(a)
(b)
(c)
(d)
Figure 2: EDS spectra of the samples. SLM samples only consisted of titanium and oxygen elements (a); MAO samples were composited with titanium, oxygen, calcium, and phosphorus elements (b); titanium, oxygen, different contents of zinc, less calcium, and phosphorus elements existed on the surface of 1 mM-Zn and 100 μM-Zn samples (c, d).