Evolution of the Properties of a Poly(L-lactic acid) Scaffold with Double Porosity During In Vitro Degradation in a Phosphate-Buffered Saline Solution

Abstract

[EN] A poly(L-lactic acid) scaffold prepared by a combination of freeze-extraction and porogen-leaching methods was submitted to static degradation in a phosphate-buffered saline solution at pH 7.4 and 37 C for up to 12 months. After 6 months of degradation, the scaffold maintained its integrity, although noticeable changes in its permeability and pore size were recorded. After 12 months, scanning electron microscopy pictures showed that most of the trabeculae were broken, and the sample disaggregated under minimum loading. Neither weight loss nor crystallinity changes in the first heating calorimetric scan were observed during the degradation experiment. However, after 12 months, a rise in the crystallinity from 13 to 38% and a drop in the glass-transition temperature from 58 to 54 C were measured in the second heating scan. The onset of thermal degradation moved from 300 to 210 C after 12 months. Although the elastic modulus suffered only a very slight reduction with degradation time, the aggregate modulus decreased 44% after 6 months.