Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Two-Stage Amplifier

13.07.2006
Coupling two enzymatic reactions: sensitive detection for immunological ELISA tests

Bioanalytical and diagnostic test methods are often based on the recognition of biomolecules by other biomolecules. However, biochemical events such as these are not directly detectable and must first be converted into physical signals, for example an electrical or optical signal. Since transient and minute amounts of substance are usually involved, which must be detected in very small test volumes, an effective "amplifier" must be employed. Enzyme reactions are a good choice as amplifiers and signal transformers: a single enzyme molecule generates a large number of detectable (e.g. fluorescent) molecules, which can be detected easily.

This principle is also the basis of a well-established method, the enzyme-labeled immunosorbant assay (ELISA). Researchers in Jerusalem have now developed a new ELISA protocol that utilizes two successive enzyme reactions. Enzyme 1 produces many copies of enzyme 2, which in turn produces many copies of a detectable fluorescent dye. In this way, the amplification effect is increased, and the assay is much more sensitive. The research group of Itamar Willner has used this new protocol to develop an ELISA test for telomerase, an important cancer marker. In comparison with traditional telomerase assays, the new method is considerably simpler, more efficient, and more sensitive.

This is how it works: Anti-telomerase antibodies are immobilized on a carrier, to which the test sample is added. The telomerase in the sample adheres to the antibodies. In the next step, another telomerase antibody is added, which recognizes the bound telomerase and binds to it. The trick: this second antibody is fitted with a binding site for a molecular "adaptor". An ecarin enzyme fitted with such an adapter can thus bind to it. Now, the two-stage amplifier can kick in: ecarin converts added prothrombin into thrombin (a reaction that incidentally plays a role in blood clotting). Thrombin is a biocatalyst that is able to liberate the fluorescent dye rhodamine from a nonfluorescent precursor. By measuring the fluorescence, the researchers were able to detect the telomerase from only 1000 cancer cells—an amount that is not detectable using previous detection methods.

The method of nonlinear amplification through coupled enzyme reactions is not only suitable for immunoassays but also for the detection of specific DNA sequences.

Author: Itamar Willner, The Hebrew University of Jerusalem (Israel), http://chem.ch.huji.ac.il/employee/willner/iwillner.htm

Title: Biocatalytic Evolution of a Biocatalyst Marker: Towards the Ultrasensitive Detection of Immunocomplexes and DNA Analysis

Angewandte Chemie International Edition 2006, 45, No. 29, 4815–4819, doi: 10.1002/anie.200600073

Itamar Willner | Angewandte Chemie
Further information:
http://chem.ch.huji.ac.il/employee/willner/iwillner.htm
http://pressroom.angewandte.org

More articles from Life Sciences:

nachricht Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>