SCIENCE & TECHNOLOGY
from the SCENEs FRO M T H E NANO SC E NE
GROWING SYMMETRIC GOLD NANOSTARS To boost signals produced by molecules in surface-enhanced Raman spectroscopy (SERS), researchers sometimes deposit the compounds on nanosized gold nuggets with jutting arms. But existing methods for building such gold nanostars create particles with wildly asymmetric and inconsistent shapes, leading to unreliable performance. Xianmao Lu of the National University of Singapore and colleagues solved this problem by first synthesizing icosahedral gold seeds and then placing them in a solution containing dimethylamine
(DMA). DMA binds to the gold surface and helps control the growth of six-sided pyramids on each face of the seed, forming 20 symmetrical spikes. The researchers estimate that 95% of the nanostars have the same geometry. The team tested the nanostars’ performance using 4-mercaptobenzoic acid, a standard SERS reference compound. SERS signals enhanced by symmetric nanostars were nearly four times as strong as signals enhanced by asymmetric ones (J. Am. Chem. Soc. 2015, DOI: 10.1021/jacs.5b05321). The equal-sided stars also offer more reproducible results: The SERS enhancement from symmetric nanostars varied within one order of magnitude, while results from their
ACS N AN O
FROM THE BIOLOGICAL SCENE
10.1021/acsnano.5b01552). Efstathios Karathanasis of Case Western Reserve NANOPARTICLES University and colleagues decorated HIT MOVING a 100-nm-diameter liposome with CANCER TARGETS peptides that bind to two surface About 90% of cancer deaths are caused proteins expressed on metastatic cancer cells: selectin and integrin. not by the initial tumor but by subBoth proteins help circulating tumor sequent tumors, or metastases, that cells exit the bloodstream, allowing often take root in the lungs, bone, them to establish a new tumor. To liver, or brain. To deliver therapies see whether the nanoparticle could to these tumors, researchers have find the rogue cancer cells, the team developed a nanoparticle that targets tested it in two types of mice with an cancer cells at two different stages extremely aggressive form of metaof metastasis (ACS Nano 2015, DOI: static breast cancer. They Radioactively injected radioactively labeled labeled nanoparticles nanoparticles into the mice and saw that highlight the nanoparticles found metastatic about 90% of the microtumors in the lungs of a metastatic sites—small mouse whose clusters of cancer cells 10 mammary to 30 µm in size. Next they tissue was plan to test this system seeded with breast cancer with a nanoparticle that’s carrying a cancer drug. cells.
The SCENE news channels are brought to you by C&EN’s Journal News & Community group. To subscribe to weekly e-mail newsletters from any of our six SCENEs, go to http://cenm.ag/newsletters.
C E N. ACS.ORG
34
Chemists built gold nanostars with 20 equally proportioned tips. Scanning electron micrographs (bottom row) show the nanostars from different angles. Scale bar is 50 nm.
asymmetrical cousins varied within two orders of magnitude.
F RO M TH E EN V I RO N M E NTA L SCE NE
LEAKS DURING METHANE PRODUCTION UNDERESTIMATED The potent greenhouse gas methane is leaking at higher-than-expected rates from a largely unstudied part of natural gas operations—facilities that collect, compress, and process natural gas for pipeline distribution (Environ. Sci. Technol. 2015, DOI: 10.1021/ acs.est.5b02275). A new study—the first national one on methane emissions from such facilities—found that these operations had methane losses twice that of earlier estimates by the Environmental Protection Agency. Anthony J. Marchese of Colorado State University and colleagues sampled ambient methane concentrations at 114 gathering facilities and 16 processing plants in 13 states and used computer methods to extrapolate their measurements to calculate nationwide losses. The new figures raise estimates of the total methane loss during oil and gas production from 1.3% to more than 1.5% of final production yields. EPA estimates that if methane leakage exceeds about 3%, the climate benefit from natural gas over coal is lost. The amount of gas lost from gathering facilities is valued at $390 million a year, Marchese says, and could provide enough gas to fuel 3.2 million households.
S E PTE M BE R 14, 20 1 5
J. AM. CHEM. SOC.
A selection of stories from C&EN’s six online TOPICAL NEWS CHANNELS
