Detection of β-amyloid peptide (1-16) and amyloid precursor protein (APP770) using spectroscopic ellipsometry and QCM techniques: a step forward towards Alzheimers disease diagnostics.
A highly sensitive method of spectroscopic ellipsometry in total internal reflection mode (TIRE) was exploited for detecting β-amyloid peptide (Aβ(1-16)) in the direct immune reaction with monoclonal DE2 antibodies (raised against Aβ(1-16)) electrostatically immobilised on the surface of gold. A rapid detection of Aβ(1-16) in a wide range of concentrations from 5 μg/ml down to 0.05 ng/ml was achieved using a cost-effective and label-free direct immunoassay format. TIRE dynamic spectral measurements proved that the immune reaction between DE2 monoclonal antibodies and Aβ(1-16) is highly specific with the affinity constant K(D)=1.46×10(-8) mol/l. The same DE2 antibodies were utilised for detection of amyloid precursor protein APP(770), a larger protein containing Aβ(1-16) domain, using the quartz crystal microbalance (QCM) measurements in liquid. A combination of QCM and TIRE kinetics results allowed the evaluation of the originally unknown concentration of APP(770) in complete medium solution containing other proteins, salts, and amino acids.
Mustafa
M K
MK
Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, S1 1WB, UK. m.k.mustafa@shu.ac.uk
Nabok
A
A
Parkinson
D
D
Tothill
I E
IE
Salam
F
F
Tsargorodskaya
A
A
D000544:Alzheimer Disease / Q000175:diagnosis* / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000032:analysis* / Q000276:immunology; D016564:Amyloid beta-Protein Precursor / Q000032:analysis* / Q000276:immunology; D000818:Animals; D055910:Antibodies, Immobilized; D000911:Antibodies, Monoclonal / Q000378:metabolism; D000937:Antigen-Antibody Reactions; D006801:Humans; D007118:Immunoassay / Q000379:methods; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D010446:Peptide Fragments / Q000032:analysis* / Q000276:immunology; D058525:Quartz Crystal Microbalance Techniques / Q000379:methods* / Q000706:statistics & numerical data; D013057:Spectrum Analysis / Q000379:methods; D020349:Surface Plasmon Resonance / Q000379:methods
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D055910:Antibodies, Immobilized; D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; C433241:amyloid beta-protein (1-16)