Sensitive detection of carcinoembryonic antigen in exhaled breath condensate using surface acoustic wave immunosensor

A sensitive and reproducible Love Wave mode surface acoustic wave (SAW) immunosensor is presented to detect carcinoembryonic antigen (CEA) in exhaled breath condensate (EBC), which utilizes gold staining method as a signal enhancement approach. A conventional sandwich immunoassay was utilized: CEA combined with gold nanoparticles (AuNPs) conjugated antibody was firstly recognized by the capture antibody which was immobilized on the sensor surface; then the sensitivity was enhanced by injecting the gold staining solution. The response of the Love Wave immunosensor was observed to be linearly relative to the CEA concentration in the range of 1-16 ng/mL and the detection limit was 1 ng/mL. A comparison between the immunosensor and a commercial instrument was also performed, and the correlation coefficient reached 0.999. Since CEA in EBC is a potential biomarker for early detection of lung cancer, this immunosensor may give an enormous impetus for a rapid and non-invasive screening to the population at a high lung cancer risk.