Sensitive and simultaneous detection of cardiac markers in human serum using surface acoustic wave immunosensor.

We present a rapid and sensitive surface acoustic wave (SAW) immunosensor that utilizes gold staining as a signal enhancement method. A sandwich immunoassay was performed on sensing area of the SAW sensor, which could specifically capture and detect cardiac markers (cardiac troponin I (cTnI), creatine kinase (CK)-MB, and myoglobin). The analytes in human serum were captured on gold nanoparticles (AuNPs) that were conjugated in advance with detection antibodies. Introduction of these complexes to the capture antibody-immobilized sensor surface resulted in a classic AuNP-based sandwich immunoassay format that has been used for signal amplification. In order to achieve further signal enhancement, a gold staining method was performed, which demonstrated that it is possible to obtain gold staining-mediated signal augmentation on a mass-sensitive device. The sensor response due to gold staining varied as a function of cardiac marker concentration. We also investigated effects of increasing operating frequency o...