Abstract: The present invention relates to the field of optical imaging. More particularly, it relates to a class of monoalkylated cyanine dyes with red to near-infrared (650-900 nm) emission characterized by pH responsiveness and to conjugates with biological ligands thereof. The invention also relates to the use of these compounds as optical diagnostic agents in imaging or therapy of solid tumors, to the methods for their preparation and to the compositions comprising them. The monoalkylated cyanine dyes have general formula (I) wherein R1 and R3 are independently selected from the group consisting of hydrogen, -SO3H, —COOH and —CONH—Y; and R2 and R4 are hydrogen, or both R1 together with R2 and R3 together with R4, respectively and with the atoms to which they are bonded, form two aryl rings, optionally substituted with from 1 to 4 -SO3H groups; R5 is an alkyl optionally substituted by a group selected from —SO3H, —COOH and —CONH2.

Abstract: The application relates to a process for the synthesis of a Near Infra-Red (NIR) fluorescent probe which is a cRGD-Cy5.5 conjugate of formula (I) known as DA364 comprising an aza-bicycloalkane based cyclic peptide labelled with a Cy5.5 dye moiety and used in the guided surgery of tumors and pathologic regions.

Abstract: The application relates to a process for the synthesis of a Near Infra-Red (NIR) fluorescent probe which is a cRGD-Cy5.5 conjugate of formula (I) known as DA364 comprising an aza-bicycloalkane based cyclic peptide labelled with a Cy5.5 dye moiety and used in the guided surgery of tumors and pathologic regions.