**4. Conclusions**

In this study, collagen was extracted from tilapia fish skin and identified as type I collagen by SDS-PAGE. A series of Col-TPU composite nanofiber membranes (Col95, Col90, Col80, and Col60) were prepared via electrospinning and shown to be stable and have a nanostructure. There was relatively good compatibility between collagen and TPU. Besides maintaining the triple-helical structures of collagen, the addition of TPU enhanced the porosity, thermal stability, and mechanical properties of the composite. Thus, it was found to be more suitable for human tissue environments for long-term growth. In vitro fibroblast culture demonstrated a high cell proliferation rate with no cytotoxicity. The Col-TPU composite nanofiber membrane allowed the proliferation and migration of MC3T3-E1 cells and promoted fibrogenesis of cells; there was good biocompatibility. These results suggested that Col-TPU composite materials with different ratios of TPU were candidate biomaterials for tissue repair.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/md20070437/s1, Figure S1: HCA scan of Col-TPU composite nanofiber membranes, scale bar is 150 μm; Table S1: Comparison of Col-TPU composite nanofiber membranes different spectral peak positions in FTIR spectra; Table S2: The thermogravimetric analysis of Col-TPU composite nanofiber membranes; Table S3: CCK-8 assay OD450 of Col-TPU composite nanofiber membranes. The sequence of letters a–d represents the size of the mean value (a > b > c > d). The same letter indicates no statistically significant difference (*p* < 0.05, *n* = 4); Table S4: Cell proliferation and cytotoxicity evaluation of Col-TPU composite nanofiber membranes respect to control, % and grade.

**Author Contributions:** J.C. conceptualization, validation, resources, writing—review and editing, supervision, project administration, funding acquisition; S.W. conceptualization, methodology, formal analysis, data curation, writing—original draft preparation; L.Y. conceptualization, methodology, software, formal analysis, data curation. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China, gran<sup>t</sup> number 42076120, 41676129, 41106149; Scientific Research Foundation of the Third Institute of Oceanography, SOA, gran<sup>t</sup> number 2019010, 2019016; The APC was funded by the Scientific Research Foundation of the Third Institute of Oceanography, SOA, gran<sup>t</sup> number 2019016.

**Institutional Review Board Statement:** Not applicable.

**Data Availability Statement:** Data is contained within the article or Supplementary Materials.

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