Micromechanical properties of synthetic hydrogels for bone regeneration

Abstract

Peri-implantitis is an infectious inflammatory process in soft tissues and bone around an osseointegrated implant ultimately leading to bone loss. To treat these bone defects the use of regenerative bone graft substitutes has been suggested. Synthetic hydrogels are a potential class of bone graft materials. The mechanical properties of the graft are very important for the subsequent healing process and determine what tissue will be formed. Namely the stiffness plays an important role for the cellular response throughout the regenerative process and was therefore investigated in this study on cellular scale. The mechanical properties of PEG based hydrogels can be regulated through several factors. In this study gels functionalized with either maleimide (MAL) or vinylsulfone (VS) groups were prepared at different polymer concentrations and characterized by AFM nanoindentation and swelling experiments. The results show that MAL gels are more densely cross-linked and stiffer than VS gels. Observations from structural and mechanical analysis are in good accordance. Nanoindentation results should be regarded with care as several problems were observed. Though, the study shows that gel properties can be controlled by the recipe within the required order of magnitude. To identify ideal gels, cell behaviour on the different gels has to be assessed.