*3.5. Wettability of the Surface*

The changes of the water droplet contact angles on the uncoated and coated Ti6Al4V with pDA and conjugated with KR12, KR12/32, KR12-5911, and KR12/32-5911 are shown in Figure 7. Three main events can be observed in the graphs: expansion of the droplet's volume from 1 μL to 6 μL, the droplet's volume of 6 μL remaining steady, and shrinkage of droplet's volume from 6 μL to 1 μL. The application of the pDA and conjugation of the peptides all decreased the water contact angle of the surface of the Ti6Al4V, as shown in Table 6. Peptides KR12 and KR12/32 showed similar decreases in contact angles of roughly 1.3◦ and 7.8◦ when compared to pDA and Ti6Al4V, respectively. The coating containing peptide KR12/32-5911 had a contact angle about 1.0◦ smaller than those with peptides KR12 and KR12/32. However, the surface coated with the peptide KR12/32-5911 showed the biggest contact angle changes of roughly 2.7◦ and 9.7◦ when compared to the Ti6Al4V sample with pDA coating and the uncoated Ti6Al4V sample that was polished to mirror finish, respectively.

**Table 6.** Overview of the water contact angles during the steady droplet volume.


**Figure 7.** *Cont.*

**Figure 7.** Changes of the water contact angles of the Ti6Al4V surface coated with (**a**) pDA, (**b**) pDA-KR12, (**c**) pDA-KR12/32, (**d**) pDA-KR12-5911, (**e**) pDA-KR12/32-5911, and (**f**) Ti6Al4V without coating, showing the changes in the water droplet's volume.
