Provided herein, among other things, is a method for synthesizing spatially addressed nucleic acid barcodes in or on a cellular sample in situ. In some embodiments, the method may comprise: obtaining a cellular sample comprising nucleic acid molecules that are protected by a reversible terminator, deprotecting the nucleic acid molecules in a set of areas of the sample by selectively applying an external stimulus to the set of areas to produce deprotected nucleic acid molecules in the areas, applying a reversible terminator nucleotide to the cellular sample, resulting in addition of a reversible terminator onto the deprotected nucleic acid molecules, optionally removing any unreacted reversible terminator nucleotide from the sample, and repeating the steps one or more times.

Methods and compositions for determining the proximity of two barcoding oligonucleotides (e.g., in a single partition or adjacent on a tissue section) using a determination of the presence of a 9 bp sequence resulting from tagmentation in different nucleic acid fragments linked to different barcoding oligonucleotides is provided.

Methods and compositions for determining the proximity of two barcoding oligonucleotides (e.g., in a single partition or adjacent on a tissue section) using a determination of the presence of a 9 bp sequence resulting from tagmentation in different nucleic acid fragments linked to different barcoding oligonucleotides is provided.

The present disclosure provides methods of processing or analyzing a sample. A method for processing a sample may comprise hybridizing a probe molecule to a target region of a nucleic acid molecule (e.g., a ribonucleic acid (RNA) molecule), barcoding the probe-nucleic acid molecule complex, and performing extension, denaturation, and amplification processes. A method for processing a sample may comprise hybridizing first and second probes to adjacent or non-adjacent target regions of a nucleic acid molecule (e.g., an RNA molecule), linking the first and second probes to provide a probe-linked nucleic acid molecule, and barcoding the probe-linked nucleic acid molecule. One or more processes of the methods described herein may be performed within a partition, such as a droplet or well. One or more processes of the methods described herein may be performed on a cell, such as a permeabilized cell.

The present disclosure provides methods of processing or analyzing a sample. A method for processing a sample may comprise hybridizing a probe molecule to a target region of a nucleic acid molecule (e.g., a ribonucleic acid (RNA) molecule), barcoding the probe-nucleic acid molecule complex, and performing extension, denaturation, and amplification processes. A method for processing a sample may comprise hybridizing first and second probes to adjacent or non-adjacent target regions of a nucleic acid molecule (e.g., an RNA molecule), linking the first and second probes to provide a probe-linked nucleic acid molecule, and barcoding the probe-linked nucleic acid molecule. One or more processes of the methods described herein may be performed within a partition, such as a droplet or well. One or more processes of the methods described herein may be performed on a cell, such as a permeabilized cell.

The invention relates to a process and a device for analysing single molecules, particularly to the parallel analysis of a plurality of single molecules. It is suitable for detecting interactions, e.g. binding between single molecules and/or reactions, e.g. elongation or degradation of single molecules. Particularly, the process of the invention relates to the sequencing of single nucleic acid molecules. The single molecule to be analysed is present in free form, i.e. dissolved or suspended in a liquid medium, within a reaction space formed around the sample spot. According to the present invention, an electrical field is applied across the reaction space, whereby a concentration of single molecules, at the sample spots is effected.

The invention relates to a process and a device for analysing single molecules, particularly to the parallel analysis of a plurality of single molecules. It is suitable for detecting interactions, e.g. binding between single molecules and/or reactions, e.g. elongation or degradation of single molecules. Particularly, the process of the invention relates to the sequencing of single nucleic acid molecules. The single molecule to be analysed is present in free form, i.e. dissolved or suspended in a liquid medium, within a reaction space formed around the sample spot. According to the present invention, an electrical field is applied across the reaction space, whereby a concentration of single molecules, at the sample spots is effected.

Disclosed are methods for determining at least one sequence of interest of a fetus of a pregnant mother. In various embodiments, the method can determine one or more sequences of interest in a test sample that comprises a mixture of fetal cellular DNA and mother-and-fetus cfDNA. In some embodiments, methods are provided for determining whether the fetus has a genetic disease. In some embodiments, methods are provided for determining whether the fetus is homozygous in a disease causing allele when the mother is heterozygous of the same allele. In some embodiments, methods are provided for determining whether the fetus has a copy number variation (CNV) or a non-CNV genetic sequence anomaly.

Disclosed are methods for determining at least one sequence of interest of a fetus of a pregnant mother. In various embodiments, the method can determine one or more sequences of interest in a test sample that comprises a mixture of fetal cellular DNA and mother-and-fetus cfDNA. In some embodiments, methods are provided for determining whether the fetus has a genetic disease. In some embodiments, methods are provided for determining whether the fetus is homozygous in a disease causing allele when the mother is heterozygous of the same allele. In some embodiments, methods are provided for determining whether the fetus has a copy number variation (CNV) or a non-CNV genetic sequence anomaly.

The invention is directed to modified oligonucleotide compositions and methods for selectively reducing unwanted nucleic acid contaminants and enriching for desired nucleic acid targets from complex genomic nucleic acid mixtures for sequencing applications. The modified oligonucleotide compositions include one or more modified groups that increase the T.sub.m of the resultant oligonucleotide composition.