Self-assembly Monolayers Modification As A Possible Approach To Modulate Endothelial Selectivity

The long-term clinic application of small diameter artificial blood vessels (＜6mm) has been proved to be unsuccessful due to the smooth muscle cells(SMCs) proliferation and subsequent thrombosis.In situ endothelialization of implants surfaces by immobilizing bioactive molecules could effectively improve the hemocompatibility of the implants.In this thesis,a model surface enlightened by the glycocalyx structure of cell membrane for studying the behavior of human umbilical vein endothelial cells(HUVECs) and human aortic smooth muscle cells(HASMCs) was constructed by self-assembling thiol-terminated biofunctional molecules onto gold surface.To make practical use of the surface design,an endothelial cells preferential polytetrafluoroethylene(PTFE) surface was developed via polydopamine-assisted self-assembly monolayers(SAMs).SAMs provides us with ideal model surfaces to study the behaviors of HUVECs and HASMCs through combination of nonspecific resistant property of polyethylene glycol(PEG) and specific recognization between bioactive peptide REDV and vascular endothelial cells.XPS,ellipsometer,contact angle and QCM-D were applied to monitor the self-assembling process of biofunctional thiol-terminated PEG2000, EG6 and CGREDVDY onto the gold surface.Cell experiments showed that both PEG2000 and EG6 modified surfaces could resist both kinds of cells,while CGREDVDY surface was preferential for HUVECs.Competition between different components during mixed SAMs formation would finally affect the biochemical property of the surfaces,in which molecules with relatively shorter length was superior.Moderately increasing the percentage of the component with nonspecific resistant property would considerably increase the selectivity.The polydopamine-assisted thiol-terminated biofunctional molecules self-assembly monolayers modification of PTFE was explored to develop an endothelial cells preferential surface.XPS,ellipsometer,contact angle and QCM-D results verified the successive self-polymerization of dopamine and the subsequent self-assembling process.After DOPA treatment,PTFE surface became favorable for both HUVECs and HASMCs without noticeable selectivity.However,for those surfaces further modified with bioactive peptide CGREDVDY,both significantly increased adhesion and specific preference for HUVECs were observed.More interestingly,surfaces with relatively lower density of CGREDVDY (PEG/CGREDVDY,1/1) exhibited similar extent of selectivity towards HUVECs as pure CGREDVDY surface.