A nanosensor based on quantum-dot haptens for rapid, on-site immunoassay of cyanotoxin in environmental water

• QD-hapten nanoprobes by conjugating carboxyl QDs with aminoethyl-MC–LR were prepared for rapid and sensitive detection of MC–LR.
• A simple analytical system by the integration of an optofluidic platform with QD-FRET-based competitive immunoassay was deveoped.
• Using portable optofluidic platform, rapid, on-site cyanotoxin detection with enhanced sensitivity, lower reagent volumes, and simplified manipulation can be achieved.
• The sensitivity, specificity, stability, and resistance to background interferents of this nanosensor are better than that of traditional techniques.

A nanoprobe based on quantum-dot (QD) haptens was synthesized by conjugating carboxyl quantum dots with aminoethyl-microcystin (MC)–leucine–arginine (LR). A two-alkyl group was introduced to supply a spacer between the QD nanoprobe and anti-MC–LR antibody to reduce the steric hindrances of immunoreaction. The sensor system based on a portable optofluidic platform exhibited a liner range of 0.10–4.0 µg/L for MC–LR with a detection limit of 0.03 µg/L. The proposed sensor has potential application in the rapid, on-site detection of MC–LR in real water samples.