Complex laboratory investigations do produce reliable results, but they are not useful for point-of-care diagnostics. This is especially true in developing countries, which must rely on simple, inexpensive test methods that do not require a power source.
The two chambers are connected to each other through a narrow opening. The required reagents are also “printed” onto the paper. On the second half of the paper, a screen-printing process is used to add two electrodes made of conductive carbon ink. When the paper is then folded down the middle according to the principles of origami—no tape or glue—a three-dimensional structure is formed. This causes the electrodes to come into contact with the chambers. Finally, the folded paper is laminated.
When a drop of the sample is put into the inlet, the liquid moves through the two channels. One of the channels contains microspheres coated with an aptamer. An aptamer is a strand of DNA that can be constructed so as to selectively bind nearly any desired analyte molecule. For the purpose of demonstration, the researchers chose an aptamer for adenosine. If adenosine is in the sample, the aptamer binds to it. This releases an enzyme that was coupled to the aptamer. The enzyme continues to flow through the channel and reaches the chamber, which contains glucose and Prussian blue (iron hexacyanoferrate).
This complex contains trivalent iron. The enzyme, glucose oxidase, oxidizes the glucose, which causes the iron in the Prussian blue to be reduced to the divalent form.
The second channel contains spheres with no aptamer. In the second chamber, therefore, no iron is reduced. Because the oxidation state of the iron in one chamber has been changed, the two chambers no longer have the same composition and an electric potential builds up. This can be measured by means of a capacitor and a measuring device like those used to test the voltage of a battery.
This principle can be used to easily and inexpensively produce rapid tests for a broad spectrum of different target molecules.About the Author
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201202929
Dr. Richard Crooks | Angewandte Chemie
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