Magnesium-based metals are considered as promising biodegradable
orthopedic implant materials due to their potentials of enhancing
bone healing and reconstruction, and in vivo absorbable characteristic
without second operation for removal. However, the rapid corrosion
has limited their clinical applications. Some problems such as osteolysis,
early fast mechanical loss, hydric bubble aggregation, gap formation between
the implant and the tissue were reported after degradation of
magnesium-based implants [1–3].
Surface modification is one of the effective methods to tailor the degradation
of magnesium. There are lots of technologies available for coating
magnesium and its alloys. These include the micro-arc oxidation
(MAO) coating, chemical conversion coating, electrodeposition coating,
bio-mimetic deposition coating, polymer coating, and so on [4–8]. Considering
the demands of various clinical needs, different modification
methods are applied in view of their specific performances. For
example, by the MAO process a relatively thick, dense and hard oxide
coating can be produced which has excellent adhesion to the substrate
and offers protection against wear and corrosion [9]. Ca-P coating obtained
by pulse electrodeposition is considered to be bioactive and can
improve the osseointegration of implants [10]. Moreover some biofunctional
coatings with addition of nutrient trace elements, such as
strontium phosphate conversion coating [11], are also developed. The
previous researches have proved their coatings' effectiveness on control
of corrosion of magnesium alloys. Concerning the orthopedics application,
e.g., bone fixation or bone defects repair, some coatings are identically
indicated their feasibility and efficacy. However, there is no report
about the comparisons among different coatings on their degradation
and relevant biological performances. As mentioned above, it is believed
that the degradation of magnesium would influence the consequent
biological performance. Thus it is meaningful to compare and select optimized
coating for further application and medical translation, which are
endowed with favorable degradation property and tissue/cell response.
In this work three kinds of coatings including Ca-P contained microarc
oxidation (MAO) coating, pulse electrodeposition (PED) Ca-P coating
and strontium phosphate conversion coating are used to compare
their in vitro degradation property and cytocompatibility. The corrosion
behavior is studied by immersion and electrochemical tests. The
cytotoxicity, cell proliferation and ALP are used to evaluate the