[Use of photoactivation in the preparation of radiopharmaceuticals. III. Human serum albumin labelled with technetium (99mTc)]

Abstract

Human serum albumin was photoactivated by UV light at 254 nm and labelled with technetium(99mTc) by reducing pertechnetate(99mTc) with stannous chloride. Radiochemical purity was evaluated using paper chromatography, columns and electrophoresis. The biodistribution of labelled albumin in rats was determined by counting the activity in isolated organs 15 and 60 minutes after administration. Photoactivation raises the number of free SH groups, a fact exerting a beneficial effect on labelling efficacy. Irradiated albumin shows a higher labelling efficacy (99%) compared with non-irradiated albumin (96%). Structural changes depend on the dose of UV radiation, on the concentration of irradiated substance and on metal ion content (Sn2+). The results obtained suggest that the elimination, from blood, of albumin whose structure has been altered by photoactivation can be accelerated thereby creating the preconditions for its application in the diagnosis of inflammatory conditions.