Biomimetic composite scaffolds based on surface modification of polydopamine on ultrasonication induced cellulose nanofibrils (CNF) adsorbing onto electrospun thermoplastic polyurethane (TPU) nanofibers.

To improve the interaction between cells and scaffolds, the appropriate surface chemical property is very important for tissue engineering scaffolds. In this study, the thermoplastic polyurethane (TPU) nanofibers was firstly fabricated by electrospinning technique, and then its surface was modified with cellulose nanofibrils (CNF) particles by ultrasonic-assisted to obtain TPU/CNF nanofibers. Subsequently, the TPU/CNF-polydopamine (PDA) composite nanofibers with core/shell structure were fabricated by PDA coating method. In comparison with TPU nanofibers, the uniformization of PDA coating layer on the surface of TPU/CNF composite nanofibers significantly increased due to the addition of CNF, which used as the active sites to guide the PDA particles accumulated along with the fiber direction. The water absorption and hydrophilicity of TPU/CNF-PDA composite nanofibers were significantly increased in comparison with those of TPU and TPU/CNF nanofibers. The mechanical properties of the TPU/CNF-PDA composite nanofibers were higher than those of the TPU and TPU/CNF nanofibers due to the formation of strong hydrogen bonds between PDA and TPU/CNF, making TPU, CNF and PDA strongly adhere to each other. The attachment and viability of mouse embryonic osteoblasts cells (MC3T3-E1) cultured on TPU/CNF-PDA composite nanofibers were obviously enhanced compared with TPU and TPU/CNF nanofibers. Those results suggested that the modified TPU/CNF-PDA composite nanofibers have excellent mechanical and biological properties, which promoting them potentially useful for tissue engineering scaffolds. The presented strategy represents a general route to modify the surface of scaffolds, which are promising for tissue engineering applications.