ELECTRONIC MATERIALS
Coiled nanotube yarn generates electricity Nanomaterial harvests electrical energy from motion This scanning electron microscopy image shows A new material could help harvest the energy from ocean waves or even human movement. The material, a carbon nanotube yarn, generates electricity when stretched or twisted. An international team, led by Seon Jeong Kim of Hanyang University and Ray H. Baughman of the University of Texas, Dallas, made the materials by twisting multiwalled carbon nanotube yarns until they became tightly coiled. Stretching decreases the ability of the yarn to store electrical charge, which increases its voltage, leading to an electrical current (Science 2017, DOI: 10.1126/science.aam8771). The scientists also coated the yarns with a gel electrolyte and then interwove the fibers with fabric in a shirt, allowing the researchers to monitor a
person’s breathing from the a tightly coiled carbon nanotube yarn that can current generated as the generate electricity when stretched or twisted. person’s chest expanded and tube, generating an average of about 2 µW contracted. According to Baughman, of power. the team’s “twistrons” generate more Large-scale harvesting of ocean wave than 100 times as much power as simienergy would be limited by the manular electricity-generating materials that facturing cost of these nanotube yarns, can be woven into fabric. The twistrons however. An important next step “is to provide enough power to transmit up to take what we’ve learned from these carbon 2 kilobytes of data over 100 meters every nanotube harvesters and apply it to less 10 seconds. expensive materials that are commercially To harvest electricity from near-shore ocean waves, the research team suspended available,” Baughman says. John A. Rogers, of Northwestern Unia 10-cm-long twistron weighing only 1 mg versity, calls the twistron technology “a between a weight and a balloon in the clever type of platform” and adds that it Gyeongpo Sea, just off the coast of South provides a variety of technological opporKorea. The weight anchored one end to tunities, particularly for powering biomedthe seafloor, and each passing wave pulled ical monitoring devices.—EMMA HIOLSKI the balloon, stretching the coiled nano-
BIOCHEMISTRY
Enzyme harnesses light to make alkanes
C R E D I T: UN I V E RS I TY O F T EXAS , DA LLAS
Newly identified enzyme powers fatty acid decarboxylation with blue light
FAP contains flavin adenine dinucleotide (FAD), which commonly serves as a redox cofactor in biological reactions. In the case of FAP, however, FAD absorbs & Biotechnologies Institute of the French Although many organisms respond to blue light to reach an excited state that Alternative Energies & Atomic Energy light, very few enzymes inside those orCommission. Beisson and colleagues knew abstracts an electron from the carboxylate ganisms use light directly as an energy group of a C12 to C18 fatty acid, which then that some species of microalgae could source for catalysis. Researchers now convert long-chain fatty acids to alkanes report a new light-driven enzyme: Chrisdecarboxylates to yield an alkane or alkene. or alkenes through a light-dependent tened fatty acid photodecarboxylase “This and other recent discoveries (FAP), it uses blue suggest a hitherto Blue O – O O – O O • O light to drive the hidden scope for biolight H+ ( )9–15 technologically useful removal of carboxyl + FAD + FAD* + FAD–• + ( )9–15 ( )9–15 ( )9–15 groups from fatty acCO2 FAD photochemistry by ids to form alkanes or means of cofactor-deFAD = flavin adenine dinucleotide alkenes (Science 2017, pendent enzymes,” mechanism and that the microalgae didn’t DOI: 10.1126/science.aan6349). writes Nigel S. Scrutton, director of the possess any genes similar to those that FAP joins a select group of so-called Manchester Institute of Biotechnology, in code for hydrocarbon-synthesizing enphotoenzymes, including DNA-repair ena commentary accompanying the report. zymes called photolyases, that use light for zymes in other organisms. That puzzle Beisson now wonders whether other eventually led them to FAP. “Initially, we catalysis on their own rather than funcflavoenzymes are unidentified photoenthought that the synthesis of the enzyme tioning as part of a larger complex such zymes. When scientists measure enzyme or its mRNA was regulated by light,” Beisas photosystems I or II, which are used by activity, he says, turning off the lights to son says. The team “didn’t imagine” that plants and algae for photosynthesis. see if the enzyme still works “isn’t someThe team that identified FAP was led by the enzyme itself would directly use light thing you usually think about.”—JYLLIAN Fred Beisson, a scientist in the Biosciences for catalysis, he says. KEMSLEY SEPTEMBER 4, 2017 | CEN.ACS.ORG | C&EN
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