Near-infrared light-enhanced colorimetric signal amplification strategy for tumor marker detection based on MoS/CuO/Au nanocomposite.

A novel signal amplification strategy was developed by combining near-infrared light with MoS/CuO/Au nanocomposite for building a colorimetric immunoassay. First, MoS/CuO/Au nanocomposite was synthesized by precipitation and photoreduction methods and characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). MoS/CuO/Au nanocomposite has oxidase-like activity and can oxidize TMB to form a blue product (TMBox). Further, the catalytic oxidation of TMB was accelerated under near-infrared (NIR) laser radiation. The sandwich-type colorimetric immunoassay was constructed using MoS/CuO/Au nanocomposite. Under the enhancement of near-infrared light, carcinoembryonic antigen (CEA) was sensitively detected in the range 0.1 to 40 ng/mL with the limit of detection of 0.03 ng/mL. Moreover, the immunosensor has excellent selectivity and anti-interference, good repeatability, and stability.