Polynucleotide synthesis performed with a substrate independent polymerase such as terminal deoxynucleotidyl transferase (TdT) is regulated by controlling the oxidation state of a metal cofactor. The oxidation state of the metal cofactor is changed to +2, thus activating the polymerase, by applying a voltage with electrodes or by introducing a chemical redox reagent. Addressable polynucleotide synthesis creates polynucleotides with different arbitrary sequences through use of spatial control of cofactor oxidation states to add nucleotides only at selected locations on an array. Control of metal oxidation states is regulated by selective activation of a microelectrode array, controlled addition of redox reagents to specific locations on the array, or controlled activation of photocatalysts at specific locations on the array. Scavengers in solution prevent cofactors distant from the selected locations from catalyzing polymerase activity and thereby maintain the localized effect of polymerase activation.

The invention relates to methods and kits for the synthesis of oligonucleotides via controlled, localised deprotection of 3′-ONH.sub.2 groups on a solid support.

An apparatus for carrying out chemical reactions is provided. The apparatus comprises a first reactor/reaction zone for carrying out a first chemical reaction and a second reactor/reaction zone for carrying out a second chemical reaction. Each reactor/reaction zone comprises: a) an inner surface and an outer surface which are spaced apart from each other to define a reaction volume configured such that, in use, a respective chemical reaction takes place in the reaction volume, and wherein the inner surface and outer surface are configured for relative rotation with respect to each other, (b) an inlet for introduction of a reagent to the reaction volume, and (b) an outlet through which a reaction product can leave the reaction volume. The reaction products of the first reactor/reaction zone comprise reagents of the second reactor/reaction zone.

A device for base calling is provided. The device includes a receptacle configured to hold a biosensor having a sample surface holding a plurality of clusters during a sequence of sampling events, an array of sensors sensing information from clusters disposed in corresponding pixel areas of the sample surface during the sampling events and generate sequences of pixel signals and a communication port configured to output the sequences of pixel signals. The device also includes a signal processor coupled to the communication port and configured to receive and process at least one pixel signal in the sequences of pixel signals that mixes light gathered from at least two clusters in a corresponding pixel area, and to base call each of the at least two clusters using the at least one pixel signal.

An apparatus includes a flow cell body, a plurality of electrodes, an integrated circuit, and an imaging assembly. The flow cell body defines one or more flow channels and a plurality of wells. Each flow channel is configured to receive a flow of fluid. Each well is fluidically coupled with the corresponding flow channel. Each well is configured to contain at least one polynucleotide. Each electrode is positioned in a corresponding well of the plurality of wells. The electrodes are operable to effect writing of polynucleotides in the corresponding wells. The integrated circuit is operable to drive selective deposition or activation of selected nucleotides to attach to polynucleotides in the wells to thereby generate polynucleotides representing machine-written data in the wells. The imaging assembly is operable to capture images indicative of one or more nucleotides in a polynucleotide.

The present invention is generally related to systems and methods for producing a plurality of droplets. The droplets may contain varying species, e.g., for use as a library. In some cases, the fluidic droplets may be rigidified to form rigidified droplets (e.g., gel droplets). In certain embodiments, the droplets may undergo a phase change (e.g., from rigidified droplets to fluidized droplets), as discussed more herein. In some cases, a species may be added internally to a droplet by exposing the droplet to a fluid comprising a plurality of species.

A biosensor for base calling is provided. The biosensor comprises a sampling device, which includes a sample surface that has an array of pixel areas and a solid-state imager that has an array of sensors. Each sensor generates pixel signals in each base calling cycle. Each pixel signal represents light gathered in one base calling cycle from one or more clusters in a corresponding pixel area of the sample surface. The biosensor further comprises a signal processor configured for connection to the sampling device. The signal processor receives and processes the pixel signals from the sensors for base calling in a base calling cycle, and uses the pixel signals from fewer sensors than a number of clusters base called in the base calling cycle. The pixel signals from the fewer sensors include at least one pixel signal representing light gathered from at least two clusters in the corresponding pixel area.

Methods of producing substrates having selected active chemical regions by employing elements of the substrates in assisting the localization of active chemical groups in desired regions of the substrate. The methods may include optical, chemical and/or mechanical processes for the deposition, removal, activation and/or deactivation of chemical groups in selected regions of the substrate to provide selective active regions of the substrate.

An apparatus includes a flow cell body, a plurality of electrodes, an integrated circuit, and an imaging assembly. The flow cell body defines one or more flow channels and a plurality of wells. Each flow channel is configured to receive a flow of fluid. Each well is fluidically coupled with the corresponding flow channel. Each well is configured to contain at least one polynucleotide. Each electrode is positioned in a corresponding well of the plurality of wells. The electrodes are operable to effect writing of polynucleotides in the corresponding wells. The integrated circuit is operable to drive selective deposition or activation of selected nucleotides to attach to polynucleotides in the wells to thereby generate polynucleotides representing machine-written data in the wells. The imaging assembly is operable to capture images indicative of one or more nucleotides in a polynucleotide.

Described herein are RNA arrays, and compositions and methods for generating RNA arrays, particularly high density RNA arrays. The disclosed methods for generating RNA arrays utilize template DNA arrays and RNA polymerase to generate RNA arrays. In some embodiments, the disclosed methods use an RNA polymerase and modified ribonucleosides to generate modified RNA arrays for various applications, e.g. RNA arrays having higher nuclease resistance, more conformationally stable RNA arrays, and higher binding affinity RNA aptamer arrays. In some embodiments, the disclosed methods are used to generate RNA bead arrays.