Piezoelectric immunosensor with gold nanoparticles enhanced competitive immunoreaction technique for quantification of aflatoxin B1.

A simple, rapid and highly sensitive piezoelectric immunosensor has been proposed and applied to detect aflatoxin B(1) (AFB(1)). It is unlikely that direct binding of small molecules such like AFB(1) to the piezoelectric sensor surface could result in a satisfactory detection limit and sensitivity. Thus, indirect competitive immunoassay technique had been used for the detection of the target and gold nanoparticles (GNP) been employed as a 'weight label' to the secondary antibody for amplifying the response. This method is proven in its ability to detect AFB(1) down to a level of 0.01 ng mL(-1) in artificially contaminated milk, which is comparable to or even exceeding the sensitivity of microtitre plate ELISA. Furthermore, the frequency responses of the immunoassay are linearly correlated to the logarithm of AFB(1) concentration in the range of 0.1-100 ng mL(-1). The sensor could be regenerated under very mild conditions simply by immersing the sensor into glycine buffer solution to desorb the combined antibody. It is found that the as-renewed sensor could be reused at least 9 runs without obvious loss of sensing sensitivity.