Owing to the desirable
degradation rate and good biocompatibility,
zinc (Zn) and Zn alloys are promising biodegradable implant metals
in orthopedic and cardiovascular applications. Surface modification,
such as deposition of coatings, is frequently implemented to further
enhance their biological properties. In this study, diamond-like carbon
(DLC) films are deposited on Zn by magnetron sputtering. The DLC films
do not change the surface morphology of Zn but alter the hydrophobic
properties with a contact angle of approximately 90°. Electrochemical
and in vitro immersion tests reveal that the corrosion resistances
of the DLC-coated Zn decrease unexpectedly, which is possibly due
to galvanic corrosion between the DLC film and Zn substrate. Furthermore,
the uncoated and coated Zn samples show hemolysis ratios less than
1%. The cells cultured in the Zn extract exhibit higher viability
than those cultured in the extract of the DLC-coated Zn, suggesting
that the DLC films decrease the cytocompatibility of Zn. The lower
corrosion resistance has little influence on the hemolysis ratio,
suggesting that hemolysis is not an obstacle for the design of Zn-based
biomaterials. Our results show that the traditional concept of protection
with DLC films may not be applicable universally and decreased corrosion
resistance and cytocompatibility are actually observed in DLC-coated
Zn.