A rapid chemical method of labelling human plasma proteins with sup(99m)Tc-pertechnetate at pH 7.4

A successful method for labelling human plasma proteins with sup(99m)Tc-pertechnetate by chemical means is described. The labelling methodology involves the production of Sup(99m)Tc-(Sn)citrate complex species with high protein binding capacity at pH 7.4 condition following initial chemical reduction of sodium sup(99m)Tc-pertechnetate by stannous chloride. A combined labelling efficiency range of 95-99% for sup(99m)Tc-labelled fibrinogen, immune gamma globulin and serum albumin is achieved. The actual amount of labelled protein content in the product is found to be 85-95% when assayed by ITLC and 74-85% by TCAA protein precipitation. In vitro experimental data indicate that sup(99m)Tc-fibrinogen contains an average of 85% clottable protein with an average clottability of 95%. This strongly suggests that the radioactive proteins retain much of their biological and physiological activities after the labelling process. (author)