Philipp Schräder (Aachen, DE), Alejandro Gomez Montoya (Aachen, DE), Norina Labude-Weber (Aachen, DE), Dr. Jörg Eschweiler (Aachen, DE), Prof. Dr. Sabine Neuß-Stein (Aachen, DE), Prof. Dr. Horst Fischer (Aachen, DE)
Abstract text (incl. figure legends and references)
Introduction: Although high-performance ceramics (HPC) like alumina and zirconia exhibit excellent wear resistance, they provide poor osseointegration capacity. To improve this issue, new techniques have been successfully developed for HPC surfaces and stable cell adhesion can be achieved by covalently bound peptides.
Objectives: We show that biofunctionalized surfaces can be sterilized without loss of functionality.
Materials and Methods: For modification of alumina‑toughened zirconia, a 3-aminopropyldiisopropylethoxysilane monolayer was applied and coupled with cyclo-RGD (cRGD) peptides by using the crosslinker BS³. Samples were sterilized using 25 kGy gamma sterilization (GS) after each step of the biofunctionalization. Stability was investigated initially by contact angle measurement. To test functionality after sterilization, all missing functionalization steps were completed. Functionality was then demonstrated using human mesenchymal stem cells (MSC) in proliferation tests and cytotoxicity assays. Immunofluorescence staining (pFAK, Actin) was conducted to evaluate the adhesion of MSC on the surfaces.
Results: It was shown that there is no significant difference between samples functionalized with cRGD before and after GS regarding contact angle, cytotoxicity, and pFAK activity. Sterilized samples showed significantly higher proliferation rates compared to non-sterilized controls. Samples sterilized after silanization or crosslinking showed no significant differences regarding their cytotoxicity and contact angle before or after GS. However, a significant decrease after GS was shown regarding cell proliferation and pFAK activity.
Conclusion: The investigated functionalization enables improved adhesion, and proliferation of MSC. It was shown that fully sterilized samples are stable against GS. This is of importance since having a sterile product is a prerequisite to start translation steps towards preclinical and subsequently first-in-man applications.