The double porogen approach as a new technique for the fabrication of interconnected poly(L-lactic acid) and starch based biodegradable scaffolds

One of the most widely used fabrication methods of three dimensional porous scaffolds involves compression moulding of a polymer salt mixture, followed by salt leaching. However, the scaffolds prepared by this technique have typically limited interconnectivity. In this study, besides salt particles, an additional polymeric porogen, poly(ethylene oxide), PEO, was added to poly(L-lactic acid), PLLA, to enhance the interconnectivity of the scaffolds. Compression moulded specimens were quenched and put into water, where PEO crystallized and phase separated. Following the leaching of PEO fraction, the permeability and interconnectivity among the macropores formed by salt leaching could be observed. The porosities obtained in the prepared scaffolds were between 76 to 86%. Moreover, the highest porosity of 86% was obtained with minimum fraction of total porogen. The water absorption of the porous scaffolds prepared with PEO could vary between 280 to 450% while water uptake of pure PLLA scaffolds was about 93%. The increase of interconnectivity induced by compounding PLLA with PEO could also be obtained in porous PLLA/starch blends and PLLA/hydroxyapatite composites demonstrating the versatility and wide applicability of this preparation protocol. The simplicity of this organic solvent free preparation procedure of three-dimensional porous scaffolds with high interconnectivity and high surface area to volume ratio holds a promise for several tissue engineering applications.