rather than become densely packed, leave polygon-shaped holes. The DNA had to be highly specialized, bearing a thiol on one end to bind to gold, single- and double-stranded segments to optimize the length and flexibility, and a four-base “sticky end” so DNA strands could connect and facilitate clathrate assemblies in solution. Jennifer N. Cha of the University of Colorado, Boulder, says, “This work will likely lead toward fabricating the next generation of unique nanoparticle architectures and expanding the scope of applications for such materials, including hostguest recognition and catalysis.”—STEVE
RITTER
ONCOLOGY
▸ Platinum-containing cancer drugs differ mechanistically Platinum-containing drugs are used to treat many types of cancer. Drugs such as carboplatin and oxaliplatin were developed to avoid some of the side effects and treatment resistance associated with traditional cisplatin. Researchers thought all these drugs kill cells by triggering a DNA-damage response. But oxaliplatin has an unusual side-effect profile and works against cancers for which other drugs, such as cisplatin, are minimally effective.
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A team led by Michael T. Hemann and Stephen J. Lippard of MIT now demonstrates that oxaliplatin works through a different mechanism (Nat. Med. 2017, DOI: 10.1038/ nm.4291). The researchers used RNA interference to target genes with known or suspected roles in cell-death signaling pathways and to see how those pathways responded to various platinum-containing drugs. They found that instead of killing cells through DNA damage, oxaliplatin induces ribosome biogenesis stress, in which cells produce large quantities of the protein-translation machinery, throwing protein production out of whack. In a bit of a vicious cycle, ribosome biogenesis stress may further sensitize cells to oxaliplatin. The findings suggest that platinum drugs don’t necessarily function inter-
ENERGY STORAGE
Tin-phosphorus anodes for potassium-ion batteries The rapidly growing lithium battery industry has spurred a high demand for lithium minerals and a subsequent concern about the limited global supply and high cost of these materials. So scientists are searching for alternatives. In terms of energy storage capacity and other electrochemical properties, potassium-ion batteries (PIBs) look more promising than sodium-ion batteries. But PIB development has been hampered by a lack of suitable anode materials, especially ones that can accommodate potassium ions’ larger size than lithium and sodium. Zhixin Chen, Zaiping Guo, and coworkers at the University of Wollongong may have come up with a solution. The team reports that a PIB anode made of an inexpensive composite of Sn4P3 and carbon exhibits high charge capacity, fast charging rates, and voltage characteristics suitable for industrial battery applications (J. Am. Chem. Soc. 2017, DOI: 10.1021/jacs.6b12185). In addition, the electrochemical profile of the material indicates that Sn4P3-carbon anodes have little risk of forming metal dendrites, which have been implicated in battery failure due to short circuiting.—MITCH
JACOBY
changeably with their derivatives, the researchers note.—CELIA ARNAUD
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▸ Muting bacteria to prevent infection Researchers have developed a new infection-blocking material made of peptide-containing nanofibers that works against antibiotic-resistant bacteria and could one day be incorporated into wound dressings (ACS Infect. Dis. 2017, DOI: 10.1021/acsinfec dis.6b00173). The approach targets bacterial quorum sensing—a mode of chemical communication used by bacteria to detect other
Electrospun fibers containing a peptide that blocks bacterial quorum sensing prevent Staphylococcus aureus from activating its infectious pathways.
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O bacteria. When they sense that enough of their This peptide blocks kind are present, quorum sensing in they can mount S. aureus. an infectious attack. Chemist Helen E. Blackwell of the University of Wisconsin, Madison, has developed peptides to block this quorum-sensing pathway, thereby preventing cells from attacking their host. Together with David M. Lynn and other Wisconsin colleagues, Blackwell electrospun one of these peptides into poly(lactide-co-glycolide) nanofibers. The researchers tested nanofiber mats against normal and deadly antibiotic-resistant strains of Staphylococcus aureus. By using a strain of S. aureus engineered to carry fluorescent reporter genes, the scientists found that the fibers with quorum-sensing inhibitors were able to block the bacteria from successful quorum sensing for up to two weeks. Moreover, when cultured in petri dishes with red blood cells, the treated bacterial cells did not rupture the blood cells, whereas untreated cells did. The presence of ruptured cells indicates that bacteria are using quorum sensing to coordinate an infection.—WUDAN YAN, special to C&EN MARCH 6, 2017 | CEN.ACS.ORG | C&EN
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