Objective      To investigate radionuclide labeling methods of small molecular inhibitory peptide targeting vascular endothelial growth factor receptor (VEGF receptor) of tumor with

99

Tc

m

.       Methods      After being modified by S-acetyl-MAG

3

GA(D)GG and HYNIC respectively

QKRKRKKSRKKH and RKRKRKKSRYIVLS were labeled

with

99

Tc

m

. Labeling efficiency and radiochemical purity was identified by paper chromatography and HPLC. The inhibitory affect of peptide to tumor cell was testified by

3

H-TdR incorporation. Receptor competition binding assay was used to testify the affinity of peptide ligand based on A549 cells.       Results      The labeling efficiency of two peptide modified by three bifunctional chelating agents was about 78%

40% and 94% respectively. The inhibitory efficiency of HYNIC-QKRKRKKSRKKH and HYNIC-RKRKRKK-SRYIVLS to A549 cells was about (32.86±3.36)% and （61.50±4.50）%

and did not have statistically significant difference with QKRKRKKSRKKH and RKRKRKKSRYIVLS. Meanwhile the

99

Tc

m

-HYNIC-QKRKRKKSRKKH and

99

Tc

m

-HYNIC-RKRKRKKSRYIVLS retained a good stability and binding activity of VEGF receptor in A549 cells.       Conclusion      HYNIC-QKRKRKKSRKKH and HYNIC-RKRKRKKSRYIVLS have a high labeling efficiency with TPPTS as a reducing agent and collaborative ligand

and the labeled agents retain inhibiting activity and binding activity of receptor to A549 cells.