Hydrolytic degradation of porous scaffolds for tissue engineering from terpolymer of l-lactide, ε-caprolactone and glycolide

The scaffolds start to degrade immediately after contact with PBS, as demonstrated by decrease in molecular weights (Mn and Mw). In the first stage (6 weeks in PBS) when the scaffolds are still dimensionally stable, the degradation is generally due to cleavage of ester bonds between glycolidyl (GG) and caproyl (Cap) groups present in chain sequences such as -GGCapCap-, -GGGCap-, as shown by 1H NMR. The analysis of FTIR spectra of the initial scaffolds and after 6 week immersion in PBS reveals a shift of the band attributed to CO vibrations and considerable changes in the shape of the bands attributed to C-O and C-O-C vibrations. These changes are due to chain-scission of polyester bonds in hydrolysis reaction. Subsequently, when the concentration of sequences containing glycol, glycolidyl and caproyl groups decreases, the influence of cleavage of polyester bonds between longer lactyl microblocks on the degradation increases gradually. As a result, two separate polymer fractions are formed.