Science Concentrates ENERGY STORAGE DRUG DELIVERY
▸ Targeting the placenta When a pregnant woman’s placenta malfunctions, such as in life-threatening preeclampsia, doctors are often forced to deliver a baby prematurely to avoid further harm to the mother or the fetus. Few companies have pursued treatments that could alleviate or cure placental disease, in part because of concerns that the drug could harm a developing baby. But what if researchers could develop a way to deliver drugs only to the placenta? A team of researchers led by the University of Manchester’s Lynda K. Harris has tackled this challenge. Noting that certain placenta cells possess the same surface proteins as solid tumor cells, the scientists suspected that they could use peptides that target tumors to perform a different job—deliver treatment cargoes to the placenta. Working with mice, the team showed that they could deliver cargoes of insulin-like growth-factor 2 to a rodent placenta, which increased the weight of the placenta and the fetus and did not harm the fetus (Sci. Adv. 2016, DOI: 10.1126/sciadv.1600349). If the results hold true for humans, the strategy could pave the way for the development of drugs for otherwise untreatable, life-threatening diseases in pregnant women.—SARAH
EVERTS
A nanowire battery that won’t die Imagine a battery that never stops holding a charge. An experimental energy storage electrode lasts as long as researchers have had the patience to charge and recharge it—so far, more than 100,000 times (ACS Energy Lett. 2016, DOI: 10.1021/acsenergylett.6b00029). Nanowire battery electrodes can provide a lot of power in a Manganese dioxide-coated nanowires small footprint, says Reginald M. charged and discharged in the presence Penner of the University of Caliof liquid electrolyte lose their MnO2 fornia, Irvine, but they are prone coating (green arrows) and fail to work to breaking. Penner’s group used after 4,000 charging cycles (top), but a test setup to study manganese those in the presence of polymethyl dioxide-coated gold nanowires, methacrylate gel electrolyte remain a potential lithium-ion battery intact and functional after 100,000 cathode material. The group cycles (bottom). tested the wires with a typical liquid electrolyte and with a polymethyl methacrylate (PMMA) gel electrolyte—commonly used in solid-state batteries. Cathodes paired with the liquid electrolyte survived 2,000 to 8,000 charge cycles, but the one with PMMA survived 100,000 full charges and discharges—even in a test system designed to encourage failure. The gel may hold the MnO2 in place, Penner says, preventing it from breaking off of the gold below. Or the gel may slowly leak into pores in the MnO2 and plasticize it, preventing fracturing, he suggests.—KATHERINE
BOURZAC, special to C&EN
SOLAR POWER can deteriorate at temperatures reached to improve a MAPbI film’s microstructure ▸ Simple treatment inside solar cells, Padture says. Last year, he by exposing the material to methylamine and his collaborators developed a method gas, causing the film to liquefy. With the gas improves turned off, the film crystallized This new cation switcheroo preserves a perovskite film’s into a more efficient light-abperovskite films microstructure and improves its thermal stability. sorbing material (Angew. Chem. A team of researchers has uncovered a pathway to efficient perovskite solar cells with improved thermal stability starting from what students call “crappy films,” according to team leader Nitin P. Padture of Brown University (J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.6b02787). Researchers can easily deposit “crappy films” of methylammonium lead triiodide, or MAPbI3, but these films possess undesirable morphologies that aren’t optimized for harvesting light. Furthermore, MAPbI3 films
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C&EN | CEN.ACS.ORG | MAY 9, 2016
Int. Ed. 2015, DOI: 10.1002/ anie.201504379). The team has now found that exposing improved films to formamidine (FA) gas at 150 °C drives a cation-displacement reaction that transforms MAPbI3 to formamidinium lead triiodide, FAPbI3, which has superior thermal stability. This reaction also preserves the morphology of the improved films. Photovoltaic devices made with these FAPbI3 films achieved efficiencies similar to conventional silicon solar cells, the team reports.—MATT
DAVENPORT
CREDIT: ACS ENERGY LETT. (NANOWIRES); J. AM . C HE M . SOC. (PEROVSKITE)
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COATINGS
SYNTHESIS
▸ New route to lead-free porcelain designs discovered
Extended third ring is a charm for indoleannulated compounds
Akae is a traditional Japanese enameling technique used to decorate porcelain. Historically, it involved combining leaded glass powder with iron(III) oxide in a water-based solution to yield a red paint. As porcelain makers have tried to switch to lead-free glass, however, they have had trouble producing high-quality akae samples. Experiments combining various particle sizes of glass and iron(III) oxide now seem to provide an optimal recipe that yields a glass particle core coated with an iron(III) oxide shell, reports a team led by Hideki Hashimoto of Kogakuin University. In contrast, the researchers find that preparing akae paint such that the iron oxide is isolated in spaces between glass particles results in a lower quality enamel (ACS Appl. Mater. Interfaces 2016, DOI: 10.1021/acsami.6b01549).
