Anti-Adhesive Si-and F-Doped DLC Coatings and Micro-Nanostructured Surfaces for Medical Implants

  • Dawei Ren

    Student thesis: Doctoral ThesisDoctor of Philosophy


    The development of biomaterials mainly focuses on the improvement of their biocompatibility. The aim of this research was to develop a range of DLC coatings and micro-nanostructured surfaces with anti-bacterial properties for biomedical applications. In this study a DLC coating and Si- and F- doped DLC coatings with various Si and F contents were prepared by a radio frequency plasma-enhanced chemical vapor deposition (rf-PECVD) technology. Under water contact angle method was used to characterize the surface properties of these DLC type coatings, and bacterial adhesion assess were performed by fluorescence microscopy to evaluate their anti-bacterial ability. The results showed that the DLC coatings can effectively decrease the bacterial adhesion, which reduced the bacterial adhesion by 65%, compared with uncoated stainless steel. The extended DLVO theory was used to explain the bacterial adhesion mechanism. Quartz Crystal Microbalance technology (QCM-D), which is a simple, efficient, reliable, real time and information-rich method for measuring bacterial adhesion and related assesses, was used to measure and record the bacterial adhesion process with time. The frequency change curves and dissipation factor change curves of bacterial adhesion onto the coatings were obtained. The electrochemical corrosion tests showed that the doped DLC coatings has excellent anti-corrosion properties and can protect stainless steel from corrosion.

    In this study the effects of material topography on bacterial adhesion were investigated both theoretically and experimentally. The interaction energies between bacteria (E.coli) and micro-nanostructure were computed by extended DLVO theory. The results showed that 350nm scale surface structure has the highest interaction energy and should be able to minimize the bacterial adhesion. To verify this finding, a series of surface micro/nano-structures (350-1000nm) were produced on PDMS samples by a soft lithography method. The bacterial adhesion assays were performed with the micro/nano-structured PDMS surfaces. The bacterial adhesion results were consistent with our theoretical prediction. In addition the sterile urine encrustation experiments were also performed with the micro/nano-structured PDMS surfaces. The experimental showed that the micro-nano-structured surfaces significantly reduced or delay the urine encrustation formation on the surfaces.
    Date of Award2015
    Original languageEnglish
    SupervisorQi Zhao (Supervisor)

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