Chromatic immunoassay based on polydiacetylene vesicles

A new approach of chromatic immunoassay based on polydiacetylene vesicles is described. Antibodies were covalently coupled with mixed vesicles of 10,12-tricosadiynoic acid (TCDA) and dimyristoylphosphatidycholine (DMPC). The vesicle-antibody conjugates were irradiated with UV light to yield a blue-colored polydiacetylene. After antigen injection, specific immunoreactions took place at the vesicle surface alter polydiacetylene conformation and lead to a color change from blue to red. The chromatic immunoassay described here is simple, rapid, sensitive; the color change was readily discernible by naked eye when the concentration of antigen is 1 ng/mL. Incorporation of DMPC in the mixed vesicles increases the sensitivity of the chromatic immunoassay.