Quantification of hydrophobicity of heparin-treated polyvinylchloride tubing

It is understood that the biocompatibility of a material depends upon the proteins that bind to its surface. It is this protein layer that interacts directly with components of the coagulation and inflammatory systems. Fibrinogen, capable of platelet binding and activation, is a particularly important protein in determining a material's biocompatibility. Hydrophobic materials tend to have a greater affinity for fibrinogen, making them less biocompatible than hydrophilic materials. We compared the hydrophobicity of three different heparin-coated polyvinylchloride (PVC) tubing preparations with uncoated PVC tubing. We also determined if there would be a difference in the applied solution; water, an ionic solution (saline), and a protein solution (fresh frozen plasma). Hydrophobicity was quantified with five separate measurements of contact angles of water, saline, and plasma, and droplet spread diameter of water and saline. We found that Duraflo II displayed hydrophobicity similar to that of uncoated PVC tubing (initial contact angles of water were 78.0 ± 1.1 and 79.6 ± 0.6 degrees, respectively). Carmeda and 3M heparin-coated tubings displayed significantly (p < .01) less hydrophobicity (initial contact angles of water were 59.8 ± 2.1 and 39.6 ± 1.9, respectively). Three minutes after initial contact, the 3M heparin coating was the only preparation that remained significantly (p < .01) less hydrophobic than the uncoated PVC. These data suggest that 3M heparin-coated PVC is the most biocompatible of the tubings we examined, followed by Carmeda, Duraflo II, and the untreated PVC tubing.