A ratiometric lysosomal pH probe based on the coumarin–rhodamine FRET system

Abstract

The ratiometric pH probe RC1 was constructed by integrating coumarin moiety as FRET donor into rhodamine moiety as FRET acceptor. The probe with a pKa of 4.98 could detect pH in the range of 4.20-6.00 and selectively stain lysosome. a In this study, we developed a coumarin-rhodamine based fluorescence resonance energy transfer (FRET) system RC1 as a ratiometric pH probe. The probe with a pKa of 4.98 was constructed by integrating coumarin moiety as an FRET donor with rhodamine moiety as an FRET accepter. Upon addition of H + , the coumarin emission at 477 nm decreased and the rhodamine emission at 582 nm increased simultaneously. The fluorescence intensity ratio (I477/I582) displayed excellent pHdependent performance and responded linearly to minor pH changes in the range of 4.20-6.00. The probe exhibited brilliant selectivity among different amino acids, metal cations and the ATP. Moreover, it has been successfully applied in fluorescence imaging in HeLa cells and the results indicated that the probe could selectively stain lysosome with low cytotoxicity and excellent photostability. We also applied RC1 to monitor intracellular pH variations induced by dexamethasone. Therefore, RC1 could act as a practical tool for the detection of pH in weakly acidic conditions and provide essential information in medicinal analysis and real biological systems.

Design and synthesis of a new rhodamine B-based fluorescent probe for selective detection of glutathione and its application for live cell imaging

“…[28][29][30] Among the fluorophores developed, rhodamine B and its derivatives are highly favorable as molecular probes in the study of complex biological systems because of their high absorption coefficients, high fluorescence quantum yields, long absorption and emission wavelengths and good cell-penetrating ability. [31][32][33][34] On the basis of the spirolactam/ring-opened amide equilibrium of rhodamine, several fluorescence-based sensing systems for metal ions have been developed to serve as a fluorescent chemosensor to detect metal ions, such as Hg 2+ , Cu 2+ , Al 3+ , Cr 3+ , Mg 2+ , and Fe 3+ . [35][36][37][38][39][40][41][42][43] However, to the best of our knowledge, rhodamine B-based fluorescent probes for GSH are still rare.…”

Sensitive detection of strong acidic condition by a novel rhodamine‐based fluorescent pH chemosensor

“…Simultaneously, the obvious pink color appeared under highly acidic condition, which was consistent with the proposed ring-opening mechanism of the probe. Specifically, the alkyl nitrogen atom of the piperazine was protonated upon the addition of trifluoroacetic acid and with the further protonation of the amide nitrogen atom in the spirolactam ring, the spirolactam ring subsequently opened to form a conjugated xanthene ring (Scheme 2), which was similar to the reported ring-opening process (36)(37)(38)(39) .…”

Synthesis and application of coumarin fluorescence probes

“…19). 49 Da En modied the 3-position substituent of compound 19 and designed a uorescent probe 21 with high sensitivity and selectivity for Fe 3+ ions in cells in 2014 ( Fig. 20).…”