The invention provides methods for controlling the density of different molecular species on the surface of a solid support. A first mixture of different molecular species is attached to a solid support under conditions to attach each species at a desired density, thereby producing a derivatized support having attached capture molecules. The derivatized support is treated with a second mixture of different molecular species, wherein different molecular species in the second mixture bind specifically to the different capture molecules attached to the solid support. One or more of the capture molecules can be reversibly modified such that the capture molecules have a different activity before and after the second mixture of molecular species are attached. In particular embodiments, the different molecular species are nucleic acids that are reversibly modified to have different activity in an amplification reaction.

The present disclosure is generally directed to strategies for template capture and amplification during sequencing.

Methods and systems for sample preparation techniques that allow amplification (e.g., whole genome amplification) and sequencing of chromatin accessible regions of single cells are provided. The methods and systems generally operate by forming or providing partitions (e.g., droplets) including a single biological particle and a single bead comprising a barcoded oligonucleotide. The preparation of barcoded next-generation sequencing libraries prepared from a single cell is facilitated by the transposon-mediated transposition and fragmentation of a target nucleic acid sequence. The methods and systems may be configured to allow the implementation of single-operation or multi-operation chemical and/or biochemical processing within the partitions.

Methods and systems for sample preparation techniques that allow amplification (e.g., whole genome amplification) and sequencing of chromatin accessible regions of single cells are provided. The methods and systems generally operate by forming or providing partitions (e.g., droplets) including a single biological particle and a single bead comprising a barcoded oligonucleotide. The preparation of barcoded next-generation sequencing libraries prepared from a single cell is facilitated by the transposon-mediated transposition and fragmentation of a target nucleic acid sequence. The methods and systems may be configured to allow the implementation of single-operation or multi-operation chemical and/or biochemical processing within the partitions.

Methods and systems for sample preparation techniques that allow amplification (e.g., whole genome amplification) and sequencing of chromatin accessible regions of single cells are provided. The methods and systems generally operate by forming or providing partitions (e.g., droplets) including a single biological particle and a single bead comprising a barcoded oligonucleotide. The preparation of barcoded next-generation sequencing libraries prepared from a single cell is facilitated by the transposon-mediated transposition and fragmentation of a target nucleic acid sequence. The methods and systems may be configured to allow the implementation of single-operation or multi-operation chemical and/or biochemical processing within the partitions.

Methods and systems for sample preparation techniques that allow amplification (e.g., whole genome amplification) and sequencing of chromatin accessible regions of single cells are provided. The methods and systems generally operate by forming or providing partitions (e.g., droplets) including a single biological particle and a single bead comprising a barcoded oligonucleotide. The preparation of barcoded next-generation sequencing libraries prepared from a single cell is facilitated by the transposon-mediated transposition and fragmentation of a target nucleic acid sequence. The methods and systems may be configured to allow the implementation of single-operation or multi-operation chemical and/or biochemical processing within the partitions.

A method for identifying molecules with desired characteristics such as high affinity for a surface or material is described. A particularly useful method covered by the present invention allows identification of molecules which bind a material with high affinity in the presence of fluid or soluble polymers, such that said molecules can be used to produce a composite in which they efficiently anchor a material in a matrix comprising solid forms of a polymer. Compositions/kits useful for identification of molecules with desired characteristics are also described.

Provided is a method for constructing a DNA library for sequencing. The method comprises A-tailing of a single 3 end to at least a portion of blunt-end DNA fragments, and a step of blunt-end ligating the obtained DNA fragments having A tailing to the single 3 end. Also provided are a DNA library for sequencing constructed with the method and a corresponding sequencing method.

Provided are methods of producing size-selected nucleic acid libraries. The methods include contacting a nucleic acid sample and a nucleic acid binding reagent including an affinity tag, under conditions in which nucleic acids of less than a desired length are substantially bound to the nucleic acid binding reagent and nucleic acids of the desired length are substantially not bound to the nucleic acid binding reagent. The conditions include the duration of the contacting, the concentration of the nucleic acid binding reagent, or both. The methods further include separating, using the affinity tag, the nucleic acids of less than the desired length bound to the nucleic acid binding reagent from the nucleic acids of the desired length not bound to the nucleic acid binding reagent, to produce a size-selected nucleic acid library. Compositions and kits that find use, e.g., in practicing the methods of the present disclosure, are also provided.

Disclosed herein are methods for the generation of nucleic acid libraries encoding for gRNA sequences. The gRNAs encoded by methods described herein may be single or double gRNA sequences. Methods described provide for the generation of gRNA libraries, as a DNA precursor or as a RNA transcription product, with improved accuracy and uniformity.