A rapid chemical method of labeling human plasma proteins with 99mTc-pertechnetate at pH 7.4

Abstract A successful method for labeling human plasma proteins with 99 m Tc-pertechnetate by chemical means is described. The labeling methodology involves the production of 99 m Tc-(Sn)citrate complex species with high protein binding capacity at pH 7.4 condition following initial chemical reduction of sodium 99 m Tc-pertechnetate by stannous chloride. A combined labeling efficiency range of 95–99% for 99 m Tc-labeled fibrinogen, immune gamma globulin and serum albumin is achieved. The actual amount of labeled 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 99 m 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 labeling process.