A highly sensitive label-free resonance light scattering assay of carcinoembryonic antigen based on immune complexes

As a kind of glycoprotein, carcinoembryonic antigen (CEA) is the important tumor marker for clinical diagnosis of the presence or recurrence of cancer. In this work, a novel label-free resonance light scattering (RLS) spectral CEA assay was developed based on the combination of highly selective immunoreaction and ultrasensitive RLS technique. In Tris–HCl buffer solution (pH 7.5), the specific immunoreaction between CEA antigen and mouse anti-CEA formed immune complexes which had a maximum RLS spectral peak at 389.0 nm, with the existence of physiological saline and polyethylene glycol 20,000 (PEG 20,000). Under the optimal conditions, the magnitude of enhanced RLS intensity (ΔIRLS) was proportional to the concentration of CEA in the range from 0.1 to 60 ng mL−1, with a detection limit (LOD, 3σ) of 0.03 ng mL−1. The characteristics of RLS, the CEA immunocomplex, the immune response, the ratio of CEA antigen and mouse anti-CEA, and the optimum conditions of the immunoreaction have been investigated. The CEA concentrations of 20 serum specimens detected by the developed assay showed consistent results in comparison with those obtained by commercially available enzyme-linked immunosorbent assay (ELISA) kit. And this method has many satisfying merits including label-free, sensitivity and high selectivity.

A novel label-free resonance light scattering (RLS) spectral CEA assay was developed based on the combination of highly selective CEA immunoreaction and ultrasensitive RLS technique. The specific immunoreaction between CEA antigen and mouse anti-CEA formed immune complexes which had a maximum RLS spectral peak at 389.0 nm. Under the optimal conditions, the magnitude of enhanced RLS intensity (IRLS) was proportional to the concentration of CEA. This new assay was successfully used to detect CEA in 20 serum specimens and it has many satisfying merits including sensitivity, label-free and high selectivity.Figure optionsDownload as PowerPoint slideHighlights
► Carcinoembryonic antigen is an important tumor marker for clinical diagnosis of tumor.
► The immunoreaction between CEA and mouse anti-CEA resulted in the enhanced RLS.
► The RLS characteristics, immune response and optimum conditions have been studied.
► This developed RLS assay was successfully applied to detect CEA in 20 serum samples.
► The assay possesses the merits of label-free, sensitivity and high selectivity.