Microfluidic Devices and Methods of Use in The Formation and Control of Nanoreactors

Abstract

The present invention provides novel microfluidic devices and methods that are useful for performing high-throughput screening assays and combinatorial chemistry. Such methods can include labeling a library of compounds by emulsifying aqueous solutions of the compounds and aqueous solutions of unique liquid labels on a microfluidic device, which includes a plurality of electrically addressable, channel bearing fluidic modules integrally arranged on a microfabricated substrate such that a continuous channel is provided for flow of immiscible fluids, whereby each compound is labeled with a unique liquid label, pooling the labeled emulsions, coalescing the labeled emulsions with emulsions containing a specific cell or enzyme, thereby forming a nanoreactor, screening the nanoreactors for a desirable reaction between the contents of the nanoreactor, and decoding the liquid label, thereby identifying a single compound from a library of compounds.

Description

FIELD OF INVENTION[0001]The present invention generally relates to systems and methods for the formation and / or control of fluidic species, and articles produced by such systems and methods. More particularly, the present invention relates to the development of high throughput microfluidic devices for precision fluid handling and use of such systems in various biological, chemical, or diagnostic assays.BACKGROUND[0002]High throughput molecular screening (HTS) is the automated, rapid testing of thousands of distinct small molecules or probes in cellular models of biological mechanisms or disease, or in biochemical or pharmacological assays. Active compounds identified through HTS can provide powerful research tools to elucidate biological processes through chemical genetic approaches, or can form the basis of therapeutics or imaging agent development programs. HTS has experienced revolutionary changes in technology since the advent of molecular biology and combinatorial chemistry, an...

AI Technical Summary

Benefits of technology

[0009]The present invention provides devices having individual fluid handling modules that can be combined into fluid processing systems so as to perform multi-step processing of isolated components, which is essential for searching through molecular libraries for rare interactions with cells, nucleic acids, enzymes, coded microbeads, and other biomaterials. Using principles based on the electrostatic and dielectrophoretic manipulation of charged and neutral droplets 20 to 100 microns in diameter, the microfluidic devices as described herein can inexpensively encapsulate reagents, combine same, analyze, and sort in the range of 1×109 droplets per day. The present invention provides a microfluidic device that includes a microfabricated substrate. The substrate can include a plurality of electrically addressable channel bearing microfluidic modules integrally arranged with each other so as to be in fluid communication. The microfabricated substrate can have, for example, (i) one or more inlet modules that have at least one inlet channel adapted to carry a dispersed phase fluid, (ii) at least one main channel adapted to carry a continuous phase fluid, wherein the inlet channel is in fluid communication with the main channel such that the dispersed phase fluid is immiscible with the continuous phase fluid and forms a plurality of droplets in the continuous phase fluid, and (iii) a coalescence module downstream from and in fluid communication with the inlet modules via the main channel, wherein two or more droplets passing there through are coalesced to form a nanoreactor. The microfluidic device of the present invention can further include a sorting module, mixing module, delay module, UV-release module, detection module, collection module, waste module and / or acoustic actuator, and or combinations thereof, in any order. These modules are in fluid communication with the main channel. The flow of the dispersed phase and continuous phase can be pressure driven, for example.

Problems solved by technology

However, there are still bottlenecks which currently limit HTS capacity, such as (a) compound collection maintenance, tracking, and disbursement, and (b) rapidity, accuracy, and content of assay instrumentation.

However, virtually all microfluidic devices are based on flows of streams of fluids; this sets a limit on the smallest volume of reagent that can effectively be used because of the contaminating effects of diffusion and surface adsorption.

As the dimensions of small volumes shrink, diffusion becomes the dominant mechanism for mixing leading to dispersion of reactants; moreover, surface adsorption of reactants, while small, can be highly detrimental when the concentrations are low and volumes are small.

As a result, current microfluidic technologies cannot be reliably used for applications involving minute quantities of reagent; for example, bioassays on single cells or library searches involving single beads are not easily performed.

However, essentially all enabling technology for microfluidic systems developed thus far has focused on single phase fluid flow and there are few equivalent active means to manipulate droplets requiring the development of droplet handling technology.

For example, as the scale of these reactors shrinks, contamination effects due to surface adsorption and diffusion limit the smallest quantities that can be used.

Although utility of electrophoretic control of droplets is great, it does have significant limitations.

First, the charging of droplets is only effectively accomplished at the nozzle.

Second, the discharge path required to eliminate screening effects also discharges the droplets.

Third, finite conductivity of the carrier fluid, however small, will eventually discharge the droplets.

Therefore, once the droplet is formed, there is essentially only one opportunity to perform any pondermotive function which relies on the droplet's charge density (such as coalescing oppositely charged droplets through their mutual Coulombic attraction, or electrophoretically sorting a droplet), and that function can only be performed as long as sufficient charge has not leaked off of the droplet.

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