Sensitive detection of carcinoembryonic antigen using surface plasmon resonance biosensor with gold nanoparticles signal amplification.

A new method for real-time detection of carcinoembryonic antigen (CEA) in human serum with high sensitivity and selectivity using surface plasmon resonance (SPR) biosensor was developed. Two kinds of antibodies were used to recognize CEA at different epitopes with high affinity and specificity. Gold nanoparticles (GNPs) modified with streptavidin (SA) were used to further enhance signal specifically via biotin-streptavidin interaction. The binding capacity of the streptavidin-modified gold nanoparticles (SA-GNPs) for ligand biotin was quantified by titration with biotin (5-fluorescein) conjugate to be 10.54 biotin binding sites per 100 nm(2). The developed GNPs enhanced sandwich SPR biosensor successfully fulfilled the sensitive detection of CEA in the range of 1-60 ng/mL with a detection limit of 1.0 ng/mL. Compared to the direct assay format, sandwich format without GNPs and SA-GNPs enhanced sandwich format led to 4.2-fold and 13.8-fold in the sensitivity, respectively. This sensor also showed good selectivity for CEA in the interference study. The results demonstrated that the proposed method could provide a high sensitivity and selectivity in the detection of CEA and offer a promising alternative for cancer biomarker than traditional clinical examinations.