Long term degradation of poly(ɛ-caprolactone) films in biologically related fluids

The aim of this work was to study the long term degradation behaviour of poly(ɛ-caprolactone) (PCL) films, potentially useful as substrates for tissue engineering, obtained by two different methods (compression moulding or casting in chloroform) in two biologically related media: phosphate buffered solution (PBS) and Dulbecco's modified Eagle's medium (DMEM). The films were characterized at different degradation times by differential scanning calorimetry (DSC), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The molecular weight was determined by Gel Permeation Chromatography (GPC). Chemiluminescence (CL) was used to assess physical or chemical changes from the early stage of the degradation. A different behaviour is observed in samples immersed in PBS when compared with those treated in DMEM. In this medium, the degradation after one year and a half (18 months) shows that although the chemical structure has been modified, the layers become more fragile but maintain their consistency. A higher degradation rate is obtained for membranes obtained by casting with respect to those obtained by compression moulding.