Heterogeneous competitive immunoassay for human IgG in disposable bio-passivated PDMS microfluidic channels using an on-chip internal fluorescent standard

A multi-layer surface treatment of a PDMS/glass microfluidic chip was developed to suppress adsorption to the channel walls. The outermost layer of the coating was patterned with antibodies that were used to carry out a heterogeneous immunoassay. Human IgG was analyzed using an electrokinetically driven competitive immunoassay with Cy5-labeled human IgG as tracer. An internal standard was implemented on-chip to meet the high level of confidence in assay results required by clinical diagnostics. This work demonstrates that it is possible to control key aspects of a chip-based immunoassay, including the fluidic properties, antibody activity and sample delivery.