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We reported that regioselectively addressable functionalized template (RAFT)-c(-RGDfK-)4 presenting four cyclic (Arg-Gly-Asp) (cRGD) peptides targets integrin αVβ3 with an improved specificity compared with monomeric cRGD. In this study, we improved this vector by creating a "stealth" molecule in which a fluorescence quencher (Q) is linked to Cy5 via a disulfide bond (-SS-). RAFT-c(-RGDfK-)4-Cy5-SS-Q fluorescence is quenched unless activated by reduction during internalization. RAFT-c(-RGDfK-)4-Cy5-SS-Q fluorescence was negligible when compared with the control but totally recovered after cleavage of the disulfide bridge. Confocal microscopy showed that only the intracellular Cy5 signal could be detected using RAFT-c(-RGDfK-)4-Cy5-SS-Q, confirming that uncleaved extracellular molecules are not visible. Whole-body imaging of mice bearing subcutaneous tumors injected intravenously with RAFT-c(-RGDfK-)4-Cy5-SS-Q showed a very significant enhancement of the fluorescent contrast in tumors compared with the unquenched molecule. Histology of the tumor confirmed the intracellular accumulation of Cy5. These results demonstrate that the presence of a labile disulfide bridge between the targeting vector and a drug mimetic is an efficient way to deliver a dye, or a drug, intracellularly. In addition, this quenched RAFT-c(-RGDfK-)4-Cy5-SS-Q probe is a very powerful vector for imaging tumor masses and investigating in vivo RGD-mediated internalization. [ABSTRACT FROM AUTHOR]

Normal fetal growth and placental development depend on active angiogenesis occurring at the fetomaternal interface throughout pregnancy. Nevertheless, reliable in vivo methods to assess placental angiogenesis are still missing. Here, we describe a quantitative and noninvasive in vivo method to specifically measure placental neovascularization in the gravid mouse. This method uses a technique based on the measurement of a fluorescent molecule Angiostamp700 that targets the alpha v beta 3 (α v β 3 ) integrin, a protein that is highly expressed by endothelial cells during the neovascularization and by trophoblast cells during invasion of the maternal decidua. Due to this noninvasive method, quantification of the fetomaternal angiogenic activity and information regarding the outcome of pregnancy are now possible., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

We reported that regioselectively addressable functionalized template (RAFT)-c(-RGDfK-)(4 )presenting four cyclic (Arg-Gly-Asp) (cRGD) peptides targets integrin alpha(V)beta(3) with an improved specificity compared with monomeric cRGD. In this study, we improved this vector by creating a "stealth" molecule in which a fluorescence quencher (Q) is linked to Cy5 via a disulfide bond (-SS-). RAFT-c(-RGDfK-)(4)-Cy5-SS-Q fluorescence is quenched unless activated by reduction during internalization. RAFT-c(-RGDfK-)(4)-Cy5-SS-Q fluorescence was negligible when compared with the control but totally recovered after cleavage of the disulfide bridge. Confocal microscopy showed that only the intracellular Cy5 signal could be detected using RAFT-c(-RGDfK-)(4)-Cy5-SS-Q, confirming that uncleaved extracellular molecules are not visible. Whole-body imaging of mice bearing subcutaneous tumors injected intravenously with RAFT-c(-RGDfK-)(4)-Cy5-SS-Q showed a very significant enhancement of the fluorescent contrast in tumors compared with the unquenched molecule. Histology of the tumor confirmed the intracellular accumulation of Cy5. These results demonstrate that the presence of a labile disulfide bridge between the targeting vector and a drug mimetic is an efficient way to deliver a dye, or a drug, intracellularly. In addition, this quenched RAFT-c(-RGDfK-)(4)-Cy5-SS-Q probe is a very powerful vector for imaging tumor masses and investigating in vivo RGD-mediated internalization.