Liquid-Infused Surfaces for Anti–Thrombogenic Cardiovascular Medical Devices

Abstract

Tethered-Liquid Perfluorocarbon (TLP) are a class of lubricant-infused surface coatings that, once infused with perfluorinated lubricants, show promise to reduce adverse reactions in medical devices implanted into the body such as reducing blood clot formation (thrombosis). A vapour phase silanisation reaction and the self-assembling properties of a fluorinated silane are exploited to form tethered perfluorocarbon (TP) layers containing nanostructured, bumpy aggregates. The vapour phase method compares favourably to the previously established liquid phase deposition method (LPD) to reproducibly create slippery coatings, without the need to control humidity conditions that often plague LPD methods. The TP layer retains perfluorinated lubricants when exposed to flow conditions seen in some medical devices, with a higher viscosity lubricant being more resistant to shear flow-induced depletion. TLP infused with more viscous lubricant, was equally effective in reducing adhesion of fibrin from human whole blood. Further in vitro biological assays revealed the wettability dependence of the intrinsic pathway of coagulation is applicable to TLP, based on factor XIIa activity and rate of plasma coagulation. Reduced adhesion of blood and loose packing of fibrin fibers on TLP coatings is attributed to the combined effects of low contact activation and enhanced mobility at the lubricant interface. Lubricant depletion dynamics under external flow was tested with a microfluidic device, combined with a dual-wavelength reflection interference contrast microscopy technique, enabling quantitative analysis of the lubricant on the nanoscale. The microfluidic platform also revealed reduced fibrin and platelet adhesion to TLP coatings exposed to blood flow. Optimised TLP coatings and greater understandings of anti-thrombogenic mechanisms open new avenues to assess TLP under blood flow for further translational development towards the next generation of blood-contacting medical devices.