Measurements of biomarkers of platelet activation in Trillium^® Biosurface circuit. (A) Soluble P-selectin levels reduced at 30 min and 55 min, with values at each time point falling within ±2 SD of the mean. All measurements are presented as normalized values over the platelet count for each time points. (B) The normalized values for GPIIb/IIIa levels in circulated bovine blood show a significant decrease at 55 min, with all measured values falling within ±2 SD of the mean. (C) Normalized values for PF4 and (D) β-TG did not show any significant changes at 5 min, 30 min, and 55 min, but all values fell within ±2 SD of the mean, indicating minimal intra-variability across technical replicates. (Mean ± SD, P < 0.05, five technical replicates). GPIIb/IIIa: Glycoprotein IIb/IIIa; PF4: Platelet Factor 4; β-TG: β-Thromboglobulin.