A novel and accurate microfluidic assay of CD62L in bladder cancer serum samples

We report a low-cost, sensitive, bead-based electrochemical immunoarray for soluble L-selectin (or CD62L protein), a potential biomarker for staging bladder cancer. We used a semi-automated modular microfluidic array with online antigen capture on superparamagnetic beads, which were subsequently delivered to a detection chamber housing multiple sensors. The assay was designed to accurately detect CD62L in diluted serum with a limit of detection (LOD) of 0.25 ng mL-1 and a dynamic range of 0.25-100 ng mL-1. The microfluidic array gave significantly better accuracy and higher sensitivity than a standard ELISA kit, which was shown to be subject to significant systematic error at high and low concentration ranges. 31 serum samples from patients with varying grades of bladder cancer and cancer-free controls were analyzed by the immunoarray and ELISA, and the CD62L levels correlated. This work establishes a new accurate assay for determining CD62L levels and highlights the potential of this protein as a biomarker for detecting locoregional progression of bladder cancer.

The Analyst. 2018 Oct 08 [Epub ahead of print]

Gayatri S Phadke, Jennifer E Satterwhite-Warden, Dharamainder Choudhary, John A Taylor, James F Rusling

Department of Chemistry (U-3060), University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, USA. ., Department of Surgery, University of Connecticut Health Center, Farmington, Connecticut 06032, USA., Department of Urology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA., Department of Chemistry (U-3060), University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, USA. and Department of Surgery, University of Connecticut Health Center, Farmington, Connecticut 06032, USA and Institute of Materials Science, University of Connecticut, 97 North Eagleville Road, Storrs, Connecticut 06269, USA and School of Chemistry, National University of Ireland, Galway, University Road, Galway, Ireland.