Science Concentrates PROCESS CHEMISTRY
▸ Solar-powered smart sunglasses Organic solar cells’ low weight, mechanical flexibility, arbitrary coloring, and other attributes provide engineers with exceptional freedom when it comes to designing applications. Researchers in Germany have capitalized on that combination of properties to conduct a case study on the fabrication, optimization, and performance of a self-powered, wearable smart device: electronic sunglasses with integrated solar cells (Energy Technol. 2017, DOI: 10.1002/ ente.201700226). The sunglasses, which were designed by Dominik Landerer, Alexander Colsmann, and coworkers at Karlsruhe Institute of Technology, feature organic solar cells embedded in the lenses. For device evaluation purposes, the team designed the glasses such that the semitransparent cells supply power to sensors that monitor illumination intensity and
ambient temperaThe lenses of ture. The temples of these sunglasses the glasses’ frame feature organic house the sensors, solar cells that microprocessor, and power sensor liquid-crystal display and display circuitry. The team circuitry housed used solution-phase in the frames. processing methods and commercially available organic polymers and fullerenes to assemble the light-absorbing photovoltaic layer. The researchers note that the sunglasses, which resemble commercial ones in appearance, weight, and eye protection against UV radiation, function reliably in intense outdoor light and typical indoor lighting.—MITCH
JACOBY
INFECTIOUS DISEASE
▸ Custom peptide neutralizes influenza If you want to thwart infection by influenza viruses, a good bet is to block the pathogen’s exterior hemagglutinin proteins
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C&EN | CEN.ACS.ORG | JUNE 26, 2017
Safer, greener route to methyl nitroacetate Methyl nitroacetate is a handy chemical building block. It can be used to produce α-amino acids, isoxazoles, and α,β-unsaturated compounds. It’s also a useful reactant in Michael additions, Mannich reactions, and cyclopropanations. But it’s expensive. One gram costs anywhere O from $22 to $115, depending on the vendor. That’s probably because the process that has been used to NO2 CH3O make methyl nitroacetate for more than 40 years is dangerous. The 1976 procedure published in Methyl nitroacetate Organic Syntheses (DOI: 10.15227/orgsyn.055.0077) requires one to dry the highly explosive intermediate dipotassium salt of nitroacetic acid in a vacuum desiccator and then grind it with a mortar and pestle. The protocol also uses carcinogenic benzene as an extraction solvent and requires two distillations. Now, Pablo E. Guzmán, Jesse J. Sabatini, and coworkers at the U.S. Army Research Laboratory have developed a safer, more environmentally friendly way to make this ester (Org. Process Res. Dev. 2017, DOI: 10.1021/acs.oprd.7b00093). The new procedure eliminates the drying and grinding steps and uses either ethyl acetate or dichloromethane as the extraction solvent. It also requires a single distillation rather than two. “While our yield is slightly lower than the original procedure, we feel it’s quite acceptable in exchange for minimizing both the safety and environmental hazards,” Sabatini tells C&EN.—BETHANY HALFORD
from binding with a host cell’s sialic acits downside, though: Only one antibody id-containing sugars. Nature already uses can bind a hemagglutinin site at a time. this interference strategy: Antibodies bind David Baker and Eva-Maria Strauch of the influenza hemagglutinin, preventing inUniversity of Washington and colleagues fection by obstructing the host-pathogen wondered if they could design a protein interaction in a variety of ways, sometimes that bound hemagglutinin in three places at the sialic acid binding simultaneously instead of site and other times with A designed protein just one, to improve on najust the antibody’s sheer (brown and orange) ture’s avidity—the overall physical bulk. This bulk has binds the influenza strength of binding. They hemagglutinin protein theorized this would be (green) at three locations possible because hemagglusimultaneously to block tinin forms regular trimers infection. on the surface of the virus. First, the team used a computational strategy to design a protein that could bind one of hemagglutinin’s sialic acid receptor sites (Nat. Biotechnol. 2017, DOI: 10.1038/nbt.3907). Then they built a scaffold that could orient three of these hemagglutinin-binding proteins simultaneously on the surface of the virus. When they tested their design, the threepronged weapon neutralized influenza in cell culture and protected mice from infection by the pathogen.—SARAH
