The invention generally relates to methods for quantifying an amount of enzyme molecules. Systems and methods of the invention are provided for measuring an amount of target by forming a plurality of fluid partitions, a subset of which include the target, performing enzyme-catalyzed reaction in the subset, and detecting the number of partitions in the sunset. The amount of target can be determined based on the detected number.

The invention generally relates to methods for quantifying an amount of enzyme molecules. Systems and methods of the invention are provided for measuring an amount of target by forming a plurality of fluid partitions, a subset of which include the target, performing an enzyme-catalyzed reaction in the subset, and detecting the number of partitions in the subset. The amount of target can be determined based on the detected number.

The invention describes a method for the identification of compounds which bind to a target component of a biochemical system or modulate the activity of the target, comprising the steps of: a) compartmentalising the compounds into microcapsules together with the target, such that only a subset of the repertoire is represented in multiple copies in any one microcapsule; and b) identifying the compound which binds to or modulates the activity of the target; wherein at least one step is performed under microfluidic control. The invention enables the screening of large repertoires of molecules which can serve as leads for drug development.

The present invention provides microfabricated substrates and methods of conducting reactions within these substrates. The reactions occur in plugs transported in the flow of a carrier-fluid.

The invention describes a method for isolating one or more genetic elements encoding a gene product having a desired activity, comprising the steps of: (a) compartmentalising genetic elements into microcapsules; and (b) sorting the genetic elements which express the gene product having the desired activity; wherein at least one step is under microfluidic control. The invention enables the in vitro evolution of nucleic acids and proteins by repeated mutagenesis and iterative applications of the method of the invention.

Various aspects of the present invention relate to the control and manipulation of fluidic species, for example, in microfluidic systems. In one aspect, the invention relates to systems and methods for making droplets of fluid surrounded by a liquid, using, for example, electric fields, mechanical alterations, the addition of an intervening fluid, etc. In some cases, the droplets may each have a substantially uniform number of entities therein. For example, 95% or more of the droplets may each contain the same number of entities of a particular species. In another aspect, the invention relates to systems and methods for dividing a fluidic droplet into two droplets, for example, through charge and/or dipole interactions with an electric field. The invention also relates to systems and methods for fusing droplets according to another aspect of the invention, for example, through charge and/or dipole interactions. In some cases, the fusion of the droplets may initiate or determine a reaction. In a related aspect of the invention, systems and methods for allowing fluid mixing within droplets to occur are also provided. In still another aspect, the invention relates to systems and methods for sorting droplets, e.g., by causing droplets to move to certain regions within a fluidic system. Examples include using electrical interactions (e.g., charges, dipoles, etc.) or mechanical systems (e.g., fluid displacement) to sort the droplets. In some cases, the fluidic droplets can be sorted at relatively high rates, e.g., at about 10 droplets per second or more. Another aspect of the invention provides the ability to determine droplets, or a component thereof, for example, using fluorescence and/or other optical techniques (e.g., microscopy), or electric sensing techniques such as dielectric sensing.

A microscale method for the characterization of one or more reaction variables that influence the formation or dissociation of an affinity complex comprising a ligand and a binder, which have mutual affinity for each other. The method is characterized in comprising the steps of: (i) providing a microfluidic device comprising a microchannel structures that are under a common flow control, each microchannel structure comprising a reaction microactivity; (ii) performing essentially in parallel an experiment in each of two or more of the plurality of microchannel structures, the experiment in these two or more microchannel structures comprising either a) formation of an immobilized form of the complex and retaining under flow conditions said form within the reaction microactivity, or b) dissociating, preferably under flow condition, an immobilized form of the complex which has been included in the microfluidic device provided in step (i), at least one reaction variable varies or is uncharacterized for said two or more microchannel structures while the remaining reaction variables are kept essentially constant; (iii) measuring the presentation of the complex in said reaction microactivity in said two or more microchannel structures; and (iv) characterizing said one or more reaction variables based on the values for presentation obtained in step (iii).

Methods and systems for processing polynucleotides (e.g., DNA) are disclosed. A processing region includes one or more surfaces (e.g., particle surfaces) modified with ligands that retain polynucleotides under a first set of conditions (e.g., temperature and pH) and release the polynucleotides under a second set of conditions (e.g., higher temperature and/or more basic pH). The processing region can be used to, for example, concentrate polynucleotides of a sample and/or separate inhibitors of amplification reactions from the polynucleotides. Microfluidic devices with a processing region are disclosed.

The present invention provides microfabricated substrates and methods of conducting reactions within these substrates. The reactions occur in plugs transported in the flow of a carrier-fluid.

The present invention provides microfabricated substrates and methods of conducting reactions within these substrates. The reactions occur in plugs transported in the flow of a carrier-fluid.