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P2‐027: Development of a gold nanoparticle ELISA to detect low‐abundant proteins in cerebrospinal fluid for diagnosis of Alzheimer's disease
Author(s) -
Müller Mareike,
Schijven Dick,
Bruggink Kim,
Venhuizen JanHendrik,
Kuiperij H. Bea,
Verbeek Marcel M.
Publication year - 2012
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2012.05.730
Subject(s) - colloidal gold , cerebrospinal fluid , apolipoprotein e , chemistry , antibody , magnetic nanoparticles , tau protein , antigen , alzheimer's disease , nanoparticle , microbiology and biotechnology , biophysics , nanotechnology , materials science , biology , disease , immunology , medicine , pathology
Background: Cerebrospinal fluid (CSF) analysis is currently becoming integrated into the diagnostic work-up of Alzheimer’s disease (AD). A combination of amyloid-b42, total and phosphorylated tau proteins can identify AD with a sensitivity and specificity above 90%. Nonetheless, their use is limited in differentiating between AD and other types of dementia, which leads to the requirement of new biomarkers with more discriminative capacity. Yet, many protein biomarkers are present at low concentrations in CSF. We hypothesize that the complex of amyloid-b with apolipoprotein E (ApoE) may serve as such low-abundant, specific biomarker for AD. We therefore aim to measure this protein complex in CSF by sandwich ELISA using gold nanoparticles as detection. Because these nanoparticles are able to bind large amounts of detection enzyme, the signal strongly increases and allows measurements of amyloid-b/ApoE complex at low concentrations. Methods: Magnetic particles, coated with an antibody against ApoE, capture the amyloid-b/ApoE complex. Gold nanoparticles are coated simultaneously with an antibody against amyloid-b, and a detection enzyme. After adding the gold nanoparticles to the magnetic-particle-antigen solution, the sandwich is formed and can be detected. The new sandwich ELISA set-up is compared to the conventional ELISA in terms of limit of detection, and amyloid-b/ApoE complex will be quantified in CSF samples. Results: Our current results demonstrate that antibodies can be coupled to both magnetic particles and gold nanoparticles. Moreover, enzymes can be successfully coupled to gold nanoparticles. Subsequently, both particles containing an antibody are also able to bind the antigen of interest, and can be implemented in a sandwich ELISA. Using gold nanoparticles, we can detect lower concentrations of the antigen than the conventional sandwich ELISA does. Conclusions: It is feasible to construct the different elements of the gold nanoparticle ELISA and to measure the antigen at low levels. Future studies will indicate whether the assay is able to measure amyloid-b/ApoE complex in CSF, and whether this complex can serve as a novel CSF biomarker for discrimination of AD and other dementias.