A highly sensitive resonance scattering spectral assay for carcinoembryonic antigen using immunonanogold as probe and nanocatalyst of NH2OH–Cu(II) particle reaction

Nanogold of 10 nm was used to label carcinoembryonic antigen antibody (CEAAb) to prepare a probe (Au-CEAAb) for carcinoembryonic antigen (CEA). In a Na2HPO4–NaH2PO4 buffer solution of pH 6.8, CEA reacted with Au-CEAAb to form a big Au-CEAAb–CEA immunocomplex that can be removed by centrifugation. The unreacted Au-CEAAb in the centrifugal supernatant exhibited catalytic effect on the Cu2O particle reaction, and the Cu2O particles displayed a resonance scattering (RS) peak at 602 nm. When CEA increased, the RS intensity at 602 nm decreased, and the decreased RS intensity (ΔI 602 nm) was linear to CEA concentration (C CEA) in the range of 0.02–12 ng mL−1, with the regression equation of ΔI 602 nm = 27.1 C CEA + 3.3, correlation coefficient of 0.9978 and detection limit of 3 pg mL−1 CEA. The proposed method was applied to detect CEA in real samples, with satisfactory results.