Wound healing is a complex process initiated by the formation of fibrin fibers that are involved in clot formation and fibroblast migration. Normally this process is triggered by thrombin cleavage of the E domain on the fibrinogen molecules, which allows them to spontaneously self-assemble into the fibers. Here we demonstrate that this process can also be initiated in the absence of thrombin. We show that by simply placing the proteins in contact with hydrocarbon functionalized clay surfaces, molecular reorientation occurs which allows fibers to form from the intact fibrinogen protein. Furthermore, using monoclonal antibodies, we determined which regions on the αC domains are involved in the formation of the new fibrinogen fibers. This allowed us to extend these findings to general hydrophobic surfaces, such as those presented by most hydrocarbon polymers. On the other hand, the carboxyl terminal part of the Aα chain, can interact with amine containing polymers, and suppress formation of the fibers. These results provide a fundamental insight into the process of fibrinogen clot formation. The results can then be directly applied to understanding and possibly eliminating spontaneous thrombosis due to stents and implants.

In order to use polymer coatings for surface modification on biomedical implants, the coating layers are required to be stable on the solid surfaces. However, most of polymer thin films can easily be ruptured since the interfacial tension between the layers is unfavorable, leading to dewetting. We have investigated the effect of the multi-walled carbon nanotubes (MWNT) on the dewetting dynamics of thin polymer films. The results indicated that long nanotubes were much more effective than short nanotubes in stabilizing the films against dewetting. The diffusion of polymer chains in the filled matrices was measured using neutron reflectivity and the result indicated no significant effect on the diffusion coefficient by either short or long nanotubes. We therefore proposed a model whereby the nanotubes did not interact with the individual polymer chains. On the other hand, the long nanotubes formed an effective entangled network which prevented long-range motion of the polymer films upon dewetting. This unique method by adding nanofillers will provide important solutions to stabilize the polymer coatings on the implant materials against dewetting and delamination.