Multiplexing applications of high-Q sensors. (A) DNA-encoded antibody libraries allow for rapid, parallel capture agent affinity profiling on a microring resonator array platform. In this case, 6 anti-prostate specific antigen (PSA) antibodies are screened in parallel with a kinetic titration (PSA concentrations, in ng/mL, noted above arrows) to allow rational selection of the best antibodies from multiple vendors. Real-time analysis allows for the calculation of association and dissociation rates. Adapted from ref . © 2011 American Chemical Society. (B) Microring resonator sensor arrays also allow for multiplexed cytokine profiling for T cell differentiation analysis. Normalized cytokine secretion levels for three differentiated primary T cell subsets (Th0, Th1, and Th2) were determined by one-step sandwich immunoassays. Control cultures on the left are compared to PMA/ionomycin-stimulated (Stim) cultures on the right, with a comparison of secretion levels by a paired difference t-test (*/** indicate significance at 95%/99%). Adapted from ref . © 2011 American Chemical Society. (C) These 96-, 384-, and 1536-well photonic crystal microplates permit high-throughput screening assays. Reproduced by permission from ref . © 2011 The Royal Society of Chemistry. (D) As an example of multiplexing applications of photonic crystal microplates, a 384-well high-throughput screen of protein-protein modulators correctly reveals rapamycin as necessary for FRB binding to immobilized FKBP12. Among the 320 compounds screened, a large peak wavelength value (PWV) only occurs in the presence of rapamycin. Reproduced by permission from ref . © 2009 American Chemical Society.