Simple and highly sensitive detection of hepatotoxin microcystin-LR via colorimetric variation based on polydiacetylene vesicles

A highly sensitive and simple approach for detecting hepatotoxin microcystin-LR (MC-LR) was developed based on color-changeable polydiacetylene (PDA) vesicles. By an EDC/NHS reaction, we successfully embedded a monoclonal antibody (mAb) of MC-LR (anti-MC-LR) onto the PDA vesicle surfaces, and a MC-LR recognition vesicle (PDA-anti-MC-LR) was formed. The optimal concentration for anti-MC-LR was determined that would guarantee the PDA immunosensor to exert its highest recognition effect. Upon application of MC-LR, a specific immunoreaction took place, which altered the PDA conformation and led to a color change. The lowest detection limit could be 1 ng/mL—the maximum concentration recommended by WHO in drinking water for humans. Although immunoassays have found applications in medical diagnostics and therapy, the procedures commonly used nowadays are too complicated. This chromatic immunosensor based on PDA reported in this paper has the advantage of high sensitivity, rapidity, cost-effectiveness, and convenience for MC-LR detection. Not only it is more adaptable for on-the-spot water detection, compared with current MC-LR detecting techniques, but the methodology here ensured optimal embedding of antibody to the PDA vesicles of great significance for fabrication of other nanosensors. This technology, based on antibody–antigen interaction, and its broadened use in PDA biosensors, has potential application in many fields.