Highly sensitive immunoassay of carcinoembryonic antigen by capillary electrophoresis with gold nanoparticles amplified chemiluminescence detection.

A noncompetitive immunoassay based on gold nanoparticles (AuNPs) amplified capillary electrophoresis (CE) chemiluminescence (CL) detection was developed for the determination of carcinoembryonic antigen (CEA). In this method, citrate-modified AuNPs were conjugated with horseradish peroxidase (HRP) labeled CEA antibody (Ab*), and incubated with limited amount of CEA antigen. CEA-Ab*-AuNPs complex and excess of Ab*-AuNPs were then separated and quantified by CE with CL detection. Highly sensitive CL detection was achieved by means of p-iodophenol (PIP) enhanced luminol-H2O2-HPR CL reaction and AuNPs amplified. Under the optimal conditions, the CE assay was accomplished within 5min. The linear range for CEA detection was 0.05-20ng/mL with a detection limit of 0.034ng/mL (signal/noise=3), which is three orders magnitude lower than that of without AuNPs amplified. The current method was successfully applied for the quantification of CEA in human serum samples. It was demonstrated that the current CE-CL AuNPs amplified noncompetitive immunoassay was sensitive and highly selective. It may serve as a tool for clinical analysis of CEA to assist in the diagnosis of cancer.