Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Biosensor reveals new information about suspected cause of Alzheimer’s disease

01.09.2005


Chemists and biologists at Northwestern University have found a way to detect and estimate the size and structure of a miniscule toxic protein suspected of triggering Alzheimer’s disease. The findings, researchers say, could help scientists better understand the underlying mechanisms of the disease and lead to the development of new treatments that could slow or possibly arrest its progression.



The findings also could potentially be used to diagnose Alzheimer’s disease in living people instead of during an autopsy, says Amanda J. Haes, Ph.D., a co-author of the study. At present, Alzheimer’s can only be accurately diagnosed after death.

Haes, a National Research Council postdoctoral researcher at the Naval Research Laboratory in Washington, conducted this work while she was a graduate student at Northwestern under the direction of Richard Van Duyne. The findings were presented today at the 230th national meeting of the American Chemical Society, the world’s largest scientific society.


Haes, in cooperation with Van Duyne, Northwestern professor William Klein and research associate Lei Chang developed a method to detect small harmful proteins in cerebrospinal fluid using nanoscale optical biosensors. The proteins, known as ADDLs (amyloid ?-derived diffusible ligands) are so small that they can’t be detected by conventional diagnostic tests. They are usually less than 5 nanometers wide and are found in extremely low concentrations.

Discovered by Klein in 1998, ADDLs accumulate in the brain tissue of individuals with Alzheimer’s disease at levels up to 70 times higher than found in people who don’t have the disease. Many researchers now suspect that ADDLs cause some of the earliest symptoms of Alzheimer’s disease. ADDLs, they theorize, attack and disrupt synapses, the sites on nerve cells that are critical for memory formation and information processing. ADDLs tend to stick together, and some researchers suspect that as they aggregate, they’re more apt to damage neurons.

"It’s becoming more evident that the size of â-amyloid (ADDL) molecules matters — that only ADDLs of a certain size cause problems for neurons in the early stages of Alzheimer’s disease," Haes says. "These nanoscale biosensors may one day allow us to determine, based on size, if an individual has ADDLs that will affect his or her cognitive function. However, there are still many hurdles that must be overcome before we can use it as a diagnostic tool."

The biosensors developed by the Northwestern team are based on tiny, triangular silver particles that absorb and scatter light. On the outside surfaces of nanoparticles is a layer of ADDL-specific antibodies. These antibodies bind specifically to any ADDL molecules found in cerebrospinal fluid. When this happens, the color of the silver nanoparticles shifts slightly. The researchers detected these color shifts using a specialized light detector called ultraviolet-visible spectrometer. In a small sample pool, comparing cerebrospinal fluid extracted from two people diagnosed with Alzheimer’s disease and two people who weren’t, Haes found that ADDL levels were elevated in the diseased patient samples in comparison to control patient samples.

Alzheimer’s disease is an irreversible disorder of the brain, robbing those who have it of memory, overall mental and physical function, and eventually leading to death. It is the most common cause of dementia among people over age 65, affecting an estimated 4.5 million Americans, according to the National Institute on Aging.

The American Chemical Society is a nonprofit organization, chartered by the U.S. Congress, with a multidisciplinary membership of more than 158,000 chemists and chemical engineers. It publishes numerous scientific journals and databases, convenes major research conferences and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.

Charmayne Marsh | EurekAlert!
Further information:
http://www.acs.org

More articles from Life Sciences:

nachricht 'Y' a protein unicorn might matter in glaucoma
23.10.2017 | Georgia Institute of Technology

nachricht Microfluidics probe 'cholesterol' of the oil industry
23.10.2017 | Rice University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>