Objective   To investigate the influence of different sterilization methods

autoclave

gamma-irradiation

hypothermal plasma

ethylene oxide and ultroviolet

on the physiochemical features of a new composite biomaterial-poly(amino acids)/calcium sulfate (PAA/CS).     Methods   PAA/CS composite was synthesized by melt polycondensation process. After the composite was sterilized by the aforementioned methods

L929 cells toxicity

structure analysis by X-ray diffraction and mechanical capacity of the composite were studied

and compared with before sterilization.     Results   The L929 cells in ethylene oxide

ultroviolet and negative control group were in well growth

cell relative growth rate (RGR) was beyond 90%，and cytotoxicity grading was between 0 and 1. Cells in other groups almost died in 24 h. The RGRs were below 50%

and cytotoxicity grading was between 3 and 4. The X-ray diffraction test demonstrated the number and morphology of crystallization peak of the composite had no visible change after sterilization. The compressive strength of the composite in the ethylene oxide and ultroviolet group was apparently decreased than that of the composite before sterilization (P0.05)

but the decrease was not seen in other group (P0.05).     Conclusion   Ethylene oxide and ultroviolet have no apparent influence on the physiochemical features of the PAA/CS composite

therefore can be used to sterilize the composite.