ORIGINS OF LIFE
CREDIT: NAT. CHEM. (CELLS); UNIVERSITY OF WASHINGTON (LOST CITY)
▸ Fluid flow fosters prebiotic chemistry When it comes to understanding the origins of life, scientists have already determined that biochemical building blocks— amino acids, nucleobases, and sugars—can form under early-Earth-like conditions. But figuring out how those simple species combined in a dilute solution to form complex macromolecules has been harder. A new study suggests a key role for fluid dynamics in microscale pore networks within mineral structures at hydrothermal vents (Proc. Natl. Acad. Sci. USA 2017, DOI: 10.1073/ pnas.1612924114). Fluid dynamics may A team led by have enriched the Victor M. Ugaz at chemical species Texas A&M Union the surfaces of versity studied a pore networks of model system of calcium carbonate pore-mimicking formations, such as cylindrical cells these at the Lost using computaCity hydrothermal tional and experifield in the midmental methods. Atlantic Ocean. They found that thermal gradients characteristic of alkaline hydrothermal vent systems result in chaotic fluid flow. That fluid flow transports organic molecules from the bulk fluid to catalytically active pore surfaces, where the species may adsorb and react. Simultaneously, the chaotic flow also provides bulk mixing that prevents localized depletion of chemical species, thereby ensuring a continuous supply of building blocks.—JYLLIAN KEMSLEY
SYNTHESIS
▸ Chemists solve olefin hydration challenge Building on recent developments in photoredox chemistry, a team led by Aiwen Lei of Wuhan University has found a new solution to one of chemistry’s long-standing synthetic challenges: the catalytic anti-Markovnikov hydration of olefins (ACS Catal. 2017, DOI: 10.1021/acscatal.6b03388). Direct addition of water to olefins to make alcohols is a well-developed industrial
POLYMERS
Method grows polymers without damaging cells Modifying the surface of cells with synthetic polymers offers a strategy for manipulating cellular behavior. Usually researchers make such modifications by attaching premade polymers to functional groups on the cell surface, but that
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“grafting-to” approach isn’t very efficient. An alternative approach involves “grafting from,” Dye-labeled polymers in which a polymer grows from an initiator on (purple) are found only the cell surface. But this has been hard to do at the surface of these in ways that keep the cells—especially mamyeast cells. The fluorescein malian cells—alive. H. Tom Soh of Stanford diacetate treatment University; Jia Niu and Craig J. Hawker of the (green) indicates that the University of California, Santa Barbara; and co- cells are still alive. workers report an approach using a light-mediated controlled radical polymerization method that is gentle enough to use with mammalian cells (Nat. Chem. 2017, DOI: 10.1038/nchem.2713). The researchers used cell-surface-anchoring derivatives of 2-(butylthiocarbonothioyl)propionic acid as the chain-transfer agents that are attached to the cells and initiate the reaction. The polymer chain (shown) grows through the addition of cell-compatible polyethylene glycol-based acrylamide monomers. Yeast cells modified this way continued to grow and divide normally. For mammalian cells, which are more delicate, the researchers switched to lipidlike anchor compounds that insert themselves into the cell membrane. They could then modify mammalian cells without harming them. The researchers plan to use the coating to control the cells’ biochemistry and to modulate cell-cell interactions.—CELIA ARNAUD
chemical reaction. For most olefins, this reagents and peroxides or precious-metal hydration process involves using an acid catalysts. Those approaches can be costly, catalyst, such as sulfuric or phosphoric acid, generate significant waste, or are hazardous and follows Markovnikov’s rule, in which the on a large scale. Lei and coworkers found hydroxyl group bonds to the double-bond that a mesityl-substituted methylacridinum carbon that has the greater number of carphotocatalyst in conjunction with diphenyl bon–carbon bonds. For terminal olefins, disulfide as a hydrogen-transfer catalyst the process produces secondary alcohols. avoids those problems and delivers high The anti-Markovnikov hydration of olefins, yields of a variety of aliphatic and aromatic in which the selectivity is reversed and the alcohols from terminal and hydroxyl group bonds to the carbon on the internal olefins on a gram other end of the double bond, converts terscale.—STEVE RITTER minal olefins to primary alcohols. But catalytic R1 R1 Photocatalyst, H anti-Markovnikov olefin diphenyl disulfide OH + hydration is not straight- R2 + H2O R2 N 3 3 forward; it requires R R ClO4 CH3 indirect hydroboration/ Catalytic anti-Markovnikov olefin hydration Photocatalyst oxidation with borane FEBRUARY 6, 2017 | CEN.ACS.ORG | C&EN
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