Fabrication of poly- DL-lactide /polyethylene glycol scaffolds using the gas foaming technique

Abstract

The aim of this study was to prepare poly- DL-lactide/polyethylene glycol (P DLLA/PEG) blends to improve medium absorption and cell proliferation in the three-dimensional (3-D) structure of their scaffolds. Carbon dioxide (CO 2) was used as a foaming agent to create porosity in these blends. The results of Fourier transform infrared (FTIR) spectroscopy demonstrated that the blends were homogeneous mixtures of P DLLA and PEG. The peak shifts at 1092 and 1744 cm −1 confirmed the presence of molecular interactions between these two compounds. Increasing the PEG weight ratio enhanced the relative crystallinity and hydrophilicity. The P DLLA/PEG blends (especially 80/20 and 70/30 weight ratios) exhibited linear degradation profiles over an incubation time of 8 weeks. The mechanical properties of P DLLA/PEG blends having less than 30 wt.% PEG were suitable for the fabrication of porous scaffolds. Increasing the concentration of PEG to above 50% resulted in blends that were brittle and had low mechanical integrity. Highly porous scaffolds with controllable pore size were produced for 30 wt.% PEG samples using the gas foaming technique at temperatures between 25 and 55 °C and pressures between 60 and 160 bar. The average pore diameters achieved by gas foaming process were between 15 and 150 μm, and had an average porosity of 84%. The medium uptake and degradation rate of fabricated P DLLA/PEG scaffolds were increased compared with neat P DLLA film due to the presence of PEG and porosity. The porous scaffolds also demonstrated a lower modulus of elasticity and a higher elongation at break compared to the non-porous film. The fabricated P DLLA/PEG scaffolds have high potential for various tissue-engineering applications.