Analysis of sterilization protocols for peptide-modified hydrogels.

Concerns about the efficacy of ethanol disinfection for implanted biomaterials prompted investigation of an alternative sterilization process, ultraviolet irradiation, for terminal sterilization of N-isopropylacrylamide-based hydrogels containing biomimetic peptides. Ultraviolet irradiation is more easily applied on a laboratory scale than gamma irradiation or electron beam, two commercially utilized methods; thus, UVC irradiation was investigated as a low-cost sterilization procedure that might be performed in laboratories prior to in vivo studies. UVC irradiation at 400 muW/cm(2) for up to 15 h did not prevent growth of Escherichia coli within the hydrogels, while ethanol disinfection did prevent growth for the duration of the experiment (120 h). Furthermore, UVC irradiation caused progressive degradation of peptides containing the Arg-Gly-Arg (RGD) domain. UVC irradiation cannot be used as a terminal sterilization process for peptide-modified materials. The system used in this study is not intended to be adequate for evaluating the sterility of medical devices in accordance with current Good Manufacturing Practice (cGMP); however, it remains a useful, low-cost system for the preliminary evaluation of sterilization procedures in terms of their ability to eliminate pathogenic organisms while preserving the structure of biologically active molecules within in a laboratory setting. Ethanol treatment is still the preferred method for disinfection of bioactive materials containing peptides or UV-degradable groups.