# Surface Characteristics and Cell Adhesion Behaviors of the Anodized Biomedical Stainless Steel
## 3 Results and Discussion
The FE-SEM investigations of cell morphology on the unmodified 316L BSS specimen and 316L BSS specimen following various modified voltages are displayed in Figure 5. As they were cultured for 12 h, the cells with protruding nuclei were found on the unmodified specimen, although certain cells were well spread, flat, and polygonal, while the cells on the anodized specimens have no clear orientation. The cells were well distributed, strongly attached, and obviously polygonal with no prominent nuclei. After culturing for 24 h, the cells had started to grow along the surface microtracks  
Figure 4: TEM micrographs of the unmodified 316L BSS and anodized 316L BSS specimens. (**a**) Bright-field image of the unmodified 316L BSS specimen, (**b**) bright-field image of the anodized 316L BSS specimen at 5 V for 5 min, (**c**) selected-area diffraction pattern taken from the area **A** in (**b**), and (**d**) selected-area diffraction pattern taken from the area **B** in (**b**). Figure 3: The XPS spectrum of O 1s of the 316L BSS specimen with anodization at 5 V for 5 min. on the unmodified 316L BSS specimen. However, it is obvious that the cells were flat attached, elongated, and irregularly networked, revealing that the anodized 316L BSS specimens had greater biocompatibility than unmodified 316L BSS specimen. The roughness surface, such as microporous and/or dual porous topographies as functionalized surface, exhibited a similar cell behavior and response [20; 28; 29]. Accordingly, cells spread on the anodized 316L BSS specimens, under different culturing periods, revealed strong attachment and biocompatible capability. The cells were fully adapted to the anodized 316L BSS specimens. As investigated above, the cells spread on the anodized 316L BSS more quickly than on the unmodified 316L BSS. It is well-known that the surface performance of implants must be treated in biocompatible and controlled processing [30]. Implants should have high biocompatibility. To induce and improve the functionality and biocompatibility of implants, it is common a method to modify the implant surfaces. Therefore, metal-based implants such as titanium, titanium alloys, as well as BSSs, are recommended for coating processes on blood contact implants. The blood cells' interaction on different implants including microporous and/or nanoporous surfaces have been clearly investigated by previous studies [31; 32; 33]. When roughness (Ra) is in the range of 0.2 mm\(\sim\)0.5 mm, the cell adhesion ability of the rough surfaces is higher than that of the smooth surfaces [23]. In addition, nitrided implants exhibit higher human salivary albumin adsorption, indicating that human albumin has a high affinity for implants [12]. Hence, importantly, surface characteristics can be modified by surface functionalization and directly influence biocompatibility. Figure 6 also presents the cell culture of the 316L BSS implant with anodization treatment. The cells exhibited good adhesion behavior on the oxidized surface with a porous structure. Therefore, it is believed that implant surfaces with porosity can enhance cell activity. Finally, more investigations should be carried out to provide scientific information concerning surface properties and in vivo biocompatibility in the presence of anodized 316L BSS. Figure 5: The SEM investigations of osteoblast-like cell (MG-63) morphology on the unmodified 316L BSS specimen and anodized 316L BSS specimens for 24 h incubation: (**a**) unmodified, (**b**) anodized at 5 V for 5 min, and (**c**) anodized at 8 V for 5 min. Figure 6: The cell culture of MG 63 on the anodized 316L BSS implant (5 V for 5 min) for 24 h: (**a**) the anodized surface before cell culture and (**b**) the anodized surface after cell culture.