Superhydrophilic versus normal polydopamine coating: A superior and robust platform for synergistic antibacterial and antithrombotic properties

Blood-contacting devices including implantation devices, indwelling medical devices, and extracorporeal circuits have been at risk of thrombus and infections, which lead to treatment failure and serious adverse clinical events. In this study, we have reported a facile and robust mussel-inspired superhydrophilic coating for use on these blood-contacting devices to combat thrombosis and infections. The coating was fabricated mainly based on the rapid formation and accumulation of polydopamine (PDA) nanoparticles and in situ-synthesized using silver nanoparticles (Ag NPs) in the presence of sodium periodate. Therefore, the stability and long-term effects of superhydrophilicity were maintained because of the synergetic contribution of hydrophilic chemical components and surface topography of stacked nanoparticles. Different from mostly reported PDA coatings (with the water contact angle > 30°) that have good affinity to protein adsorption and cause blood coagulation, the superhydrophilic PDA coating in this work effectively reduced the nonspecific adsorption of proteins, maintained the native conformation of the adhered proteins, and further inhibited thrombus formation. Meanwhile, the superhydrophilic surface with Ag+ also demonstrated significant antibacterial properties against both Staphylococcus aureus (Gram-positive bacteria) and Pseudomonas aeruginosa (Gram-negative bacteria). Besides, the embedded Ag+ presented meaningful sustained release with less than 25% released amount even after 30 days incubation, suggesting effective and safe antibacterial ability in a low dose-dependent manner, due to the reduced protein adsorption platform supported killing and releasing of bacteria. Such a superhydrophilic surface-supported low-fouling platform will be proposed as a new strategy for combating thrombotic and infection, especially for blood-contacting devices.