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. 2018 Jan 16;115(5):E925–E933. doi: 10.1073/pnas.1718283115

Fig. 4.

Fig. 4.

Comparison of PLA methods at different probe concentrations for TNF-α. (A) c-PLA results offer a larger signal-to-background ratio than t-PLA. (B) Individual components for 100 pM signal-to-noise ratio. The greater signal-to-noise ratio for c-PLA is a consequence of higher stringency in c-PLA, which produces lower overall signals and larger differences between positive signal (100 pM) and negative background noise. (C) Dose–response curves showing that the higher signal-to-background ratios result in a more than 10-fold improvement in limit of detection (7 pM) for c-PLA when the probe concentrations are increased 10-fold compared with t-PLA (1×). Error bars denote 1 SD (n = 9), and the dashed lines denote limit of detection, defined as the mean signal of a blank sample +3 SD. Ag, antigen.