The development of state-of-the-art blood-contacting medical devices can be advanced by integrating hemocompatibility, durability, and anticoagulant functionalities within  nano-scale surface coatings. To enable all-aqueous assembly of nanocoatings combining omniphobic features with potent anticoagulant activity of hydrophilic heparin, two novel fluoropolymers containing cationic functionalities were synthesized - poly[(trifluoroethoxy)(dimethylaminopropyloxy)phosphazene], PFAP-O and poly[(trifluoroethoxy)(dimethylaminopropylamino)phosphazene], PFAP-A. Despite a relatively high content of fluorinated pendant groups - approximately 50% (mol.), both polymers displayed solubility in aqueous solutions and were able to spontaneously form stable supramolecular complexes with heparin, as determined by dynamic light scattering (DLS) and asymmetric flow field flow fractionation (AF4) methods. Heparin-containing coatings were then assembled by layer-by-layer deposition in aqueous solutions. Nano-assembled surfaces were evaluated for potential thrombogenicity in three important categories of in vitro tests - coagulation by thrombin generation, platelet retention, and hemolysis. In all assays, heparin-containing fluoro-coatings consistently displayed superior performance compared to untreated titanium surfaces or fluoro-coatings assembled using poly(acrylic acid) in the absence of heparin. Short-term stability studies reveal non-eluting nature of these non-covalently assembled coatings.

Cationic fluoropolyphosphazenes: Synthesis and assembly with heparin within hemocompatible coatings

ACS Spring 2022

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