**5. Conclusions**

In this study, MC and CHA were extracted from *P. olivaceus* byproducts (skin and bone), and a 3D scaffold reinforced with CHA and coated with MC was fabricated to evaluate bone regeneration. First, CHA and MC extracted from the *P. olivaceus* byproducts were analyzed to determine that they had the characteristics of HA and collagen. By fabricating a 3D scaffold, osteogenic differentiation was confirmed using MC3T3-E1 cells, and bone regeneration was confirmed in a mouse calvarial defect model. Micro-CT and histological analysis revealed that the tissue regeneration of the defect site in the 10% HA/MC/PCL and 10% CHA/MC/PCL groups was superior to that in the non-treatment and PCL scaffold groups. These results sugges<sup>t</sup> that marine byproduct-derived materials can be valuable alternatives for land animal-derived materials. Based on the results, further study is needed to develop bone mimic scaffold with blood vessels, in order to understand bone regenerative mechanism.

**Author Contributions:** Conceptualization and methodology, S.-C.K. and S.-Y.H.; Technical execution, S.-C.K., S.-Y.H. and G.-W.O.; Discussion of results, S.-C.K., M.Y. and W.-K.J.; Writing—Original Draft Preparation, S.-C.K. and S.-Y.H.; Writing—Review and Editing, S.-C.K., M.Y. and W.-K.J.; Funding Acquisition, W.-K.J. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2021R1A6A1A03039211) and NRF gran<sup>t</sup> funded by the Ministry of Science and ICT (2019R1A2C1007218). This research was also supported by Development of technology for biomaterialization of marine fisheries by-products of Korea institute of Marine Scinece & Technology Promotion (KIMST) funded by the Ministry of Oceans and Fisheries (KIMST-20220128).

**Institutional Review Board Statement:** All experimental procedures were approved by the institutional animal care and utilization committee of Pukyong National University (Number PKNUIACUC-2018-07).

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
