"Building upon our earlier work with lead (Pb) sensors, we constructed colorimetric sensors that are based on the lateral flow separation of aptamer-linked nanostructures," said Yi Lu, a chemistry professor at the U. of I., and a researcher at the Beckman Institute for Advanced Science and Technology.
"The new sensors offer a quick and convenient test that can be utilized by first responders or emergency room staff to quickly screen individuals for a variety of drugs and other chemicals." Lu said.
Aptamers are single-stranded nucleic acids that can bind to specific molecules in three-dimensions. For each molecular target, such as cocaine, a corresponding aptamer can be selected from a large DNA library.
By using lateral flow devices as platforms to separate aptamer-linked nanoparticle aggregates, Lu, postdoctoral researcher Juewen Liu and graduate student Debapriya Mazumdar created highly sensitive and selective colorimetric sensors that mimic litmus paper tests. The researchers describe their work in a paper accepted for publication in the journal Angewandte Chemie International Edition, and posted on its Web site.
"Our lateral flow devices take advantage of the difference in size between dispersed and aggregated gold nanostructures," Lu said. "This provides critical control for the performance of the devices."
The lateral flow device consists of four overlapping pads – wicking, conjugation, membrane and absorption. The appropriate aptamer-linked nanoparticle aggregates are placed on the conjugation pad, streptavidin is applied as a thin line to the membrane pad, and the device is then dried.
When dipped into a solution, or swabbed with a sample, the wicking pad carries the fluid to the nanoparticle aggregates on the conjugation pad. The rehydrated aggregates then migrate to the edge of the membrane, which they cannot penetrate because of their large size.
The aptamers quickly bind to any targeted molecules that are present, freeing some of the gold nanoparticles. The red-colored nanoparticles then migrate along the membrane, where they are captured by the streptavidin and form a red line. The intensity of the line is an indicator of how much of the targeted molecule was in the sample solution.
So far, the researchers have successfully demonstrated their dipstick technology on both adenosine (a nucleotide consisting of adenine and ribose) and cocaine, in human blood serum.
"Our results show that the aptamer-based dipstick is compatible with biological samples, making applications in medicinal diagnostics possible," Lu said.
James E. Kloeppel | EurekAlert!
Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory
Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine