In Vitro and In Vivo biocompatibility study of fluorinated polyphosphazene coatings for blood-contacting medical devices

Implant-induced thromboembolic events are the most common complication of blood contacting medical devices. Coatings are a promising approach to improve the biocompatibility of current biomaterials and devices. Poly[bis(trifluoroethoxy) phosphazene] (TFE) has been demonstrated to be biocompatible, anti-inflammatory, and antithrombogenic as a device coating over the past decades; however, its inherently poor mechanical properties make applications in medical devices challenging, especially regarding potential detachment from devices. Our previous work developed a new fluorinated polyphosphazene, poly[bis(octafluoropentoxy) phosphazene] (OFP), and incorporated allylphenoxy side groups to the P-N backbone to make the polymer crosslinkable (X-OFP). In this study, we applied this X-OFP coating on central venous catheters and investigated the surface properties and biocompatibility of the coatings. In vitro and in vivo studies demonstrated that X-OFP has a similar antithrombogenic performance as TFE, but its mechanical properties including adhesion strength of coating-to-substrate are significantly improved, thereby enhancing the stability of the coating. The success of X-OFP will provide a platform to incorporate other side groups to the polymer backbones and generate new fluorinated polyphosphazene polymers having improved biocompatibility and mechanical properties for coating applications in blood-contacting medical devices.

Statement of significance

Implant-induced thrombosis is a major complication of blood-contacting medical devices. This study demonstrated a new fluorinated polyphosphazene coating suitable for the medical device with the significant improvement of the biocompatibility of catheters. Compared to the traditional fluorinated polyphosphazene coating, poly[bis(trifluoroethoxy) phosphazene] (TFE), crosslinkable poly[bis(octafluoropentoxy) phosphazene] (X-OFP) contains a higher amount of fluorocarbon content with the octafluoropentoxy side group and is crosslinkable with the allylphenoxy side group. TFE and X-OFP were applied on central venous catheters as coatings. In vitro and in vivo studies demonstrated that X-OFP has a similar antithrombogenic performance as TFE, but its mechanical properties including adhesion strength of coating-to-substrate are significantly improved, thereby enhancing the stability of the coating.