Hyaluronic Acid and Chitosan Surface Grafted Polylactide Single Crystals as Hydrophilic Building Blocks for Scaffold Materials

Polylactide has a well-known biocompatibility and processability, but its surface hydrophobicity could limit their use as a proper scaffold for cell growth and proliferation. The present work aims to fabricate the polylactide scaffolds by a bottom-up approach from pre-modified building blocks as an efficient way to overcome such a challenge and to provide a surface with a spatially organized chemical structure. Pre-modified polylactide single crystals (PLLA(sc)) with chitosan or hyaluronic acid, which are hydrophilic and bioactive macromolecules, were assembled into three-dimensional scaffolds. PLLA(sc) were hydrolyzed to introduce carboxylic groups at the surface and then the grafting reactions were carried out by carbodiimide chemistry. Although chitosan was grafted directly, the hydrolyzed surface was endowed with adipic acid dihydrazide as a spacer before hyaluronic acid grafting. The analyses of the modified surfaces verified the enhancement in surface hydrophilicity without any drastic effects on single crystals properties. By fabricating the scaffolds by using a compression molding salt leaching technique in the absence of heat or gluing materials, they were found to have an open interconnected structure, a hydrophilic surface and sustainable mechanical properties. Biological activity of scaffolds was examined by using mouse fibroblasts. Scaffolds having hyaluronic acid and chitosan surface grafted PLLA(sc) showed better interface for cell growth than pristine ones. Obviously, prefunctionalized PLLA(sc) with biomacromolecules could be used as proper building blocks for designing polymer scaffolds.