Texas A&M University, College Station, TX 77843;
cDepartment of Nuclear Engineering, Texas A&M University, College Station, TX 77843;
dDepartment of Biomedical Engineering, Texas A&M University, College Station, TX 77843
Edited by Howard A. Stone, Princeton University, Princeton, NJ, and approved December 19, 2016 (received for review August 3, 2016)
Fig. 1: Hydrothermal conveyor based on chaotic thermal convection.
Significance
We describe a physical mechanism capable of achieving simultaneous mixing and focused enrichment in hydrothermal pore microenvironments. Microscale chaotic advection established in response to a temperature gradient paradoxically promotes bulk homogenization of molecular species, while at the same time transporting species to discrete targeted locations on the bounding sidewalls where they become highly enriched. This process delivers an order of magnitude acceleration in surface reaction kinetics under conditions naturally found in subsea hydrothermal microenvironments, suggesting a new avenue to explain prebiotic emergence of macromolecules from dilute organic precursors—a key unanswered question in the origin of life on Earth and elsewhere.
Abstract
Porous mineral formations near subsea alkaline hydrothermal vents embed microenvironments that make them potential hot spots for prebiotic biochemistry. But, synthesis of long-chain macromolecules needed to support higher-order functions in living systems (e.g., polypeptides, proteins, and nucleic acids) cannot occur without enrichment of chemical precursors before initiating polymerization, and identifying a suitable mechanism has become a key unanswered question in the origin of life. Here, we apply simulations and in situ experiments to show how 3D chaotic thermal convection—flows that naturally permeate hydrothermal pore networks—supplies a robust mechanism for focused accumulation at discrete targeted surface sites. This interfacial enrichment is synchronized with bulk homogenization of chemical species, yielding two distinct processes that are seemingly opposed yet synergistically combine to accelerate surface reaction kinetics by several orders of magnitude. Our results suggest that chaotic thermal convection may play a previously unappreciated role in mediating surface-catalyzed synthesis in the prebiotic milieu.
thermal convection prebiotic biochemistry hydrothermal vents chaos
Footnotes
1To whom correspondence should be addressed. Email: ugaz@tamu.edu.
Author contributions: A.P., Y.A.H., and V.M.U. designed research; A.P. and Y.Y. performed research; Y.A.H. contributed new reagents/analytic tools; A.P., Y.Y., and V.M.U. analyzed data; and A.P. and V.M.U. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1612924114/-/DCSupplemental.
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