Squaraine Rotaxanes: Superior Substitutes for Cy‐5 in Molecular Probes for Near‐Infrared Fluorescence Cell Imaging

Abstract

Quadratisch, praktisch, gut: Squarain‐Rotaxane ähneln in ihren photophysikalischen Eigenschaften stark dem gängigen Cy‐5‐Fluorophor, sind jedoch viel lichtbeständiger und zeigen im aggregierten Zustand keinerlei Selbstlöschung. Sondenmoleküle mit Squarain‐Rotaxan‐Einheiten (siehe Beispiel) erwiesen sich als leistungsfähige NIR‐Fluoreszenz‐Markierungen für die In‐vitro‐Fluoreszenzbildgebung von Zellen (Mitte) und die Abbildung ganzer lebender Mäuse (rechts).

High expression of integrin αvβ3 enables uptake of targeted fluorescent probes into ovarian cancer cells and tumors

“…They have the same squaraine fluorophore whose narrow and intense emission could be readily imaged in cell culture and also in living subjects. 25 Furthermore, the untargeted probe, Sq, has the same brightness as the two targeted versions (Table S1) which facilitated comparative image analysis. The targeting group was the cyclic peptide cRGD, an antagonist for the α v β 3 receptor, and there were two targeted fluorescent probes, monovalent SqRDG1 with one cRGD targeting unit and divalent SqRGD2 with two cRGD targeting units.…”

Self-assembly of Functional Molecular Shuttles Based on Organic Conjugated Molecules

“…For cyanine dye rotaxane, 2 + -CD, encapsulation of the chromophore increases its stability towards photobleaching, and increases the kinetic chemical stability of the radicals formed by oxidation and reduction, enabling the recording of the ESR and absorption spectrum of the persistent dicationradical 2 + -CD [32]. The rotaxane 3 in which a dumbbell-shaped squaraine moiety was used to template the formation of a Leightype amide-containing macrocycles displayed improved chemical resistance of the squaraine dye [33][34]. And Chiu used the encircling molecular cage to protect the squaraine moiety from polar solvents----enhancing its quantum yield substantially, and from nucleophiles-----increasing its stability toward chemical attack.…”

Cyclodextrin-based rotaxanes

“…It was established that the above described method improves chemical stability of the chromophore and can be used for stabilization of longer cyanine dyes, containing (CH) 9 and (CH) 11 polymethine bridges. One should note that rotaxane formation increases the water solubility of the dye enabling its medical application [63,64].…”