Molecular design of fluorescent pH sensors based on reduced rhodol by structure-pKa relationship for imaging of lysosome. (January 2021)

• Record Type: Journal Article
• Authors: More, Kunal N.; Mun, Seul-Ki; Kang, Julie; Kim, Jong-Jin; Yee, Sung-Tae; Chang, Dong-Jo
• Is Part Of: Dyes and pigments. Volume 184(2021)
• Publication Date: 2021-01
• Subjects: Reduced rhodol -- pH-sensitive fluorescent probe -- Structure-pKa relationship -- Lysosomal sensing -- Live cell imaging; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2020.108785
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: pH-homeostasis is crucial for maintaining a living system of cells. Lysosome, a digestive system of cells, contains a number of hydrolytic enzymes which can normally function in a narrow range of acidic pH (4.5–5.5). Abnormal pH in lysosomes leads to lysosomal dysfunction, which results in various diseases such as lysosomal storage disorders, cancer, cardiovascular diseases, and neurodegenerative diseases. We previously reported a series of reduced xanthene fluorophores including fluorescein, rhodol and rhodamine, and discovered a reduced rhodol, Rh–OMe, with a methoxy and a free amino group in a xanthene ring. In this work, a series of novel pH-sensitive fluorescent sensors for monitoring acidic lysosomes was developed by structure-pKa relationship study of Rh–OMe . Rh–OMe derivatives with various substituents in an alkoxy group on xanthene ring were designed and evaluated by the analysis of pH-titration curves and photochemical properties. Reduced rhodol probes with a para -substituted benzyloxy group showed excellent fluorescence transition triggered by acidic pH, and they were successfully applied to in vitro imaging of lysosomes in HepG2 cells. Graphical abstract: Image 1 Highlights: Reduced rhodol probes were developed by the structure-pKa relationship study for fluorescence imaging of acidic lysosomes. Reduced rhodols with both amino and alkoxy groups showed acidic pH-sensitive fluorescence transition triggerd by protonation. Reduced rhodols with an -NH2 and a p -substituted benzyloxy group were highly fluorescent in acidic pH but not in neutral pH. pH-Sensors, including Rh-OBn, Rh-OBnNO2 and Rh-OBnCF3, showed successful fluorescence imaging of lysosomes in HepG2 cells.