A series of radiopaque polyurethanes used for prosthetic disc nucleus were prepared via polycondensation between polyurethane prepolymer and N

N'-bis(1

3-dihydroxypropyl)-2

3

5

6-tetra iodoterephthalamide (BDTIP)

which was synthesized as crosslinker and X-ray contrast agent.The structure of BDTIP was characterized by 1H-NMR.Infrared spectroscopy was used to monitor the reaction degree of BDTIP.The developing effect of modified polyurethane was characterized by X-radiography.Meanwhile

the cytotoxicity was tested by the method of thiazolyl blue tetrazolium bromide (MTT) colorimetric assay using mouse fibroblast

and the mechanical properties of radiopaque polyurethanes with different iodine contents were also studied.The results of 1H-NMR showed that the hydrogen atoms on benzene ring were replaced by iodine completely and expected structure was obtained.Polyether polyurethane structure

demonstrated by FTIR

was also obtained.The X-radiography results showed that polymer had a good radiopacity which is almost equivalent to that of a 2 mm thick aluminum wedge when the iodine content was very small

while the mechanical properties were still excellent.There was nearly no change of compression modulus when the iodine content is low and within half an hour after the compression test the shape of prosthetic disc nucleus were restored to the state before compression

which demonstrated that the addition of BDTIP had little effect on the mechanical properties of prosthetic disc nucleus of polyurethane.The cell proliferation rate (RGR) of all modified polyurethanes was more than 75%

they were all biomaterials without cytotoxicity.This study provides a new modification way for preparing radiopaque polyurethane used for prosthetic disc nucleus.