Effect of swelling of poly(vinyl alcohol) layers on complement activation

Polymers carrying hydroxyl groups have the potential ability to activate the complement system when in contact with blood. However, the effects of their surface structure on complement activation are still not fully understood. In this study, we examined complement activation by poly(vinyl alcohol) (PVA) layers formed on a gold surface modified with aldehyde groups. The complement system was strongly activated by a PVA surface with a dry thickness of 2.9 nm, while it was poorly activated by a PVA surface with a dry thickness of 7.4 nm. Annealing of the latter for 2 h at 150 °C converted the surface into a complement activating surface. The difference in complement activation between PVA layers was associated with the water content of PVA layers. These results suggest that complement activation by hydrated polymers highly depends on the water content of the polymer layers.