Optical evaluation of immunocomplex of liquid crystal bound amyloid
beta-42 levels associated with Alzheimer's disease
Abstract
We present an optical biosensor in this study which is based on the LC
orientation as a function of the peptide concentration to detect
amyloid-beta-42 (Aβ42) antigen-antibody binding events. These binding of
Aβ42 peptide to an Aβ42 antibody which is on a
Dimethyloctadecyl[3-(trimethoxysilyl)propyl] ammonium chloride
(DMOAP) occurs on an immobilized surface forming an immunocomplex. The
disturbed orientation of LCs as a result of the binding of the formed
immunocomplex observed using the polarized optical microscope. The
microscopic and optical response of the LC-immunocomplex was determined
as a function of decreasing Aβ42 peptide concentration. Aβ42 peptide
concentrations as of 1000 pg/ml, 500 pg/ml, 200 pg/ml, 100 pg/ml, 50
pg/ml, 25 pg/ml, 20 pg/ml, 15 pg/ml, 10 pg/ml, 5 pg/ml, and 1 pg/ml,
respectively were interacted with the optimum Aβ42 antibody
concentration as of 25 µg/ml. There was a remarkable change in the
reflection spectra of the samples with the decreasing Aβ42 peptide
concentration. The concentration as low as 1 pg/ml of Aβ42 peptide was
able to successfully detected in our system.