| Summary: | Neurological diseases such as Alzheimer’s, Parkinson’s, MS, which are common
around the world and particularly in developed countries with high proportion of
elderly, stimulate the development of bio-sensors for early diagnostics of such diseases.
For instance the treatment of Alzheimer’s patients constitutes a substantial proportion of
NHS budget nowadays. Therefore, the development of highly sensitive optical devices
for early diagnoses of Alzheimer’s disease (AD) will be beneficial to society. This PhD
is mainly dedicated to the application of the method of Spectroscopic Ellipsometry for
AD diagnostics. Total Internal Reflection Ellipsometry (TIRE) was utilized in this work
as an immunosensor for detection of Amyloid Precursor Protein 770 (APP7 7 0 ) and beta
amyloid peptide (Api_i6). The detection of low concentrations o f APP7 7 0 in a complex
medium containing other proteins, salts, and amino acids was achieved using the
method of TIRE in direct immuno assay with monoclonal DE2 antibodies. The
calibration of TIRE with a complementary QCM measurements in air allowed the
evaluation of (originally unknown) concentration of APP7 7 0 as 121 p m o l/l. The
immune reaction between APP7 7 0 and DE2 antibodies was also tested using QCM
technique operating in liquid. The application of TIRE was extended to the detection of
much smaller peptide Api_i6 which bind to the same DE2 antibody. The results were
very encouraging since low concentrations (0.05ng/ml) of A(3i-i6 were detected; this
showed good prospects for detection of Ap40.4 2 , an actual marker o f AD.
The second part of this work was dedicated to detection of mycotoxins, a hazardous
contaminant in agriculture products (grains) and associated food and feed. Two
mycotoxins, namely Aflatoxins B1 and Zearalenone, were detected in TIRE direct
immunoassay. Zearalenone was also detected using TIRE competitive assay. The
obtained limits of detection of 0.04 ng/ml. for Aflatoxin and 0 .1 ng/ml for Zearalenone
are well below the legislation limit. Such remarkable results are due to a combination of
high sensitivity of TIRE method and the aggregation of hydrophobic molecules of
mycotoxins in aqueous solutions. A new method of purification o f substances
contaminated with mycotoxins based on the use of polyelectrolyte microcapsules
functionalized with specific antibodies was successfully tested in this work.
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