Platelet interactions with polyurethane nanocomposites: effect of organic modifier terminal functionality

Surface modification is a flexible approach for manipulating blood–material interactions with the advantage that many different forms of devices can be modified without changing the bulk material properties. This study hypothesises that organic modifiers (OMs) used to prepare silicates for incorporation into polyurethane (PU) nanocomposites can migrate and be expressed on the PU surface and directly affect biological interactions. Two OMs of equivalent chain length with COOH or CH3 end groups were used, and their surface expression was measured. Results suggested that surface expression occurred only in nanocomposites with methyl modified silicates. Platelet adhesion to the CH3 and COOH modified nanocomposites showed significantly lower adhesion on the CH3 nanocomposites. Similarly, platelet activation was lower on CH3 nanocomposites as indicated by morphological differences in degree of spreading. Finally, surface roughness showed little correlation between material type and platelet adhesion, indicating that roughness was not a significant factor influencing platelet interactions. This study proposes that a nanocomposite approach with migrating OMs can provide an elegant platform for surface modification of polymers for biomedical applications.