**4. Conclusions**

We used EPD to modify metal surfaces to stably and slowly deliver BMs. GO coating increased surface hydrophilicity and hardness and ALP activity (a feature of osteogenic differentiation). Hydrophilic GO combined with BMs to form GO-BM complexes that uniformly coated a metal. Coatings with internal (not only surface-attached) BMs were optimal, and will find many applications in medicine.

**Author Contributions:** Conceptualization, E.-J.L.; methodology, J.-S.O. and J.-H.J.; investigation, E.-J.L., J.-S.O. and J.-H.J.; writing—original draft preparation, E.-J.L., J.-S.O. and J.-H.J.; writing— review and editing, E.-J.L., J.-S.O. and J.-H.J.; supervision, E.-J.L.; project administration, E.-J.L.; funding acquisition, E.-J.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the National Research Foundation of Korea (NRF), which is funded by the Ministry of Science and Information and Communications Technologies (MSIT; NRF-2018M3C1B7021994 and NRF-2020R1A2C1012454).

**Data Availability Statement:** Not applicable.

**Acknowledgments:** This work was supported by the National Research Foundation of Korea (NRF), which is funded by the Ministry of Science and Information and Communications Technologies (MSIT; NRF-2018M3C1B7021994 and NRF-2020R1A2C1012454).

**Conflicts of Interest:** The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
