Microfluidic Ping Pong for cytokine detection

Dynamic bead-based microarrays offer an ideal platform for chemical and biological applications, including on-site chemical analysis, point-of-care medical diagnostics and synthetic biology on a chip. Despite significant development of dynamic microarrays, challenges have remained for achieving multi-stage fluidic reactions and analyses. Here we present a novel bead-based microarray platform - Microfluidic Ping Pong (MPP) - and demonstrate this system by detecting the inflammatory cytokine, interferon-gamma (IFN-γ), via a six-step aptamer-based sandwich assay with five additional wash steps. Using aptamer beacons immobilized on 15 μm diameter polystyrene microbeads, 100 pM concentrations of IFN-γ were detected in the MPP system.