Prostate specific antigen detection using microgapped electrode array immunosensor with enzymatic silver deposition.

BACKGROUND Analysis of trace proteins plays an essential role in the fields of biomedical research and clinical diagnosis. Development of methods for the detection of proteins at very low concentrations has historically been a challenge in immunochemistry. We have developed an electrical immunosensor for the detection of prostate specific antigen (PSA). METHODS The electrical immunosensor uses a microgapped interdigitated electrode array (MGIDEA) based on enzymatic silver deposition reaction. The deposition of silver was dispersed over the microgaps and allows the microgapped interdigitated electrodes to be electrically connected, resulting in an increase in electrical conductance of MGIDEA that is used to quantify the analyte concentration. We used this electrical immunosensor to measure PSA in human serum samples from patients with prostate diseases. RESULTS This electrical immunosensor exhibited a linear response with PSA concentrations over a 6-decade range from 1.0 pg/L to 1.0 microg/L, with detection limit of 0.9 pg/L. PSA concentrations using this immunosensor agreed within 10% of those obtained using a commercial chemiluminescent immunoassay. CONCLUSIONS The MGIDEA method has characteristics (analyte specific, low background, low limit of detection) that provide potential for molecular detection in various biomedical areas.