SCIENCE & TECHNOLOGY
from the SCENEs A selection of stories from C&EN’s six online TOPICAL NEWS CHANNELS
FROM THE BIOLOGICAL SCENE
NANOPARTICLES TRICK MALARIA PARASITES Researchers have designed polymer nanoparticles to prevent malaria parasites from infecting red blood cells. The particles’ outer coatings mimic red blood cells’ surfaces (ACS Nano 2014, DOI: 10.1021/ nn5054206). If this strategy works in the body, it could help treat the deadliest type
SIMPLE PAPER DEVICE TITRATES ACIDS AND BASES
FROM THE ENVIRONMENTAL SCENE
Kaneta and Shingo Karita of Okayama University, in Japan, built a prototype that measures NaOH concentrations by printing a wax layer onto a piece of filter paper, creating a sunburst pattern of 10 radial channels. Test solutions applied to the center of the device travel up each channel to a reaction reservoir containing a certain concentration of acid; the concentrations in each
U.S. VEHICLE FLEET DIRTIER AFTER RECESSION
ANAL. CHEM.
When scientists want to titrate a sample in the field, they can now leave their volumetric flasks at the lab. Researchers have developed a simple and inexpensive paper-based device that deter-
A 30- by 30-mm paper-based device titrates basic solutions of NaOH. The number at the end of each spoke indicates the concentration of acid in the reaction reservoir. The reservoirs at the tips contain phenolphthalein, which turns magenta if the concentration of NaOH exceeds that of the acid.
mines the concentration of an acid or base in less than a minute (Anal. Chem. 2014, DOI: 10.1021/ac5039384). Takashi
channel increase clockwise around the device. Then the solutions flow into a detection reservoir. Any hydroxide ions left over after neutralizing the acid react with a dye to produce a color change. By observing which channels turned color, the team could determine the concentration of NaOH solutions ranging from 0.1 to 1 M, as well as correctly differentiate among 0.25-, 0.27-, and 0.29-M solutions.
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.
CEN.ACS.ORG
27
copolymer containing heparin and mixed it in water with another block copolymer that forms hollow spheres. The resulting heparin-coated particles were 100 times as effective at binding merozoites as free heparin. Also, when the team added the particles to a dish containing healthy and infected red blood cells, merozoites that escaped the infected cells became covered with nanoparticles and couldn’t infect the healthy cells.
Sales of new passenger vehicles slowed after the 2008 recession, making the current U.S. fleet older than expected and increasing the rate of air pollutants released by the fleet (Environ. Sci. Technol. 2014, DOI: 10.1021/es5043518). In During the Great 2013, Gary A. Bishop and Recession, U.S. Donald H. Stedman of consumers held the University of Denver on to old cars, hit the road in Los Anwhich made the geles, Denver, and Tulsa 2013 fleet dirtier to measure pollutants than it would have been in a in the exhaust plumes robust economy. of passing cars. Using a remote exhaust detector, they studied more than 68,000 vehicles and determined that the mean age of the 2013 fleet was nine years—two years older than the average age for the two decades before the recession. The team compared the average amount of pollution released per kilogram of fuel burned with what would have been emitted if the 2013 fleet weren’t so old. For the three cities, emissions of carbon monoxide, hydrocarbons, nitrogen oxide, and ammonia were up to 30% greater than expected. Bishop says that although emissions rates increased, the aging fleet may not have worsened air quality if people overall drove less after the recession. SHUTTERSTOCK
FROM THE ANALYTICAL SCENE
of malaria, which is caused by the Plasmodium falciparum parasite. Wolfgang Meier of the University of Basel, in Switzerland, and colleagues designed nanoparticles to target the parasite at a growth stage called the merozoite. To get into blood cells, merozoites first bind to the polysaccharide heparan sulfate on the cells’ surfaces. The drug heparin has a similar chemical structure and attracts merozoites. So Meier’s group made a block
JANUARY 12, 2015
