A dendritic nanosilica-functionalized electrochemical immunosensor with sensitive enhancement for the rapid screening of benzo[a]pyrene

A novel electrochemical immunosensor has been fabricated for the detection of benzo[a]pyrene using dendritic SiO2 nanoparticles for biomolecule immobilization. Initially, carboxyl-terminated dendritic SiO2 nanoparticles were synthesized, characterized by TEM, contact angle and thermogravimetric analyses, and then immobilized onto an ethylenediamine-modified electrode. Aminopyrene–BSA was captured with the carboxyl groups of dendritic SiO2 nanoparticles, followed by the corresponding antibody and HRP-labeled secondary antibody. Finally, with the aid of H2O2 and hydroquinone, the changes in the cathodic current were recorded. Based on a competitive immunoassay, benzo[a]pyrene, which can compete with the immobilized aminopyrene–BSA in the association ability of the antibody, was successfully detected. The results showed that the cathodic currents were linearly dependent on the logarithm of benzo[a]pyrene concentrations between 0.01 and 10μM with a detection limit of 8nM. The proposed electrochemical immunosensor provided a new alternative to the application of other antigens or other bioactive molecules.