Polylactide macroporous biodegradable implants for cell transplantation. II. Preparation of polylactide foams by liquid-liquid phase separation

Abstract

Potential of thermally induced phase separation as a porogen technique has been studied in an effort to produce a surgical implant suitable for cell transplantation. Emphasis has been placed on the liquid-liquid phase separation of solutions of amorphous poly DL-lactide and semicrystalline poly L-lactide in an 87/13 dioxane/water mixture. The related temperature/composition phase diagrams have been set up by turbidimetry, and the possible occurrence of a gel has been discussed. Freeze-drying of some phase-separated polylactide solutions can produce flexible and tough foams with an isotropic morphology. Interconnected pores of 1-10 microns in diameter are expected to result from the spinodal decomposition of the polylactide solutions with formation of co-continuous phases. Thermodynamics of the polymer/solvent pair has a decisive effect on the final macroporous foams, as shown by the dependence of their porosity, density, porous morphology, and mechanical behavior on molecular weight and crystallinity of polylactide and concentration of the original solutions. On the basis of the foam characteristics, potential of the liquid-liquid phase separation (spinodal decomposition) has been compared with the solid/liquid phase separation (solvent crystallization) as a porogen technique.

Biocompatibility of Bioresorbable Poly(L-lactic acid) Composite Scaffolds Obtained by Supercritical Gas Foaming with Human Fetal Bone Cells

“…[14][15][16] The combination of ceramic and polymer should result in porous composite structures that maintain their shape, with improved mechanical properties, enhanced bioactivity, and controlled resorption rates. 17 To process scaffolds, several techniques have been reported such as solvent casting/particulate leaching, 18 emulsion freeze-drying or thermally induced phase separation, 19,20 three-dimensional printing, 21 and gas foaming. [22][23][24] It was previously shown that supercritical gas foaming of poly(L-lactic acid) (PLA) polymers can be used to obtain porous structures with controlled parameters particularly important for bone tissue engineering, such as porosity, pore size, and connectivity.…”

Synthetic Polymer Scaffolds for Stem Cell Transplantation in Retinal Tissue Engineering

“…To approximate this highly ordered physical characteristics of the retina, a variety of techniques have been attempted. RPCs attached to the PLGA porous scaffolds created by phase-inversion casting and solid-liquid phase separation [77] demonstrated down-regulation of immature markers and up-regulation of markers of differentiation. These cells also exhibited morphologies consistent with photoreceptors, including a high degree of polarization of the cells and high survival [46].…”

Preparation and characterization of dense nanohydroxyapatite/PLLA composites

“…Materials Science and Engineering C j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m s e c is usually achieved by various processes such as solvent casting/ particle leaching [18], phase separation [19,20], foaming [21], and fast prototyping [22]. In order to isolate the effect of nano-hydroxyapatite particles incorporation on the bulk properties of HA/PLLA composites, this study is focused on dense materials, in a hope to gain clear information on their intrinsic mechanical properties.…”