Design and Preparation of m-Bimodal Porous Scaffolds for Tissue Engineering

The aim of this study was to prepare poly-epsilon-caprolactone (PCL) foams, with a well defined micrometric and bimodal open-pore dimension distribution, suitable as scaffolds for tissue engineering. The porous network pathway was designed without using toxic agents by combining gas foaming and selective polymer extraction techniques. PCL was melt-mixed with thermoplastic gelatin in concentrations range from 40 to 60 wt%, to achieve a co-continuous blend morphology. The blends were subsequently gas foamed by using N2-CO2 mixtures, with N2 amount ranging from 0 to 80 vol%. Foaming temperature was changed from 38 to 110 °C and different pressure drop rates were used. After foaming, thermoplastic gelatin was removed by soaking in H2O. The effect of blend compositions and gas foaming process parameters on foam morphologies was investigated. Results showed that different combinations of thermoplastic gelatin weight ratios and gas foaming parameters allowed the modulation of macroporosity fraction, microporosity dimension and degree of interconnection. By optimizing the process parameters it was possible to tailor the morphologies of highly interconnected PCL scaffolds for tissue engineering.