Provided herein are methods for de-crosslinking fixed biological samples (e.g., fixed biological samples including aminal crosslinks). The compositions and methods disclosed can de-crosslink oligonucleotides (e.g., DNA or RNA) or proteins from fixed biological samples (e.g., fixed biological samples with aminal crosslinks), wherein the de-crosslinked biological sample is compatible with and can be used in spatial gene expression analysis.

Provided herein are methods for de-crosslinking fixed biological samples (e.g., fixed biological samples including aminal crosslinks). The compositions and methods disclosed can de-crosslink oligonucleotides (e.g., DNA or RNA) or proteins from fixed biological samples (e.g., fixed biological samples with aminal crosslinks), wherein the de-crosslinked biological sample is compatible with and can be used in spatial gene expression analysis.

The present invention relates to a method for analyzing DNA including forming labeled DNA fragments by cleaving genomic DNA into DNA fragments, selectively functionalizing any non-methylated CpG sites present in the DNA with a linker including a hydrolyzable moiety, and attaching a label to the linker. The method further includes the step of separating the labeled DNA fragments from any non-labeled DNA fragments, hydrolyzing the hydrolyzable moiety of the linker of the separated labeled DNA fragments so as to release the DNA fragments from the label, and sequencing the released DNA fragments.

The present invention relates to a method for analyzing DNA including forming labeled DNA fragments by cleaving genomic DNA into DNA fragments, selectively functionalizing any non-methylated CpG sites present in the DNA with a linker including a hydrolyzable moiety, and attaching a label to the linker. The method further includes the step of separating the labeled DNA fragments from any non-labeled DNA fragments, hydrolyzing the hydrolyzable moiety of the linker of the separated labeled DNA fragments so as to release the DNA fragments from the label, and sequencing the released DNA fragments.

The invention is directed to methods for synthesizing a plurality of oligonucleotides in the same reaction vessel, and in some embodiments, using the synthesized oligonucleotides in an oligonucleotide-based assay in such reaction vessel. In some embodiments, methods of the invention are implemented by steps of (a) providing a plurality of different initiators attached to one or more supports, each different initiator having a terminal nucleotide with a different 3-O-blocking group; (b) for each different initiator, synthesizing a polynucleotide by repeated cycles of template-free enzymatic additions of 3′-O-blocked nucleoside triphosphates, wherein the blocking group of the 3-O-blocked nucleoside triphosphate is removable under deblocking conditions orthogonal to the deblocking conditions for removing blocking groups of the other initiators; and (c) releasing the oligonucleotides from the polynucleotides and the one or more solid supports.

The invention is directed to methods for synthesizing a plurality of oligonucleotides in the same reaction vessel, and in some embodiments, using the synthesized oligonucleotides in an oligonucleotide-based assay in such reaction vessel. In some embodiments, methods of the invention are implemented by steps of (a) providing a plurality of different initiators attached to one or more supports, each different initiator having a terminal nucleotide with a different 3-O-blocking group; (b) for each different initiator, synthesizing a polynucleotide by repeated cycles of template-free enzymatic additions of 3′-O-blocked nucleoside triphosphates, wherein the blocking group of the 3-O-blocked nucleoside triphosphate is removable under deblocking conditions orthogonal to the deblocking conditions for removing blocking groups of the other initiators; and (c) releasing the oligonucleotides from the polynucleotides and the one or more solid supports.

The invention is directed to a method for detecting RNA, DNA or protein target sequences by a) Hybridizing a library of probes having the general formula (I)

P—(CL-D).sub.x  (I)  With P: probes having at least 10 nucleotides or amino acids CL: cleavable linker D: fluorescent dye X: integer between 1 and 5  to RNA, DNA or protein target sequences wherein the library comprises probes P having different sequences of nucleotides or amino acids and cleavable linkers CL of different groups which are cleavable with different means b) Removing unhybridized probes and detecting the hybridized probes via the fluorophores D by a first image c) Cleaving sequentially by different means each group of chemical linkers CL from the hybridized probes; removing the thus cleaved fluorophores D and detecting the remaining hybridized probes via their fluorophores D by a second image d) Detecting the removed fluorophores D by comparing the first and second image. e) Obtaining a part of the sequence information of the target sequences via the sequence information of the probes P associated with the removed fluorophores D f) Repeating step c) until all groups of chemical linkers CL are cleaved.

The invention is directed to a method for detecting RNA, DNA or protein target sequences by a) Hybridizing a library of probes having the general formula (I)

P—(CL-D).sub.x  (I)  With P: probes having at least 10 nucleotides or amino acids CL: cleavable linker D: fluorescent dye X: integer between 1 and 5  to RNA, DNA or protein target sequences wherein the library comprises probes P having different sequences of nucleotides or amino acids and cleavable linkers CL of different groups which are cleavable with different means b) Removing unhybridized probes and detecting the hybridized probes via the fluorophores D by a first image c) Cleaving sequentially by different means each group of chemical linkers CL from the hybridized probes; removing the thus cleaved fluorophores D and detecting the remaining hybridized probes via their fluorophores D by a second image d) Detecting the removed fluorophores D by comparing the first and second image. e) Obtaining a part of the sequence information of the target sequences via the sequence information of the probes P associated with the removed fluorophores D f) Repeating step c) until all groups of chemical linkers CL are cleaved.

The present disclosure relates to determining the location of analytes in fixed biological samples.

The present disclosure relates to determining the location of analytes in fixed biological samples.