Fabrication of a porous wall and higher interconnectivity scaffold comprising gelatin/chitosan via combination of salt-leaching and lyophilization methods

A novel gelatin/chitosan scaffold with higher porosity and interconnectivity was designed through salt-leaching/lyophilization (SLL) method. The properties of the fabricated scaffolds were compared with conventional scaffolds, which are obtained by thermally induced phase-separation (TIPS) method. The scaffolds made by phase-separation method have high tensile strength, but suffer from less channel interconnectivity, pore uniformity and also low surface porosity. The microstructure, porosity, phosphate-buffered saline (PBS) solution absorption and tensile strength of the prepared scaffolds by SLL method were studied. In this work, SLL as a two-step technique is introduced for creating porosity to improve both channel interconnectivity and pore uniformity for water-soluble polymers in comparison with the TIPS method. The SLL technique includes two mechanisms: the first, leaching of mixed sodium chloride crystals and particles created during recrystallization of the dissolved NaCl and the second, phase separation during lyophilization at the pore walls. These two steps in porosity formation lead to special pore morphology, which is more suitable for cell culturing because of higher interconnectivity and rich surface porosity in comparison with the phase-separated scaffolds. The prepared scaffolds, using this technique with different salt/polymer ratios and salt crystal size, have 91-97% porosity and 94-190 mu m mean pore size with tensile strength of 72-215 kPa and PBS solution absorption between 12.4 and 19 times dry weight. The pore size of scaffolds prepared using the SLL method could be adjusted independently of polymer solution concentration. These scaffolds have a great potential in skin tissue engineering application.