Abstract
Abstract Under the limitations of advanced instruments and professional operations, straightforward readouts play an increasingly vital role in immunoassays. Herein, a Ag2CO3@Ag nanocomposite-mediated colorimetric and photothermal immunoassay was developed to detect carcinoembryonic antigen (CEA). The Ag2CO3@Ag nanocomposites could oxidize 3,3’,5,5’-tetramethylbenzidine to form blue oxidation products (TMBox) due to the acidic dissolution of Ag2CO3 under acidic conditions. TMBox presented a strong photothermal effect driven by a near-infrared (NIR) laser. Therefore, TMBox could act as a photothermal probe to convert immunoassay signals into thermal signals. The Ag2CO3@Ag nanocomposite was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD). Then, a sandwich-type immunoassay was built on the surface of a magnetic bead, and CEA was quantified using a common thermometer based on the photothermal effect. Under optimal conditions, the temperature increased with increase of CEA concentrations in the range of 0.1 ng/mL–5 ng/mL. More importantly, this system exhibited high selectivity, good repeatability and outstanding stability.
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