Publication Date:
2020
Description:
〈p〉Publication date: Available online 21 January 2020〈/p〉
〈p〉〈b〉Source:〈/b〉 Sensors and Actuators B: Chemical〈/p〉
〈p〉Author(s): Jaehyun Park, Bumhee Lim, Na Keum Lee, Ji Hye Lee, Kyungkuk Jang, San Won Kang, Suzi Kim, Ikyon Kim, Hyonseok Hwang, Jeeyeon Lee〈/p〉
〈h5〉Abstract〈/h5〉
〈div〉〈p〉Current fluorescent probes for lysosomes have practical limits due to their pH sensitivity, which makes them unsuitable for long-term tracking of lysosomes in live cell imaging. In addition, viscosity probes are also responsive to polarity, which imposes considerable challenges in cellular imaging. Here, we report 〈strong〉IQ-LV〈/strong〉s, which can serve as viscosity sensors at the lysosomal pH. In contrast to the majority of current molecular rotors that exhibit blue and green emission, 〈strong〉IQ-LV〈/strong〉s showed red-shifted emission (∼95 nm) upon increasing the viscosity at pH 4.5. Among the synthesized viscosity sensors, 〈strong〉IQ-LV57〈/strong〉 and 〈strong〉IQ-LV70〈/strong〉 lacking an aromatic ring at R〈sub〉1〈/sub〉 displayed 15-fold and 116-fold enhancement of red-shifted emission, respectively, upon changes in viscosity. They showed negligible polarity dependency, while the pH sensitivity was minimized by tuning R〈sub〉2〈/sub〉 as we envisioned. Our 1D 〈sup〉1〈/sup〉H-NMR titrations along with TCSPC analysis revealed that 〈strong〉IQ-LV〈/strong〉s exhibit two emissions in lysosomes, viscosity-insensitive green emission (〈sup〉+〈/sup〉HA’-IQH〈sup〉+〈/sup〉) and viscosity-sensitive red-shifted emission (A’-IQH〈sup〉+〈/sup〉), which enabled live cell imaging for tracking lysosomes during the autophagy process. In fluorescence confocal imaging, the red emission was enhanced upon the increase in lysosomal viscosity in HeLa and MCF7 cells, and the observed emission from 〈strong〉IQ-LV57〈/strong〉 and 〈strong〉IQ-LV70〈/strong〉 had a longer duration than that of LysoTracker™ Deep Red in time-lapse images of live MCF7 cells. Furthermore, treatment of 〈strong〉IQ-LV37〈/strong〉 in MCF7 cells resulted in increased autophagosomes and autolysosomes during the autophagy process. Further western blot analysis revealed that 〈strong〉IQ-LV37〈/strong〉 and 〈strong〉IQ-LV57〈/strong〉 block the degradation of autophagosomes, serving as autophagy inhibitors.〈/p〉〈/div〉
〈h5〉Graphical abstract〈/h5〉
〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925400520301118-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉
Print ISSN:
0925-4005
Electronic ISSN:
1873-3077
Topics:
Chemistry and Pharmacology
,
Electrical Engineering, Measurement and Control Technology
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