Shake it or shrink it: Mass transport and kinetics in surface bioassays using agitation and microfluidics

Mass transport is an often neglected aspect in the optimization of surface bioassays. We compare two modalities of generating mass transport,- shakers and microfluidic systems - and assess their kinetic performance. Microfluidics show a more uniform signal across the reaction area (~5% variation vs. 37% in a shaker) product of a constant shear rate, and superior binding kinetics of antibodies and antibody-coated gold nanoparticles. Based on this we provide guidance for surface assay optimization.