Colorimetric Analysis of Carcinoembryonic Antigen Using Highly Catalytic Gold Nanoparticles-Decorated MoS2 Nanocomposites.

Sensitive detection of carcinoembryonic antigen (CEA) is very important for early detection and cancer therapy monitoring. We utilized the highly catalytic activity of MoS2-gold nanoparticles (MoS2-AuNPs) nanocomposites to construct a colorimetric immunoassay for CEA detection, which could catalyze sodium borohydride (NaBH4) to reduce 4-nitrophenol (4-NP) and make the yellow solution colorless. MoS2-AuNPs nanocomposites could efficiently load antibodies (Ab1 and Ab2) because of their good biocompatibility and high adsorption ability, forming Ab1-MoS2-AuNPs nanoprobes for capturing CEA and Ab2-MoS2-AuNPs nanoprobes for catalytic reaction. It should be pointed out that Ab2-MoS2-AuNPs nanoprobes retained high catalytic activity because no blocking agent was used to block the catalytic sites. After the formation of the classical "sandwich" structure, parts of Ab2-MoS2-AuNPs nanoprobes remained in the supernatant after centrifugation, making the catalytic reaction occur and obtaining a colorless solution. As expected, a linear function between absorbance peak intensity and the logarithm of 5 pg/mL-10 ng/mL CEA was observed, and the detection limit was obtained as 0.5 pg/mL. This colorimetric immunosensor showed acceptable selectivity and repeatability for CEA detection, which could be successfully employed to detect CEA in serum.