Continued advancement in bioresponsive fluorescence imaging requires new classes of activatable fluorescent probes that emit near-infrared (near-IR) fluorescence with wavelengths above 740 nm. A new synthetic strategy is employed to create a generalizable class of hydrophilic bioresponsive near-IR fluorescent probes with appended sulfonates that provide excellent physiochemical properties. The fluorescent probes are based on heptamethine cyanine dyes, each prepared by ring opening of a Zincke salt, with a central 4‘-carboxylic ester group on the heptamethine chain that is converted to a 4‘-caboxylate group that greatly enhances the fluorescence brightness to give a “turn on” effect. A prototype version is triggered by nitroreductase enzyme that is overexpressed in hypoxic cancer cells. Near-IR fluorescence imaging of hypoxia is very useful in many different areas of biomedical research and clinical treatment. A series of different chemical structures were tested and dyes with propargyloxy auxochromes were found to exhibit less self-aggregation, along with rapid reduction by nitroreductase enzyme to produce a large “turn on” near-IR fluorescence. The outcome is a new fluorescent molecular probe platform for translation towards in vivo applications.

Structure activity studies of NIR fluorescent probes for hypoxia imaging

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.