Selective delivery molecules and methods of use

1. A selective delivery molecule of Formula I, having the structure:

[D A - c A ]-A-[ c M -M]-X-B-[ c B -D B ]  Formula I

wherein,

X is a peptide linker cleavable by a protease;

A is a peptide with a sequence comprising a series of 5 glutamates (SEQ ID NO:5);

B is a peptide with a sequence comprising a series of 8 arginines (SEQ ID NO:6);

c A , c B , and c M are each independently 0-1 naturally-occurring amino acid or non-naturally-occurring amino acid;

M is a polyethylene glycol (PEG) polymer having an average molecular weight of 500 Da to 10 kDa; and

D A and D B are a pair of acceptor and donor fluorescent moieties that are capable of undergoing Försters/fluorescence resonance energy transfer with the other; and

wherein [c M -M] is bound to at any position on X, [D A -c A ] is bound to any amino acid on A, and [c B -D B ] is bound to any amino acid on B.

2. The molecule of claim 1 , wherein c A , c B , and c M are each independently selected from cysteine, glutamate, lysine, and para-4-acetyl L-phenylalanine.

3. The molecule of claim 2 , wherein c B is cysteine.

4. The molecule of claim 2 , wherein c A is glutamate or lysine.

5. The molecule of claim 2 , wherein c M is para-4-acetyl L-phenylalanine.

6. The molecule of claim 1 , wherein X is cleavable by a matrix metalloproteinase.

7. The molecule of claim 6 , wherein X comprises an amino acid sequence that is cleavable by MMP2, MMP7, MMP9, or MMP14.

8. The molecule of claim 1 , wherein X comprises an amino acid sequence selected from: PLGLAG (SEQ ID NO:2), PLG-C(me)-AG (SEQ ID NO:1), RPLALWRS (SEQ ID NO:7), ESPAYYTA (SEQ ID NO:8), DPRSFL (SEQ ID NO:9), PPRSFL (SEQ ID NO:10), RLQLKL (SEQ ID NO:11), and RLQLK(Ac) (SEQ ID NO:12).

9. The molecule of claim 1 , wherein D A and D B are selected from: Cy5 and Cy7, Cy5 and IRDye750, Cy5 and IRDye800, and Cy5 and ICG.

10. The molecule of claim 1 , wherein at least one of c A , c B , and c M is independently an amino acid or at least two of c A , c B , and c M are each independently an amino acid.

11. The molecule of claim 1 , wherein the molecule of Formula I is: SDM-23, SDM-24, SDM-25, SDM-26, SDM-27, or SDM-32.

12. The molecule of claim 1 , wherein M is a PEG polymer having an average molecular weight of 500 Da, 2 kDa, 5 kDa, or 10 kDa.

13. A method of visualizing a tissue of interest in an individual in need thereof, comprising:

i) administering to the individual a selective delivery molecule of claim 1 ; and

ii) visualizing at least one of D A or D B .

14. The method of claim 13 , wherein the tissue of interest is cancerous tissue.

15. The method of claim 13 , wherein the tissue of interest is: breast cancer tissue, colorectal cancer tissue, squamous cell carcinoma tissue, skin cancer tissue, prostate cancer tissue, melanoma tissue, thyroid cancer tissue, ovarian cancer tissue, cancerous lymph node tissue, cervical cancer tissue, lung cancer tissue, pancreatic cancer tissue, head and neck cancer tissue, esophageal cancer tissue, or sarcoma.

16. The method of claim 13 , further comprising surgically removing the tissue of interest from the individual.

17. The method of claim 13 , wherein the surgical margin surrounding the tissue of interest is decreased.

18. The method of claim 13 , wherein the visualizing is used to guide surgery, to stage cancer tissue, to stage lymph nodes, or allows a surgeon to minimize the removal of healthy tissue.

19. A method of delivering a pair of acceptor and donor fluorescent moieties to a tissue of interest, comprising contacting the tissue of interest with a selective delivery molecule of claim 1 .

20. An excised tissue sample comprising (a) an isolated tissue removed from a human body, and (b) a selective delivery molecule of claim 1 .