Fused-ring systems are special structural features of many natural product and synthetic compounds, contributing to the bioactivity that makes them useful as pharmaceuticals and agrochemicals. Chemists have numerous methods for generating small rings with six or fewer members, such as Diels-Alder and other cycloaddition reactions. They also have ways of constructing large rings with
N H
CREDIT: ACS APPL. MATER. INTERFACES (DISH)
The superbug methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital infections. Serge Van Calenbergh of Ghent University and co-
Iridium catalyst, chiral phosphoramidite ligand
N H
n
n
OC02CH3
Ph = phenyl; m, n = 1 or 2
7- to 9-membered rings
10 or more members, including macrolactonization and ring-closing metathesis. However, the direct synthesis of medium-sized rings, especially enantioselectively, has remained a challenge because of steric constraints. Lin Huang, LiXin Dai, and Shu-Li You of Shanghai Institute of Organic Chemistry have now discovered a pathway around this roadblock by developing an intramolecular cascade reaction for building asymmetric seven- to nine-membered rings onto indole frameworks (J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.6b02678). As an example, the team found that a chiral iridium catalyst can drive dearomatization of an allylic carboline to form a bridged intermediate. A subsequent ring-opening retro-Mannich step followed by hydrolysis results in expanding the size of the piperidine ring (shown). The researchers anticipate that their method will facilitate synthesis of new indole-annulated compounds to join those already among the ranks of commercial products.—STEVE RITTER
workers have now developed a potentiator that helps overcome MRSA resistance to antibiotics by disrupting quorum sensing (Angew. Chem. Int. Ed. 2016, DOI: 10.1002/ anie.201601973). Potentiators are agents
O O O
HO HO
OH
HO OH OH O
HO
OH OH O
Hamamelitannin
ANTIBIOTICS
▸ Agent uses quorum sensing to kill bacteria
NH
m
N
Japanese researchers have figured out how to make highquality, lead-free red akae enamel designs, such as the one on this dish. The group succeeded in preparing the core-shell material by combining 2-µm glass particles with 100-nm iron(III) oxide particles, but the details of the preparation method were key: They blended the particles with green tea solution in a mortar and let the mixture dry, repeating the process a total of three times. Because mortars and pestles are commonly used by porcelain artisans, the authors believe that the method should be easy to implement.—JYLLIAN KEMSLEY
m
Ph
O Cl
NH O
HO
OH N H
O
Most potent hamamelitannin analog
that boost the sensitivity of microbes to existing drugs, and quorum sensing is a communication system bacteria use to regulate virulence. To find a potentiator for anti-MRSA drugs, Van Calenbergh and coworkers started with hamamelitannin, a natural product from witch hazel. Hamamelitannin potentiates anti-MRSA agents by modulating quorum sensing but is weakly active and metabolically unstable. The researchers synthesized 58 analogs designed to have better drug properties. When the best of these analogs was administered with the antibiotic cephalexin to infected mice, it killed MRSA about five times as potently as hamamelitannin combined with cephalexin and about 100 times as well as cephalexin alone. The group is currently collaborating with Elanco Animal Health to examine the use of an optimized compound to treat mastitis, a MRSA infection of breast tissue, in cattle.—STU BORMAN MAY 9, 2016 | CEN.ACS.ORG | C&EN
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