The use of thermal analysis in assessing the effect of bound water content and substrate rigidity on prevention of platelet adhesion

Abstract

Implant surface-induced initiation of blood coagulation leading to thrombus formation is a major problem. It is an important challenge in biomedical research to enhance thromboresistance of polymer coatings of blood-contacting implants and devices by the reduction of platelet adhesion to their surfaces. Currently, the molecular mechanisms responsible for interfacial processes related to regulation of protein adsorption and platelet adhesion in antithrombotic coatings are not yet clearly understood. We studied the role of water binding energy in chitosan molecules using differential scanning calorimetry and thermogravimetric analysis and the role of chitosan coating rigidity using dynamic mechanical thermal analysis in the prevention of platelet adhesion. It was found that the presence of loosely bound water in chitosan coatings increases platelet adhesion. The high molecular weight (HMW) chitosan coating that contains only tightly bound water prevents platelet adhesion. The high molecular weight (HMW) chitosan coating is more rigid and has higher platelet adhesion compared with more soft LMW chitosan coatings. The degree of hydration of thromboresistant coatings is significant parameter that must be taken into account in the design of blood-contacting surfaces.