Enhancing Polyurethane: Innovative Surface Modifications for Better Blood Compatibility

Polyurethanes (PUs) have gained attention in biomedical applications, particularly due to their potential for improved blood compatibility. Recent advances in surface modifications have focused on enhancing the antithrombotic properties of PUs, acknowledging that the surface chemistry of materials plays a vital role in determining their interaction with blood. Various techniques have emerged to modify PU surfaces, including grafting, coating, and chemical reactions.

Grafting techniques, such as the work of McCoy et al., have explored the effects of sulphonated and alkyl grafted derivatives on platelet deposition. Their research revealed that while alkyl grafted C18 polyurethane was found to be the most thrombogenic, sulfonated PUs consistently exhibited nonthrombogenic behavior. This highlights the importance of careful selection and evaluation of surface modifications, as conflicting results can arise from different testing methodologies.

In a notable study involving the grafting of 2-acrylamido-2-methylpropane sulphonic acid (AMPS) onto Pellethane™, researchers found that while in vitro tests indicated reduced platelet adhesion, in vivo tests showed increased thrombus formation. These findings underscore the complexity of translating laboratory results into real-world biological responses, emphasizing the need for caution in interpreting in vitro data.

Another approach involved the polymerization of acrylamide and dimethylacrylamide (DMAA) to PU surfaces via oxidation reactions. Studies demonstrated that DMAA-grafted surfaces led to less clot formation compared to non-grafted surfaces. The findings suggest that DMAA may alter the interaction dynamics between the material and blood components, enhancing biocompatibility.

Additionally, the incorporation of phosphorylcholine groups into PU surfaces through photochemical methods has shown promise in prolonging clotting times and reducing platelet adhesion. Research indicates that as the concentration of phosphorylcholine increased on the PU surface, the material's blood compatibility improved significantly.

Recent advancements also include the grafting of photo-reactive alpha-propylsulphate-poly(ethylene oxide) on PU surfaces. Studies have demonstrated improved blood compatibility through reduced platelet adhesion and anti-factor Xa activity. These innovative techniques exemplify the ongoing exploration of surface modifications to enhance the performance of polyurethanes in medical applications, paving the way for safer and more effective biomaterials.