Microfluidic Fabrication of Encoded Hydrogel Microparticles for Application in Multiplex Immunoassay

Recent interests in comprehensive protein surveys and protein biomarker studies have led to an increased demand for simultaneous measurement of multiple proteins in a single sample. Among various multiplex techniques, bead-based immunoassays, which use encoded particles attached with capture probes, have demonstrated distinct advantages of fluid-phase kinetics, high precision, and flexible target selection. In particular, encoded hydrogel particles composed of porous, hydrophilic, three-dimensional polymers have received positive attention because they enhance the binding kinetics of proteins, reduce protein denaturation, and increase the loading density of capture probes. Microfluidic techniques have been extensively used to fabricate the encoded hydrogel particles for multiplex immunoassays, enabling mass-production of highly monodisperse particles with complex morphologies in mild synthesis conditions. In this paper, we review microfluidic techniques available for the synthesis of encoded hydrogel particles and the important design parameters that determine the particles’ immunoassay performance. We also discuss currently reported multiplex immunoassay platforms that are based on encoded hydrogel particles.