Evolution of the properties of a poly(l-lactic acid) scaffold with double porosity duringin vitrodegradation in a phosphate-buffered saline solution (original) (raw)

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