Chaotic Synchronization of Surface Chemistry and Vesicular Assembly in Hydrothermal Microenvironments
Victor Ugaz and Yassin Hassan of Texas A&M University are supported by the Chemistry of Life Processes Program in the Division of Chemistry to understand the interplay between thermal convection, chaotic mixing, and surface chemical reaction kinetics in microscale, pore-mimicking surroundings. The Cellular and Biochemical Engineering Program in the Division of Chemical, Bioengineering, Environmental, and Transport Systems (CBET) also contributes to this award. An unanswered question is how long-chain molecules were first synthesized from elementary building blocks. Pore networks permeating mineral formations near underwater hydrothermal vents such as those discovered recently in the Lost City and Mid-Atlantic Ridge have emerged as potential hot spots for such biochemical processes, both on Earth and elsewhere. However, the detailed synthesis mechanism remains unclear, because concentrations of the precursor compounds in the surrounding ocean waters would have been too dilute to initiate polymerization. Ugaz and Hassan''s research is exploring a new transport process-chaotic thermal convection-that naturally arises in hydrothermal microenvironments. This process continually shuttles molecular precursors from the bulk fluid to targeted locations on catalytically-active solid boundaries. The investigators are quantitatively mapping the enrichment of biomolecular species that can be achieved via this process, utilizing a new experimental platform to probe its influence on surface reaction kinetics within microscale pore surroundings. The research is also exploring the use of this transport mechanism to orchestrate the assembly of macromolecular species into protocell-like vesicular bodies, to package long-chain molecules and maintain localized pH gradients. The design and construction of such protocells can provide valuable insight into cellular function, and has practical application to the design of biosynthetic reaction systems for biomanufacturing. The project is enhancing student education and training through innovative hands-on modules to design, build, and operate microscale convective reactors representative of prebiotic hydrothermal scenarios and key physicochemical processes central to the origin of life. Companion computational modules integrate practical simulations of convective flow (using lava lamps as a relatable example) with biochemical reaction kinetics, through combined lectures and computer labs.Professors Ugaz and Hassan are performing coordinated experiments and simulations to understand how microscale chaotic thermal convection synergistically promotes mixing of chemical species in the bulk, while simultaneously accelerating enrichment and vesicular protocell assembly and packaging at discrete locations in a microfluidic reactor. A coupled 3D computational flow and reaction model is being developed to quantify how bulk flow characteristics govern surface reaction and vesicular assembly kinetics. This framework is being applied to identify the role of chaos in mediating targeted enrichment, and in defining the range of thermal and geometric conditions conducive to accelerated surface reactions and protocell formation. These results are laying the foundation to elucidate the ability of chaotic thermal convection to mediate assembly of macromolecular species and their encapsulation in protocells, under conditions representative of subsea hydrothermal networks. The knowledge and insights gained from these studies are providing a deeper understanding of possible pathways through which the necessary precursors to metabolic and replicating systems can spontaneously emerge, both on Earth and elsewhere. Important processes beyond biochemistry are also catalyzed in hydrothermal microenvironments, suggesting a compelling role for thermal convective phenomena in governing the transport and reaction of carbon dioxide. The conceptual simplicity and relatability of microscale convective flows is providing the foundation for innovative hands-on educational experiences that guide students through the process of designing, building, and operating microscale convective reactors representative of hydrothermal activity.This award reflects NSF''s statutory mission and has been deemed worthy of support through evaluation using the Foundation''s intellectual merit and broader impacts review criteria.