Labeling of graphene oxide with [¹³¹I]AgI and its stability analysis

To explore the new iodine labeling method of nanomaterials, graphene oxide (GO) was labeled by ¹³¹I with AgI nanoparticles. As a control, GO was also labeled by ¹³¹I with chloramine-T method. The stability of the two ¹³¹I labeling materials, viz. [¹³¹I]AgI-GO and [¹³¹I]I-GO was evaluated. The results show that [¹³¹I]AgI-GO is very stable in inorganic environment such as PBS and saline. However, it is not stable enough in serum. The instability of [¹³¹I]AgI-GO in serum can be attributed to the higher affinity of Ag to S of thiol group in cysteine than iodine ions and much more chance of interaction between thiol group and [¹³¹I]AgI nanoparticles on two-dimensional GO than in three-dimensional nanomaterials.