Portable microfluidic immunoassay platform for the detection of inflammatory protein biomarkers†

Cytokines and acute-phase proteins are promising biomarkers for inflammatory disease. Despite its potential, early diagnosis based on these biomarkers remains challenging without technology enabling highly sensitive protein detection immediately after sample collection, because of the low abundance and short half-life of these proteins in bodily fluids. Enzyme-linked immunosorbent assay (ELISA) is a gold-standard method for such protein analysis, but it often requires labor-intensive and time-consuming sample handling and as well as a bulky benchtop platereader, limiting its utility in the clinical site. We developed a portable microfluidic immunoassay device capable of sensitive, quantitative, and high-throughput protein detection at point-of-need. The portable microfluidic system performs eight magnetic bead-based sandwich immunoassays from raw samples in 40 min. An innovative bead actuation strategy was incorporated into the system to automate multiple sample handling steps with minimal user intervention. The device enables quantitative protein analysis with picomolar sensitivity, as demonstrated using human samples spiked with interleukin-6 and C-reactive protein. The affinity-based assays are highly specific to the target without cross-reactivity. Therefore, we envision the reported device offering ultrasensitive and field-deployable immunoassay tests for timely and accurate clinical diagnosis.