Preparation of chitosan scaffolds with a hierarchical porous structure.

Development of porous scaffolds with open surface pore structures is required for tissue engineering to deliver cells into the three-dimensional spaces in the scaffolds and improve cell distribution. This study demonstrated a new type of funnel-like chitosan sponge prepared using ice particulates as a template. The funnel-like chitosan sponges had a hierarchical bilayer porous structure of a surface layer and an interconnected bulk porous layer. The top surface porous layer consisted mainly of large open pores. The bulk porous layer was beneath the large surface pores and consisted of small pores that were connected with the large surface pores. The large surface pores were dependent on the shape, dimension, and density of the embossing ice particulates, while the bulk pores were dependent on the freezing temperature. The large open surface pores and interconnected bulk pores in the funnel-like chitosan sponges facilitated cell seeding and cell distribution from the surface into the inner bulk pores. Cells cultured in the funnel-like chitosan sponges showed high viability, high proliferation, and homogenous tissue formation. Such funnel-like chitosan sponges will be useful for tissue engineering.