The present invention provides novel microfluidic devices and methods that are useful for performing high-throughput screening assays and combinatorial chemistry. The invention provides for aqueous based emulsions containing uniquely labeled cells, enzymes, nucleic acids, etc., wherein the emulsions further comprise primers, labels, probes, and other reactants. An oil based carrier-fluid envelopes the emulsion library on a microfluidic device, such that a continuous channel provides for flow of the immiscible fluids, to accomplish pooling, coalescing, mixing, sorting, detection, etc., of the emulsion library.

A method of characterizing candidate agents including steps of (a) providing a library of candidate agents attached to nucleic acid tags; (b) contacting the library with a solid support to attach the candidate agents to the solid support, whereby an array of candidate agents is formed; (c) contacting the array with a screening agent, wherein one or more candidate agents in the array react with the screening agent; (d) detecting the array to determine that at least one candidate agent in the array reacts with the screening agent; (e) sequencing the nucleic acid tag to determine the tag sequences attached to candidate agents in the array; and (f) identifying the at least one candidate agent in the array that reacts with the screening agent based on the tag sequence that is attached to the at least one candidate agent.

A method of characterizing candidate agents including steps of (a) providing a library of candidate agents attached to nucleic acid tags; (b) contacting the library with a solid support to attach the candidate agents to the solid support, whereby an array of candidate agents is formed; (c) contacting the array with a screening agent, wherein one or more candidate agents in the array react with the screening agent; (d) detecting the array to determine that at least one candidate agent in the array reacts with the screening agent; (e) sequencing the nucleic acid tag to determine the tag sequences attached to candidate agents in the array; and (f) identifying the at least one candidate agent in the array that reacts with the screening agent based on the tag sequence that is attached to the at least one candidate agent.