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Session: Body - implant interfacing
Session starts: Friday 25 January, 13:00
Presentation starts: 13:00
Room: Lecture room 559

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Mahya Ganjian (TU Delft)
Khashayar Modaresifar (TU Delft)
Kees Hagen (TU Delft)
Peter-Leon Hagedoorn (TU Delft)
Linda Otten (TU Delft)
Michelle Minneboo (TU Delft)
Lidy Fratila-Apachitei (TU Delft)
Amir A Zadpoor (TU Delft)

Abstract:
Upon implants insertion in the human body, both host and bacterial cells compete for adhesion and growth on the surface of the implants. Surfaces that can stimulate new tissue formation while preventing bacterial growth are therefore desirable. Topography represents one of the surface properties of implants that can be used to influence cell behavior. In this regard, methods that enable generation of controlled topographies on appropriate biomaterials are of great interest. One such method is Inductively Coupled Plasma Reactive Ion Etching (ICP RIE) which can generate high aspect ratio nanostructures (e.g., inspired by Dragonfly wings [1]) on large areas very fast, without the need for masks and wet processes as in the case of lithography-based methods. Several studies applied this method to generate nanostructures on Si wafers, known as black Si [1]–[3]. However, Si is not the material of choice for implants. Creating these topographies on Ti is clinically relevant for bone implants. The aim of this study was twofold; firstly, the effects of the ICP RIE conditions on the morphology, wettability and mechanical properties of resultant titanium structures were investigated. Secondly, the in vitro response of preosteoblast and bacterial cells on such surfaces was assessed. Titanium foil was used as the substrate. The titanium samples were first polished and then etched using a Plasmalab System 100 (Oxford Instruments). ICP RIE conditions included Cl2/Ar flow rates, chamber pressure, temperature, and etching time. Depending on the ICP RIE conditions used, nanoporous and high aspect ratio nanopillars were obtained. These different morphologies induced changes in wettability and mechanical properties of the structures. In addition, a differential response of preosteoblasts and bacterial cells was observed indicating the potential of these topographies for achieving bone implants with dual biofunctionalities. [1] E. P. Ivanova et al., “Bactericidal activity of black silicon,” Nat. Commun., pp. 1–7, 2013. [2] S. Ghosh et al., “Analysis of killing of growing cells and dormant and germinated spores of Bacillus species by black silicon nanopillars,” no. December, pp. 1–13, 2017. [3] C. M. Bhadra et al., “Subtle Variations in Surface Properties of Black Silicon Surfaces Influence the Degree of Bactericidal Efficiency,” Nano-Micro Lett., vol. 10, no. 2, 2018.