Simultaneous quantitation of cytokeratin-19 fragment and carcinoembryonic antigen in human serum via quantum dot-doped nanoparticles

A novel quantum dot-doped polystyrene nanoparticles-based lateral flow test strips (QPs-LFTS) system was developed to simultaneously detect a cytokeratin-19 fragment (CYFRA 21-1) and carcinoembryonic antigen (CEA) in human serum to aid the diagnosis and prognosis of lung cancer. Quantum dot-doped carboxylatefunctionalized polystyrene nanoparticles (QPs) were prepared and introduced as fluorescent reporters in QPsLFTS. The detection was based on a sandwich immunoassay and performed on lateral flow test strips, with an assay time of 15 min. The strips were read by a fluorescence strip reader to obtain the '' fluorescence peak heights of the test lines (H-T) and the control line (H-c). The ratio of H-T/H-c was used for quantitation. The QPs showed excellent photoproperties and good performance. Under optimal conditions, the QPs-LFTS system exhibited a wide linear range for CYFRA 21-1 (1.3-480 ng/mL) and CEA (2.8-680 ng/mL). The detection limits for CYFRA 21-1 and CEA were 0.16 and 0.35 ng/mL, respectively. The recovery and reproducibility of the method were satisfactory. Furthermore, excellent correlations (n =120, R-2 =0.9862, P < 0.0001 for CYFRA 21-1; n =70, R-2 =0.9509, P < 0.0001 for CEA) were obtained between the QPs-LFTS and commercially available chemiluminescence immunoassay kits in clinical serum testing. The results indicate that this developed test system is highly efficient and is expected to be useful for early screening and prognosis evaluation for lung cancer patients.