Novel automated flow-based immunosensor for real-time measurement of the breast cancer biomarker CA15-3 in serum

A novel automated immunosensor assay has been developed for real-time measurement of the breast cancer biomarker CA15-3 in serum. The assay employed the kinetic-exclusion analytical technology of the KinExA™ 3200 instrument. Polymethylmethacrylate (PMMA) beads coated with CA15-3 were used as capturing reagent, mouse anti-CA15-3 monoclonal antibody was used as primary antibody, and the fluorescence was monitored and recorded during the flow of the fluorescent-labeled antibody through the beads. The fluorescence signal retained on the beads was plotted versus CA15-3 concentration to generate a calibration curve. The concentrations of CA15-3 in the samples were then obtained by interpolation on the curve. The assay limit of detection was 0.2 IU mL−1. This highly sensitive automated system allowed rapid and reliable quantification of CA15-3 without any matrix effect; analytical recovery of serum-spiked CA15-3 was 90.7%–108.6%±2.05%–7.45%. The precision of the sensor was satisfactory; relative standard deviation (RSD) was 3.8%–5.1% and 5.2%–7.4% for the intra- and inter-assay precision, respectively. The analytical performance of the proposed sensor was superior to the non-competitive sandwich immunoassays for CA15-3. The automated analysis by the sensor facilitated the processing of a large number of specimens, and the new sensor-based assay is anticipated to have a great value in measurement of CA15-3.