Methods, compositions, and kits for blocking a capture probe on a spatial array

Abstract

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.