The combined effect of humidity and electron beam irradiation on collagen type I - implications for collagen-based devices

Collagen is a biocompatible and bioresorbable material, an excellent active component for the formulation of medical dressings and scaffolds. Its current popularity and the developing methods of producing such medical materials imply the need for methods of controlling and processing collagen used in medicine. One of the basic methods used to sterilize medical devices is radiation sterilization. In this study, we undertook the determination of the influence of humidity, radiation sterilization, and the influence of these factors on the structure of collagen. Spectroscopic tests (EPR, DRS UV–VIS, FTIR), gas chromatography, and thermal methods (TGA, DSC) were used. Humidity appears to affect the amount, and especially the rate, of oxidative damage and the reorganization of oxygen addition products. Despite radiation damage observed by spectral methods, from the point of view of its thermal properties, collagen I remains stable upon irradiation within the dose range up to 50 kGy, probably due to its unique macromolecular and intermolecular structure, containing numerous crosslinks. The high thermal stability of collagen I in response to radiation gives good indications for radiation sterilization of collagen I based medical products. This is in agreement with the observed structural stability of radiation-sterilized collagen scaffolds used in skin wound healing. Nevertheless, oxidative modification was observed, which ultimately introduced new oxygen-containing functional groups in collagen. The result should be considered when designing and sterilizing collagen-based dressing materials and scaffolds.