[Liposome immunosensor for picloram in water based on electrochemical polymerization].

A "sandwich-type" immunosensor for the determination of picloram in water environment was developed based on the immunoliposomes prepared by crosslinking rabbit antibody against picloram (anti-picloram) and potassium ferrocyanide-encapsulated liposomes with glutaraldehyde. The working conditions including modification components on the electrode were optimized. The best performance is obtained using 0.5% of Nafion, 10 mg x mL(-1) of multiwalled carbon nanotubes (MWCNTs) and 50 microg x mL(-1) of anti-picloram. The preparation and detection process of immunosensor was as follows. Cyclic voltammetry was applied to urge the electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) and the anti-picloram was immobilized on the modified glassy carbon electrode (GCE). Then the electrode was incubated with the analytes and immunoliposomes sequentially. The bound liposomes were lysed with TritonX-100, and square-wave voltammetry was applied to determine current response of picloram concentration. The whole process was able to be completed in 70 min. The immunosensor has good reproductivity after being soaked in 0.1 mol x L(-1) of H3PO4 in 5 min. The result shows that lower detection limit for picloram is 10(-10) mol x L(-1) with linear range of 10(-10)-10(-4) mol x L(-1), which meets the detection requirement of picloram for the safety of drinking water.