Electrospun\n“Hard-Soft” Interpenetrating\nNanofibrous Tissue Scaffolds Facilitating Enhanced Mechanical Strength\nand Cell Proliferation

“Soft” hydrogel-based macroporous scaffolds\nhave\nbeen widely used in tissue engineering and drug delivery applications\ndue to their hydrated interfaces and macroporous structures, but have\ndrawbacks related to their weak mechanics and often weak adhesion\nto cells. In contrast, “hard” poly(caprolactone) (PCL)\nelectrospun fibrous networks have desirable mechanical strength and\nductility but offer minimal interfacial hydration and thus limited\ncapacity for cell proliferation. Herein, we demonstrate the fabrication\nof interpenetrating nanofibrous networks based on coelectrospun PCL\nand poly(oligoethylene glycol methacrylate) (POEGMA) nanofibers that\nexhibit the mechanical benefits of PCL but the interfacial hydration\nbenefits of hydrogels. The electrospinning process results in partially\naligned but interpenetrating fiber network with minimal internal phase\nseparation, leading to anisotropic but strong mechanical properties\neven in the hydrated state; apparent ultimate tensile strengths of\nthe swollen scaffolds ranged from 429 ± 39 kPa in the direction\nof fiber alignment (longitudinal) to 86 ± 25 kPa perpendicular\nto fiber alignment (cross-longitudinal), typical of PCL-based scaffolds\nand enabling efficient suture retention in different directions. However,\ncontact angle measurements indicate hydrogel-like interfacial properties\ndue to the presence of the interpenetrating POEGMA network. C2C12\nmyoblast proliferation in the PCL–POEGMA scaffolds was 50%\nhigher than that observed on PCL-only scaffolds, a result attributed\nto the presence of the more hydrophilic POEGMA interpenetrating nanofiber\nnetwork. Overall, this method is demonstrated to represent a facile\nsingle-step strategy to fabricate strong macroporous but still interfacially\nhydrophilic scaffolds for tissue engineering applications.