Microfabricated renewable beads-trapping/releasing flow cell for rapid antigen-antibody reaction in chemiluminescent immunoassay.

A renewable flow cell integrating a microstructured pillar-array filter and a pneumatic microvalve was microfabricated to trap and release beads. A bead-based immunoassay using this device was also developed. This microfabricated device consists of a microfluidic channel connecting to a beads chamber in which the pillar-array filter is built. Underneath the filter, there is a pneumatic microvalve built across the chamber. Such a device can trap and release beads in the chamber by "closing" or "opening" the microvalve. On the basis of the pneumatic microvalve, the device can trap beads in the chamber before performing an assay and release the used beads after the assay. Therefore, this microfabricated device is suitable for "renewable surface analysis". A model analyte, 3,5,6-trichloropyridinol (TCP), was chosen to demonstrate the analytical performance of the device. The entire fluidic assay process, including beads trapping, immuno binding, beads washing, beads releasing, and chemiluminesence signal collection, could be completed in 10 min. The immunoassay of TCP using this microfabricated device showed a linear range of 0.20-70 ng/mL with a limit of detection of 0.080 ng/mL. The device was successfully used to detect TCP spiked in human plasma at the concentration range of 1.0-50 ng/mL, with an analytical recovery of 81-110%. The results demonstrated that this device can provide a rapid, sensitive, reusable, low-cost, and automatic tool for detecting various biomarkers in biological fluids.