3D-printed scaffolds for tissue engineering applications using thermosensitive hydrogels based on biopolymer blends

Three-dimensional (3D) printing is an emerging technology for the construction of complex 3D constructs used for tissue engineering applications. In this study, we are proposing the preparation of 3D printing hydrogel inks consisting of the synthetic polymers poly(caprolactone) and poly(lactic acid), the biopolymer chitosan, and naturally derived gelatin. In addition, pluronic F-127 was used to improve the miscibility between the hydrophobic and hydrophilic components due to its amphiphilic character, as well as for its good 3D printability. The printability of the hydrogel inks was optimized by varying the composition, the extrusion nozzle, and the temperature, while the integrity of the 3D scaffolds was secured via sol-gel transition. The produced hydrogels with PCL-pluronic-chitosan-gelatin/15-20-4-2 wt% (PC3.75-Pl5-CG) and PLA-pluronic-chitosan-gelatin/10-20-4-2 wt% (PL2.5-Pl5-CG) presented the best printability, producing smooth and uniform porous scaffolds. The prepared hydrogels were formed via the interactions between the polymers through hydrogen bonding. Additionally, the produced hydrogels exhibited temperature-dependent swelling behavior, and the scaffolds with PCL presented lower swelling capacity than the scaffolds with PLA. The produced scaffolds presented slower hydrolyzation rate in simulated body fluid (SBF) at 25 degrees C compared to 37 degrees C. Biological studies proved that the 3D-printed porous scaffolds were non-cytotoxic and promoted human adipose-derived mesenchymal stem cell adhesion.