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

Abstract

Provided herein are methods for determining a location of a protein in a biological sample including: disposing the sample onto an array comprising a plurality of capture probes, where a first and second capture probe include a first and second spatial barcode, respectively, and a capture domain. The second capture probe is not covered by the sample and is contacted with a solution comprising TdT and one or more dideoxynucleotides, where a dideoxynucleotide is incorporated into the second capture domain. Analyte capture agents comprising an analyte binding moiety that binds protein and an oligonucleotide including an analyte capture sequence and an analyte binding moiety barcode are contacted with the sample. The analyte capture sequence hybridizes to the first capture domain, and the sequence of the first spatial barcode and the analyte binding moiety barcode, or complements thereof, are used to determine the location of the protein in the biological sample.