Effects of sterilisation by high-energy radiation on biomedical poly-(e-caprolattone) / hydroxyapatite composites

he effects of a high energy sterilization treatment on poly-e-caprolactone/carbonated hydroxyapatite composites have been investigated. Poly-e-caprolactone is a biodegradable polymer used as long-term bioresorbable scaffold for bone tissue engineering and carbonated hydroxyapatite is a bioactive material able of promoting bone growth. The biomaterials were irradiated by gamma-rays up to doses higher than those recommended for sterilization (up to 50 kGy) under air or nitrogen atmosphere. The effects of the irradiation treatment were evaluated by vibrational spectroscopy (IR and Raman spectroscopies) coupled to thermal analysis measurements (Differential Scanning Calorimetry and Thermogravimetry) and Electron Spin Resonance spectra. Structural changes and damaging effects observed after irradiation were acceptable for the doses required for sterilisation: only a very slight fragmentation of the polymeric chains as well as some defects in the inorganic part of the composites were induced. Moreover, the radiation sensitivity of the biomaterials was found to be almost identical under the two different atmospheres.