Preparation Of Brush - Like Carbon Oxide / Polyurethane Nanocomposites And Its Biological Properties

The research and development of new biomaterials has become an important means to promote the progress of modern medicine and improve the level of clinical medicine. However, when a biomedical material is in touch with a living tissue, directly contacting the blood, a cascade of the host reactions occur at the interface between the blood and the material, including those with the material surface with water, protein, and blood cells from the body fluids, most probably, coagulation occurs and leads to the formation of the thrombus, which in the arterial or the venous circulation is the proximal cause of most cases of myocardial infarction, strokes, and cardiovascular-associated death. Thus, the biocompatibility is a critical issue of interventional biomedical devices, especially when it comes to the body fluid contact aspect. Even though, a great deal of effort has been made to develop the experimental or clinical applications of biomaterials.In this work, a range of functional graphene oxide based on the biomimetic monomer MPC (GO-g-pMPC) were synthesized by RATRP in alcoholic media using peroxide groups as initiator. These functional graphene oxide were combined with Hep with further reaction using the active grafted polymer chains to adjust the anticoagulant activity of Hep, then a range of brush-functional graphene oxide (GO-g-pMPC-Hep) were obtained. Surface structure, thermodynamic property, wettability were characterized by Fouriter transform infrared spectra (FTIR), Raman, X-ray diffraction (XRD), TGA, X-ray photoelectron spectroscopy measurement (XPS), water contact angle measurement, respectively. Antibacterial performance analysis showed that the modified oxidized graphene (GO-g-pMPC-Hep) has a certain inhibitory effect on E. coli and S. aureus. Hemolysis rate of the material was less than 5%, and the recalcification time was greatly prolonged than the pure plasma, which indicated that the material had good blood compatibility. Vitro cytotoxicity showed that the relative growth rate (RGR) of all GeneO-g-pMPC-Hep nanocomposites were outnumbered 90% compared with negative control, which illustrated that all the modified functional GeneO nanocomposites were no cytotoxic according to the grading standards of cytoxicity.Then well defined zwitterionic-Heparin polymer brushes with good blood compatibility were studied. The polyurethane (PU)/brush-functional graphene oxide nanocomposite films (PU/GO-g-pMPC-Hep) were prepared by filling PU into the GO-g-pMPC-Hep through solution intercalation method. The ATR-FTIR, XRD, SEM, SCA and TEM indicated that the GO-g-pMPC-Hep powders were dispersed in the polymer matrix in the nanoscale. What is more, mechanical properties of nanocomposite films (PU/GO-g-pMPC-Hep) had been combined with dielectric spectroscopy to investigate the reasons for the changes of mechanical, hydrophilic and biocompatible properties from the microscopic strycture in details. The mechanical properties of PU were greatly enhanced with the increase of GO-g-pMPC-Hep content. The dielectric spectroscopy was recorded with both solid films and films in water, which indicated that the length of the "brush" chains and the density of the polar group determined the relaxation time of PU/GO-g-pMPC-Hep.Biomaterials have good anticoagulation properties as well as proterties will doubtless be a better choice. In the last work, the biocompatibility properties, antibacterial properties and tissue compatibility were studied in details. The blood compatibility of the PU substrates was evaluated by protein adsorption tests, plasma recalcification profiles test and platelet adhesion tests in vitro. It was found that all PU functionalized with GO-g-pMPC-Hep showed improved resistance to nonspecific protein adsorption and platelet adhesion and had good blood compatibility. Bacteriostasis experiments showed that the obtained materials have varying bacteriostasis effect for E. coli. Vitro cytotoxicity showed that all the modified functional GeneO nanocomposites were no cytotoxic according to the grading standards of cytoxicity.Functionalized graphene oxide was synthesized under the intercalation with polyurethane complexes through the Reverse Atom Transfer Radical Polymerization, which could avoid the losses of the polymer chain from the surface due to several reasons such as the decline of the mechanical properties, the flush of the blood, body fluids, etc. All in all, the novel biomedical polymer materials can be prepared by synergies of the zwitterionic monomer and heparin along with the special biological effects of graphene oxide.