Unmodified, amine-modified, and carboxylate-modified polystyrene latex nanoparticles were incubated for 2 hours and subjected to shear flow conditions of 0.85 cm/s (flow rate mimicking the median cubital vein blood flow) and 8.5 cm/s (flow rate mimicking arterial blood flow) and recirculated using a peristaltic pump mimicking physiological conditions, using a previously described method . A significant increase in mean nanoparticle diameter was observed for all particles studied following incubation within protein media under physiological shear flow conditions (median cubital vein) with a 31% increase in mean diameter observed for unmodified particles (vs 0 hr baseline), and a 24% increase for carboxylate-modified nanoparticles. The most significant increase in mean diameter was observed for amine-modified particles with a 118 % increase. A further increase in mean particle diameter (49%) was observed for unmodified particles when incubated under higher shear flow conditions (8.5 cm/s) (Figure , Table ).