Sensor May Detect Alzheimer's Markers

DUNEDIN, Fla., Feb. 2, 2006 -- An Ocean Optics UV/VIS spectrometer is part of a nanosensor used by researchers at Northwestern University in Illinois to examine the behavior of molecules that may have a role in Alzheimer’s disease. The device has provided new information relevant to the understanding and possible diagnosis of the disease.

At present, there is no definite clinical diagnosis for Alzheimer’s disease, but ADDLs (amyloid-derived diffusible ligands) -- miniscule toxic proteins suspected of triggering the disease -- are present at levels up to 70 times greater in autopsied brain samples from humans with Alzheimer’s disease than in humans without it. A sensitive way to detect ADDLs in body fluid could, therefore, be a basis for the laboratory diagnosis of Alzheimer’s disease, Ocean Optics said.

The nanosensor developed for ADDLs is based on tiny, triangular silver particles that absorb and scatter light. The extinction spectrum (the sum of adsorbed and scattered light) of the nanoparticles varies as the environment surrounding the nanoparticles changes. To control this change, the nanoparticles’ surfaces are modified with a layer of ADDL-specific antibodies. These antibodies bind specifically to any ADDL molecules found in the samples studied. When this happens, the spectral properties of the silver nanoparticles shift slightly.

Using this technique, the researchers were able to detect ADDL levels that were elevated in diseased patient samples in comparison to control patient samples. The researchers detected these color shifts using an Ocean Optics S2000 fiber optically coupled spectrometer.

"The research has shown the potential of nanoscale optical biosensors is far-reaching and will aid in the development of other successful nanotechnology-based devices," Ocean Optics said in a statement. The company's line of spectrometers, chemical sensors, metrology instrumentation, optical fibers, thin films and optics are used in applications including medical and biological research, environmental monitoring, science education, and entertainment lighting and displays.

For more information, visit: www.oceanoptics.com