Materials and methods for assaying living cells

1. A device for assaying living cells comprising a substrate, wherein the substrate comprises a tethering molecule, wherein the tethering molecule adheres to the substrate and is capable of directly interacting with a cell membrane of a cell, wherein the cell maintains a free-floating, non-adherent character when bound to the tethering molecule, wherein the device exhibits an optical clarity of at least about 90%, wherein the substrate is coated with one or more layers of one or more materials that substantially inhibit the cells from adhering to the substrate, wherein a surface of the substrate is capable of being fixed to the cell by a chemical fixative.

2. The device of claim 1 , wherein the substrate is coated with polyelectrolyte multilayer films (PEMs).

3. The device of claim 2 , wherein the PEMs are formed from a combination of polymethacrylic acid (PMA) and polyacrylamide (PAAm).

4. The device of claim 2 , wherein the PEMs have a thickness of from about 10 nm to about 100 nm.

5. The device of claim 2 , wherein the PEMs incorporate tethering molecules in their top surface.

6. The device of claim 2 , wherein PEMs are prepared by adsorption of alternating layers of polycationic and polyanionic aqueous solutions to the substrate that assemble through electrostatic or hydrogen bonding.

7. The device of claim 1 , wherein the device is a microfluidic device and the substrate is a microfluidic slide or microfluidic channel.

8. The device of claim 1 , wherein the tether is a charged lipid molecule.

9. The device of claim 1 , wherein the tether is selected from the group consisting of glycerophospholipid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, phosphatidylinositol, phosphatidylinositolphosphate, phosphatidic acid, 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 18:O-LysoPG and 15:O(3)-16:1-CA.

10. The device of claim 1 , wherein the tethering molecules are crosslinked to the substrate using a crosslinking agent.

11. The device of claim 1 , further comprising a cell directly bound to the tethering molecule.

12. The device of claim 11 , wherein the cell is selected from the group consisting of a blood cell, a bone marrow cell, a lymph cell, a stem cell, an oocyte, a muscle cell, an epithelial cell and a tumor cell.

13. The device of claim 12 , wherein the tumor cell is from a cancer selected from the group consisting of breast cancer, prostate cancer, lung cancer, bladder cancer, pancreatic cancer, brain cancer, liver cancer, testicular cancer, thyroid cancer, skin cancer, colon cancer, ovarian cancer, cervical cancer, and uterine cancer.

14. The device of claim 12 , wherein the tumor cell is a primary tumor cell that has been isolated from a solid tumor from a subject.

15. The device of claim 13 , wherein the tumor cell comprises one or more microtentacles.

16. The device of claim 14 , wherein the tumor cell is isolated directly from a non-removed tumor, from a tumor cell biopsy, from circulating tumor cells, or from a tumor that is surgically removed.

17. The device of claim 1 , wherein the device is a microfluidic device comprising one or more channels.

18. The device of claim 1 , wherein the device comprises tethering molecules that are organized into an array pattern on the substrate.

19. The device of claim 18 , wherein the tethering molecules are organized into an array pattern on the substrate by a process comprising photo-crosslinking of the tether to the substrate at defined sites.

20. The device of claim 1 , wherein the substrate is coated with one or more cationic and/or anionic polymers.

21. The device of claim 1 , wherein the tethering molecule holds the cell in a substantially fixed position.

22. The device of claim 1 , wherein the substrate is substantially optically clear to enable visualization of the cells using microscopy.

23. The device of claim 1 , wherein the device comprises tethering molecules that are organized into an array pattern on the substrate by a process comprising microcontact printing.

24. The device of claim 1 , wherein the tether comprises an aryl azide group that can be photo-crosslinked to the substrate.

25. The device of claim 1 , wherein the device comprises tethering molecules that are organized into an array pattern on the substrate, wherein the pattern array comprises islands of from about 4-15 μm in size with about 25-100 μm center spacing.

26. The device of claim 1 , wherein the device comprises tethering molecules that are organized into an array pattern on the substrate, wherein the pattern array comprises islands of about 7 μm in size with about 40 μm center spacing.

27. The device of claim 1 , wherein the substrate is made of plastic or glass.

28. A method for imaging microtentacles on isolated, living, primary tumor cells from a cancer subject, comprising:

i) obtaining one or more living primary tumor cells that has been isolated from a solid tumor from the subject;

ii) adding the one or more cells to the substrate of the device of claim 1 ; and

iii) imaging the one or more living primary tumor cells and detecting the microtentacles, wherein the one or more tumor cells are non-adherently tethered to the substrate during imaging of the tumor cells.

29. A method of identifying a subject with an increased likelihood of having or developing metastatic cancer comprising:

i) obtaining one or more living primary tumor cells that has been isolated from a solid tumor from the subject;

ii) adding the one or more cells to the substrate of the device of claim 1 ;

iii) imaging the one or more living primary tumor cells, wherein the one or more tumor cells are non-adherently tethered to the substrate during imaging of the tumor cells; and

iv) scoring the one or more imaged cells for microtentacles to determine whether the subject has an increased likelihood of having or developing metastatic cancer.

30. A method for determining whether a candidate drug inhibits or promotes microtentacle formation and/or stability on isolated, living, primary tumor cells from a cancer subject comprising:

i) obtaining one or more living primary tumor cells that has been isolated from a solid tumor from the subject;

ii) adding the one or more cells to the substrate of the device of claim 1 ;

iii) contacting the one or more living primary tumor cells with the candidate drug;

iv) imaging the one or more living primary tumor cells treated with the candidate drug, wherein the one or more tumor cells are non-adherently tethered to the substrate during imaging of the tumor cells; and

v) scoring the one or more imaged cells for microtentacles to determine whether a candidate drug inhibits or promotes microtentacle formation and/or stability.

31. A method for determining the stem cell potential of tumor cells from a cancer subject comprising:

i) obtaining one or more living primary tumor cells that has been isolated from a solid tumor from the subject;

ii) adding the one or more cells to the substrate of the device of claim 1 ;

iii) optionally treating the cells with a candidate drug;

iv) imaging the one or more living primary tumor cells, wherein the one or more tumor cells are non-adherently tethered to the substrate during imaging of the tumor cells; and

v) performing one or more of the following steps to determine the stem cell potential of the tumor cell:

a. scoring the tethered cells for microtentacles;

b. scoring tethered cells for their ability to form stem cell spheres; and

c. tracking the fates of individual tethered cells to determine their ability to form stem cell spheres.