Potential core-shell designed scaffolds with a gelatin-based shell in achieving controllable release rates of proteins for tissue engineering approaches.

The biomaterials design as core-shell structures opens a new door to the release of susceptible biomolecules in a controllable manner and enables to place natural biomaterials as shell layers to impart the effective biofunctional features at surfaces. In this study, core-shell designed scaffolds were prepared using coaxial electrospinning with hybrid of gelatin (GT)/polycaprolactone (PCL) at different weight ratios as their shell and protein solution as their core, followed by cross-linking to impart controllable release rates, tunable mechanical properties, and enhanced cytocompatibility. SEM, FM, and TEM confirmed the successful production of uniform core-shell nanofibers and homogeneous protein distribution. Results showed that an increase in GT proportion in the shell resulted in a decrease in fiber diameter, an increase of Young's modulus, and an intense burst release of BSA 0.2% which could be controlled through cross-linking. The mechanical tests revealed that the GT/PCL combining and cross-linking improved mechanical properties which correlated with an increase in spreading and proliferation of HUVECs. A slight burst release was also detected from BSA 0.05% and EGF encapsulated GT73P-cross-linked scaffold which demonstrated their applicability for a controlled release of dilute proteins. We were able to successfully incorporate two types of protein with different concentrations without supporting polymer into the GT shell to provide scaffolds possessing tunable mechanical properties and controllable release rates through blending with PCL at different ratios and/or cross-linking. These findings are promising to promote delivery systems of angiogenic growth factors that are needed a sustained release with different rates at each angiogenesis stage. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.