Surface characterization of heparin-complexing poly(amido amine) chains grafted on polyurethane and glass surfaces

Poly(amido-amine) chains grafted onto polyurethanes and glass form stable complexes with heparin yielding potential nonthrombogenic surfaces. The characterization of the surfaces, and the product of each chemical reaction including final heparinized surfaces, has been studied by contact angle data and scanning electron microscopy (SEM). Air in water, octane in water, and drop-on-plate contact angle data were used to estimate surface (gamma sv) and interfacial (gamma sw) free energies. Solid-water work of adhesion (Wa) and its dispersive (Wda) and polar (Ipsw) components were calculated for all studied surfaces. It has been found that the viscosity of polyurethane solution used for film casting influences wetting properties of these films. It has also been found that a direct correlation exists between the Ipsw/Wda values and the degree of coverage of the surfaces by cellular deposits after their exposure to platelet-rich plasma. Final heparinized polyurethane and glass materials are hydrophilic, their Ipsw/Wda ratio is high, and little or no cellular deposit is observed on their surfaces.