Apparatus and method for multiple reactions in small volumes

1. An apparatus for improving retention of non-adherent cells on a plate, the apparatus comprising:

a plate comprising a number of elements having a first surface energy arranged in an array with an overlay, on the plate, having a second surface energy, the first surface energy resulting in a hydrophilic surface and the second surface energy resulting in a hydrophobic surface, wherein:

a diameter of the elements is at least 1 mm; and

a height of the overlay having the second surface energy, which results in a hydrophobic surface, is between 5% and 100% of the diameter of the elements; and

a wall circumferential to the plate.

2. The apparatus of claim 1 , wherein the height of the overlay over the elements is between 10% and 80% of the diameter of the elements.

3. The apparatus of claim 1 , wherein the height of the overlay over the elements is between 20% and 50% of the diameter of the elements.

4. The apparatus of claim 1 , wherein the wall circumferential to the plate defines a reservoir and the apparatus includes an oil within the reservoir.

5. The apparatus of claim 1 , wherein the diameter of the elements is at least 2 mm.

6. The apparatus of claim 1 , wherein the overlay is made of polytetrafluoroethylene.

7. A method for performing multiple reactions, comprising:

(a) providing (i) an apparatus for improving retention of non-adherent cells on a plate, the apparatus comprising the plate comprising a number of elements having a first surface energy arranged in an array with an overlay, on the plate, having a second surface energy, the first surface energy resulting in a hydrophilic surface and the second surface energy resulting in a hydrophobic surface, wherein a diameter of the elements is at least 1 mm and a height of the overlay having the second surface energy, which results in a hydrophobic surface, is between 5% and 100% of the diameter of the elements; and (ii) a wall circumferential to the plate;

(b) adding a first reagent-containing liquid under conditions where the first reagent in the liquid adheres to the elements on the plate;

(c) adding rinsing oil to said plate in an amount necessary to cover said plate;

(d) draining excess rinsing oil from the plate resulting from step (c);

(e) adding a liquid, said liquid containing a second reagent suspected of reacting with the first reagent;

(f) washing the apparatus; and

(g) detecting reaction of the second reagent with the first reagent.

8. The method of claim 7 , wherein the first reagent is a cell.

9. The method of claim 8 , wherein the cell is selected from the group consisting of an adherent cell, a non-adherent cell, and a permeabilized cell.

10. The method of claim 8 , wherein the second reagent is selected from the group consisting of an agonist or an antagonist.

11. The method of claim 7 , wherein the first reagent is a binding agent.

12. The method of claim 11 , wherein the binding agent is selected from the group consisting of a single-stranded nucleic acid molecule, an antibody, and a ligand.

13. The method of claim 7 , wherein step (g) is performed using a third reagent.

14. The method of claim 13 , wherein the third reagent is detectably labeled.

15. The method of claim 7 , wherein the height of the overlay over the elements is between 10% and 80% of the diameter of the elements.

16. The method of claim 7 , wherein the height of the overlay over the elements is between 20% and 50% of the diameter of the elements.

17. The method of claim 7 , wherein the wall circumferential to the plate defines a reservoir and the apparatus includes an oil within the reservoir.

18. The method of claim 7 , wherein the diameter of the elements is at least 2 mm.

19. The method of claim 7 , wherein the overlay is made of polytetrafluoroethylene.