Science Concentrates TOXICOLOGY BIOLOGICS
▸ Making antibodies minus the cells Monoclonal antibodies (mAbs)—proteins engineered to bind to particular antigens— can serve as medications for cancer, autoimmune diseases, and other conditions. During mAb development, researchers often tweak the antibody’s underlying DNA sequence and screen for variants that give the highest yields when expressed in cells. Chinese hamster ovary (CHO) cells are typically used to produce these variants for screening, but that process takes a minimum of seven days to express the proteins. Researchers have now taken cells out of the equation to develop a faster, cell-free synthesis platform for making mAbs by modifying the formulation of a commercially available CHO cell extract (ACS Synth. Biol. 2017, DOI: 10.1021/ acssynbio.7b00001). Michael C. Jewett of Northwestern University, Varnika Roy of biologics company MedImmune, and colleagues added a glutathione buffer solution and isomerase enzymes to the CHO extract to ensure the correct formation of the disulfide bonds that hold together the antibodies’ four subunits. They then used the system to synthesize mAb-A, a standard antibody used by MedImmune, and confirmed with an assay that it binds its antigen. The cellfree system takes only 24 hours, which could significantly speed up the antibody screening process, the researchers say.—ERIKA
Arsenic poultry feed additive may be more problematic than believed The arsenic-containing feed additive roxarsone was used for more than 60 years to promote weight gain and to prevent parasitic infections in poultry and swine before its use was halted in Europe and North America because of concerns of exposure to cancer-causing arsenic metabolites. But the additive is still used in Asia. Researchers led by the University of Alberta’s X. Chris Le and Wuhan University’s Bin Hu were interested in identifying and assessing arsenic-containO O ing metabolites that people who HO OH H3 C OH eat roxarsone-fed poultry may As As be exposed to. They conducted a study of 1,600 chickens that ate either standard chicken feed NO2 R or feed containing roxarsone. OH OH The researchers then sampled Roxarsone Methylated the birds’ livers for arsenic-conphenylarsenical taining metabolites. Previously, metabolites R = NO2, NH2, NHCOCH3 they reported eight of these metabolites in chickens that consumed roxarsone. Now, they have identified three others, all of which are methylated phenylarsenical metabolites (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201700736). The metabolites were found in chicken livers even five days after roxarsone supplementation had been halted—a typical preslaughter safety window used by the poultry industry for the additive to clear—raising concerns about human exposure to the potentially toxic metabolites if the chicken livers are consumed.—BETHANY HALFORD
GEBEL BERG, special to C&EN
CREDIT: SHUTTERSTOCK (CHICKEN); CH EM . M AT E R . (ELECTRODE MATERIAL)
ENERGY STORAGE
▸ ‘Flat water’ provides a battery boost A popular approach for developing better batteries and other energy-storage devices is incorporating atoms-thick sheets of solid-state materials. This strategy may hold for liquids, too. Researchers have found that test devices using tungsten oxide electrodes have improved energy-storage kinetics when thin layers of water are
Alternating layers of water sheets and tungsten oxide crystals—shown in purple in the illustration—appear as stripes in the electron micrograph of electrode material shown on the right.
confined between crystalline WO3 sheets (Chem. Mater. 2017, DOI: 10.1021/acs. chemmater.6b05485). Hydrated electrodes charge and discharge faster than their anhydrous counterparts, reports a team led by Veronica Augustyn of North Carolina State University. Further, the hydrated material better maintains its charge capacity and energy efficiency at these faster timescales. The intercalated water layers likely
lower the energetic barrier encountered by ions moving from liquid electrolytes to solid electrodes, although the team is investigating this hypothesis. Tungsten oxide provides a good model system for these types of fundamental studies, though the material is too heavy for commercial applications, Augustyn says. Still, she’s not alone in thinking this work can help further develop other, more attractive materials, including two-dimensional carbides and nitrides known as MXenes (pronounced maxenes). “I’m confident this concept can be applied to many other 2-D and layered materials, helping us to develop high-power and high-energy-storage devices,” comments MXene pioneer and innovator Yury Gogotsi of Drexel University.—MATT DAVENPORT MAY 15, 2017 | CEN.ACS.ORG | C&EN
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