A biotin-conjugated highly stable cationic viologen derivative for live-cell imaging.

Traditional cancer imaging modalities cannot achieve ideal diagnostic results. Fluorescence imaging is an emerging modality for tumor imaging because of its high selectivity and sensitivity. However, conventional imaging agents have some drawbacks, including significant photobleaching, low fluorescence quantum yield, and inadequate targeting specificity. Therefore, there is an urgent need for the development of new imaging agents. Viologen derivatives have been widely used in the optical field owing to their excellent water solubility and good optical properties. However, because of its propensity to readily obtain electrons and form free radicals, its biological toxicity is significant, restricting its further application in the field of biological staining. To solve these problems, this study incorporated phenyl viologen as the primary fluorescent structure, which is capable of directly forming a quinone structure in a single step, thereby mitigating the impact of free radicals on cells. Furthermore, the introduction of biotin further enhanced the targeting of the imaging agent, ensuring that it was delivered more precisely to the desired cellular locations. This dual approach not only minimizes the harmful effects of free radicals but also improves the specificity and efficiency of cellular imaging. Experimental results demonstrate that the developer exhibits high photostability, excellent biosafety, and outstanding biocompatibility. This study investigated the application of cationic viologen derivatives in living cell imaging, laying a foundation for the advancement of cationic viologen derivatives in the biological field.