MEDICINAL CHEMISTRY
Controlling bacteria with light Chemists propose using light to turn bacterial quorum sensing on and off
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Artificial hips, prosthetic knees, new disks in the spine. The surfaces of these commonly used implants are all susceptible to colonization by bacteria that form hardy biofilms, and these infections can be a major reason why the implants fail. Preventing these failures is one of the reasons Ben Feringa and his team at the University of Groningen are interested in disrupting quorum sensing (QS)—the communication between bacteria. “This is a serious issue,” Feringa says. “So if we can find ways to collaborate and help doctors in the clinic a little bit, I would be very pleased.” By adding an azobenzene photoswitch to a QS molecule, the team has managed to create a light-controlled on-off switch for bacterial communication and organization (Chem 2019, DOI: 10.1016/j.chempr.2019.03.005). “This is a great paper that demonstrates the usefulness of photopharmacology to control bacterial communities,” says Dirk Trauner at New York University, who is one of the pioneers of photopharmacology, or light-activated drugs and treatments. QS processes kick in when bacteria increase in number and need to change their behavior to survive. As the number of bacteria increases, so do the levels of QS molecules. Once this chemical chatter reaches a critical level, the cellular pathways activated by those molecules allow bacteria to act as a group. Feringa’s team made compounds based on a QS molecule from the bacteria Pseudomonas aeruginosa.
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UV light switches the configuration of the N=N bond in AHL5, changing it from an inhibitor (top) to an activator (bottom) of quorum sensing.
One of the photoswitching N compounds, AHL5 AHL5, converts between two isomers that activate and inactivate QS pathways with a 700-fold difference in activity when tested in cultures of P. aeruginosa and Escherichia coli. Feringa admits that AHL5 can’t yet be used in a clinical setting. For example, AHL5 switches between its trans and cis forms with ultraviolet light, which is not clinically useful because it doesn’t penetrate deeply into tissue. Red light would be a better way to trigger these molecules, he says. Feringa points out that as well as medical treatments, being able to control bacterial communication with light could also help study the molecular biology behind bacterial behavior.—LAURA HOWES
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PUBLISHING
Machine writes chemistry book Springer Nature uses algorithm to summarize lithiumion battery research Springer Nature, the world’s second-biggest academic publisher, has published the first scholarly book authored entirely by machines. The book, which is free to read and download, consists of four chapters summarizing studies about lithium-ion batteries. It is based on 150 papers published between 2016 and 2018 on SpringerLink, the publisher’s database of more than 1,200 scholarly journals. The algorithm sifts through studies analyzing keywords using similarity-based clustering, a computational technique often used in the fields of machine learning, pattern recognition, and image analysis. It groups together text on similar topics, producing succinct paraphrased summaries central to the topic of interest. According to Christian Chiarcos, a computational linguist at Goethe University Frankfurt who created the algorithm that wrote the book, the only thing users need to provide beforehand is the number of topical chapters and sections they want the generated book to have. “The book did a fairly good job in identifying the numerous materials [that have] been studied in the literature and provided a great summary of the research in each area across the field,” says Jun Liu, a chemical engineer at the University of Washington and the Pacific Northwest National Laboratory. Chiarcos says the process will inevitably vary between different disciplines. “For example, chemists didn’t want us to summarize experiments, which makes sense because if you miss some step in between, an experiment might fail,” he notes. Henning Schoenenberger, director of product data and metadata management at Springer Nature, says the company deliberately didn’t manually polish or copyedit the book. “It was our intention to highlight the current status and the remaining boundaries of machine-generated content,” he explains.—DALMEET SINGH CHAWLA,
special to C&EN
APRIL 22, 2019 | CEN.ACS.ORG | C&EN
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