Poly(lactic acid)/poly(ethylene glycol) blends for the production of porous scaffold biomaterials

Details

Supervisors

Jonas, Alain M. ; Demoustier-Champagne, Sophie

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil biomédical, à finalité spécialisée

Abstract

Tissue engineering is a promising field that aims to repair or replace damaged tissues. Tissue engineering requires the production of porous scaffold biomaterials, exhibiting both micro- and macroporosity. In this study, we created polymer blends and induced microporosity in these blends. Poly(lactic acid) (PLA) was blended with poly(ethylene glycol) (PEG); the blends were first melted, then subjected to crystallization along with liquid-solid phase separation between PEG and PLA, leading to PEG rich regions within PLA, and the PEG phase was extracted to create pores in the samples. Two parameters were studied to optimize the pore size and distribution: PEG molar mass, and PEG content in the blend. The porosity was studied using polarized-light optical microscopy (POM), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). Both PEG content and PEG molar mass proved to have an influence on blend porosity. All blends exhibit inter- as well as intraspherulitic porosity. Blends made with a smaller amount of PEG with higher molar masses show interspherulitic porosity as well as interfibrillar porosity, within the spherulites. Indeed, during PLA crystallization, PEG diffuses outwards from PLA spherulites but some PEG is trapped within the growing PLA spherulites, in interfibrillar regions. When the PEG is extracted, pores remain in the regions where PEG was located. Pore sizes vary from a few tens of nanometers to 5 µm, allowing nutrients and cells to diffuse through the scaffold. However, when the PEG content is too high, large quantities of PEG accumulate in interspherulitic regions and large holes remain in these regions after PEG extraction; the samples are therefore brittle. When PEG molar mass is too low, PEG diffuses at a faster rate outside the growing PLA spherulites during crystallization, large amounts of PEG segregate in interpherulitic regions and larger pores are present in interspherulitic regions after PEG extraction, making the sample too brittle as well. According to the obtained results, PLA/PEG blends with PEG extraction can be an appropriate candidate for use in tissue engineering applications. The content of PEG in the blend and its molar mass must be carefully chosen. However, many aspects of the scaffold remain to be studied, such as mechanical properties, degradability and biocompatibility.