Another PhD from the department!
Benjamin Müller has publicly defended his doctoral dissertation Bone-mimetic TiO2 scaffolds with improved corrosion resistance. Department of Biomaterials congratulates Benjamin on his great achievement!
All implants are liable to corrosion when implanted into the human body which may ultimately alter their properties: the mechanical strength of an implant may for example be reduced due to corrosion or chemical changes on the implant surface may cause unwanted inflammatory response in the surrounding tissues.
Ceramic implant materials typically have high resistance to corrosion, although only few studies have been conducted in this field with most studies focussing on dense materials. This thesis investigated the corrosion resistance of highly porous titanium dioxide (TiO2) bone scaffolds, which can be used to restore or repair lost bone tissue in the body. Such porous scaffolds function as three-dimensional support for bone cells to attach to and guide their growth into the porous scaffold. The corrosion mechanism in these porous ceramic scaffolds was analysed, and it was found that the scaffolds were particularly prone to so called grain boundary corrosion, which drastically reduced their mechanical strength.
Different preventive measures were investigated to improve the corrosion resistance of TiO2 scaffolds. Alterations in the high-temperature processing cycle of the ceramic scaffolds resulted in significant improvement in corrosion resistance, while the use of a thin protective TiO2 coatings produced by atomic layer deposition prevented from grain boundary corrosion from occurring when expose to low physiological pH.
The findings of the corrosion studies were then related to an in vivo study, where no signs of corrosion were observed, indicating that the scaffold structure retains its mechanical stability over time.
However, this in vivo study revealed another challenge regarding the highly porous structure of the TiO2 bone scaffolds: soft tissue was seen to preferentially grow into the pores of the scaffold from the adjacent tissues, hindering the formation of new bone tissue within the bone defect into which the scaffold was implanted. A pore-graded structure was therefore developed to ensure bone formation also occurs also within the outer margins of the TiO2 scaffold. The developed pore-graded scaffolds were shown to be biocompatible and to promote bone cell adhesion and growth on their surface.
- Lecturer Jonny Blaker, School of Materials, University of Manchester, UK
- Associate Professor Spyridon Diplas, Department of Chemistry, University of Oslo
- Senior Academic Librarian Jessica Lönn-Stensrud, Science Library, University of Oslo