Amperometric Immunosensor Based on Layer-by-layer Assembly for Detecting PCB77 in Sludge Samples

A new type of amperometric immunosensor for the determination of PCB77 was reported. Gold nanoparticles, glutaraldehyde and chitosan were assembled layer-by-layer into films on the gold electrode modified by L-cysteine for fabrication of the immunosensor. The preparation procedure of the sensor was characterized and the operation conditions, such as the pH value of supporting solution, incubated temperature and time were studied by differential pulse voltammetry. Under the optimized working conditions, the current response of the immunosensor was proportional to the concentration of naphthalene in the range of 0.1-160 ng/mL with a detection limit of 0.01 ng/mL (R = 0.9964). This method was applied to the PCB77 detection in sludge samples and the recovery was ranging in 95.0%-112.5%. The reported immunosensor exhibited high sensitivity and long-term stability for PCB77 detection, and was easy to be prepared and regenerated.