Abstract
Due to the lack of a proper imaging approach, a veracious pH map of normal and abnormal cell is still rare. In this work, we presented a rhodamine-salicylaldehyde combination (Rh-SA2) as a novel pH probe, which has dual sensitive units for both acidic and basic environment. This dual sensitive probe acts like a chameleon in living cells and offers the doubling guarantees for endocellular pH mapping. Moreover, a quantitative measurement of cellular pH changes was allowed and the endocellular pH values under drug-associated stimuli were also investigated.
Highlights
The development of a novel fluorescent probe which meets all of our criteria, allowing for the facile and accurate mapping and detection of pH in living cells
As for the hydroxyl ion sensitive portion, we chose the salicylaldehyde framework since this moiety exhibits a unique emission band discriminant from rhodamine and it is able to provide a phenolic hydroxyl under basic condition[40,41]
A facile one-step conjugation of the rhodamine and salicylaldehyde moieties was employed to afford a novel dual-sensitive pH fluorescent probe which possesses two unique emission bands and can be analyzed using two discrete excitation source allow for efficient pH mapping of entire living cells and quantitative detection of pH alteration under different stimuli
Summary
A dual-channel spectral analysis of HeLa cells stained with Rh-SA2 provided more information about the fluorescent intensity changes upon addition of either of these two drugs Combined, these results demonstrate that Rh-SA2 can afford high-efficiency pH mapping of normal living cells, but it has the capacity for pH mapping of abnormal cells under external stimuli. There are some orange spots just like ROI 3 in c2 of Fig. 4C, in which the pH value was calculated as 5.61 These results verify that dexamethasone can lead to the acidification of living cells by gathering the lysosomes, which can further induce apoptosis. The green channel exhibited much stronger fluorescence following treatment with a pH 7.0 PBS buffer solution (c1–c4) These data suggest that Rh-SA2 is capable to penetrate into and stain tissue, in addition to being a two-color (green and red) ratiometric pH-based imaging agent
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