Oligonucleotide probes and uses thereof

1. A method of enriching an oligonucleotide library comprising a plurality of oligonucleotides, the method comprising:

(a) performing at least one round of positive selection, wherein the positive selection comprises:

(i) contacting at least one sample with the plurality of oligonucleotides, wherein the at least one sample comprises tissue; and

(ii) recovering members of the plurality of oligonucleotides that associated with the at least one sample;

(b) performing at least one round of negative selection, wherein the negative selection comprises:

(i) contacting at least one additional sample with the plurality of oligonucleotides, wherein at least one additional sample comprises tissue;

(ii) recovering members of the plurality of oligonucleotides that did not associate with the at least one additional sample; and

(c) amplifying the members of the plurality of oligonucleotides recovered in at least one or step (a)(ii) and step (b)(ii),

wherein the tissue in the at least one sample in step a(i) and/or the tissue in the at least one additional sample in step b(i) is lysed, or scraped from a substrate thereby enriching the oligonucleotide library.

2. The method of claim 1 , wherein the recovered members of the plurality of oligonucleotides in step (a)(ii) are used as the input for the next iteration of step (a)(i).

3. The method of claim 1 , wherein the recovered members of the plurality of oligonucleotides in step (b)(ii) are used as the input for the next iteration of step (a)(i).

4. The method of claim 1 , wherein the unenriched oligonucleotide library comprises a plurality of oligonucleotide aptamers, wherein each aptamer sequence comprises a 5′ region (5′ CTAGCATGACTGCAGTACGT (SEQ ID NO. 4)) followed by a random naïve aptamer sequence of 35 nucleotides and a 3′ region (5′ CTGTCTCTTATACACATCTGACGCTGCCGACGA (SEQ ID NO. 5)).

5. The method of claim 1 , wherein the at least one sample and/or at least one additional sample comprise fixed tissue.

6. The method of claim 5 , wherein the fixed tissue comprises formalin fixed paraffin embedded (FFPE) tissue.

7. The method of claim 6 , wherein the FFPE tissue comprises at least one of a fixed tissue, unstained slide, bone marrow core or clot, biopsy sample, surgical sample, core needle biopsy, malignant fluid, and fine needle aspirate (FNA).

8. The method of claim 7 , wherein the FFPE tissue is fixed on a substrate.

9. The method of claim 8 , wherein the at least one sample and/or the at least one additional sample are fixed on different substrates.

10. The method of claim 8 , wherein the at least one sample and/or the at least one additional sample is fixed on a single substrate.

11. The method of claim 1 , wherein the at least one sample and the at least one additional sample differ in a phenotype of interest.

12. The method of claim 11 , wherein the at least one sample and the at least one additional sample are from different sections of a same substrate.

13. The method of claim 12 , wherein the at least one sample and the at least one additional sample are scraped from the same substrate.

14. The method of claim 11 , wherein the phenotype comprises a tissue, anatomical origin, medical condition, disease, disorder, or any combination thereof.

15. The method of claim 14 , wherein the tissue comprises muscle, epithelial, connective and nervous tissue, or any combination thereof.

16. The method of claim 11 , wherein the phenotype comprises the presence of or likelihood of developing a tumor, neoplasm, or cancer, or characterizing the tumor, neoplasm, or cancer.

17. The method of claim 1 , further comprising determining a target of the enriched members of the oligonucleotide library.

18. The method of claim 1 , further comprising one or more washing steps.

19. The method of claim 1 , further comprising epitope retrieval prior to (a).