Functionalization of Ti-40Nb implant material with strontium by reactive sputtering

Markus Göttlicher, Marcus Rohnke, Yannik Moryson, Jürgen Thomas, Joachim Sann, Anja Lode, Matthias Schumacher, Romy Schmidt, Stefan Pilz, Annett Gebert, Thomas Gemming, Jürgen Janek

Research output: Contribution to journalArticleAcademicpeer-review


Background: Surface functionalization of orthopedic implants with pharmaceutically active agents is a modern
approach to enhance osseointegration in systemically altered bone. A local release of strontium, a verified bone
building therapeutic agent, at the fracture site would diminish side effects, which could occur otherwise by oral
administration. Strontium surface functionalization of specially designed titanium-niobium (Ti-40Nb) implant alloy
would provide an advanced implant system that is mechanically adapted to altered bone with the ability to
stimulate bone formation.
Methods: Strontium-containing coatings were prepared by reactive sputtering of strontium chloride (SrCl2) in a
self-constructed capacitively coupled radio frequency (RF) plasma reactor. Film morphology, structure and composition
were investigated by scanning electron microscopy (SEM), time of flight secondary ion mass spectrometry (ToF-SIMS)
and X-ray photoelectron spectroscopy (XPS). High-resolution transmission electron microscopy (HR-TEM) was used for
the investigation of thickness and growth direction of the product layer. TEM lamellae were prepared using the focused
ion beam (FIB) technique. Bioactivity of the surface coatings was tested by cultivation of primary human osteoblasts and
subsequent analysis of cell morphology, viability, proliferation and differentiation. The results are correlated with the
amount of strontium that is released from the coating in biomedical buffer solution, quantified by inductively coupled
plasma mass spectrometry (ICP-MS).
Results: Dense coatings, consisting of SrOxCly, of more than 100 nm thickness and columnar structure, were prepared.
TEM images of cross sections clearly show an incoherent but well-structured interface between coating and substrate
without any cracks. Sr2+ is released from the SrOxCly coating into physiological solution as proven by ICP-MS analysis.
Cell culture studies showed excellent biocompatibility of the functionalized alloy.
Conclusions: Ti-40Nb alloy, a potential orthopedic implant material for osteoporosis patients, could be successfully
plasma coated with a dense SrOxCly film. The material performed well in in vitro tests. Nevertheless, the Sr2+ release must
be optimized in future work to meet the requirements of an effective drug delivery system.
Original languageEnglish
Article number18
Pages (from-to)1-11
Number of pages12
JournalBiomaterials research
Publication statusPublished - 2017
Externally publishedYes

Cite this