EVERTS
CREDIT: ENERGY TECHNOL. (GLASSES); DAVID BAKER/U WASHINGTON (INFLUENZA PROTEIN)
SOLAR POWER
PROCESS CHEMISTRY
CREDIT: H. KRISP/WIKIMEDIA COMMONS (SNAKE); ANGEW. CHEM. INT. ED. (DDT)
▸ Continuous crystallization of carbamazepine As continuous manufacturing makes inroads in drug production, the process of continuous crystallization—in which active pharmaceutical ingredients are purified via solidification from a liquid phase—has proven to be a major roadblock. Looking to understand the risks involved with such systems and how they might be mitigated, scientists led by Celia N. Cruz at the U.S. Food & Drug Administration’s Office of Pharmaceutical Quality designed and built a lab-scale continuous crystallization platform for the anticonvulsant compound N carbamazepine (Org. Process Res. Dev. 2017, O NH2 DOI: 10.1021/acs. oprd.7b00130). CarCarbamazepine bamazepine has four crystalline polymorphs, making it a good model compound for troubleshooting. The continuous crystallization system uses an automated, two-stage mixed-suspension and mixed-product removal platform and integrates two process analytical technology tools, Raman microscopy and focused-beam reflectance microscopy, to monitor the crystallization process in real time. The researchers were able to use the analytical tools to address two major problems with continuous crystallization— clogging and particle settling. They plan to optimize the system further to evaluate more advanced strategies for controlling continuous crystallization processes.—
NATURAL PRODUCTS
Green mamba venom could treat kidney disorder A green mamba bite results in dizziness, nausea, difficulty breathing, irregular heartbeats, convulsions, and sometimes death. But the snake’s deadly venom contains a small peptide that could one day save lives. Researchers led by Christiane Mendre of the University of Montpellier, Ralph Witzgall of the University of Regensburg, Nicolas Gilles of Paris-Saclay University, and colleagues plucked a peptide out of the venom that might help people with polycystic kidney disease (Proc. Natl. Acad. Sci. USA 2017, DOI: 10.1073/ pnas.1620454114). These individuals develop water-filled cysts on their kidneys that interfere with the organ’s function and can eventually be fatal. Treatment for the disease currently involves so-called vaptan drugs that interfere with a protein called the type 2 vasopressin receptor. But the drugs are toxic to another organ—the liver. The team of researchers noticed that a 57-residue peptide in the green mamba venom called mambaquaretin-1 also targets the receptor but is more selective than existing drugs. “With high selectivity and without toxic metabolic by-products associated with its peptidic nature, mambaquaretin-1 could become the preferential treatment for these disorders,” they note.—SARAH EVERTS
BETHANY HALFORD
MATERIALS
▸ New crystal structure of DDT identified A newly identified crystal structure of DDT suggests that reformulating the compound to boost its insecticidal properties may be possible (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201703028). The advance could lead to ways of using DDT more efficiently and in smaller quantities, thereby reducing its broader environmental effects. DDT was developed in the 1940s as an insecticide, and many countries still use it for malaria control. But it
Crystalline DDT shows spherulites of form I (orange) in fields of form II (gray). The orange color of form I arises from its interaction with polarized light. is also a persistent organic pollutant that is banned elsewhere because of its toxicity to other species. Since DDT’s discovery,
scientists have believed that it had only one crystal structure, dubbed form I. Inspired by a stock micrograph that suggested helical twisting of DDT crystals, a team led by Bart Kahr and Michael D. Ward of New York University has now experimentally characterized a second crystal structure, form II. Computational analysis points to two more possibilities. DDT adsorbs on insects’ hydrophobic footpads when walking on crystals, a first step toward insecticide uptake. So the researchers hypothesized that different crystal structures could influence adsorption. Experiments with Drosophila melanogaster fruit flies indicated that form II is a more potent insecticide than form I, at least for that species.—JYLLIAN
KEMSLEY JUNE 26, 2017 | CEN.ACS.ORG | C&EN
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