Morphologies and polarization of macrophages on various samples in vitro. (a) SEM morphologies of macrophages in single-culture condition (i, ii, iii, and iv) and co-culture condition (v, vi, vii, and viii) after cultured for 4 d on samples at high magnifications (i and v present Ti; ii and vi present Zn-Ti; iii and vii present Cu-Ti; iv and viii present Ag-Ti). (b) Immunofluorescent staining images of macrophages in single-culture condition (i) and co-culture condition (ii) on various samples after cultured for 4 d; iNOS (green) was selected as M1 macrophage marker, CD206 (red) was selected as M2 macrophage marker, nuclei were stained with DAPI (blue). (c) Flow cytometry analyses of cell-surface markers on macrophages in single-culture condition (i, ii, iii, and iv) and co-culture condition (v, vi, vii, and viii) (i and v present Ti; ii and vi present Zn-Ti; iii and vii present Cu-Ti; iv and viii present Ag-Ti).