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 Nerves control the body’s bacterial community
26.09.2017 | Christian-Albrechts-Universität zu Kiel

nachricht Ageless ears? Elderly barn owls do not become hard of hearing
26.09.2017 | Carl von Ossietzky-Universität Oldenburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The fastest light-driven current source

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.

Graphene is up to the job

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Nerves control the body’s bacterial community

26.09.2017 | Life Sciences

Four elements make 2-D optical platform

26.09.2017 | Physics and Astronomy

Goodbye, login. Hello, heart scan

26.09.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>