Preparation And Cytocompatibility Investigation Of A Fluorine-contained Polymer Thin Film On Ti6Al4V

At present, titanium and titanium alloys, mainly Ti6A14V alloys, are still most commonly used as implant materials and surgical instruments in medical application. However, several studies found that when Ti6A14V alloy was placed in the complicated and invasive environment filled with physiological fluids for long term, the thin TiO2 film of titanium alloy surface was unstable, non-resistant and likely to be stripped, which would probably result in the release of toxic metal ions and the implant failure. Therefore, it is vitally significant to provide protection for substrates and to improve biocompatibility of Ti6A14V alloys as biomaterials by means of the surface modification.In this thesis, a stable and durable fluorine-contained polymer thin film denominated as P(PFSt-r-4-VBCB) has been prepared on Ti6A14V alloy surface via spin-coating followed by thermal cross-linking to afford long-term protection and improve the biocompatibility for the substrates when soaked in body liquid environment as implant materials. And then, the chemical compositions, the wettability and the surface morphologies of Ti6A14V alloy modified or not with the fluorine-contained polymer thin film were characterized, respectively. Moreover, the surface roughnesses (Ra) were quantified. The stability and electrochemical corrosion behaviors of bare Ti6A14V and modified Ti6A14V were compared with by soaking in SBF for a long time, respectively. The cytocompatibility of Ti6A14V alloy with and without modification of the fluorine-contained polymer thin film were investigated by direct contact in vitro cytotoxicity test and MTT colorimetric assay with MC3T3-E1 osteoblasts after immersion test. Meanwhile, the osteoblast adhesion and morphologies on the surfaces of bare Ti6AI4V and modified Ti6A14V were observed by fluorescence microscope and field emission scanning electron microscope (FE-SEM). respectively. The results showed that the surface modification of Ti6A14V alloy could simultaneously transform the surface chemical constitution and reduce the surface energy evidently. However, the surface morphology and roughness of the Ti6A14 V substrate were hardly changed after the modification. After being soaked with SBF for 32 days, the fluorine-contained polymer thin films seemed neither to be changed nor destroyed.And then by the electrochemical corrosion tests in SBF, the corrosion current density of this film was obvious lower than that of Ti6A14V alloy indicating that the corrosion of titanium alloy in SBF was more serious than that of the film.Meanwhile, after immersion, in vitro cytotoxicity assessment and MTT results demonstrated that the fluorine-contained polymer thin films promoted the proliferation of osteoblasts after 2 and 4 days of cell seeding, and that the cytocompatibility of the films could meet the requirements of the cell security. The observation from SEM images confirmed that the osteoblastic cells had normal morphology on the fluorine-contained polymer thin film.Therefore, the fluorine-contained polymer thin films possessed super stability and excellent corrosion resistance implying the films could achieve impregnable surface modification of Ti6A14V alloys and provide durable protection for substrates. And owing to the admirable cytocompatibility of the fluorine-contained polymer thin films, the biocompatibility of the modified Ti6A14V alloys were apparently enhanced. In addition, the fluorine-contained polymer thin film could be easily fabricated on Ti6A14V substrates surfaces, and the robust film has potentially extensive applications in the biomedical field.