Material characterization and biocompatibility of polycarbonate-based polyurethane for biomedical implant applications

Polycarbonate polyurethane (PCU) resins are widely used in biomedical applications due to their excellent mechanical properties, biocompatibility, and resistance to degradation. The performance of these materials in implantable devices depends on factors such as hardness, molecular weight, and their interactions with cells and tissues. Understanding the relationship between material properties and biological outcomes is essential for optimizing their use in medical devices. In this study, three PCU resins were selected for evaluation as potential polymer implant materials: Chronoflex (CF) 65D, and two Carbothane (CB) samples 95A with different molecular weights. Dynamic mechanical analysis (DMA) revealed that the storage modulus was primarily influenced by the hard domain content, with greater elasticity observed at higher frequencies and lower temperatures. Tensile hysteresis behavior at room temperature was strongly correlated with hardness, with lower hardness samples demonstrating improved strain recovery. Cytotoxicity testing indicated cell viability above 70% for both CF and CB films. Normal Human Lung Fibroblasts (NHLF) grown on CF films exhibited a more homogeneous distribution across the surface, adopting an elongated morphology that conformed closely to the underlying topography. In contrast, cells on CB films tend to aggregate, forming clustered structures. This study demonstrates that the mechanical and biological performance of PCU resins is closely linked to their hardness, molecular weight, and structural composition. The results highlight that a morphology with a higher proportion of hard domains produces a more uniform and favorable environment for cell adhesion and organization.