Fluorescent small molecule probes, which can be used as cellular stains, labels for biomolecules, environmental indicators, and biosensors, are essential tools for biomedical applications. Compared to fluorescent proteins, fluorophores often benefit from their small size, brightness, and photostability, although potential cell toxicity, impermeability, and low sensitivity can be a tradeoff. Unfortunately, these characteristics are difficult to predict through calculations or rational design, making the development of a core scaffold that is amenable to late stage functionalization particularly desirable. We present a fluorescent dimethylamino quinoline (DMAQ) core that can be synthesized in two steps, yielding two variable domains that can then be functionalized sequentially. As demonstrated in previous work from the group, modification of one domain allows for the tuning of photophysical properties as a function not only of the electronics of the compound itself but also of the environment in which the molecule is present. Modification at a second domain would then allow for the installation of a reaction handle that can be used to label biomolecules for more targeted study. This work details the installation of an azide motif, which quenches fluorescence through photoinduced electron transfer (PeT) prior to bioorthogonal click chemistry, allowing for a no-wash labeling probe. We can observe both in vitro and in cellulo a primary turn-on in overall fluorescence following triazole formation as well as a secondary shift in fluorescence that indicates environmental change. To the best of our knowledge, this work presents the first multi turn-on quinoline probe that demonstrates both chemical and environmental turn-on.

Quinoline-based fluorescent dyes as highly modular, environmentally sensitive probes for biological studies

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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