Based on ZnSe quantum dots labeling and single particle mode ICP-MS coupled with sandwich magnetic immunoassay for the detection of carcinoembryonic antigen in human serum.

A highly sensitive sandwich-type magnetic immunoassay based on inductively coupled plasma mass spectrometry detection in single particle mode, with ZnSe Quantum dots (QDs) serving as model tags, was proposed. The transient signals induced by the flash of ions (64Zn+) in the plasma torch from the ionization of nanoparticles tagged on antibody were recorded in a single particle mode. The frequency of transient signals is directly related to the concentration of nanoparticle tags, and the concentration of nanoparticle tagged antibodies can be quantified by the frequency of transient signals. Amino-modified magnetic nanoparticles (AMNPs) were synthesized and conjugated with primary carcinoembryonic antigen (CEA) antibody to extract the target biomarker. ZnSe QDs were synthesized as a probe to determine CEA by ICP-MS. A detection limit of 0.006 ng mL-1 was obtained for CEA after immunoreactions, and a wide linear range of 0.02-100 ng mL-1 with the relative standard deviation (RSD) was 4.4%. The method was successfully applied to human serum samples.