CHEMICAL BONDING
▸ New complexes have more than 1 uranium-metal bond Researchers created rare complexes with uranium and nickel atoms that feature multiple uranium-nickel single bonds (Nat. Chem. 2019, DOI: 10.1038/s41557-0180195-4). Congqing Zhu of Nanjing University and colleagues chelated heptadentate R Downloaded via WEBSTER UNIV on March 2, 2019 at 21:35:11 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.
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ligands containing nitrogen and phosphorus with uranium atoms. Then they added a nickel reagent, which formed bridges between the uranium-ligand complexes. Uranium chemistry expert Suzanne C. Bart of Purdue University said the researchers drew on decades of research to design the ligands that make these unusual complexes possible. Zhu says the complexes are stabler than the two previously reported compounds with multiple uranium-metal bonds. Two of the group’s complexes contain four U-Ni bonds, and a third has six. The researchers say density functional theory calculations by coauthor Laurent Maron of Paul Sabatier University suggest uranium atoms in two of the complexes have a 5f26d1 electron configuration rather than the expected 5f36d⁰ configuration, a result of the U-Ni bonds’ partly ionic character.—SAM LEMONICK
DIAGNOSTICS
▸ Fidget-spinner centrifuge separates blood from plasma A fidget spinner, the toy twirled endlessly between the fingers of schoolkids, can act as a makeshift centrifuge and separate blood plasma sufficiently for an HIV test (Anal. Chem. 2018, DOI: 10.1021/acs.
GENE EDITING
New CRISPR enzyme shows unusual properties CRISPR-CasX—James Bond villain or next gene-editing superspy? Researchers led by Jennifer Doudna of the University of California, Berkeley, have uncovered some unusual features in a new gene-editing enzyme found in a search of bacterial DNA in groundwater. CasX, first described in 2016, is smaller than its more famous cousins, Cas9 and Cas12a. This makes it a potentially better candidate for medicinal use as the field turns to viruses to try to get CRISPR systems into the human body, says coauthor Benjamin Oakes, also of UC Berkeley. In addition, by studying crystal structures of CasX, the team found an unusual domain that they then named the non-target strand binding (NTSB) domain, which seems to stabilize unwound DNA, facilitating double-stranded cuts. And after clipping the first strand of DNA, CasX seems to bend the second strand toward the active site, Oakes says, making
CasX features a unique domain, NTSB, which seems to stabilize unwound DNA and facilitate cleavage.
the second snip easier (Nature 2019, DOI: 10.1038/s41586-019-0908-x). The team continues to characterize CasX, including its potential to be detected and deactivated by the human immune system. Cas9 and Cas12a come from known human pathogens, and as many people have been exposed to those pathogens, it’s not clear whether their immune systems will react to proteins that come from them. CasX’s groundwater source will hopefully allow it to do its work unseen, Oakes says.—MEGHA SATYANARAYANA
analchem.8b04860). For tubes, sealed them, and blood tests, red blood taped them to each of cells must be separated the three spinning arms from the plasma, usually of a commercially availwith a fast-spinning cenable fidget spinner. After trifuge, but these are exspinning the device for pensive and require elec4–7 min, the team sepatricity to operate, which rated about 30% of the may not be feasible in replasma from the blood source-limited regions of sample—with 99% puthe world, says Chien-Fu rity. A paper-based HIV A fidget spinner can separate Chen of the Institute of test detected the target red blood cells from plasma. Applied Mechanics at Naproteins in the separated tional Taiwan University. Along with Chien- plasma. This makeshift centrifuge could be Cheng Chang and colleagues, Chen put used to detect other diseases with plasma human blood spiked with a common HIV-1 biomarkers as well, Chen says.—LEIGH diagnostic protein in 50 mm long plastic KRIETSCH BOERNER, special to C&EN FEBRUARY 11, 2019 | CEN.ACS.ORG | C&EN
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