Science Concentrates MATERIALS
▸ Frozen zebrafish embryos thaw better with lasered nanorods Zebrafish are widely used as model organisms for developmental biology research. But after being frozen and thawed, zebrafish embryos rarely survive, meaning they can’t be stored for later experiments or shared with other labs. Now, researchers report that propylene glycol, a biocompatible antifreeze, when combined with gold nanorods can improve the embryos’ viability when they are thawed (ACS Nano 2017, DOI: 10.1021/ acsnano.7b02216).
Zebrafish embryos (1 mm diameter), frozen with an antifreezegold-nanorod combination, survive thawing with a laser pulse (top) but not with a conventional water bath (bottom). John C. Bischof of the University of Minnesota, Twin Cities, and colleagues injected the antifreeze-nanorod combination into zebrafish embryos and then froze them in liquid nitrogen. After a few minutes, the team thawed the embryos with a millisecond laser pulse. The nanorods absorbed the light energy and warmed the embryos quickly and evenly, limiting damage to cell membranes from needlelike ice crystals and damage to sensitive proteins. One hour later, 31% of the embryos were viable and developed normally over the next 24 hours. In contrast, embryos warmed conventionally using a water bath did not survive thawing because they were heated unevenly or not quickly enough. With further refinement, the researchers believe the technique could also serve as a tool to conserve endangered species that have large, hard-to-freeze embryos. The work is “very creative,” says Mehmet Toner of Harvard Medical School. “Zebrafish are a very important molecular biology tool, and the embryos are extremely difficult to cryopreserve, but this technique could make it cost-effective and practical for many laboratories.”—JYOTI MADHU-
SOODANAN, special to C&EN
12
C&EN | CEN.ACS.ORG | AUGUST 14/21, 2017
New borate crystal boosts UV optical applications The ability of inorganic crystals known as nonlinear optical (NLO) materials to alter the properties of a beam of laser light—for example, doubling its frequency—makes them indispensable for applications in fiber optics, photolithography, and laser micromachining. Few NLO materials can generate coherent light deep in the ultraviolet range (< 200 nm). KBe2BO3F2 (KBBF) is an exception. But the toxicity of beryllium and the low intensity of KBBF’s NLO properties limit its application. A team of researchers led by Shilie Pan of Xinjiang Technical Institute of Physics & Chemistry and Kenneth R. Poeppelmeier of Northwestern University may have come up with a solution—NH4B4O6F NH4B4O6F is a promising new Be-free NLO material for applications in the deep-UV (ABF), a beryllium-free range (< 200 nm); N is gray, H is white, B deep-ultraviolet NLO material is blue, O is red, F is black. (J. Am. Chem. Soc. 2017, DOI: 10.1021/jacs.7b05943). The researchers report that ABF’s nonlinear coefficients are roughly 2.5 times as large as KBBF’s values. They also note that their synthesis method, based on the high-temperature reaction of B2O3 with NH4F, leads to high-quality crystals that tend to be thicker than typical KBBF crystals, which benefits applications in laser optics. One source of the improved crystal growth is hydrogen bonding between lattice layers, which results from replacing potassium ions in KBBF with ammonium ions in ABF.—MITCH JACOBY
ENERGY STORAGE
a carbon-coated NaTi2(PO4)3 anode in contact with one of three sodium-based electrolytes: a sodium sulfate solution, intravenous saline, or a cell culture medium. In a belt-shaped design, the cathode and anode sandwich an electrolyte-soaked separator. And a fiber-shaped design has carbon nanoResearchers are developing batteries and tube electrodes embedded with cathode energy-storing supercapacitors that flex and anode nanomaterials and surrounded with the body while powering wearable by electrolyte. The batteries have charge and implantable medical devices. But so capacities and power outputs per unit far these power sources have used elecvolume comparable to those of previously trolytes containing strong acids, strong reported flexible lithium-ion batteries and bases, or toxic and flammable organic supercapacitors. But for now their power solutions, which can cause harm if they output per unit mass and maximum opleak. Yonggang Wang, Huisheng Peng, and erating voltage are too coworkers at Fudan Unilow to be commercially versity have now created This belt-shaped aqueous practical. In future work, bendable sodium-ion sodium-ion battery comes with the researchers hope to batteries containing reduced chemical risk. improve the batteries biofriendly aqueous by using higher capacity electrolytes (Chem electrode materials and 2017, DOI: 10.1016/j. to test their ability to chempr.2017.05.004). energize actual medical The batteries have a devices.—STU BORMAN Na0.44MnO2 cathode and
▸ Flexible batteries get safer with sodium
C R E D I T: J . A M. CH EM . S OC. ( ST RU CTU R E ) ; ACS NA NO ( EM BRYO S ) ; C HE M ( BAT T E RY )
BIOLOGICAL CHEMISTRY
