Simultaneous determination of the cytokeratin 19 fragment and carcinoembryonic antigen in human serum by magnetic nanoparticle-based dual-label time-resolved fluoroimmunoassay

A highly sensitive, rapid and novel simultaneous measurement method for cytokeratin 19 fragment (CYFRA 21-1) and carcinoembryonic antigen (CEA) in human serum by magnetic nanoparticle-based dual-label time-resolved fluoroimmunoassay was developed. On the basis of a sandwich-type immunoassay format, analytes in the samples were captured by antibodies coated onto the surface of the magnetic beads and sandwiched by other antibodies labeled with europium and samarium chelates. The lower limit of quantitation of the present method for CYFRA 21-1 was 0.77 ng mL(-1) and CEA was 0.85 ng mL(-1). The coefficient variations of the method were less than 7%, and the recoveries were in the range of 90-110% for serum samples. The concentrations of CYFRA 21-1 and CEA serum samples determined by the present method were compared with those obtained by the chemiluminescence immunoassay. A good correlation was obtained with the correlation coefficients of 0.961 for CYFRA 21-1 and 0.938 for CEA. This novel method demonstrated high sensitivity, wide effective detection range and excellent reproducibility for the simultaneous determination of CYFRA 21-1 and CEA, which can be useful for the early screening and prognosis evaluation of patients with lung cancer.