In vitro haemocompatibility evaluation of PET surfaces using the quartz crystal microbalance technique.

Owing to the complex influences of several experimental conditions on the in vitro alteration of blood, there is still a lack of viable in vitro tests and methods for blood compatibility evaluation of biomaterials. The aim of this research was to study a new approach for the haemocompatibility assessment of differently modified PET surfaces using the quartz crystal microbalance with dissipation unit (QCM-D) technique and measure the mass increase caused by clot formation under physiological conditions. For this purpose some of the most frequently applied in vitro methods for haemocompatibility determination, i.e., clotting time measurement and observation of red blood cells' mobility, were applied and their accuracy and sensitivity compared to the new QCM-D approach. Haemocompatibility was evaluated for non-modified poly(ethylene terephthalate) (PET) surfaces and PET surfaces coated with dextran sulphate and heparin. The basic anti-coagulant properties of heparin and dextran sulphate were analysed by means of their activated partial thromboplastine time (APTT). PET, as well as different polysaccharides coatings were chosen for this study due to their promising biocompatible properties and numerous possibilities for biomedical applications. The results showed that the new QCM-D technique to study clot formation in contact with PET surfaces under physiological environment was the most informative and accurate for in vitro haemocompatibility assessment. Although the results achieved with the other two methods were in good correlation, they did not provide such a high level of sensitivity.