Modular microfluidic system for on-chip extraction, preconcentration and detection of the cytokine biomarker IL-6 in biofluid

The cytokine interleukin 6 (IL-6) is involved in the pathogenesis of different inflammatory diseases, including cancer, and its monitoring could help diagnosis, prognosis of relapse-free survival and recurrence. Here, we report an innovative microfluidic approach that uses the fluidization of magnetic beads to specifically extract, preconcentrate and fluorescently detect IL-6 directly on-chip. We assess how the physical properties of the beads can be tuned to improve assay performance by enhancing mass transport, reduce non-specific binding and multiply the detection signal threefold by transitioning between packed and fluidization states. With the integration of a full ELISA protocol in a single microfluidic chamber, we show a twofold reduction in LOD compared to conventional methods along with a large dynamic range (10 pg/mL to 2 ng/mL). We additionally demonstrate its application to IL-6 detection in undiluted serum samples.

Automated summary

This study reports an innovative microfluidic approach using magnetic bead fluidization to directly extract, preconcentrate, and detect IL-6 on a chip. By tuning the physical properties of the beads, assay performance can be improved by enhancing mass transport, reducing non-specific binding, and amplifying the detection signal threefold. By integrating a full ELISA protocol in a single microfluidic chamber, a twofold reduction in LOD and a large dynamic range are achieved.