STABLE [CO-57] BLEOMYCIN COMPLEX WITH A VERY HIGH SPECIFIC RADIOACTIVITY FOR USE AT VERY LOW CONCENTRATIONS

A method for the preparation of 57Co-labelled bleomycin (BLM) possessing very high specific radioactivity and suitable for use at the nanomolar concentration range is described, and validated using a biological assay. Chelation of BLM with Co(II) results in a very stable complex. However, association does not occur below the micromolar concentration range. A nanomolar [57Co]BLM solution with maximal specific radioactivity can be easily prepared, without handling unreasonable amounts of radioactivity, provided that : equimolar solutions of BLM and [57Co]Cl2 are first mixed at the micromolar concentration range and that the mixture is then diluted a thousand times to reach the nanomolar concentration range. © 1990 Academic Press, Inc.