Wesley G. Cochrane; Amber L. Hackler; Valerie J. Cavett; Alexander K. Price; Brian M. Paegel
Anal. Chem., 2017, 89, 24, 13227-13234
https://doi.org/10.1021/acs.analchem.7b03070

Abstract

Reaction incubation is ubiquitous in high-throughput screening workflows, including those at the microfluidic droplet scale. Fully integrated microfluidic processors that generate, incubate, and sort droplets for continuous droplet screening must passively handle a flowing emulsion such that droplet-droplet incubation time variation is minimized. Here, we disclose an integrated microfluidic emulsion creamer that close packs assay droplets by draining away excess oil through microfabricated drain channels. The drained oil co-flows with creamed emulsion and then reintroduces the oil to disperse the droplets at the circuit terminus for analysis. Creamed droplet emulsion assay incubation time dispersion was 1.7%, 3-fold less than other reported incubators. The integrated, continuous emulsion creamer (ICEcreamer) was used to miniaturize and optimize measurements of various enzymatic activities (phosphodiesterase, kinase, bacterial translation) under multiple- and single-turnover conditions. Combining the ICEcreamer with current integrated microfluidic DNA-encoded library bead processors eliminates potentially cumbersome instrumentation engineering challenges and provides a rich array of target classes and assay formats for distributed small molecule discovery.