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Phage display technique is a powerful approach for discovering new tumor-and organ-targeting ligands,and radiolabeled phage has a potential to analyze the phage-binding sensitivity and specific imaging.In this study,phage Ⅱ (the spleen-targeting phage) in mice was isolated after three rounds biopanning,and labeled by 99mTc using mercaptoacetyltriglycine (MAG3) as chelator to evaluate their binding properties in vivo.The amount of phage Ⅱ eluted from spleen was enriched by plague assay each round.99mTc-MAG3-phage Ⅱ showed the less retention in blood at any time point than half that of 99mTc-MAG3-phage Ⅰ (the radiolabeled original Ph.D-12 phage as control).The accumulation in spleen between 99mTc-MAG3-phage Ⅰ and Ⅱ was of different tendency.The highest uptake of 99mTc-MAG3-phage Ⅱ in spleen was 24.80 %ID/g at 30 min;and of 99mTc-MAG3-phage I,30.93% ID/g at 5 min.After circulating 99mTc-MAG3-phage Ⅱ for 120 min,its accumulation in spleen decreased though higher than that of 99mTc-MAG3-phage Ⅰ.In other organs,the 99mTc-MAG3-phage Ⅱ showed low retention and high spleen-to-organ or tissue ratios.In conclusion,the radiolabeled phage Ⅱ is convenient for studying the binding and specificity of spleen-targeting peptides found via phage display in vivo.
Phage display technique is a powerful approach for discovering new tumor-and organ-targeting ligands, and radiolabeled phage has a potential to analyze the phage-binding sensitivity and specific imaging. In this study, phage II (the spleen-targeting phage) in mice was isolated after three rounds biopanning, and labeled by 99mTc using mercaptoacetyltriglycine (MAG3) as chelator to evaluate their binding properties in vivo. The amount of phage II eluted from spleen was enriched by plague assay each round. 99mTc-MAG3-phage II showed the less retention in blood at any time point than half that of 99mTc-MAG3-phage I (the radiolabeled original Ph.D-12 phage as control). The accumulation in spleen between 99mTc-MAG3-phage I and II was of different tendency. The highest uptake of 99mTc-MAG3-phage II in spleen was 24.80% ID / g at 30 min; and of 99mTc-MAG3-phage I, 30.93% ID / g at 5 min. After circulating 99mTc-MAG3-phage II for 120 min, its accumulation in spleen decreased though higher than that o f 99mTc-MAG3-phage I. In other organs, the 99mTc-MAG3-phage II showed low retention and high spleen-to-organ or tissue ratios. In conclusion, the radiolabeled phage II is convenient for studying the binding and specificity of spleen -targeting peptides found via phage display in vivo.