title: Effects of sterilization methods on the physical, chemical, and biological properties of silk fibroin membranes.
abstract: Silk fibroin has been widely explored for many biomedical applications, due to its biocompatibility and biodegradability. Sterilization is a fundamental step in biomaterials processing and it must not jeopardize the functionality of medical devices. The aim of this study was to analyze the influence of different sterilization methods in the physical, chemical, and biological characteristics of dense and porous silk fibroin membranes. Silk fibroin membranes were treated by several procedures: immersion in 70% ethanol solution, ultraviolet radiation, autoclave, ethylene oxide, and gamma radiation, and were analyzed by scanning electron microscopy, Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction, tensile strength and in vitro cytotoxicity to Chinese hamster ovary cells. The results indicated that the sterilization methods did not cause perceivable morphological changes in the membranes and the membranes were not toxic to cells. The sterilization methods that used organic solvent or an increased humidity and/or temperature (70% ethanol, autoclave, and ethylene oxide) increased the silk II content in the membranes: the dense membranes became more brittle, while the porous membranes showed increased strength at break. Membranes that underwent sterilization by UV and gamma radiation presented properties similar to the nonsterilized membranes, mainly for tensile strength and FTIR results.
authors.affiliation: School of Chemical Engineering, University of Campinas, UNICAMP, 13083-852, Campinas, SP, Brazil.
authors.forename: Mariana Agostini
authors.initials: MA
authors.lastname: de Moraes
authors.forename: Raquel Farias
authors.initials: RF
authors.lastname: Weska
authors.forename: Marisa Masumi
authors.initials: MM
authors.lastname: Beppu
mesh_terms: D000818:Animals; D012831:Bombyx; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D000431:Ethanol / Q000494:pharmacology; D005027:Ethylene Oxide / Q000494:pharmacology; D005349:Fibroins / Q000737:chemistry / Q000187:drug effects / Q000528:radiation effects / Q000633:toxicity; D005720:Gamma Rays; D006358:Hot Temperature; D006813:Humidity; D008422:Materials Testing; D008567:Membranes, Artificial; D016062:Porosity; D047011:Silk / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013242:Sterilization / Q000379:methods*; D013696:Temperature; D013718:Tensile Strength; D014466:Ultraviolet Rays; D014961:X-Ray Diffraction
chemical_list: D008567:Membranes, Artificial; D047011:Silk; C482288:fibroin, silkworm; D000431:Ethanol; D005349:Fibroins; D005027:Ethylene Oxide
keywords: biomaterials; dense membranes; fibroin; porous membranes; sterilization