High-throughput electrochemical microfluidic immunoarray for multiplexed detection of cancer biomarker proteins

Microchip-based microfluidic electrochemical arrays hold great promise for fast, high-throughput multiplexed detection of cancer biomarker proteins at low cost per assay using relatively simple instrumentation. Here we describe an inexpensive high-throughput electrochemical array featuring 32 individually addressable micro electrodes that is further multiplexed with an 8-port manifold to provide 256 sensors. The gold electrode arrays were fabricated by wet etching commercial gold compact discs (CD-R) followed by patterned insulation. A print-and-peel method was used to create sub-microliter hydrophobic wells surrounding each sensor to eliminate cross contamination during immobilization of capture antibodies. High throughput analyses were realized using eight 32-sensor immunoarrays connected to the miniaturized 8-port manifold, allowing 256 measurements in <1 h. This system was used to determine prostate cancer biomarker proteins prostate specific antigen (PSA), prostate specific membrane antigen (PSMA), interleukin-6 (IL-6), and platelet factor-4 (PF-4) in serum. Clinically relevant detection limits (0.05 to 2 pg mL(-1)) and 5-decade dynamic ranges (sub pg mL(-1) to well above ng mL(-1)) were achieved for these proteins utilizing precapture of analyte proteins on magnetic nanoparticles decorated with enzyme labels and antibodies.