OPEN Analytical chemistry | 28 Jan 2016
AK Price, AB MacConnell and BM Paegel
With the potential for each droplet to act as a unique reaction vessel, droplet microfluidics is a powerful tool for high-throughput discovery. Any attempt at compound screening miniaturization must address the significant scaling inefficiencies associated with library handling and distribution. Eschewing microplate-based compound collections for one-bead-one-compound (OBOC) combinatorial libraries, we have developed hνSABR (Light-Induced and -Graduated High-Throughput Screening After Bead Release), a microfluidic architecture that integrates a suspension hopper for sedimentation-mediated compound library bead introduction, droplet generation, microfabricated waveguides that precisely irradiate (365 nm) the droplet flow and photochemically cleave the compound from the bead to dose the droplet, incubation, and laser-induced fluorescence for assay readout. Avobenzone-doped PDMS (0.6% w/w) patterning confines UV exposure to the desired illumination region, generating in-droplet compound concentrations (> 10 µM) that are reproducible between devices. Beads displaying photocleavable pepstatin A were distributed into droplets and exposed with 5 different UV intensities to demonstrate dose-response screening in an HIV-1 protease activity assay. This microfluidic architecture introduces a new analytical approach for OBOC library screening, and represents a key component of a next-generation distributed small molecule discovery platform.
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