The disclosure relates to novel compositions comprising an electrochemiluminescence (ECL) co-reactant. In embodiments, the composition further comprises an ionic component, a surfactant, or combination thereof. In embodiments, the ECL co-reactant is triethanolamine (TEA), tert-butyldiethanolamine (tBDEA), methyldibutylethanolamine (MDEA), 3-[Bis-(2-hydroxy-ethyl)-amino]-propane-1-sulfonic acid (DEA-PS), or a combination thereof. Methods of using the compositions and kits comprising the compositions are also provided herein, including methods using ECL-labeled oligonucleotide probes having quenching moieties.

The disclosure relates to novel compositions comprising an electrochemiluminescence (ECL) co-reactant. In embodiments, the composition further comprises an ionic component, a surfactant, or combination thereof. In embodiments, the ECL co-reactant is triethanolamine (TEA), tert-butyldiethanolamine (tBDEA), methyldibutylethanolamine (MDEA), 3-[Bis-(2-hydroxy-ethyl)-amino]-propane-1-sulfonic acid (DEA-PS), or a combination thereof. Methods of using the compositions and kits comprising the compositions are also provided herein, including methods using ECL-labeled oligonucleotide probes having quenching moieties.

Provided are methods for determining a location of a target nucleic acid in a biological sample including: disposing the biological sample onto an array including a plurality of capture probes, where a first capture probe includes a first spatial barcode and a capture domain and a second capture probe includes a second spatial barcode and the capture domain. The second capture probe is not covered by the biological sample on the array and is contacted with a solution comprising TdT and one or more dideoxynucleotides, such that a dideoxynucleotide is incorporated into the second capture domain. Target nucleic acids are captured by the first capture probe, and the sequence of the first spatial barcode or a complement thereof and all or a portion of a sequence of the target nucleic acid, or a complement thereof, are used to determine the location of the target nucleic acid in the biological sample.

Provided are methods for determining a location of a target nucleic acid in a biological sample including: disposing the biological sample onto an array including a plurality of capture probes, where a first capture probe includes a first spatial barcode and a capture domain and a second capture probe includes a second spatial barcode and the capture domain. The second capture probe is not covered by the biological sample on the array and is contacted with a solution comprising TdT and one or more dideoxynucleotides, such that a dideoxynucleotide is incorporated into the second capture domain. Target nucleic acids are captured by the first capture probe, and the sequence of the first spatial barcode or a complement thereof and all or a portion of a sequence of the target nucleic acid, or a complement thereof, are used to determine the location of the target nucleic acid in the biological sample.

Disclosed herein are methods and compositions for corresponding positions on an array with differently labeled affinity reagents immobilized at the positions. A first and a second affinity reagents are immobilized on at least some of the first and second positions, respectively. The first affinity reagent and the second affinity reagent are associated with a first luciferase polypeptide and a second luciferase polypeptide, respectively. The first luciferase polypeptide does not cross react with the second substrate and the second luciferase polypeptide does not cross react with the first substrate. The method further comprises contacting the array with the first substrate, which reacts with the first luciferase polypeptide and detecting the first luminescent signal and detecting the second luminescent signal at positions, thereby corresponding positions on an array with the first affinity reagent or the second affinity reagent immobilized at the positions.

Disclosed herein are methods and compositions for corresponding positions on an array with differently labeled affinity reagents immobilized at the positions. A first and a second affinity reagents are immobilized on at least some of the first and second positions, respectively. The first affinity reagent and the second affinity reagent are associated with a first luciferase polypeptide and a second luciferase polypeptide, respectively. The first luciferase polypeptide does not cross react with the second substrate and the second luciferase polypeptide does not cross react with the first substrate. The method further comprises contacting the array with the first substrate, which reacts with the first luciferase polypeptide and detecting the first luminescent signal and detecting the second luminescent signal at positions, thereby corresponding positions on an array with the first affinity reagent or the second affinity reagent immobilized at the positions.

Provided herein are methods, compositions, and kits for determining a location of a target analyte in a biological sample that include the use of terminal deoxynucleotidyl transferase.

Provided herein are methods, compositions, and kits for determining a location of a target analyte in a biological sample that include the use of terminal deoxynucleotidyl transferase.

Disclosed are methods for isolating polymerase complexes from a mixture of polymerase complex components. The polymerase complexes can comprise a nanopore to provide isolated nanopore sequencing complexes. The methods relate to the positive and negative isolation of the polymerase complexes and/or nanopore sequencing complexes. Also disclosed is a nucleic acid adaptor for isolating active polymerase complexes, polymerase complexes comprising the nucleic acid adaptor, and methods for isolating active polymerase complexes using the nucleic acid adaptor.

Disclosed are methods for isolating polymerase complexes from a mixture of polymerase complex components. The polymerase complexes can comprise a nanopore to provide isolated nanopore sequencing complexes. The methods relate to the positive and negative isolation of the polymerase complexes and/or nanopore sequencing complexes. Also disclosed is a nucleic acid adaptor for isolating active polymerase complexes, polymerase complexes comprising the nucleic acid adaptor, and methods for isolating active polymerase complexes using the nucleic acid adaptor.