Gamma sterilization of collagen/hydroxyapatite composites: Validation and radiation effects

• Published in: Applied radiation and isotopes Vol. 174; p. 109758
• Main Authors: Gomes, Anderson D., de Oliveira, Agda A.R., Houmard, Manuel, Nunes, Eduardo H.M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2021
• Subjects: Biocompatible Materials; Biological assays; Calorimetry, Differential Scanning; Cobalt Radioisotopes; Collagen; Collagen - chemistry; Durapatite - chemistry; Gamma Rays; Gamma sterilization; Humans; Hydroxyapatite; Mesenchymal Stem Cells - radiation effects; Spectroscopy, Fourier Transform Infrared - methods; Sterilization - methods; Structural characterization; Gamma sterilization; Hydroxyapatite; Biological assays; Collagen; Structural characterization
• ISSN: 0969-8043; 1872-9800
• DOI: 10.1016/j.apradiso.2021.109758

In this work, gamma sterilization was validated, and the impact of this sterilization process on collagen/hydroxyapatite (Col/HAp) composites was investigated. It has been already recognized that the improper sterilization of healthcare products may lead to infection and mortality/morbidity issues in patients. Gamma sterilization has emerged as a promising sterilization method because it shows advantages such as low cost, a small increase in temperature of irradiated materials, and no production of toxic residues. Moreover, gamma rays can reach the products even when contained in sealed packages. The dose of gamma radiation applied in this study ranged from 17.5 to 50 kGy. The studied samples were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). No apparent effect of gamma radiation on HAp was observed even when doses as high as 50 kGy were applied. On the other hand, Col was greatly affected by gamma radiation, displaying cross-linking and degradation after sterilization. These structural changes may alter Col's properties, which could, in turn, impact its medical use. As a consequence, it is strongly recommended that the irradiation dose used to sterilize the Col/HAp composites shall be kept as low as possible to mitigate the structural changes induced in Col. It was noticed that a radiation dose of 17.5 kGy was sufficient to sterilize the examined samples because a sterility assurance level (SAL) below 10−6 was detected. Although dramatic structural changes were observed in Col when this dose was applied, the sterilized samples showed no toxicity to human mesenchymal stem cells. Based on these results, we established a VDMax of 17.5 kGy for Col/HAp-based healthcare products. •Collagen/hydroxyapatite (Col/HAp) composites sterilized with gamma radiation.•Samples irradiated with a cobalt-60 source and doses ranging from 17.5 to 50 kGy.•Col was greatly affected by gamma radiation, showing cross-linking and degradation.•We suggest keeping the radiation dose at 17.5 kGy to mitigate structural changes.•Samples exposed to this radiation level showed biocompatibility to human stem cells.