| Abstract
| - Biotinylated, highly luminescent CdSe−ZnS quantum dot(QD) conjugates were prepared and used in immunofiltration assays. Water-soluble quantum dot surfaceshaving a homogeneous negative charge density at basicpH were initially coated with a two-domain recombinantmaltose-binding protein appended with a positively chargedleucine zipper. Biotin functionalization of these electrostatically stabilized QD−protein complexes was thencarried out using amine-reactive NHS biotin. These protein-coated biotin-functionalized quantum dot conjugates wereincorporated into flow immunofiltration/displacementassays employing Affi-gel agarose resin for antibody immobilization, analyte capture, and immune complex formation with a second biotinylated antibody. A key component of the assay was the use of tetranitromethane-modified NeutrAvidin, used to link the biotinylated QDsto the immune complexes and facilitate their release atbasic pH for subsequent quantification. This assay methodology was used to detect as little as 10 ng/mL staphylococcal enterotoxin type-B.
|
