| Synthesized polymeric materials have been widely used as implantation biomedical materials, such as the variation of a man-made apparatus in cardiovascular system. But the Biomaterial Centered Infection (BCI) is a serious problem that frustrates the clinic applications biomedical polymeric materials. The BCI, which occurs with high probability and has no efficient therapy usually, lasts until the implanted material is taken off. Since the whole process of the BCI starts with the reversible stage of bacterial attachment on material surface, the focus of the research work in this field has been moved on how to establish an antibacterial surface on polymeric biomaterials by means of surface modification. The objective of this work is to immobilize chitosan molecules, which have antibacterial properties, onto the surface of artificial heart valve sewing cuffs material-Dacron (Polyethylene terephthalate, PET). A three-step treatment with various surface modification technologies was designed. The first step is to introduce the peroxide groups onto the surface of the PET. Ar plasma treatment, immersion in peroxide solution at room temperature and immersion in peroxide solution under the radiation of UV light were applied to introduce the peroxide groups. The second step is to make acrylic acid graft polymerized onto the PET surface. Water bath immersion and UV radiation were carried out to achieve this aim. In the last step, the PET films, which were already pretreated during the last two steps, were immersed into the WSC solution and the chitosan solution respectively to immobilize the chitosan molecular them. The influence factors of the hydrophilic property, such as the power of plasma discharge, the gas flow ratio, the UV irradiation time and the immersion time in peroxide solution of different PET films were investigated. The result shows that under the circumstances of Arplasma with the power of 50W and the gas flow ratio of 50ml/min, the modified PET has the best hydrophilic property and the highest density of -OOH on PET surface.Surface test approaches include attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), which reveal the component and functional groups on the PET surface. Surface energy and the free energy of adhesion (â–³F_adh) were calculated by the results of static contact angle measurement. In vitro bacterial adherence test and in vitro platelet adherence test were also carried out to evaluate the antibacterial and the anticoagulant properties of the material. The results of the X-ray photoelectron spectroscopy (XPS) show that chitosan molecules were successfully grafted onto the PET surface when PET treated by using the modification methods of "Ar plasma + AA grafting with 400W UV irradiation + chitosan immobilization with WSC" and "immersion in peroxide solution at room temperature + AA grafting with 400W UV irradiation + chitosan immobilization with WSC". And the amount of grafted chitosan of the first method is obviously is much more than that of the second method. The Attenuated Total Reflection-Fourier Transform Infrared spectroscopy (ATR-FTIR) analysis also testifies that there are -NH2 groups, which are the characteristic groups of chitosan, on the modified PET surface. Water, formamide and diiodomethane were used as test liquids of static contact angle measurement. And the surface energy and components were calculated by using the Lifithiz-van der Waals formula.The capacities of Staphylococcus Epidermidis (SE) adhering to different PET surfaces are quantitatively determined by the plate counting in vitro, by which we can draw the conclusion that the process of bacterial adherence is as a dynamic process as the bacterial propagation. The amount of bacteria adhered on material... |
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