Stable Near-infrared-emitting Radical Nanoparticles for Fluorescence Imaging

Abstract

Stable neutral luminescent radicals with unpaired electrons exhibit unique spin-allowed doublet-doublet transitions, which has attracted significant attention. Although they are pure organic molecules without metal ions thus thought to have low biological toxicity, the application of luminescent radicals to bioimaging has rarely been reported. Here, a stable radical with efficient near-infrared(NIR) emission and good photostability was designed and synthesized. After being wrapped into nanoparticles, it was applied to cell fluorescence imaging. The cytotoxicity experiments suggested that the nanoparticles have remarkable biocompatibility and excellent stability. An NIR fluorescent signal was successfully observed in the cytoplasm of HCT116 cells. The experimental results gave the first example of NIR emitting radical nanoparticles for cell fluorescence imaging and proved the feasibility of the application of luminescent radicals to fluorescence imaging.

Keywords

Fluorescence imaging / Near-infrared emission / Radical / Luminescent radical / Doublet emission

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