Methods and compositions for enhancing immunoassays
Embodiments of the methods, compositions, and systems provided herein relate to enzymatic enhancement of immunoassays using photonic sensor arrays.
1. A method of detecting interleukin-2 (IL-2) comprising:
(a) obtaining a fluidic cell comprising an optical ring resonator having a first anti-cytokine antibody attached thereto, wherein the first anti-cytokine antibody is anti-IL-2 from clone 555051 antibody;
(b) contacting the first anti-cytokine antibody with a sample comprising IL-2 that selectively binds to the anti-cytokine antibody;
(c) contacting the bound IL-2 with a second anti-cytokine antibody that selectively binds to the IL-2, wherein the second anti-cytokine antibody is a biotinylated anti-IL-2 from clone 555040 antibody;
(d) contacting the biotinylated second anti-cytokine antibody with a streptavidin-horseradish peroxidase conjugate;
(e) contacting the horseradish peroxidase with a substantially continuous flow of a solution comprising 4-chloro-1-naphthol and hydrogen peroxide, under conditions that oxidize 4-chloro-1-naphthol to 4-chloro-1-naphthon, whereby the 4-chloro-1-naphthon precipitates on the surface of the optical ring resonator during the substantially continuous flow of the solution; and
(f) measuring a change in resonance wavelengths of the optical ring resonator, thereby indicating the presence of the IL-2.
2. The method of claim 1 , wherein the concentration of hydrogen peroxide is less than about 0.003%.
3. The method of claim 1 , wherein a concentration of the cytokine less than about 100 pg/ml is detected.
4. The method of claim 1 , wherein a continuous flow of reagents contacting the optical ring resonator having a first anti-cytokine antibody attached thereto is maintained for step (b).
5. The method of claim 1 , wherein a substantially continuous flow of reagents contacting the optical ring resonator having a first anti-cytokine antibody attached thereto is maintained for each of steps (b), (c), (d), and (e).
6. The method of claim 1 , wherein a continuous flow of reagents contacting the optical ring resonator having a first anti-cytokine antibody attached thereto is maintained for each of steps (b), (c), (d), and (e).
7. The method of claim 1 , wherein steps (b)-(e) comprise maintaining a flow of reagents contacting the optical ring resonator having a first anti-cytokine antibody attached thereto.
8. The method of claim 7 , wherein the flow rate of the reagents is about 30 μL/min.
9. The method of claim 1 , wherein a continuous flow of the solution is maintained for step (e).
10. The method of claim 9 , wherein the continuous flow of the solution is maintained for steps (e) and (f).