A new mass amplification piezoelectric immunosensing method in gas phase was developed for the Schistosoma-Japonicum antibody (SjAb), which is based on the enzymatic catalyzation deposition of silver. On the surfaces of quartz crystals with a resonant frequency of 9 MHz, a molecular antigen of Schistosoma Japonicum (SjAg) was covalently immobilized via a self-assembly membrane of 2-mercaptoethylamine. By exposing the crystals to the SjAb solution and the alkaline phosphatase (ALP) labeled second antibody solution in turn, the ALP was bounded to the quartz crystal surfaces by a “sandwhich” format, and it was then used as a biocatalyst for the hydrolyzation of 2-phospho-L-ascorbic acid to form the reductive ascorbic acid and further to yield mental silver deposit on the surfaces of quartz crystals, resulting in an amplified mass sensing effect. The sensing method is quite simple and sensitive, and the SjAb can be linearly determined in the range of 1～225 ng/mL, and the detection limit reaches as low as 1 ng/mL.

Key words: silver deposition, enzymatic catalyzation, gas piezoelectric immunosensor, Schistosoma-Japonicum