The research has shown that the potential of nanoscale optical biosensors is far-reaching and will aid in the development of other successful nanotechnology-based devices
Researchers in the department of chemistry and the department of neurobiology and physiology at Northwestern University, Illinois, have used a nanosensor to examine the behaviour of molecules that may be involved with Alzheimer's disease.
The nanosensor, which incorporates an Ocean Optics UV/vis spectrometer, has provided new information relevant to the understanding and possible diagnosis of the disease.
At the present time there is no definite clinical diagnosis for Alzheimer's disease, but ADDLs (amyloid-derived diffusible ligands), a miniscule toxic protein suspected of triggering the disease, is present at levels up to 70 times greater in autopsied brain samples from humans with Alzheimer's disease than in humans without the disease.
A sensitive method of detecting ADDLs in body fluid could, therefore, provide a basis for the laboratory diagnosis of Alzheimer's disease.
The nanosensor developed for ADDLs is based on tiny, triangular silver particles that absorb and scatter light.
The extinction spectrum (sum of adsorbed and scattered light) of the nanoparticles varies as the environment surrounding the nanoparticles change.
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 colour shifts using an Ocean Optics S2000 fibre optically coupled spectrometer.
