This article describes the synthesis and characterization of a new type of discrete microparticle immunosensor employing macroporous methacrylate polymer microspheres. The microspheres are produced using a simple microfluidic tubing co-flow droplet generator to produce large populations of microparticles with exceptional size uniformity and controllable macroporosity. Subsequent grafting treatments are demonstrated to anchor immunoactive ligands on the porous surfaces, converting the microspheres into discrete immunosensor elements, with direct immunoassay tests demonstrating good detection limits and capturing specificity. This work demonstrates the adaptation of a traditional polymer monolith stationary phase material into a discrete microparticle immunosensor format using a synthesis and functionalization path with significant flexibility toward a diverse range of biological and chemical sensing applications. (C) 2012 Elsevier Ltd. All rights reserved.