title: Effect of different gamma-irradiation doses on cytotoxicity and material properties of porous polyether-urethane polymer.
abstract: Biomaterials respond to sterilization methods differently. Steam sterilization might decrease the performance of thermoplastic polyether-urethane (TPU); however, the effect of different gamma-radiation doses on this polymer is contradictory in present literature. The purpose of this study was to investigate the differences between irradiative doses in comparison with steam sterilization on a porous TPU scaffold produced by a new processing method. No significant differences in the surface chemical structure were found with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis when comparing with the sterilization methods. The molecular weight (M(w)) had a net increase from 11.5 +/- 0.039 to 13.2 +/- 0.072 kDa by gamma-sterilization from 10 to 60 kGy. The samples that were irradiated (>60 kGy) had also an increase in polydispersity index (PDI; 1.45 +/- 0.007) in comparison with the nonsterile ones (1.31 +/- 0.017), which indicate branching. Liquid chromatography/mass spectroscopy (LC/MS) analysis showed that there was a correlation between the concentration of the breakdown product, methyl dianiline, and cytotoxicity. The concentration of this compound was found to be four times higher in steam-sterilized sample (1.3 +/- 0.01 ppb) compared with that of the polymer sample gamma-sterilized at 10 kGy (0.3 +/- 0.01 ppb). The cytotoxicity of TPU was found to decrease with higher radiation doses, and was significantly higher for the steam-sterilized samples. It is recommended that TPU produced with the described foaming method should be sterilized by gamma-irradiation at 25 kGy or higher doses.
authors.affiliation: Department of Biomaterials, Institute for Clinical Dentistry, University of Oslo, PO Box 1109 Blindern, NO-0317 Oslo, Norway. h.j.haugen@odont.uio.no
authors.forename: H J
authors.initials: HJ
authors.lastname: Haugen
authors.forename: M
authors.initials: M
authors.lastname: Brunner
authors.forename: F
authors.initials: F
authors.lastname: Pellkofer
authors.forename: J
authors.initials: J
authors.lastname: Aigner
authors.forename: J
authors.initials: J
authors.lastname: Will
authors.forename: E
authors.initials: E
authors.lastname: Wintermantel
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry / Q000528:radiation effects* / Q000633:toxicity*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D005720:Gamma Rays; D008422:Materials Testing; D011140:Polyurethanes / Q000737:chemistry / Q000528:radiation effects* / Q000633:toxicity*; D017550:Spectroscopy, Fourier Transform Infrared; D013242:Sterilization / Q000379:methods; D013816:Thermodynamics
chemical_list: D001672:Biocompatible Materials; D011140:Polyurethanes; C115016:polyetherurethane