Antigen-antibody interaction from quartz crystal microbalance immunosensors based on magnetic CoFe2O4/SiO2 composite...

A new quartz crystal microbalance immunoassay for the detection of carcinoembryonic antigen (CEA) was developed by means of immobilizing anti-CEA onto magnetic CoFe2O4/SiO2 composite nanoparticles-functionalized biomimetic interface. Under optimal conditions, the frequency shift was proportional to the CEA concentration in the range of 2.5-55 ng/mL with a detection limit of 0.5 ng/mL at a signal-to-noise ratio of 3. Moreover, the immunosensor system showed an acceptable reproducibility and stability. Clinical serum specimens were assayed with this method, and the results were in acceptable agreement with those obtained from ELISA. Compared with the conventional ELISA assay, the proposed immunoassay system was simple and rapid without multiple labeling and separation steps. Importantly, the developed immunoassay protocol could be further extended for the determination of other antigens.