Simultaneous and combined detection of multiple tumor biomarkers for prostate cancer in human serum by suspension array technology

Tumor markers (TMs) play an important role in clinical rapid screening and diagnosis for prostate cancer (PCa). In this study, we describe a competitive method to establish the multiplex suspension array by tumor biomarkers coated on distinguishable microbeads which competing with free biomarkers for their complementary antibodies (Ab) in one single reaction system for simultaneous and combined detection of prostate TMs in human serum. The volumes of the targets coupled onto the beads and their complementary Abs were optimized. The suspension array standard curves correlated well with PCa biomarkers (R-2 > 0.9968). PCa biomarker levels were quantified using median fluorescent intensities. The working ranges of prostate-specific antigen (PSA), prostate stem cell antigen (PSCA), prostate-specific membrane antigen (PSMA) and prostatic acid phosphatase (PAP) were 0.47-502.94, 1.00-923.35, 1.00-524.79, and 1.73-176.07 ng mL(-1) in serum samples, respectively. This method was compared to indirect competitive enzyme linked immunosorbent assay. It was found that high concordance between the two technologies resulted from serum samples of the eight PCa patients. The multiplex suspension array technology is specific to PCa biomarkers, displayed no significant cross-reactivity, and remains stable for 6 months. We also characterized the bead surface microstructures under different conditions employing a field emission scanning electron microscope. The suspension array is a straightforward and reliable method for analysis of multiple TMs with simple operation, high sensitivity at a low cost. (C) 2013 Elsevier E.V. All rights reserved.