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  • 1 Centre for Clinical Research 34 No. 4501 and/ 45 and 47, Kohly, Playa C. Habana CP 11300 Cuba
  • 2 St Bartholomew’s Hospital Department Nuclear Medicine London EC1A 7BE UK
  • 3 Centre of Genetic Engineering and Biotechnology 31 and/ 158 and 190, Cubanacan, Playa C. Habana CP 10600 Cuba
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The aim of this work was to characterize the in vitro behavior of N4- and N3S-RGDS-derivative peptides labeled with 99mTc. Peptides AGGG-Abu-GRGDSPK-NH2 (F22) and C(acm)-GGG-Abu-GRGDSPK-NH2 (SMA1) were synthesized by solid phase. The stability of 99mTc-labeled peptides was assessed in a 30-fold molar excess of cysteine and in plasma. The affinity for plasma proteins was also evaluated. Labeling yield was >95% for both peptides. 99mTc-F22 was not stable in presence of cysteine, but 63% of 99mTc remained chelated to SMA1 up to 24 hours. Both peptides showed low affinity to plasma proteins. N3S-RGDS-derivative peptide (SMA1) showed more stable coordination binding with 99mTc and a higher stability in plasma with regard to N4-RGDS-derivative peptide (F22).