An amplified mass piezoelectric immunosensor for Schistosoma japonicum

An ultrasensitive piezoelectric immunosensor using an amplification path based on an insoluble biocatalyzed precipitation product has proposed for Schistosoma japonicum. A mercapto Schistosoma japonicum antigen was self-assembled onto the quartz crystal surface via an Au nanoparticle mediator monolayer to sense the Schistosoma japonicum antibody (SjAb). And the horseradish peroxidase labeled protein A conjugate which was bounded to the SjAb by a “sandwich” format was used as a biocatalyst for the oxidative precipitation of 4-chloro-1-naphthol by H2O2 to yield the insoluble product benzo-4-chlorohexadienone, resulting in an amplified mass sensing of antigen–antibody interaction. The amount of the precipitate accumulated on the quartz crystal is controlled by the antibody concentration. The SjAb can be linearly determined in the range of 10–200 ng ml−1 and the detection limit reaches as low as 5 ng ml−1.