Fig 2: Representative TDP-43 standard curves generated on five consecutive days. The MSD signal is shown in the Y-axis and the TDP-43 concentration in the X-axis. Error bars representing standard deviation (SDs) are included for each standard curve from replicate samples at each protein concentration.

Fig 3: Dilution linearity of the plasma and serum samples using the TDP-43 assay. Panel (A) and (B) illustrate the dilution linearity assessment in plasma and serum, respectively. A linear relationship between dilution factors and TDP-43 concentration was observed both in plasma and serum, with the assay maintaining a stable measurement of TDP-43 even at dilutions up to 64-fold. Error bars (+/− SD) are shown for each sample.

Fig 4: Assessment of precision and sensitivity of the TDP-43 assay. (A) Intra-assay TDP-43 concentration values for 10 replicates of 3 separate plasma (left) and serum (right) samples. The intra-assay coefficient of variation (CV) ranged from 2.7% to 6.3% in plasma and from 4.9% to 5.0% in serum, indicating minimal variability within the same day. (B) Inter-assay variability observed in the assay across multiple replicates of the assay conducted on different days for 3 separate plasma and serum samples. Each bar represents the average of replicate wells for each sample, with error bars representing +/− SD for each sample.

Fig 5: Stability of endogenous TDP-43 in plasma and serum across freeze–thaw cycles. The bar plots represent the freeze–thaw stability of TDP43 across four freeze–thaw cycles of plasma (A) and serum (B). The results show minimal impact on assay performance and TDP-43 protein concentrations across the first two or three cycles. A modest reduction in TDP-43 concentration was noted in the fourth freeze–thaw cycle for plasma and the third or fourth freeze–thaw cycle for serum. The bars represent the average of replicate samples for each sample, with error bars representing +/− SD for each sample.