Methods of labeling or barcoding molecules within one or more portions of a plurality of cells are provided. Kits and systems for labeling or barcoding molecules within one or more portions of a plurality of cells are also provided. The methods, kits, and systems may utilize photo-controlled adapter sequences, nucleic acids tags, and/or linkers.

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.

Provided in the present invention is a method for constructing single cell sequencing libraries, comprising the following steps: a) lysing a single cell to obtain a single cell lysate; b) separating the nucleus and the cytoplasm in the single cell lysate obtained in step a) to obtain a nuclear solution and a total RNA solution; and c) constructing a chromatin DNA library with the nuclear solution obtained in step b) to obtain a chromatin-accessibility sequencing library of the single cell; and constructing a transcriptome library with the total RNA solution obtained in step b) to obtain a transcriptome sequencing library of the single cell.

Provided are a CAR library used to screen scFvs that can be functional in CAR-T cells, and an scFv manufacturing method in which the CAR library is used. A chimeric antigen receptor (CAR) library of the present invention includes nucleic acids coding for first CARs. Each of the first CARs includes a first antigen-binding domain, a first transmembrane domain, and a first intracellular signaling domain. The first antigen-binding domain includes a first single-chain antibody (scFv) to be screened for the ability to bind to a target antigen. The first scFv includes a first heavy-chain variable region and a first light-chain variable region. The first heavy-chain variable region and the first light-chain variable region meet a predetermined condition.

Methods are provided that, for example, include (a) combining ssDNA containing a modified nucleotide (e.g., a ssDNA with a modified nucleotide proximate to its 5′ end) with a DNA cleavage enzyme capable of cleaving the ssDNA at the modified nucleotide (e.g., to generate a first ssDNA fragment having a 3′OH and a second ssDNA fragment having the modified nucleotide); wherein the ratio of enzyme to DNA substrate is less than 1:1 molar ratio (m/m); and (b) cleaving at least 95% of the ssDNA at the modified nucleotide. In some embodiments, a method may comprise (a) combining (i) a ssDNA comprising a modified nucleotide (e.g., proximate to its 5′ end) with (ii) a DNA cleavage enzyme capable of cleaving the ssDNA at the modified nucleotide (e.g., to generate (after cleavage) a first ssDNA fragment having a 3′OH and a second ssDNA fragment comprising the modified nucleotide) wherein the ratio of enzyme to DNA substrate is less than 1:1 molar ratio and cleaving at least 95% of the ssDNA at the modified nucleotide. In some embodiments, methods provided herein may include (a) combining (i) a ssDNA (1) immobilized on a substrate and (2) comprising a modified nucleotide with (ii) a ssDNA cleaving enzyme capable of cleaving the ssDNA at the modified nucleotide (e.g., to generate (after cleavage) a first ssDNA fragment having a 3′OH and a second ssDNA fragment comprising the modified nucleotide) ; and (b) cleaving the immobilized ssDNA to release the second single stranded DNA fragment from the substrate. At least 95% (m/m) of an ssDNA comprising a modified nucleotide may be cleaved in less than 60 minutes.

Provided in the present invention is a method for constructing a PacBio sequencing library, comprising the following steps: (1) obtaining a target double-stranded DNA; (2) adding a thermostable RNA ligase to respectively connect two ends of the double-stranded DNA to form a closed loop to obtain a dumbbell-shaped DNA library; (3) purifying the dumbbell-shaped DNA library; and (4) binding with sequencing primers and adding a DNA polymerase to obtain a PacBio sequencing library.

Provided are methods and systems useful for screening large libraries of effector molecules. Such methods and systems are particularly useful in microfluidic systems and devices. The methods and systems provided herein utilize encoded effectors to screen large libraries of effectors.

The present disclosure relates to methods of encoding pre-existing compounds with oligonucleotide tags. In particular, libraries of pre-existing compounds are tagged with oligonucleotides in order to encode identifying information, thereby improving methods of screening and identifying compounds having a desired property.

Provided are methods and systems useful for screening large libraries of effector molecules. Such methods and systems are particularly useful in microfluidic systems and devices. The methods and systems provided herein utilize encoded effectors to screen large libraries of effectors.

Provided herein is a method for making a pool of probes by primer extension. In certain embodiments, the method comprises hybridizing a first population of oligonucleotides comprising a top strand sequence having the following formula V1-B-3′ with a second population of oligonucleotides comprising a bottom strand sequence having the following formula V2′-B′-3′ to provide a population of duplexes. After hybridizing, the 3′ ends of the oligonucleotides in the duplexes are extended to produce a population of double stranded products comprising a top strand sequence having the following formula V1-B-V2, where V2 is complementary to V2′.