4.4.1. Ultracentrifugation
After thawing the sequentially centrifuged plasma (FPS), it was filtered through 0.2 μm surfactant-free cellulose acetate filters (16534, Sartorius, Goettingen, GER). In order to test different starting amounts, samples of 0.25, 0.5 and 1 mL of plasma with phosphate-buffered saline without calcium/magnesium (PBS–/–), to add up to 10 mL, were centrifuged at 120,000× 