The purpose of this study was to synthesis and label antisense probe 99Tcm -EC-ASODN which had good stability and biobehavior for tumor imaging. Ethylenedicysteine（EC） was used as a chelator

and conjugated to antisense oligodeoxynucleotides （ASODN） using sulfo-N-hydroxysuccinimide and 1-ethyl-3-（3-dimethyl- aminopropyl） carbodiimide-HCl as coupling agents to form compound EC-ASODN. EC-ASODN is evaluated by 1H nuclear magnetic resonance spectroscopy（1H-NMR）

infrared spectroscopy （IR）

ultraviolet absorption（UV） and electrophoresis. 99Tcm was labeled to EC-ASODN and the labeling yield

radiochemical purity and stability were assessed. Results of 1H-NMR

IR

UV and electrophoresis confirmed that EC was joined to ASODN

with labeling yield of 77.28%

radiochemical purity of 97.52%

Rf =0.95—1

and very good stability in 4 hours.