Figure 5. Theophylline and caffeine standard curves at optimal MBS and MBC concentration.

Using 10 nM MBC and 10 nM MBS, the standard curves for theophylline (circles) and caffeine (squares) show a dynamic range for theophylline of over two orders-of-magnitude, while maintaining nearly four order-of-magnitude discrimination against the structurally-similar caffeine (* denotes signal significantly higher than background, p< 0.05). For simplicity, the fractional MBS binding at each analyte concentration was calculated as counts of eluted MBSs relative to counts of total MBS input. Relative values were equivalent to those normalized to the total counts recovered from the sum of supernatant, wash and elution from beads.