Fluorocarbon Architecture Tuning Enables Superior Platelet Adhesion Resistance in Medical Polyurethane with Limited Change in Apparent Surface Hydrophobicity

Abstract

The improved platelet adhesion resistance of fluorinated polyurethane (PU) is often attributed to the fluorination-induced surface hydrophobicity. Here, we show that superior platelet adhesion resistance can be achieved with limited changes in the apparent surface hydrophobicity as well. Dual-anchored fluorinated polyurethane prepolymers (FPUPs) with different nominal fluorocarbon-site densities were synthesized and blended with a biomedical PU matrix. X-ray photoelectron spectroscopy (XPS) showed that the surface fluorine content varied from 8.7 to 37.3% across the formulations, whereas most films exhibited static water contact angles comparable to the value for the PU matrix. Thus, variations in the FPUP architecture were associated with substantial differences in surface composition without proportional changes in the static water contact angle. Among the tested formulations, FPUP35 exhibited the most favorable overall biointerfacial performance: FPUP35–5.0 reduced long-term fibrinogen (Fib) adsorption by 44.4%; FPUP35–2.5 reduced platelet adhesion density by 69%, and platelet morphologies on the fluorinated surfaces were qualitatively consistent with reduced activation-associated spreading; FPUP35–7.5 also exhibited an HUVEC/L929 adhesion ratio of 1.85 after 24 h in separate monocultures. These results indicate that biointerfacial performance does not simply correlate with surface fluorine content but is associated with overall FPUP architecture, including nominal fluorocarbon-site density and covarying molecular weight and segment composition. Nominal fluorocarbon-site density is therefore a potentially useful component of the molecular design space for platelet-adhesion-resistant PU surfaces.