A novel magnetic particle-modified electrochemical sensor for immunosensor applications

In this study, a novel magnetic particle-modified capacitive sensor was reported for the detection of cancer markers. A gold interdigitated (GID) capacitor transducer was modified using magnetic beads (MB) for signal enhancement and the optimal frequency range and magnetic bead amount were determined. The platform was initially tested using C-reactive protein (CRP) as the model analyte and the methodology was then transferred for multiple marker detection with the aim of precise disease diagnostics. For the first time, the protein biomarkers of lung cancer including carcinoembryonic antigen (CEA), epidermal growth factor receptor (hEGFR) and cancer antigen 15-3 (CA15-3) were investigated with a capacitive sensor. The threshold levels of the markers to indicate the cancer are higher than 5 ng mL−1 (CEA), 64 ng mL−1 (hEGFR) and 50 U mL−1 (CA15-3), respectively. CEA and hEGFR could successfully be detected in the concentration range of 5 pg mL−1 to 1 ng mL−1 while CA15-3 was detected in the range of 1–200 U mL−1 with a high specificity. Our study demonstrates a highly specific capacitive immunoassay, presenting a potential alternative tool for early and precise diagnosis of cancer disease.